ALBERT

Notes: The abundance and morphology of microdiamond in dolomite marble from Kumdy-kol in the Kokchetav Massif, are unusual; a previous study estimated the maximum content of diamonds in dolomite marble to be about 2700 carat ton−1. Microdiamond is included primarily in garnet, and occasionally in diopside and phlogopite pseudomorphs after garnet. They are classified into three types on the basis of their morphology: (1) S-type: star-shaped diamond consisting of translucent cores and transparent subhedral to euhedral very fine-grained outer parts; (2) R-type: translucent crystals with rugged surfaces; and (3) T-type: transparent, very fine-grained crystals. The S-type is the most abundant.Micro-Laue diffraction using a 1.6-µm X-ray beam-size demonstrated that the cores of the star-shaped microdiamond represent single crystals. In contrast, the most fine-grained outer parts usually have different orientations compared to the core. Laser–Raman studies indicate that the FWHM (Full Width at Half Maximum) of the Raman band of the core of the S-type diamond is slightly larger than that for the outer parts. Differences in morphology, crystal orientations, and in the FWHM of the Raman band between the core and the fine-grained outer-parts of S-type microdiamond suggest that the star-shaped microdiamond was formed discontinuously in two distinct stages.

Notes: Oscillatory zoning in low δ18O skarn garnet from the Willsboro wollastonite deposit, NE Adirondack Mts, NY, USA, preserves a record of the temporal evolution of mixing hydrothermal fluids from different sources. Garnet with oscillatory zoning are large (1–3 cm diameter) euhedral crystals that grew in formerly fluid filled cavities. They contain millimetre-scale oscillatory zoning of varying grossular–andradite composition (XAdr = 0.13–0.36). The δ18O values of the garnet zones vary from 0.80 to 6.26‰ VSMOW and correlate with XAdr. The shape, pattern and number of garnet zones varies from crystal to crystal, as does the magnitude of the correlated chemistry changes, suggesting fluid system variability, temporal and/or spatial, over the time of garnet growth. The zones of correlated Fe content and δ18O indicate that a high Fe3+/Al, high δ18O fluid mixed with a lower Fe3+/Al and δ18O fluid. The high δ18O, Fe enriched fluids were likely magmatic fluids expelled from crystallizing anorthosite. The low δ18O fluids were meteoric in origin.These are the first skarn garnet with oscillatory zoning reported from granulite facies rocks. Geochronologic, stable isotope, petrologic and field evidence indicates that the Adirondacks are a polymetamorphic terrane, where localized contact metamorphism around shallowly intruded anorthosite was followed by a regional granulite facies overprint. The growth of these garnet in equilibrium with meteoric and magmatic fluids indicates an origin in the shallow contact aureole of the anorthosite prior to regional metamorphism. The zoning was preserved due to the slow diffusion of oxygen and cations in the large garnet and protection from deformation and recrystallization in zones of low strain in thick, rigid, garnetite layers. The garnet provide new information about the hydrothermal system adjacent to the shallowly intruded massif anorthosite that predates regional metamorphism in this geologically complex, polymetamorphic terrane.

Notes: The blueschist and greenschist units on the island of Sifnos, Cyclades were affected by Eocene high-pressure (HP) metamorphism. Using conventional geothermobarometry, the HP peak metamorphic stage was determined at 550–600 °C and 20 kbar, close to the blueschist and the eclogite facies transition. The retrograde P–T paths are inferred with phase diagrams. Pseudosections based on a quantitative petrogenetic grid in the model system Na2O–CaO–FeO–MgO–Al2O3–SiO2–H2O reveal coeval decompression and cooling for both the blueschist and the greenschist unit. The conditions of the metamorphic peak and those of the retrograde stages conform to a similar metamorphic gradient of 10–12 °C km−1 for both units. The retrograde overprint can be assigned to low-pressure blueschist to HP greenschist facies conditions. This result cannot be reconciled with the (prograde) Barrovian-type event, which affected parts of the Cyclades during the Oligocene to Miocene. Instead, the retrograde overprint is interpreted in terms of exhumation, directly after the HP stage, without a separate metamorphic event. Constraints on the exhumation mechanism are given by decompression-cooling paths, which can be explained by exhumation in a fore-arc setting during on-going subduction and associated crustal shortening. Back-arc extension is only responsible for the final stage of exhumation of the HP units.

Notes: Metabasic rocks from the Adula Nappe in the Central Alps record a regional high-pressure metamorphic event during the Eocene, and display a regional variation in high-pressure mineral assemblages from barroisite, or glaucophane, bearing garnet amphibolites in the north to kyanite eclogites in the central part of the nappe. High-pressure rocks from all parts of the nappe show the same metamorphic evolution of assemblages consistent with prograde blueschist, high-pressure amphibolite or eclogite facies conditions followed by peak-pressure eclogite facies conditions and decompression to the greenschist or amphibolite facies. Average PT calculations (using thermocalc) quantitatively establish nested, clockwise P–T paths for different parts of the Adula Nappe that are displaced to higher pressure and temperature from north to south. Metamorphic conditions at peak pressure increase from about 17 kbar, 640 °C in the north to 22 kbar, 750 °C in the centre and 25 kbar, 750 °C in the south. The northern and central Adula Nappe behaved as a coherent tectonic unit at peak pressures and during decompression, and thermobarometric results are interpreted in terms of a metamorphic field gradient of 9.6 ± 2.0 °C km−1 and 0.20 ± 0.05 kbar km−1. These results constrain the peak-pressure position and orientation of the nappe to a depth of 55–75 km, dipping at an angle of approximately 45° towards the south. Results from the southern Adula Nappe are not consistent with the metamorphic field gradient determined for the northern and central parts, which suggests that the southern Adula Nappe may have been separated from central and northern parts at peak pressure.

Notes: The Priest pluton contact aureole in the Manzano Mountains, central New Mexico preserves evidence for upper amphibolite contact metamorphism and localized retrograde hydrothermal alteration associated with intrusion of the 1.42 Ga Priest pluton. Quartz–garnet and quartz–sillimanite oxygen isotope fractionations in pelitic schist document an increase in the temperatures of metamorphism from 540 °C, at a distance of 1 km from the pluton, to 690 °C at the contact with the pluton. Comparison of calculated temperature estimates with one-dimensional thermal modelling suggests that background temperatures between 300 and 350 °C existed at the time of intrusion of the Priest pluton. Fibrolite is found within 300 m of the Priest pluton in pelitic and aluminous schist metamorphosed at temperatures 〉580 °C. Coexisting fibrolite and garnet in pelitic schist are in oxygen isotope equilibrium, suggesting these minerals were stable reaction products during peak metamorphism. The fibrolite-in isograd is coincident with the staurolite-out isograd in pelitic schist, and K-feldspar is not observed with the first occurrence of fibrolite. This suggests that the breakdown of staurolite and not the second sillimanite reaction controls fibrolite growth in staurolite-bearing pelitic schist. Muscovite-rich aluminous schist locally preserves the Al2SiO5 polymorph triple-point assemblage – kyanite, andalusite and fibrolite. Andalusite and fibrolite, but not kyanite, are in isotopic equilibrium in the aluminous schist. Co-nucleation of fibrolite and andalusite at 580 °C in the presence of muscovite and absence of K-feldspar suggests that univariant growth of andalusite and fibrolite occurred. Kyanite growth occurred during an earlier regional metamorphic event at a temperature nearly 80 °C lower than andalusite and fibrolite growth. Quartz–muscovite fractionations in hydrothermally altered pelitic schist and quartzite are small or negative, suggesting that late isotopic exchange between externally derived fluids and muscovite, but not quartz, occurred after peak contact metamorphism and that hydrothermal alteration in pelitic schist and quartzite occurred below the closure temperature of oxygen self diffusion in quartz (〈500 °C).

Notes: Abstract Concordant U–Pb ages of c. 530–510 Ma and c. 470–420 Ma on titanite from calcsilicate, orthogneiss and amphibolite rocks constrain the age of high-T metamorphism in the Early Palaeozoic mobile belt at the western margin of Proterozoic Gondwana (Argentina, 26–29°S). The U–Pb ages document the time of titanite formation at high-T conditions according to the stable mineral paragenesis and occurrence of titanite in the metamorphic fabric. The presence of migmatite at all sample sites indicates temperatures were 〉 c. 650 °C. Titanite formed at similar metamorphic conditions at different times on the regional and on the outcrop scale. The titanite crystals preserved their U–Pb isotopic signatures and chemical composition under ongoing upper amphibolite to granulite facies temperatures. Different thermal peaks or deformations are only detected by the different U–Pb ages and not by changes in the mineral paragenesis or metamorphic fabric of the samples. The range of U–Pb ages, e.g. in the Ordovician and Silurian (c. 470, 460, 440, 430, 420 Ma), is interpreted as the effect polyphase deformation with deformation-enhanced recrystallization of titanite and/or different thermal peaks during a long-standing, geographically fixed, high-T regime in the mid-crust of a continental magmatic arc. A clear correlation of the different ages with distinct tectonic events, e.g. collision of terranes, is not possible based on the present knowledge of the region.

Notes: Abstract The garnet blueschists from the Ile de Groix (Armorican Massif, France) contain millimetre- to centimetre-sized pseudomorphs consisting of an aggregate of chlorite, epidote and paragonite. The pseudomorphed phase developed at a late stage of the deformation history, because it overgrows a glaucophane–epidote–titanite foliation. Garnet growth occurred earlier than the beginning of the ductile deformation, and thus garnet is also included in the pseudomorphs. Microprobe analyses show that garnet is strongly zoned, with decreasing spessartine and increasing almandine and pyrope contents from core to rim. Grossular content is higher in garnet cores (about 35 mole%) compared to garnet rims (about 30 mole%). Blue amphibole has glaucophane compositions with a low Fe3+ content and become more magnesian when inclusions in garnet (XMg = 0.62–0.65) are compared with matrix grains (XMg = 0.67–0.70). Matrix epidote has a pistacite content of about 50 mole%. On the basis of their shape and the nature of the breakdown products, the pseudomorphs are attributed to lawsonite. A numerical model (using Thermocalc) has been developed in order to understand the reactions controlling both the growth and the breakdown of lawsonite. Lawsonite growth could have taken place through the continuous hydration reaction Chl + Ep + Pg + Qtz + Vap = Gln + Lws, followed by the fluid-absent reaction Chl + Ep + Pg = Grt + Gln + Lws. Peak P–T conditions are estimated at about 18–20 kbar, 450 °C. This indicates that lawsonite growth took place at increasing P and T, hence can be used as a geobarometer in the buffering assemblage garnet–glaucophane–epidote. The final part of the history is recorded by lawsonite breakdown, after cessation of the ductile deformation, and recording the earliest stages of the exhumation.

Notes: Previous models of hydrodynamics in contact metamorphic aureoles assumed flow of aqueous fluids, whereas CO2 and other species are also common fluid components in contact metamorphic aureoles. We investigated flow of mixed CO2–H2O fluid and kinetically controlled progress of calc-silicate reactions using a two-dimensional, finite-element model constrained by the geological relations in the Notch Peak aureole, Utah. Results show that CO2 strongly affects fluid-flow patterns in contact aureoles. Infiltration of magmatic water into a homogeneous aureole containing CO2–H2O sedimentary fluid facilitates upward, thermally driven flow in the inner aureole and causes downward flow of the relatively dense CO2-poor fluid in the outer aureole. Metamorphic CO2-rich fluid tends to promote upward flow in the inner aureole and the progress of devolatilization reactions causes local fluid expulsion at reacting fronts. We also tracked the temporal evolution of P-T-XCO2conditions of calc-silicate reactions. The progress of low- to medium-grade (phlogopite- to diopside-forming) reactions is mainly driven by heat as the CO2 concentration and fluid pressure and temperature increase simultaneously. In contrast, the progress of the high-grade wollastonite-forming reaction is mainly driven by infiltration of chemically out-of-equilibrium, CO2-poor fluid during late-stage heating and early cooling of the inner aureole and thus it is significantly enhanced when magmatic water is involved. CO2-rich fluid dominates in the inner aureole during early heating, whereas CO2-poor fluid prevails at or after peak temperature is reached. Low-grade metamorphic rocks are predicted to record the presence of CO2-rich fluid, and high-grade rocks reflect the presence of CO2-poor fluid, consistent with geological observations in many calc-silicate aureoles. The distribution of mineral assemblages predicted by our model matches those observed in the Notch Peak aureole.

Notes: The Swakane Gneiss and the overlying Napeequa Complex in the North Cascade range, Washington, were metamorphosed and deformed during development of a Cretaceous-Paleogene continental arc, and are among the structurally deepest exposed rocks within the Cordilleran arcs of North America. Peak metamorphic conditions in both the Swakane Gneiss and Napeequa Complex were c. 640–750 °C, 9–12 kbar. Clockwise paths and widespread evidence for high-P metamorphism in meta-supracrustal rocks (burial to 〉40 km) document major vertical tectonic motion during arc construction and unroofing.These and other moderately high-pressure rocks in the North Cascades-Coast Mountains experienced a dramatically different tectonometamorphic history than metamorphic rocks within other Cordilleran arcs. The exhumed arc complexes of the Sierra Nevada and Peninsular Ranges are dominated by relatively low-P metamorphic and plutonic rocks (typically 〈6 kbar). There is no evidence that the northern Cordillera was thickened to a greater degree than these other belts, suggesting that the greater magnitude of vertical motion in the Cascades may have been related to exhumation mechanisms: Eocene extension in the northern Cordillera vs. erosional unroofing in the central and southern Cordillera.

Notes: High-pressure (HP) granulites and eclogitized metagabbro are exposed along an orogen-parallel high-P belt that was developed at c. 1050–1020 Ma in the NE Grenville Province. Among these rocks, mafic granulites derived from a Labradorian anorthosite suite of the Lelukuau terrane contain garnet, Al-Na diopside, and, depending on bulk composition, plagioclase and kyanite. Moreover, the distribution of phases is influenced by the original igneous texture. For instance, in high XMgO leucocratic varieties, garnet porphyroblasts nucleated together with kyanite in An-rich cores of plagioclase domains whereas in low XMgO rocks garnet occurs together with clinopyroxene within formerly igneous ferromagnesian domains and kyanite is missing. In contrast, garnet pseudomorphs after igneous plagioclase in melanocratic varieties display evidence of earlier corona development. Metamorphic textures are consistent with a two stage evolution: (a) development of garnet and Al-Na-diopside (Cpx1) under high-P metamorphic conditions, concomitant with elimination of plagioclase in the mesocratic to melanocratic varieties; and (b) partial loss of Al-Na from Cpx1 resulting in production of new andesitic plagioclase, and growth of new clinopyroxene (Cpx2) after garnet and quartz in leucocratic to mesocratic rocks consistent with decompression. Widespread equilibrium textures between garnet-Pl2-Cpx2 and/or reset Cpx1 are consistent with development at the thermal peak. Estimated P–T conditions for the presumed thermal peak fall in the range 1500–1800 MPa and 800–900 °C and are comparable to those recorded by eclogitized gabbros from other parts of the high-P belt of the NE Grenville province. Low jadeite content of clinopyroxene from the HP granulites is attributed to the low bulk Na2O/(Na2O + CaO) of these rocks relative to common basaltic compositions. Scarcity of apparent retrograde textural overprint in both the HP granulites and the eclogites suggests fast subsequent cooling, consistent with extrusion of the high-P belt towards the foreland shortly after the metamorphic peak.

Notes: The upper deck of the East Athabasca mylonite triangle (EAmt), northern Saskatchewan, Canada, contains mafic granulites that have undergone high P–T metamorphism at conditions ranging from 1.3 to 1.9 GPa, 890–960 °C. Coronitic textures in these mafic granulites indicate a near-isothermal decompression path to 0.9 GPa, 800 °C. The Godfrey granite occurs to the north adjacent to the upper deck high P–T domain. Well-preserved corona textures in the Godfrey granite constrain igneous crystallization and early metamorphism in the intermediate-pressure granulite field (Opx + Pl) at 1.0 GPa, 775 °C followed by metamorphism in the high pressure granulite field (Grt + Cpx + Pl) at 1.2 GPa, 860 °C. U–Pb geochronology of zircon in upper deck mafic granulite yields evidence for events at both c. 2.5 Ga and c. 1.9 Ga. The oldest zircon dates are interpreted to constrain a minimum age for crystallization or early metamorphism of the protolith. A population of 1.9 Ga zircon in one mafic granulite is interpreted to constrain the timing of high P–T metamorphism. Titanite from the mafic granulites yields dates ranging from 1900 to 1894 Ma, and is interpreted to have grown along the decompression path, but still above its closure temperature, indicating cooling following the high P–T metamorphism from c. 960–650 °C in 4–10 Myr. Zircon dates from the Godfrey granite indicate a minimum crystallization age of 2.61 Ga, without any evidence for 1.9 Ga overgrowths. The data indicate that an early granulite facies event occurred at c. 2.55–2.52 Ga in the lower crust (c. 1.0 GPa), but at 1.9 Ga the upper deck underwent high P–T metamorphism, then decompressed to 0.9–1.0 GPa. Juxtaposition of the upper deck and Godfrey granite would have occurred after or been related to this decompression. In this model, the high P–T rocks are exhumed quickly following the high pressure metamorphism. This type of metamorphism is typically associated with collisional orogenesis, which has important implications for the Snowbird tectonic zone as a fundamental boundary in the Canadian Shield.

Notes: Orthopyroxene-free garnet + clinopyroxene + plagioclase ± quartz-bearing mineral assemblages represent the paragenetic link between plagioclase-free eclogite facies metabasites and orthopyroxene-bearing granulite facies metabasites. Although these assemblages are most commonly developed under P–T conditions consistent with high pressure granulite facies, they sometimes occur at lower grade in the amphibolite facies. Thus, these assemblages are characteristic but not definitive of high pressure granulite facies. Compositional factors favouring their development at amphibolite grade include Fe-rich mineral compositions, Ca-rich garnet and plagioclase, and Ti-poor hornblende. The generalized reaction that accounts for the prograde development of garnet + clinopyroxene + plagioclase ± quartz from a hornblende + plagioclase + quartz-bearing (amphibolite) precursor is Hbl + Pl + Qtz=Grt + Cpx + liquid or vapour, depending on whether the reaction occurs above or below the solidus. There are significant discrepancies between experimental and natural constraints on the P–T conditions of orthopyroxene-free garnet + clinopyroxene + plagioclase ± quartz-bearing mineral assemblages and therefore on the P–T position of this reaction. Semi-quantitative thermodynamic modelling of this reaction is hampered by the lack of a melt model and gives results that are only moderately successful in rationalizing the natural and experimental data.

Notes: Schlieren are trains of platy or blocky minerals, typically the ferromagnesian minerals and accessory phases, that occur in granites and melt-rich migmatites, such as diatexites. They have been considered as: (1) unmelted residue from xenoliths or the source region; (2) mineral accumulations formed during magma flow; (3) compositional layering; and (4) sites of melt loss. In order to help identify schlieren-forming processes in the diatexites at St Malo, differences in the size, shape, orientation, distribution and composition of the biotite from schlieren and from their hosts have been investigated.Small biotite grains are much less abundant in the schlieren than in their hosts. Schlieren biotite grains are generally larger, have greater aspect ratios and have, except in hosts with low (〈 10%) biotite contents, a much stronger shape preferred orientation than host biotite. The compositional ranges of host and schlieren biotite are similar, but schlieren biotite defines tighter, sharper peaks on composition-frequency plots. Hosts show magmatic textures such as imbricated (tiled), unstrained plagioclase. Some schlieren show only magmatic textures (tiled biotite, no crystal-plastic strain features), but many have textures indicating submagmatic and subsolidus deformation (e.g. kinked grains) and these schlieren show the most extensive evidence for recrystallization.Magmas at St Malo initially contained a significant fraction of residual biotite and plagioclase crystals; smaller biotite grains were separated from the larger plagioclase crystals during magma flow. Since plagioclase was also the major, early crystallizing phase, the plagioclase-rich domains developed rapidly and reached the rigid percolation threshold first, forcing further magma flow to be concentrated into narrowing melt-rich zones where the biotite had accumulated, hence increasing shear strain and the degree of shape preferred orientation in these domains. Schlieren formed in these domains as a result of grain contacts and tiling in the grain inertia-regime. Final amalgamation of the biotite aggregates into schlieren involved volume loss as melt trapped between grains was expelled after the rigid percolation threshold was reached in the biotite-rich layers.

Notes: The eclogite type locality in the Eastern Alps (the Koralpe and Saualpe region) is the largest region in the Eastern Alps that preserves high-pressure metamorphic rocks from the Eo-Alpine orogenic event of the Cretaceous age. Thermobarometric data from the metapelitic gneisses in the region indicate that a metamorphic field gradient across the region can be divided into three parts. The northern part shows continuously increasing P–T from 10 ± 1.5 to 14 ± 1.5 kbar and 500 ± 68 to 700 ± 68 °C over a distance of 40 km. The continuous increase in P–T indicates that no major tectonic boundaries were active in this part during the Eo-Alpine orogeny. Small discontinuities in the pressure gradient of the northern part can be correlated with more localized deformation. The central part exposes amphibolite–eclogite facies rocks with 15 ± 1.5 kbar and 700 ± 68 °C over about 20 km length. The southern part shows decreasing P–T conditions from 15 ± 1.5 to 10 ± 1.5 kbar and 700 ± 68 to 600 ± 63 °C over a distance of 10 km beyond which conditions remain roughly constant for the remainder of the profile.Overall, the field gradient is characterized by: (i) an increase in age with decreasing metamorphic grade and (ii) a T/P ratio that is lower than common metamorphic geotherms. The age–grade relationship is consistent with the timing relationship along piezothermal arrays predicted by simple models for regional metamorphism. However, the T/P ratio of the field gradient is inconsistent with such an interpretation. These inconsistencies indicate that the profile is not simply an obliquely exposed crustal section. We suggest that the exhumation of the transect is best explained with a two dimensional model of an extruding wedge, as has recently been suggested as a typical scenario for other large scale compressional orogens.

Notes: A largely undocumented region of eclogite associated with a thick blueschist unit occurs in the Kotsu area of the Sanbagawa belt. The composition of coexisting garnet and omphacite suggests that the Kotsu eclogite formed at peak temperatures of around 600 °C synchronous with a penetrative deformation (D1). There are local significant differences in oxygen fugacity of the eclogite reflected in mineral chemistries. The peak pressure is constrained to lie between 14 and 25 kbar by microstructural evidence for the stability of paragonite throughout the history recorded by the eclogite, and the composition of omphacite in associated eclogite facies pelitic schist. Application of garnet-phengite-omphacite geobarometry gives metamorphic pressures around 20 kbar. Retrograde metamorphism associated with penetrative deformation (D2) is in the greenschist facies. The composition of syn-D2 amphibole in hematite-bearing basic schist and the nature of the calcium carbonate phase suggest that the retrograde P–T path was not associated with a significant increase or decrease in the ratio of P–T conditions following the peak of metamorphism. This P–T path contrasts with the open clockwise path derived from eclogite of the Besshi area. The development of distinct P–T paths in different parts of the Sanbagawa belt shows the shape of the P–T path is not primarily controlled by tectonic setting, but by internal factors such as geometry of metamorphic units and exhumation rates.

Notes: Previous studies suggest that the metamorphic evolution of the ultrahigh-pressure garnet peridotite from Alpe Arami was characterized by rapid subduction to a depth of c. 180 km with partial chemical equilibration at c. 5.9 Gpa/1180 °C and an initial stage of near-isothermal decompression followed by enhanced cooling. In this study, average cooling rates were constrained by diffusion modelling on retrograde Fe–Mg zonation profiles across garnet porphyroclasts. Considering the effects of temperature, pressure and garnet bulk composition on the Fe–Mg interdiffusion coefficient, cooling rates of 380–1600 °C Myr−1 for the interval from 1180 to 800 °C were obtained. Similar or even higher average cooling rates resulted from thermal modelling, whereby the characteristics of the calculated temperature-time path depend on the shape and size of the hot peridotite body and the boundary conditions of the cooling process. The very high cooling rates obtained from both geospeedometry and thermal modelling imply extremely fast exhumation rates of c. 15 mm yr−1 or more. These results agree with the range of exhumation rates (16–50 mm yr−1) deduced from geochronological results. It is suggested that the Alpe Arami peridotite passively returned towards the surface as part of a buoyant sliver, caused as a consequence of slab breakoff.

Notes: We report SHRIMP U–Th–Pb monazite, conventional U–Pb titanite, Sm–Nd garnet and Rb–Sr muscovite and biotite ages for metamorphic rocks from the Danba Domal Metamorphic Terrane in the eastern Songpan-Garzê Orogenic Belt (eastern Tibet Plateau). These ages are used to determine the timing of polyphase metamorphic events and the subsequent cooling history. The oldest U–Th–Pb monazite and Sm–Nd garnet ages constrain an early Barrovian metamorphism (M1) in the interval c. 204–190 Ma, coincident with extensive Indosinian granitic magmatism throughout the Songpan-Garzê Orogenic Belt. A second, higher-grade sillimanite-grade metamorphic event (M2), recorded only in the northern part of the Danba terrane, was dated at c. 168–158 Ma by a combination of U–Th–Pb monazite and titanite and Sm–Nd garnet ages. It is suggested that M1 was a thermal event that affected the entire orogenic belt while M2 may represent a local thermal perturbation. Rb–Sr muscovite ages range from c. 138–100 Ma, whereas Rb–Sr biotite ages cluster at c. 34–24 Ma. These ages document regional cooling at rates of c. 2–3 °C Myr−1 following the M1 peak for most of the terrane. However, those parts of the terrane affected by the higher-temperature M2 event (e.g. the migmatite zone) experienced initially more rapid (c. 8 °C Myr−1) cooling after peak M2 before joining the regional slow cooling path defined by the rest of the terrane at c. 138 Ma. Regional slow cooling between c. 138 and c. 30 Ma is thought to be the result of post-tectonic isostatic uplift after extensive crustal thickening caused by collision of the South and North China Blocks. The clustering of biotite Rb–Sr ages marks the onset of rapid uplift across the entire terrane commencing at c. 30–20 Ma. This cooling history is shared with many other regions of the Tibet Plateau, suggesting that uplift of the Tibet Plateau (including the Songpan-Garzê Orogenic Belt) occurred predominantly in the last c. 30 Myr as a response to the continuing northwards collision of India with Eurasia.

Notes: Recent studies have used the relative rotation axis of sigmoidal and spiral-shaped inclusion trails, known as Foliation Inflexion/Intersection Axis (FIA), to investigate geological processes such as fold mechanisms and porphyroblast growth. The geological usefulness of this method depends upon the accurate measurement of FIA orientations and correct correlation of temporally related FIAs. This paper uses new data from the Canton Schist to assess the variation in FIA orientations within and between samples, and evaluates criteria for correlating FIAs. For the first time, an entire data set of FIA measurements is published, and data are presented in a way that reflects the variation in FIA orientations within individual samples and provides an indication of the reliability of the data. Analysis of 61 FIA trends determined from the Canton Schist indicate a minimum intrasample range in FIA orientations of 30°. Three competing models are presented for correlation of these FIAs, and each of the models employ different correlation criteria. Correlation of FIAs in Model 1 is based on relative timing and textural criteria, while Model 2 uses relative timing, orientation and patterns of changing FIA orientations, and Model 3 uses relative timing and FIA orientation as correlation criteria. Importantly, the three models differ in the spread of FIA orientations within individual sets, and the number of sets distinguished in the data. Relative timing is the most reliable criterion for correlation, followed by textural criteria and patterns of changing FIA orientations from core to rim of porphyroblasts. It is proposed that within a set of temporally related FIAs, the typical spread of orientations involves clustering of data in a 60° range, but outliers occur at other orientations including near-normal to the peak distribution. Consequently, in populations of FIA data that contain a wide range of orientations, correlation on the basis of orientation is unreliable in the absence of additional criteria. The results of this study suggest that FIAs are best used as semiquantitative indicators of bulk trends rather than an exact measurement for the purpose of quantitative analyses.

Notes: Documentation of pressure–temperature (P–T) histories across an epidote-amphibolite facies culmination provides new insight into the tectono-thermal evolution of the Brooks Range collisional orogen. Thermobarometry reveals that the highest grade rocks formed at peak temperatures of 560–600 °C and at pressures of 8–9.5 kbar. The thermal culmination coincides with the apex of a structural dome defined by oppositely dipping S2 crenulation cleavages suggesting post-metamorphic doming. South of the thermal culmination, greenschist facies and lowermost epidote-amphibolite facies rocks preserve widespread evidence for an early blueschist facies metamorphism. In contrast, no evidence for an early blueschist facies metamorphism was found in similar grade rocks of the northern flank, indicating that the southern flank underwent initial deeper burial during southward underthrusting of the continental margin. Thus, while the dome shows a symmetric distribution of peak temperatures, the P–T paths followed by the two flanks must have varied. This variation suggests that final thermal re-equilibration to greenschist and epidote–amphibolite facies conditions did not result from a simple process of southward underthrusting followed by thermal re-equilibration from the bottom upward. The new data are inconsistent with a previous model that invokes such re-equilibration, along with northward thrusting of epidote–amphibolite facies rocks over lower grade rocks presently on the southern flank of the culmination, to produce an inverted metamorphic field gradient. Instead, it is suggested that following blueschist facies metamorphism, rocks of the southern and northern flanks were juxtaposed, during which time the more deeply buried south flank was partially emplaced above rocks to the north, where they escaped Albian epidote–amphibolite facies overprinting. Porphyroblast growth, which post-dates the main fabric on the north flank of the culmination may be the result of Albian thermal re-equilibration following this deformation. Post-metamorphic doming resulted from a combination of Albian-Cenomanian extension and Tertiary deformation.

Notes: Spiral inclusion trails in garnet porphyroblasts are likely to have formed due to simultaneous growth and rotation of the crystals, during syn-metamorphic deformation. Thus, they contain information on the strain rate of the rock. Strain rates may be interpreted from such inclusion trails if two functions are known: (1) The relationship between rotation rate and shear strain rate; (2) the growth rate of the crystal. We have investigated details of both functions using a garnetiferous mica schist from the eastern European Alps as an example. The rotation rate of garnet porphyroblasts was determined using finite element modelling of the geometrical arrangement of the crystals in the rock. The growth rate of the porphyroblasts was determined by using the major and trace element distributions in garnet crystals, thermodynamic pseudosections and information on the grain size distribution. For the largest porphyroblast size fraction (size L=12 mm) we constrain a growth interval between 540 and 590 °C during the prograde evolution of the rock. Assuming a reasonable heating rate and using the angular geometry of the spiral inclusion trails we are able to suggest that the mean strain rate during crystal growth was of the order of 〈inlineGraphic alt="inline image" href="urn:x-wiley:02634929:JMG441:JMG_441_mu1" location="equation/JMG_441_mu1.gif"/〉=6.6 × 10−14 s−1. These estimates are consistent with independent estimates for the strain rates during the evolution of this part of the Alpine orogen.

Notes: Mineral textures in metapelitic granulites from the northern Prince Charles Mountains, coupled with thermodynamic modelling in the K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–Fe2O3 (KFMASHTO) model system, point to pressure increasing with increasing temperature on the prograde metamorphic path, followed by retrograde cooling (i.e. an anticlockwise P–T path). Textural evidence for the increasing temperature part of the path is given by the breakdown of garnet and biotite to form orthopyroxene and cordierite in sillimanite-absent rocks, and through the break-down of biotite and sillimanite to form spinel, cordierite and garnet in more aluminous assemblages. This is equated to the advective addition of heat from the regional emplacement of granitic and charnockitic magmas dated at c. 980 Ma. A subsequent increase in pressure, inferred from the break-down of spinel and quartz to sillimanite, cordierite and garnet in aluminous rocks, is attributed to crustal thickening related to upright folding dated at 940–910 Ma. The terrane attained peak metamorphic temperatures of c. 880 °C at pressures of c. 6.0–6.5 kbar during this event. Subsequent cooling is inferred from the localised breakdown of cordierite and garnet to form biotite and sillimanite that developed in the latter stages of the same event. The textural observations described are interpreted via the application of P–T and P–T–X pseudosections. The latter show that most rock compositions preserve only fragments of the overall P–T path; a result of different rock compositions undergoing mineral assemblage changes, or changes in mineral modal abundance, on different sections of the P–T path. The results also suggest that partial melting during granulite facies metamorphism, coupled with melt loss and dehydration, initiated a switch from pervasive ductile, to discrete ductile/brittle deformation, during retrograde cooling.

Notes: Fluid flow at greenschist facies conditions during exhumation of the western Alps occurred in several penecontemporaneous systems, including shear zones at lithological contacts, deformed contacts between serpentinite bodies and metabasalts, albite veins within metabasalts, and calcite + quartz veins within calcareous schists. Fluid flow in shear zones that juxtapose metasediments and ophiolitic rocks within the Piemonte Unit reset O and H isotope ratios. δ18O values are buffered by the wall rocks; however, calculated fluid δ2H values are similar within all the shear zones suggesting that they formed an interconnected network. The similarity of δ2H values of the sheared rocks and those of unsheared calcareous schists suggests that the fluids were derived from, or had equilibrated with, the schists that envelop the ophiolite rocks. Time-integrated fluid fluxes at the sheared contacts estimated from changes in Si in metabasalts were up to 105 m3 m−2, with the fluid flowing up temperature driven either by topography or seismic pumping. Individual shear zones were active for c. 2–3 Myr, implying average fluid fluxes of up to 10−9 m3 m−2 s−1. Rocks in shear zones within the ophiolite away from contacts with the metasediments show much less marked isotopic and geochemical changes, implying that fluid volumes decreased into the ophiolite unit, consistent with the source of fluids being the metasediments. Fluids were generated by dehydration reactions that were intersected during exhumation and, while many rocks show the affects of fluid–rock interaction, large-scale fluid flow between major units was not common.

Notes: Eclogites from the south Tianshan, NW China are grouped into two types: glaucophane and hornblende eclogites, composed, respectively, of garnet + omphacite + glaucophane + paragonite + epidote + quartz and garnet + omphacite + hornblende (sensu lato) + paragonite + epidote + quartz, plus accessory rutile and ilmenite. These eclogites are diverse both in mineral composition and texture not only between the two types but also among the different selected samples within the glaucophane eclogite. Using thermocalc 3.1 and recent models of activity–composition relation for minerals, a P–T projection and a series of P–T pseudosections for specific samples of eclogite have been calculated in the system Na2O–CaO–FeO–MgO–Al2O3–SiO2–H2O (NCFMASH) with quartz and water taken to be in excess. On the basis of these phase diagrams, the phase relations and P–T conditions are well delineated. The three selected samples of glaucophane eclogite AK05, AK11 and AK17 are estimated to have peak P–T conditions, respectively, of 540–550 °C at c. 16 kbar, c. 560 °C at 15–17 kbar and c. 580 °C at 15–19 kbar, and two samples of hornblende eclogite AK10 and AK30 of 610–630 °C and 17–18 kbar. Together with H2O-content contours in the related P–T pseudosections and textural relations, both types of eclogite are inferred to show clockwise P–T paths, with the hornblende eclogite being transformed from the glaucophane eclogite assemblage dominantly through increasing temperature.

Notes: This study uses field, petrographic and geochemical methods to estimate how much granitic melt was formed and extracted from a granulite facies terrane, and to determine what the grain- and outcrop-scale melt-flow paths were during the melt segregation process. The Ashuanipi subprovince, located in the north-eastern Superior Province of Quebec, is a large (90 000 km2) metasedimentary terrane, in which 〉 85% of the metasediments are of metagreywacke composition, that was metamorphosed at mid-crustal conditions (820–900 °C and 6–7 kbar) in a late Archean dextral, transpressive orogen. Decrease in modal biotite and quartz as orthopyroxene and plagioclase contents increase, together with preserved former melt textures indicate that anatexis was by the biotite dehydration reaction: biotite + quartz + plagioclase = melt + orthopyroxene + oxides. Using melt/orthopyroxene ratios for this reaction derived from experimental studies, the modal orthopyroxene contents indicate that the metagreywacke rocks underwent an average of 31 vol% partial melting.The metagreywackes are enriched in MgO, CaO and FeOt and depleted in SiO2, K2O, Rb, Cs, and U, have lower Rb/Sr, higher Rb/Cs and Th/U ratios and positive Eu anomalies compared to their likely protolith. These compositions are modelled by the extraction of between 20 and 40 wt %, granitic melt from typical Archean low-grade metagreywackes. A simple mass balance indicates that about 640 000 km3 of granitic melt was extracted from the depleted granulites.The distribution of relict melt at thin section- and outcrop-scales indicates that in layers without leucosomes melt extraction occurred by a pervasive grain boundary (porous) flow from the site of melting, across the layers and into bedding planes between adjacent layers. In other rocks pervasive grain boundary flow of melt occurred along the layers for a few, to tens of centimetres followed by channelled flow of melt in a network of short interconnected and structurally controlled conduits, visible as the net-like array of leucosomes in some outcrops. The leucosomes contain very little residual material (〈 5% biotite + orthopyroxene) indicating that the melt fraction was well separated from the residuum left in situ as melt-depleted granulite. Only 1–3 vol percentage melt remained in the melt-depleted granulites, hence, the extraction of melt generated by biotite dehydration melting in these granulites, was virtually complete under conditions of natural melting and strain rates in a contractional orogen.

Notes: Abstract Three experiments were undertaken to investigate the influence of seed mixture on the establishment of a target grassland community on a site with high available phosphorus. In the first experiment autumn- and spring-sown commercial seed mixtures were compared with seed harvested from a nature reserve with respect to their ability to produce an inundation grassland community similar to that described by the British National Vegetation Classification (NVC) as Agrostis stolonifera–Alopecurus geniculatus grassland (MG13). In the second experiment the composition and sowing rate of a commercial seed mixture were altered to investigate whether these factors were significant in the establishment of a sward similar to MG13. Similarly, in the third experiment the composition of a commercial seed mixture designed to achieve an alternative community, Cynosurus cristatus–Caltha palustris grassland (NVC code MG8), was sown. The vegetation resulting from each of these treatments was monitored with permanent quadrats for a 3-year period, and the hydrological regime of each quadrat location was modeled and quantified. The results showed that seed mixture, timing of sowing, and seeding rate had an initial effect on the vegetation that established. However, by the third year of monitoring there were no significant differences between these treatments, and hydrological regime had become the most important factor in determining the distribution of species. The vegetation was less diverse than predicted from germination tests and decreased in diversity over the monitoring period. It is suggested that this may be a result of the hydrological regime being unsuitable for several of the sown species or due to the extremely high available phosphorus concentration in the soil. This study highlights the need to understand the soil and hydrological conditions of a site before choosing a target community and designing a seed mixture.

Notes: Abstract Introduced perennial grasses are one of the greatest constraints to prairie restoration. Herbicides suppress but do not eliminate introduced grasses, so we explored the interaction of herbicide with two additional controls: heavy clipping (to simulate grazing) and competition from native species. A 50-year-old stand of the introduced perennial grass Agropyron cristatum (crested wheatgrass) in the northern Great Plains was seeded with native grasses and treated with herbicide annually for 7 years in a factorial experiment. Clipping was applied as a subplot treatment in the final 3 years. Both herbicide and clipping significantly reduced the cover of A. cristatum, but clipping produced an immediate and consistent decrease, whereas herbicide control varied among years. The cover of A. cristatum decreased significantly with increasing cover of a seeded native grass, Bouteloua gracilis (blue grama), suggesting that both top-down (i.e., grazing) and bottom-up (i.e., resource competition) strategies can contribute to A. cristatum control. No treatment had any effect on the seed bank of A. cristatum. Even in the most effective control treatments, A. cristatum persisted at low amounts (approximately 5% cover) throughout the experiment. The cover of B. gracilis increased significantly with seed addition and herbicide, and, after 7 years, was similar to that in undisturbed prairie. The total cover of native species increased significantly with clipping and herbicide, and species richness was significantly higher in plots receiving herbicide. Clipping season had no effect on any variable. In summary, no method extirpated A. cristatum, but clipping reduced its cover by 90% and doubled the cover of native species. Extirpation might not be a realistic goal, but relatively simple management allowed coexistence of native species.

Notes: Abstract The reduction and fragmentation of forest habitats is expected to have profound effects on plant species diversity as a consequence of the decreased area and increased isolation of the remnant patches. To stop the ongoing process of forest fragmentation, much attention has been given recently to the restoration of forest habitat. The present study investigates restoration possibilities of recently established patches with respect to their geographical isolation. Because seed dispersal events over 100 m are considered to be of long distance, a threshold value of 100 m between recent and old woodland was chosen to define isolation. Total species richness, individual patch species richness, frequency distributions in species occurrences, and patch occupancy patterns of individual species were significantly different among isolated and nonisolated stands. In the short term no high species richness is to be expected in isolated stands. Establishing new forests adjacent to existing woodland ensures higher survival probabilities of existing populations. In the long term, however, the importance of long-distance seed dispersal should not be underestimated because most species showed occasional long-distance seed dispersal. A clear distinction should be made between populations colonizing adjacent patches and patches isolated from old woodland. The colonization of isolated stands may have important effects on the dynamics and diversity of forest networks, and more attention should be directed toward the genetic traits and viability of founding populations in isolated stands.

Notes: Abstract The effects of the earthworm Pontoscolex corethrurus (Muller) on the rate of mineralization of cattle dung-amended iron (Fe2+) ore mine wastes and its preference for partially decomposed leaf litter with contrasting chemical composition were studied in pot trials. The growth and survival rates of earthworms showed significant positive correlations with percent of organic matter. During 96 days of exposure, the earthworms significantly increased exchangeable Ca2+, Mg2+, PO43− and NH4-N. Iron ore mine wastes amended with 5–10% organic matter supported earthworm fauna better than mine wastes amended with 0–3% organic matter. The leaf litter preference shown by the earthworm was, in descending order, Phyllanthus reticulatus, Tamarindus indica, Anacardium occidentale, Casuarina equisetifolia, Acacia auriculiformis, and Eucalyptus camaldulensis. A significant positive correlation was observed between the survival and growth rates of earthworms and the nutrient contents of partially decomposed leaf litter. The first three plant species were significantly richer in nutrients, mainly organic carbon, calcium, phosphorus, and nitrogen, than the other two plant species. Acacia auriculiformis and E. camaldulensis litter were preferred less because of their high lignin and polyphenolic compounds, despite being rich in other macronutrients like nitrogen and phosphorus. It is concluded that the introduction of P. corethrurus to cattle dung-amended (5–10%) iron ore mine wastes or revegetation of the sites with P. reticulatus, T. indica, and A. occidentale plant species should be attempted before earthworm introduction. The litter from these species acts as a source of food for earthworms, thereby hastening the process of restoration of abandoned iron ore mines of Goa, India.

Notes: Abstract River and stream rehabilitation projects are increasing in number, but the success or failure of these projects has rarely been evaluated, and the extent to which buffers can restore riparian and stream function and species composition is not well understood. In New Zealand the widespread conversion of forest to agricultural land has caused degradation of streams and riparian ecosystems. We assessed nine riparian buffer zone schemes in North Island, New Zealand that had been fenced and planted (age range from 2 to 24 years) and compared them with unbuffered control reaches upstream or nearby. Macroinvertebrate community composition was our prime indicator of water and habitat quality and ecological functioning, but we also assessed a range of physical and water quality variables within the stream and in the riparian zone. Generally, streams within buffer zones showed rapid improvements in visual water clarity and channel stability, but nutrient and fecal contamination responses were variable. Significant changes in macroinvertebrate communities toward “clean water” or native forest communities did not occur at most of the study sites. Improvement in invertebrate communities appeared to be most strongly linked to decreases in water temperature, suggesting that restoration of in-stream communities would only be achieved after canopy closure, with long buffer lengths, and protection of headwater tributaries. Expectations of riparian restoration efforts should be tempered by (1) time scales and (2) spatial arrangement of planted reaches, either within a catchment or with consideration of their proximity to source areas of recolonists.

Notes: Abstract One of the greatest challenges for ecologists this century will be restoring forests on degraded tropical lands. This restoration will require understanding complex processes that shape successional pathways, including interactions between trees and other plants. Shrub species often quickly invade disturbed tropical lands, yet little is known about whether they facilitate or inhibit subsequent tree recruitment and growth. We examined how shrubs and other vegetation (e.g., vines, grasses, herbs) affect tree recruitment, survival, and growth during the first 6 years of forest succession in Kibale National Park, Uganda. The study was undertaken in two recently logged exotic softwood plantations. We studied the successional trajectories in two recently logged areas that varied in their initial densities of trees and shrubs. Analyses suggested tree seedling presence and density were not strongly related to shrub density or height during succession. Tree sapling presence and density were positively significantly related to shrub density and height. We found little response in the tree community to experimental shrub removal, and although removal of all nontree vegetation temporarily enhanced tree growth, the effect disappeared after 2 years. Some early-successional trees benefited from reduced competition, whereas some mid-successional trees benefited from the presence of other vegetation. Some specific tree species responded strongly to vegetation removal. We interpret our findings in light of designing manipulations promoting forest restoration for biodiversity conservation and conclude with four tentative guidelines: (1) manage at the species level, not the community level; (2) increase facilitation for seedlings, reduce competition for saplings; (3) be cautious of assumptions about plant interactions; and (4) be adaptable and creative with new strategies when manipulations fail.

Notes: Abstract Soil chemical properties and soil mesofauna composition were assessed at a forest site in northern Austria, where 20 years earlier an amelioration treatment had been performed. The site had been treated with limestone, a high P slag, and ammonium nitrate to replace the poorly growing pine (Pinus sylvestris) forest with a Norway spruce (Picea abies) stand. This treatment was at that time a common means for the amelioration of nutrient-poor forest soils with recalcitrant forest floor layers. After treatment, a dense cover of a nitrophilic stinging nettle (Urtica dioica) developed. Most likely, the site had been over-fertilized, and inadvertently, an experiment with extreme N enrichment had been conducted. The abundance of collembolans increased, and dominance structure shifted from Isotomiella minor, Lipothrix lubbocki, and Isotoma notabilis at fertilizer treatment to Friesea mirabilis, Isotomiella minor, and Sphaeridia pumilis in the control, but the abundance of soil mesofauna generally decreased in the fertilizer treatment. Fertilization reduced the mass of the litter layer from 7.6 to 2.4 kg/m2. The total carbon pool in the soil was reduced due to reduction of the litter layer. However, the content of soil organic matter in the upper mineral soil was significantly increased. A part of the applied and mineralized nitrogen had been lost from the soil, but N retention in the upper mineral soil was still considerable. Soil pH and the base saturation were sustainably increased. Carbon losses upon mineralization of the litter layer were not offset by the increase in C content of the mineral soil. Presently, the C pool in the soil of the fertilized treatment is lower than in the control. However, the overall nutrient enrichment of the soil may facilitate C sequestration in the fertilized site in the future.

Notes: Abstract Poor growth of Quercus robur L. (oak) trees has been reported on mine sites where overburden and subsoil have been used in the reinstatement of surface layers. This stunting has been attributed to a lack of macronutrients and to an adverse soil environment for root growth and mycorrhizal development. Growth, mineral nutrition, and ectomycorrhizal colonization of Q. robur seedlings were studied in an experiment carried out under controlled growing conditions in which mine spoil material was enriched with a leaf litter mulch. Enrichment of mine spoil material was found to produce a significant increase in growth and foliar N concentrations of oak seedlings. Inoculation with three taxa of ectomycorrhizal fungi did not benefit seedlings when mine spoil was the only substrate, possibly due to the poor physical properties of the unamended spoil and lack of nutrients. Inoculation with two taxa, Laccaria laccata and Hebeloma crustuliniforme, isolated from 3-year-old trees produced a significant stimulation of growth in the organically enriched treatment, which was believed to be due to greater uptake of mineralized N. However, Cortinarius anomalus isolated from fruit bodies associated with a 15-year-old tree did not increase biomass. The presence of organic matter was found to result in a significant stimulation of mycorrhizal infection by both inoculum and contaminant mycobionts. Recommendations are made for improving the establishment and growth of oak seedlings on reinstated sites.

Notes: Abstract Prairie restoration at the northern edge of the Great Plains can be frustrated by previously established non-native perennial grasses. We compared the emergence of a widely introduced grass, Agropyron cristatum, and a common native grass, Bouteloua gracilis, in a 4-year-old field experiment in which the Agropyron-dominated vegetation had either been left intact or treated annually with herbicide. This was done at two levels of water supply, reflecting conditions expected in wet and dry years, to examine the effects of among-year variability in precipitation. Water addition significantly increased the emergence of both surface-sown and buried (1 cm deep) seeds. Herbicide treatment of neighbors did not increase the emergence of experimentally added seeds. Emergence was much greater for buried (80%) than surface-sown seeds (20%). Significantly more Bouteloua than Agropyron germinated from experimentally buried seeds. Whereas only a single seedling of Bouteloua emerged from the existing seed bank, the mean density of Agropyron seedlings emerging from the seed bank was 930/m2 (range, 0 to 6,455/m2). Surprisingly, the emergence of Agropyron from the seed bank was not decreased by 4 years of herbicide treatment, possibly because herbicide may release Agropyron from intraspecific competition and allow increased seed production to compensate for decreased plant abundance. In summary, we found few differences between Agropyron and Bouteloua in spring and summer emergence at high or low water availability. The persistence of Agropyron stands despite repeated herbicide application may be partly due to increased seed production.

Notes: Abstract The effect of increasing planting unit size and stabilizing sediment was examined for two seagrass planting methods at Carnac Island, Western Australia in 1993. The staple method (sprigs) was used to transplant Amphibolis griffithii (J. M. Black) den Hartog and the plug method was used to transplant A. griffithii and Posidonia sinuosa Cambridge and Kuo. Transplant size was varied by increasing the number of rhizomes incorporated into a staple and increasing the diameter of plugs. Planting units were transplanted into bare sand, back into the original donor seagrass bed, or into a meadow of Heterozostera tasmanica, which is an important colonizing species. Sprigs of A. griffithii were extracted from a monospecific meadow; tied into bundles of 1, 2, 5, and 10 rhizomes; and planted into unvegetated areas. Half the units were surrounded by plastic mesh and the remainder were unmeshed. All treatments were lost within 99 days after transplanting, and although larger bundles survived better than smaller ones, no significant differences could be attributed to the effects of mesh or sprig size. Plugs of P. sinuosa and A. griffithii were extracted from monospecific meadows using polyvinyl chloride pipe of three diameters, 5, 10, and 15 cm, and planted into unvegetated areas nearby. Half the units were surrounded by plastic mesh and the remainder were unmeshed. Posidonia sinuosa plugs were also placed within a meadow of H. tasmanica (Martens ex Aschers.) den Hartog. Only 60% of A. griffithii plug sizes survived 350 days after transplanting back into the donor bed; however, survival of transplants at unvegetated areas varied considerably, and analysis of variance indicated a significant two-way interaction between treatment and plug size. Transplants survived better when meshed (90% survived) and survival improved with increasing plug size. Posidonia sinuosa transplants survived poorly (no plugs survived beyond 220 days in bare or meshed treatments) regardless of size. Survival of 10- and 15-cm plugs was markedly better than the 5-cm plugs in vegetated areas, including the H. tasmanica meadow. The use of large seagrass plugs may be appropriate for transplantation in high-energy wave environments.

Notes: Abstract Dominance-diversity curves have been previously constructed for a range of ecosystems around the world to illustrate the dominance of particular species and show how their relative abundances compare between communities separated in time or space. We investigate the usefulness of dominance-diversity curves in rehabilitated areas to compare the floristic composition and abundance of “undisturbed” areas with disturbed areas, using bauxite mining rehabilitation in Western Australia as an example. Rehabilitated pits (11–13 years old) subjected to prescribed fire in autumn and spring were compared with unburned rehabilitated areas and the native jarrah (Eucalyptus marginata) forest. Dominance diversity curves were constructed by ranking the log of the species density values from highest to lowest. Species were categorized according to a variety of functional responses: life form (trees, shrubs, subshrubs, and annuals), fire response syndrome (seeder or resprouter), nitrogen fixing capability, and origin (native or adventive). Exponential functions showed extremely good fits for all sites (r2 = 0.939–0.995). Dominance diversity graphs showed that after burning of rehabilitated areas, sites exhibited a more similar dominance-diversity curve than before burning. This was emphasized in a classification (UPGMA) of the regression equations from the dominance-diversity curves that showed that sites burned in spring were more similar to the native forest than sites burned in autumn. There was no significant segregation of the nitrogen-fixing and species origin categories, although the life form and fire response groupings showed significant segregation along the dominance-diversity curve. Resprouters tended to be over-represented in the lower quartiles and under-represented in the upper quartiles of post-burn sites. It is suggested that using dominance-diversity curves in the monitoring of rehabilitated areas may be a useful approach because it provides an easily interpretable visual representation of both species richness and abundance relationships and may be further utilized to emphasize categories of plants that are over- or under-represented in rehabilitated areas. This will assist in the post-rehabilitation management of these sites.

Notes: Abstract The wave-exposed nature of much of the southwestern Australian coastline considerably reduces the protective influence of seagrasses, and sediment movement appears to be relatively unaffected by their presence. Present seagrass restoration efforts focus on the deployment of large mechanically transplanted “sods” of seagrass as a means of combating the negative effects of water motion on transplant survival. The aim of this study was to investigate the combined role of wave energy and transplant spacing on sediment movement and transplant survival to provide guidance for seagrass transplantation in areas of high wave energy. One hundred sixty sods (0.25 m2) of seagrass were mechanically extracted from a mixed meadow consisting of Amphibolis griffithii (Cymodoceaceae) and Posidonia coriacea (Posidoniaceae) and planted in a high wave energy site with the treatments configured as three replicates of 16 sods placed in 4 × 4–meter squares at distances of 0.5, 1.0, and 2.0 meters apart. An additional 16 single sods were planted randomly throughout the site. Monitoring was conducted at two monthly intervals and consisted of counting the number of sods surviving and measuring the shoot density of seagrass species within each surviving sod. Sediment height was monitored using a series of sediment plates and an electronic sediment level sensor. Sod spacing had no significant effect upon transplant survival, which remained above 90% for 4 months after transplantation and then declined with the onset of winter (June to August). After 14 months individual sod survival was between 9% and 40%. Initial shoot densities were 200 to 500 shoots/m2 and declined to less than 50 shoots/m2. Sediment fluctuations up to 35 cm were noted, occasionally taking place over a matter of hours, and storms during winter caused significantly increased sediment movement. This probably curtailed rhizome extension and prevented the expansion of the transplants. This study indicates that the ability of seagrasses to influence sediment would appear to vary with the prevailing hydrodynamic regime and that a reappraisal of the notion that all seagrass communities trap sediment is necessary.

Notes: Zircon from a lower crustal metapelitic granulite (Val Malenco, N-Italy) display inherited cores, and three metamorphic overgrowths with ages of 281 ± 2, 269 ± 3 and 258 ± 4 Ma. Using mineral inclusions in zircon and garnet and their rare earth element characteristics it is possible to relate the ages to distinct stages of granulite facies metamorphism. The first zircon overgrowth formed during prograde fluid-absent partial melting of muscovite and biotite apparently caused by the intrusion of a Permian gabbro complex. The second metamorphic zircon grew after formation of peak garnet, during cooling from 850 °C to c. 700 °C. It crystallized from partial melts that were depleted in heavy rare earth elements because of previous, extensive garnet crystallization. A second stage of partial melting is documented in new growth of garnet and produced the third metamorphic zircon. The ages obtained indicate that the granulite facies metamorphism lasted for about 20 Myr and was related to two phases of partial melting producing strongly restitic metapelites.Monazite records three metamorphic stages at 279 ± 5, 270 ± 5 and 257 ± 4 Ma, indicating that formation ages can be obtained in monazite that underwent even granulite facies conditions. However, monazite displays less clear relationships between growth zones and mineral inclusions than zircon, hampering the correlation of age to metamorphism. To overcome this problem garnet–monazite trace element partitioning was determined for the first time, which can be used in future studies to relate monazite formation to garnet growth.

Notes: A suite of spinel–cordierite granulites from Viziangram, Eastern Ghats Belt, India preserve mineral assemblages and reaction textures indicative of peak metamorphic conditions of 〉1000 °C, 〉8〈10 kbar, followed successively by near isobaric cooling (down to 750–800 °C), near isothermal decompression (to 4–5 kbar), and late hydration. P–T conditions of each stage are evaluated through a combination of petrogenetic grid approach and thermobarometry. Sapphirine is developed in sillimanite-bearing acid pegmatite veins that intruded the spinel–cordierite granulite close to peak metamorphic conditions, and also in the host rock in immediate contact with the pegmatite. Both sillimanite and sapphirine in the pegmatite are considered to be magmatic phases. Field observations and textural characteristics suggest that Al-metasomatism of the spinel–cordierite granulite due to the intrusion of pegmatite was responsible for sapphirine formation in the spinel granulite.

Notes: Whereas geologists have known for three-quarters of a century that there was significant crustal thickening in the central East Greenland Caledonides, the crucial role of extensional faulting during Caledonian orogenesis has only been recognized during the past decade. In this paper, new petrographic and thermobarometric observations are presented from migmatitic metasedimentary gneisses of the Forsblad Fjord region (c. 72.5°N). Samples of the Krummedal Sequence, collected from the footwall of the upper of two significant splays of the main extensional fault system in the region—the Fjord Region Detachment (FRD)—enable us to establish a relative sequence of metamorphism. Our pressure (P)–temperature (T) results imply a clockwise loop in P–T space. As recorded by mineral assemblages in the Krummedal gneisses, prograde metamorphism involved a net increase of c. 4 kbar and 250 °C, with peak conditions of c. 10.5 kbar at 785 °C. Early burial and heating was followed by near-isothermal decompression of 4.5 kbar, a process which is attributed to roughly 18 km of tectonostratigraphic throw on the upper splay of the FRD. Combining data reported here with the published data, it is estimated that the approximate tectonostratigraphic throw along the lower splay of the FRD was c. 16 km. In situ U–Th–Pb-monazite electron microprobe dating suggests that the earliest phase of metamorphism recorded in the Krummedal Sequence gneisses of Forsblad Fjord occurred during the Caledonian orogeny. Furthermore, the combination of our new data with existing conventional TIMS U-Pb and 40Ar/39Ar data imply that: (1) movement along the uppermost splay of the FRD (c. 425–423 Ma) occurred at maximum time-averaged slip-rates equivalent to c. 9 mm of vertical displacement per year; and (2) that the final stages of metamorphism occurred prior to c. 411 Ma, although part of this denudation was likely accommodated on overlying extensional structures that may have been active more recently. There is close agreement between our data and results from the Krummedal Sequence north of the field area (72.5°−74°N), and rocks of the Smallefjord Sequence (75°−76°N) that are suggested to correlate with the Krummedal Sequence. This leads us to infer that the events recorded in the Forsblad Fjord region are of orogen-scale significance.

Notes: New data on the metamorphic petrology and zircon geochronology of high-grade rocks in the central Mozambique Belt (MB) of Tanzania show that this part of the orogen consists of Archean and Palaeoproterozoic material that was structurally reworked during the Pan-African event. The metamorphic rocks are characterized by a clockwise P–T path, followed by strong decompression, and the time of peak granulite facies metamorphism is similar to other granulite terranes in Tanzania. The predominant rock types are mafic to intermediate granulites, migmatites, granitoid orthogneisses and kyanite/sillimanite-bearing metapelites. The meta-granitoid rocks are of calc-alkaline composition, range in age from late Archean to Neoproterozoic, and their protoliths were probably derived from magmatic arcs during collisional processes. Mafic to intermediate granulites consist of the mineral assemblage garnet–clinopyroxene–plagioclase–quartz–biotite–amphibole ± K-feldspar ± orthopyroxene ± oxides. Metapelites are composed of garnet-biotite-plagioclase ± K-feldspar ± kyanite/sillimanite ± oxides. Estimated values for peak granulite facies metamorphism are 12–13 kbar and 750–800 °C. Pressures of 5–8 kbar and temperatures of 550–700 °C characterize subsequent retrogression to amphibolite facies conditions. Evidence for a clockwise P–T path is provided by late growth of sillimanite after kyanite in metapelites. Zircon ages indicate that most of the central part of the MB in Tanzania consists of reworked ancient crust as shown by Archean (c. 2970–2500 Ma) and Palaeoproterozoic (c. 2124–1837 Ma) protolith ages. Metamorphic zircon from metapelites and granitoid orthogneisses yielded ages of c. 640 Ma which are considered to date peak regional granulite facies metamorphism during the Pan-African orogenic event. However, the available zircon ages for the entire MB in East Africa and Madagascar also document that peak metamorphic conditions were reached at different times in different places. Large parts of the MB in central Tanzania consist of Archean and Palaeoproterozoic material that was reworked during the Pan-African event and that may have been part of the Tanzania Craton and Usagaran domain farther to the west.

Notes: Abstract An analytical electron microscope study of almandine garnet from a metamorphosed Al–Fe-rich rock revealed detailed composition profiles and defect microstructures of resorption zoning along fluid-infiltrated veins and even into the garnet/ilmenite (inclusion) interface. This indicates a limited volume diffusion for the cations in substitution (mainly Ca and Fe) and an interface-controlled partition for the extension of a composition-invariant margin. A corrugated interface between the Ca-rich margin/zone and the almandine garnet core is characterized by dislocation arrays and recovery texture further suggesting a resorption process facilitated by diffusion-induced recrystallization, diffusion-induced dislocation migration and diffusion–induced grain boundary migration. Integrated microstructural and chemical studies are essential for understanding the underlying mechanisms of processes such as garnet zoning and its modification. Without this understanding, it will not be possible to reliably use garnet compositions for thermobarometry and other applications that rely on garnet chemical information.

Notes: Abstract Granulite facies metapelites of the Mather and Filla Paragneisses within the Rauer Group, east Antarctica, possess markedly different compositions. The metamorphic evolution of the two metapelite types has been interpreted as temporally distinct, with the Rauer Group preserving at least two distinct granulite facies tectonothermal episodes. Calculated P–T pseudosections and orthopyroxene Al content indicate the revised maximum-preserved P–T conditions within the Mather Paragneiss to lie in the vicinity of 950–975 °C and 10–10.6 kbar, less extreme than previous estimates. The range of possible P–T paths for the Mather Paragneiss consistent with mineral textural relationships and pseudosections contoured for mineral proportion are significantly shallower (dP/dT) than previous estimates. A near-isothermal decompression P–T path, and extreme peak metamorphic conditions, are not necessary to explain the development of preserved mineral reaction textures. The Filla Paragneiss contains pelitic assemblages less amenable to rigorous quantitative analysis. Nevertheless, possibilities for the shared or otherwise metamorphic evolution of the Mather and Filla Paragneisses may be postulated on the basis of calculated pseudosections in the context of existing geochronology for the Rauer Group and preserved microstructures. A shared evolution, most likely during Pan-African granulite facies metamorphism, is plausible and consistent with mineral assemblage development, geochronology and microstructures. A revised interpretation of the Rauer Group's preserved metamorphic evolution may warrant the revision of existing tectonic models, applicable also to the remainder of Prydz Bay. More generally, the employed approach may incite a revision of peak P–T and P–T paths in other granulite facies terranes.

Notes: The solid-state reaction magnesite (MgCO3) + calcite (aragonite) (CaCO3) = dolomite (CaMg(CO3)2) has been identified in metapelites from western Tianshan, China. Petrological studies show that two metamorphic stages are recorded in the metapelites: (1) the peak mineral assemblage of magnesite and calcite pseudomorphs after aragonite which is only preserved as inclusions within dolomite; and (2) the retrograde glaucophane-chloritoid facies mineral assemblage of glaucophane, chloritoid, dolomite, garnet, paragonite, chlorite and quartz. The peak metamorphic temperatures and pressures are calculated to be 560–600 °C, 4.95–5.07 GPa based on the calcite–dolomite geothermometer and the equilibrium calculation of the reaction dolomite = magnesite + aragonite, respectively. These give direct evidence in UHP metamorphic rocks from Tianshan, China, that carbonate sediments were subducted to greater than 150 km depth. This UHP metamorphism represents a geotherm lower than any previously estimated for subduction metamorphism (〈 3.7 °C km−1) and is within what was previously considered a ‘forbidden’ condition within Earth. In terms of the carbon cycle, this demonstrates that carbonate sediments can be subducted to at least 150 km depth without releasing significant CO2 to the overlying mantle wedge.

Notes: Field data define two lithologically distinct basement-cover sequences within the ultrahigh-pressure metamorphic (UHPM) unit of the Dabie Shan, eastern China. One of the cover units, the Changpu unit, comprises calc-arenitic metasediments in stratigraphic contact with a basement consisting of gneisses of the Yangtze craton. The second cover unit, the Ganghe unit, consists of felsic-intermediate metavolcanics and clastic metasediments. Basement exposure of the Ganghe unit is not known. Fold axes in the Ganghe unit are oblique to those of the Changpu unit, which are parallel to those of the Yangtze gneisses. Preservation of primary textures in some volcanic rocks, and tectonic separation from the Yangtze gneisses by a greenschist facies mylonite, support an interpretation of the Ganghe unit as a low-strain domain. Protolith associations in the Ganghe and Changpu units are compatible with deposition in a rift setting and along a passive continental margin, respectively. A U–Pb single zircon age of 761 ± 33 Ma for volcanoclastic rocks of the Ganghe unit demonstrates a Neoproterozoic deposition age, concordant with inferred rifting at that time. Eclogite facies parageneses in the gneisses and both cover units, along with P–T data demonstrate regional UHPM in the Dabie Shan.

Notes: The Xugou garnet peridotite body of the southern Sulu ultrahigh-pressure (UHP) terrane is enclosed in felsic gneiss, bounded by faults, and consists of harzburgite and lenses of garnet clinopyroxenite and eclogite. The peridotite is composed of variable amounts of olivine (Fo91), enstatite (En92−93), garnet (Alm20−23Prp53−58Knr6−9Grs12−18), diopside and rare chromite. The ultramafic protolith has a depleted residual mantle composition, indicated by a high-Mg number, very low CaO, Al2O3 and total REE contents compared to primary mantle and other Sulu peridotites. Most garnet (Prp44−58) clinopyroxenites are foliated. Except for rare kyanite-bearing eclogitic bands, most eclogites contain a simple assemblage of garnet (Alm29−34Prp32−50Grs15−39) + omphacite (Jd24−36) + minor rutile. Clinopyroxenite and eclogite exhibit LREE-depleted and LREE-enriched patterns, respectively, but both have flat HREE patterns. Normalized La, Sm and Yb contents indicate that both eclogite and garnet clinopyroxenite formed by high-pressure crystal accumulation (+ variable trapped melt) from melts resulting from two-stage partial melting of a mantle source.Recrystallized textures and P–T estimates of 780–870 °C, 5–7 GPa and a metamorphic age of 231 ± 11 Ma indicate that both mafic and ultramafic protoliths experienced Triassic UHP metamorphism in the P–T forbidden zone with an extremely low thermal gradient (〈 5 °C km−1), and multistage retrograde recrystallization during exhumation. Develop of prehnite veins in clinopyroxenite, eclogite, felsic blocks and country rock gneiss, and replacements of eclogitic minerals by prehnite, albite, white mica, and K-feldspar indicate low-temperature metasomatism.

Notes: This paper provides further evidence for the ongoing discussion as to whether the Dabie UHPM belt formed in Triassic or Palaeozoic time, and whether the Sulu UHPM belt formed in Triassic or Neoproterozoic time. Combined use of laser Raman spectrometer (LR), cathodoluminescence imaging (CL), and ion probe U–Pb in-situ dating (SHRIMP) provided accurate ages of UHPM from rocks collected from Weihai, NE Sulu UHPM belt. LR was used to identify coesite and other UHP minerals as inclusions in zircon separates from an amphibolized peridotite and an eclogite. CL was used to examine the zoning structure of these zircon, and SHRIMP dating was performed on specific spots on zircon to obtain ages of different geological events. An age of 221 ± 12 Ma was obtained for coesite-bearing zircon from the amphibolized peridotite; an age of 228 ± 29 Ma for eclogite was obtained from the lower intercept of a concordia plot. These ages are interpreted as the time of UHPM in the Weihai region. Ultramafic rocks to the east of Weihai yield a magmatic age at 581 ± 44 Ma. The zircon in the ultramafic rocks possibly also records a thermal event at c. 400 Ma, but no independent geological evidence for this event has been found. The eclogite protolith formed in the Middle Proterozoic (1821 ± 19 Ma), which is similar to the age of country rock gneisses of 1847–1744 Ma. The new geochronological data confirm that UHPM occurred in the Triassic in the Sulu area when subduction took the ultramafic body and the eclogite protolith, together with the adjacent supracrustal rocks, to mantle depths.

Notes: Oxygen isotopic compositions of silicates in eclogites and whiteschists from the Kokchetav massif were analyzed by whole-grain CO2-laser fluorination methods. Systematic analyses yield extremely low δ18O for eclogites, as low as −3.9‰ for garnet; these values are comparable with those reported for the Dabie-Sulu UHP eclogites. Oxygen isotopic compositions are heterogeneous in samples of eclogite, even on an outcrop scale. Schists have rather uniform oxygen isotope values compared to eclogites, and low δ18O is not observed. Isotope thermometry indicates that both eclogites and schists achieved high-temperature isotopic equilibration at 500–800 °C. This implies that retrograde metamorphic recrystallization barely modified the peak-metamorphic oxygen isotopic signatures. A possible geological environment to account for the low-δ18O basaltic protolith is a continental rift, most likely subjected to the conditions of a cold climate. After the basalt interacted with low δ18O meteoric water, it was tectonically inserted into the surrounding sedimentary units prior to, or during subduction and UHP metamorphism.

Notes: A combined oxygen-isotope and fluid-inclusion study has been carried out on high- and ultrahigh-pressure metamorphic (HP/UHPM) eclogites and garnet clinopyroxenite from the Dabie-Sulu terranes in eastern China. Coesite-bearing eclogites/garnet clinopyroxenite and quartz eclogites have a wide range in whole-rock δ18OVSMOW, from 0 to 11‰. The high-T oxygen-isotope fractionations preserved between quartz and garnet preclude significant retrograde isotope exchange during exhumation, and the wide range in whole-rock oxygen-isotope composition is thought to be a presubduction signature of the precursors. Aqueous fluids with variable salinities and gas species (N2-, CO2-, or CH4-rich), are trapped as primary inclusions in garnet, omphacite and epidote, and in quartz blebs enclosed within eclogitic minerals. In high-δ18O HP/UHPM rocks from Hujialin and Shima, high-salinity brine and/or N2 inclusions occur in garnet porphyroblasts, which also contain inclusions of coesite, Cl-rich blue amphibole and dolomite. In contrast, in low-δ18O eclogites from Qinglongshan and Huangzhen, the Cl concentrations in amphibole are very low, 〈 0.2 wt.%, and low-salinity aqueous inclusions occur in quartz inclusions in epidote porphyroblasts and in epidote cores. These low-salinity fluid inclusions are believed to be remnants of meteoric water, although the fluid composition was modified during pre- and syn-peak HP/UHPM. Eclogites at Houshuichegou and Hetang contain CH4-rich fluid inclusions, coexisting with high-salinity brine inclusions. Methane was probably formed under the influence of CO2-rich aqueous fluids during serpentinisation of mantle-derived peridotites prior to or during plate subduction. Remnants of premetamorphic low- to high-salinity aqueous fluid with minor N2 and/or other gas species preserved in the Dabie-Sulu HP/UHPM eclogites and garnet clinopyroxenite indicate a great diversity of initial fluid composition in the precursors, implying very limited fluid–rock interaction during syn- and post-peak HP/UHPM.

Notes: Coesite relics were discovered as inclusions in clinopyroxene in eclogite and as inclusions in zircon in felsic and pelitic gneisses from Higher Himalayan Crystalline rocks in the upper Kaghan Valley, north-west Himalaya. The metamorphic peak conditions of the coesite-bearing eclogites are estimated to be 27–32 kbar and 700–770 °C, using garnet–pyroxene–phengite geobarometry and garnet–pyroxene geothermometry, respectively. Cathodoluminescence (CL) and backscattered electron (BSE) imaging distinguished three different domains in zircon: inner detrital core, widely spaced euhedral oscillatory zones, and thin, broadly zoned outermost rims. Each zircon domain contains a characteristic suite of micrometre-sized mineral inclusions which were identified by in situ laser Raman microspectroscopy. Core and mantle domains contain quartz, apatite, plagioclase, muscovite and rutile. In contrast, the rim domains contain coesite and minor muscovite. Quartz inclusions were identified in all coesite-bearing zircon grains, but not coexisting with coesite in the same growth domain (rim domain). 206Pb/238U zircon ages reveal that the quartz-bearing mantle domains and the coesite-bearing rim were formed at c. 50 Ma and 46.2 ± 0.7 Ma, respectively. These facts demonstrate that the continental materials were buried to 100 km within 7–9 Myr after initiation of the India–Asia collision (palaeomagnetic data from the Indian oceanic floor supports an initial India-Asia contact at 55–53 Ma). Combination of the sinking rate of 1.1–1.4 cm year−1 with Indian plate velocity of 4.5 cm year−1 suggests that the Indian continent subducted to about 100 km depth at an average subduction angle of 14–19°.

Notes: The Solund–Hyllestad–Lavik area affords an excellent opportunity to understand the ultrahigh-pressure Scandian orogeny because it contains a near-complete record of ophiolite emplacement, high-pressure metamorphism and large-scale extension. In this area, the Upper Allochthon was intruded by thec. 434 Ma Sogneskollen granodiorite and thrust eastward over the Middle/Lower Allochthon, probably in the Wenlockian. The Middle/Lower Allochthon was subducted to c. 50 km depth and the structurally lower Western Gneiss Complex was subducted to eclogite facies conditions at c. 80 km depth by c. 410–400 Ma. Within 〈 5–10 Myr, all these units were exhumed by the Nordfjord–Sogn detachment zone, producing shear strains 〉 100. Exhumation to upper crustal levels was complete by c. 403 Ma. The Solund fault produced the last few km of tectonic exhumation, bringing the near-ultrahigh-pressure rocks to within c. 3 km vertical distance from the low-grade Solund Conglomerate.

Notes: New petrographic evidence and a review of the latest radiometric age data are taken to indicate that formation of the ultra-high pressure (UHP) eclogites within the Western Gneiss Region of Norway probably occurred within the 400–410 Ma time frame. Thus, this event took place significantly later than the previous, widely accepted age of c. 425 Ma for the timing of the high pressure metamorphism in this part of the Scandinavian Caledonides. Garnet growth under UHP (coesite-stable) conditions is recognised as a discrete, younger event following on from earlier garnet formed under firstly amphibolite facies then quartz-stable, eclogite facies conditions. Currently, the best constrained and most precise age, specifically for UHP mineral growth, is the 402 ± 2 Ma U–Pb age for metamorphic zircon (some of which retain coesite inclusions) from the Hareidland eclogite. Exhumation must have followed shortly thereafter and, based on synoptic pressure–temperature and depth–time curves, must have been very fast. Our data and those of others indicate an initial fast exhumation to about 35 km depth by about 395 Ma at a mean rate of about 10 mm a−1. This rapid exhumation rate may have been driven by the appreciable residual buoyancy of the deeply subducted continental crustal slab due to incomplete eclogitization of the dominant Proterozoic orthogneisses during the short-lived UHP event. Subsequent exhumation to 8–10 km depth by about 375 Ma occurred at a much slower mean rate of about 1.3 mm a−1 with the late-stage extensional collapse of the Caledonian orogen playing an increasingly important role, especially in the final unroofing of the Western Gneiss Region with some remarkably preserved UHP rocks.

Notes: Widespread evidence for ultrahigh-pressure (UHP) metamorphism is reported in the Dulan eclogite-bearing terrane, the North Qaidam–Altun HP–UHP belt, northern Tibet. This includes: (1) coesite and associated UHP mineral inclusions in zircon separates from paragneiss and eclogite (identified by laser Raman spectroscopy); (2) inclusions of quartz pseudomorphs after coesite and polycrystalline K-feldspar + quartz in eclogitic garnet and omphacite; and (3) densely oriented SiO2 lamellae in omphacitic clinopyroxene. These lines of evidence demonstrate that the Dulan region is a UHP metamorphic terrane. In the North Dulan Belt (NDB), eclogites are characterized by the peak assemblage Grt + Omp + Rt + Phn + Coe (pseudomorph) and retrograde symplectites of Cpx + Ab and Hbl + Pl. The peak conditions of the NDB eclogites are P = 2.9–3.2 GPa, and T = 631–687 °C; the eclogite shows a near-isothermal decompression P–T path suggesting a fast exhumation. In the South Dulan Belt (SDB), three metamorphic stages are recognized in eclogites: (1) a peak eclogite facies stage with the assemblage Grt + Omp + Ky + Rt + Phn at P = 2.9–3.3 GPa and T = 729–746 °C; (2) a high-pressure granulite facies stage with Grt + Cpx (Jd 〈 30) + Pl (An24–29) + Scp at P = 1.9–2.0 GPa, T = 873–948 °C; and (3) an amphibolite facies stage with the assemblage Hbl + Pl + Ep/Czo at P = 0.7–0.9 GPa and T = 660–695 °C. The clockwise P–T path of the SDB eclogites is different from the near-isothermal decompression P–T path from the NDB eclogites, which suggests that the SDB was exhumed to a stable crustal depth at a slower rate. In essence these two sub-belts formed in different tectonic settings; they both subducted to mantle depths of around 100 km, but were exhumed to the Earth's surface separately along different paths. This UHP terrane plays an important role in understanding continental collision in north-western China.

Notes: Mineral assemblages in Al2O3-rich, SiO2- and K2O-poor metapelitic rocks from the western Odenwald Crystalline Complex (Variscan Mid-German Crystalline Rise, southern Germany) include corundum, spinel, cordierite, sillimanite, garnet and staurolite. Quartz is absent from almost all samples. Therefore, the applicability of conventional geothermobarometry is very limited or even impossible. Detailed petrographic investigation on selected samples permits inference of the sequence of appearance and disappearance of several mineral assemblages. The recognition of such partial re-equilibration stages and their associated mineral assemblages, together with mineral stabilities predicted from KFMASH pseudosections, enables the determination of the pressure-temperature (P–T) trajectories experienced by these rocks during the Variscan metamorphism. The rocks were metamorphosed under low-P/high-T conditions and underwent an anti-clockwise P–T evolution. A pressure increase from about 2 kbar to 4 ± 0.5 kbar was accompanied by heating. Peak metamorphic conditions were reached at pressures of 4 ± 0.5 kbar and temperatures of at least 640 °C, probably even higher. The retrograde evolution is characterised by near-isobaric cooling from ≥ 640 °C to approximately 550 °C. The rocks underwent the anti-clockwise evolution in a subduction-related magmatic arc setting. The close spatial association of the low-P/high-T rocks with recently discovered metabasic eclogites in the eastern part of the Odenwald Crystalline Complex may indicate a fossil paired metamorphic belt in the Central European Variscides.

Notes: The influx of a H2O–CO2-dominated fluid into actinolite-bearing metabasic rocks during greenschist facies metamorphism in the Kalgoorlie area of Western Australia resulted in a zoned alteration halo around inferred fluid conduits that contain gold mineralisation. The alteration halo is divided into two outer zones, the chlorite zone and the carbonate zone, and an inner pyrite zone adjacent to the inferred fluid conduits. Reaction between the fluid and the protolith resulted in the breakdown of actinolite and the development of chlorite, dolomite, calcite and siderite. In addition, rocks in the pyrite zone developed muscovite-bearing assemblages as a consequence of the introduction of potassium by the fluid. Mineral equilibria calculations undertaken using the computer software thermocalc in the model system Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–CO2 show that mineral assemblages in the outer zones of the alteration halo are consistent with equilibrium of the protoliths with a fluid of composition XCO2 = CO2/(CO2 + H2O) = 0.1–0.25 for temperatures of 315–320 °C. The inner zone of the alteration halo reflect equilibrium with a fluid of composition XCO2≈ 0.25. Fluid-rock buffering calculations show that the alteration halo is consistent with interaction with a single fluid composition and that the zoned structure of the halo reflects the volume of this fluid with which the rocks reacted. This fluid is likely to have also been the one responsible for the gold mineralisation at Kalgoorlie.

Notes: Nanometric solid inclusions in diamond incorporated in garnet and zircon from felsic gneiss of the Kokchetav massif, Kazakhstan, have been examined utilizing electron microscopy and focused ion beam techniques. Host garnet and zircon contain numerous pockets of multiple inclusions, which consist of 1–3 diamond crystals intergrown with quartz, phengite, phlogopite, albite, K-feldspar, rutile, apatite, titanite, biotite, chlorite and graphite in various combinations. Recalculation of the average chemical composition of the entrapped fluid represented by multiple inclusion pockets indicates that such fluid contained a low wt% of SiO2, suggesting a relatively low-temperature fluid rather than a melt. Transmission electron microscopy revealed that the diamond contains abundant nanocrystalline inclusions of oxides, rare carbonates and silicates. Within the 15 diamond crystals studied, abundant inclusions were found of SiO2, TiO2, FexOy, Cr2O3, ZrSiO4, and single grains of ThxOy, BaSO4, MgCO3, FeCr2O4 and a stoichiometric Fe-rich pyroxene. The diversity of trace elements within inclusions of essentially the same stoichiometry suggests that the Kokchetav diamond crystallized from a fluid containing variable amounts of Si, Fe, Ti, Cr, Zr, Ba, Mg and Th and other minor components such as K, Na, P, S, Pb, Zn, Nb, Al, Ca, Cl. Most of the components in crystals included in diamond appear to have their origin in the subducted metasediments, but some of them probably originate from the mantle. It is concluded that Kokchetav diamond most likely crystallized from a COH-rich multicomponent supercritical fluid at a relatively low temperature (hence the apparently low content of rock-forming elements), and that the diversity of major and minor components suggests interactions between subducted metasediments and mantle components.

Notes: A high-P granulite facies gneiss complex occurs in north-west Payer Land (74°28′−74°47′N) in the central part of the East Greenland Caledonian (Ordovician–Devonian) orogen. High-P metamorphism of the Payer Land gneiss complex resulted in formation of the assemblages Grt + Cpx + Amp + Qtz + Ru ± Pl in mafic rocks, and Grt + Ol + Cpx + Opx + Spl in rare ultramafic pods. Associated metapelites experienced anatexis in the kyanite stability field. Peak metamorphic assemblages formed around 800–850 °C at pressures of c. 1.4–1.7 GPa, corresponding to crustal depths of c. 50 km. Mafic granulites contain abundant reaction textures, including the replacement of garnet by symplectites of Opx + Spl + Pl, indicating that the high-P event was followed by decompression while the granulites remained at elevated temperatures. Charnockitic gneisses from Payer Land show evidence of late Archean (c. 2.8–2.4 Ga) crustal growth and subsequent Palaeoproterozoic (c. 1.85 Ga) metamorphism. The gneiss complex experienced intense reworking during the Caledonian continental collision. On the basis of Caledonian monazite ages recorded from the high-P anatectic metapelites, the clockwise P–T evolution and formation of the high-P granulite facies assemblages is related to Caledonian crustal thickening, which resulted in formation of eclogites approximately 300 km north of Payer Land. The Payer Land granulites comprise a metamorphic core complex, which is separated from the overlying low-grade supracrustal rocks (the Neoproterozoic Eleonore Bay Supergroup) by a late Caledonian extensional fault zone, the Payer Land Detachment. The steep, nearly isothermal, unloading P–T path recorded by the granulites can be explained by erosional and tectonic unroofing along the Payer Land Detachment.

Notes: High-pressure granulites are characterised by the key associations garnet-clinopyroxene-plagioclase-quartz (in basic rocks) and kyanite-K-feldspar (metapelites and felsic rocks) and are typically orthopyroxene-free in both basic and felsic bulk compositions. In regional metamorphic areas, two essential varieties exist: a high- to ultrahigh-temperature group and a group representing overprinted eclogites. The high- to ultrahigh-temperature type formerly contained high-temperature ternary feldspar (now mesoperthite) coexisting with kyanite, is associated with garnet peridotites, and formed at conditions above 900 °C and 1.5 GPa. Clinopyroxene in subordinate basic rocks is Al-rich and textural evidence points to a high-pressure–high-temperature melting history. The second variety contains symplectite-like or poikilitic clinopyroxene-plagioclase intergrowths indicating former plagioclase-free, i.e. eclogite facies assemblages. This type of rock formed at conditions straddling the high-pressure amphibolite/high-pressure granulite field at around 700–850 °C, 1.0–1.4 GPa. Importantly, in the majority of high-pressure granulites, orthopyroxene is secondary and is a product of reactions at pressures lower than the peak recorded pressure. In contrast to low- and medium-pressure granulites, which form at conditions attainable in the mid to lower levels of normal continental crust, high-pressure granulites (of nonxenolith origin) mostly represent rocks formed as a result of short-lived tectonic events that led to crustal thickening or subduction of the crust into the mantle. Short times at high-temperature conditions are reflected in the preservation of prograde zoning in garnet and pyroxene. High-pressure granulites of both regional types, although rare, are known from both old and young metamorphic terranes (e.g. c. 45 Ma, Namche Barwa, E Himalaya; 400–340 Ma, European Variscides; 1.8 Ga Hengshan, China; 1.9 Ga, Snowbird, Saskatchewan and 2.5 Ga Jianping, China). This spread of ages supports proposals suggesting that thermal and tectonic processes in the lithosphere have not changed significantly since at least the end of the Archean.

Notes: The Mollendo–Camana Block (MCB) is a 50 × 150 km Precambrian inlier of the Andean belt that outcrops along the Pacific coast of southern Peru. It consists of stromatic migmatites of Paleoproterozoic heritage intensely metamorphosed during the Grenville event (c. 1 Ga; U-Pb and U-Th-Pb ages on zircon and monazite). In the migmatites, aluminous mesosomes (FMAS) and quartzofeldspathic leucosomes (KFMASH), contain various amounts of K-feldspar (Kfs), orthopyroxene (XMg Opx = 0.86), plagioclase (Pl), sillimanite (Sil; exceptionally kyanite, Ky) ilmenite (Ilm), magnetite (Mag), quartz (Qtz), and minor amounts of garnet (XMg Grt = 0.60), sapphirine (XMg Spr = 0.87), cordierite (XMg Crd = 0.92) and biotite (XMg Bt = 0.83). The ubiquitous peak mineral assemblage is Opx-Sil-Kfs-Qtz-(± Grt) in most of the MCB, which, together with the high Al content of orthopyroxene (10% Al2O3) and the local coexistence of sapphirine-quartz, attest to regional UHT metamorphism (〉 900 °C) at pressures in excess of 1.0 GPa. Fluid-absent melting of biotite is responsible for the massive production of orthopyroxene that proceeded until exhaustion of biotite (and most of the garnet) in the southern part of the MCB (Mollendo-Cocachacra areas). In this area, a first stage of decompression from 1.1–1.2 to 0.8–0.9 GPa at temperatures in excess of 950 °C, is marked by the breakdown of Sil-Opx to Spr-Opx-Crd assemblages according to several bivariant FMAS reactions. High-T decompression is also shown by Mg-rich garnet being replaced by Crd-Spr- and Crd-Opx-bearing symplectites, and reacting with quartz to produce low-Al-Opx-Sil symplectites in quartz-rich migmatites. Neither osumilite nor spinel-quartz assemblages being formed, isobaric cooling at about 0.9 GPa probably followed the initial decompression and proceeded with massive precipitation of melts towards the (Os) invariant point, as demonstrated by Bt-Qtz-(± pl) symplectites in quartz-rich migmatites (melt + Opx + Sil = Bt + Grt + Kfs + Qtz). Finally, Opx rims around secondary biotite attest to late fluid-absent melting, compatible with a second stage of decompression below 900 °C. The two stages of decompression are interpreted as due to rapid tectonic denudation whereas the regional extent of UHT metamorphism in the area, probably results from large-scale penetration of hot asthenospheric mantle at the base of an over-thickened crust.

Notes: The Arthur River Complex is a suite of gabbroic to dioritic orthogneisses in northern Fiordland, New Zealand. The Arthur River Complex separates rocks of the Median Tectonic Zone, a Mesozoic island arc complex, from Palaeozoic rocks of the palaeo-Pacific Gondwana margin, and is itself intruded by the Western Fiordland Orthogneiss. New SHRIMP U/Pb single zircon data are presented for magmatic, metamorphic and deformation events in the Arthur River Complex and adjacent rocks from northern Fiordland. The Arthur River Complex orthogneisses and dykes are dominated by magmatic zircon dated at 136–129 Ma. A dioritic orthogneiss that occurs along the eastern margin of the Complex is dated at 154.4 ± 3.6 Ma and predates adjacent plutons of the Median Tectonic Zone. Rims on zircon cores from this sample record a thermal event at c. 120 Ma, attributed to the emplacement of the Western Fiordland Orthogneiss. Migmatitic Palaeozoic orthogneiss from the Arthur River Complex (346 ± 6 Ma) is interpreted as deformed wall rock. Very fine rims (5–20 µm) also indicate a metamorphic age of c. 120–110 Ma. A post-tectonic pegmatite (81.8 ± 1.8 Ma) may be related to phases of crustal extension associated with the opening of the Tasman Sea. The Arthur River Complex is interpreted as a batholith, emplaced at mid-crustal levels and then buried to deep crustal levels due to convergence of the Median Tectonic Zone arc and the continental margin.

Notes: Petrological data provide a good record of the thermal structure of deeply eroded orogens, and, in principle, might be used to relate the metamorphic structure of an orogen to its deformational history. In this paper, we present two-dimensional thermal modelling of various subduction models taking into account varying wedge geometry as well as variation of density and topography with metamorphic reactions.The models clearly show that rock type accreted in the wedge has important effects on the thermal regime of orogenic wedges. The thermal regime is dominated by radiogenic heat production. Material having high radioactive heat production, like the granodioritic upper crust, produces high temperature metamorphism (amphibolitic conditions). Material with low radioactive heat production results in low temperature metamorphism of greenschist or blueschist types depending on the thickness of the wedge.Application of this model to seemingly unrelated areas of the Central Alps (Lepontine Dome, Grisons) and Eastern Alps (Tauern Window) explains the coexistence and succession of distinct Barrovian and blueschist facies metamorphic conditions as the result of a single, continuous tectonic process in which the main difference is the composition of the incoming material in the orogenic wedge. Accretion of the European upper continental crust in the Lepontine and Tauern Domes produces Barrovian type metamorphism while accretion of oceanic sediments results in blueschist facies metamorphism in the Valaisan domain.

Notes: Abstract Logging, fire suppression, and urbanization have all contributed to the serious decline and fragmentation of Pinus palustris (longleaf pine) ecosystems in the southeastern United States. Effective management of the remaining patches of these pyrogenic communities must incorporate periodic low-intensity fires, even where they are located on private lands in populated urban and suburban areas. To explore the effects of fire and its potential use for restoration and management of small fragments surrounded by suburban development, we conducted growing season prescribed fires in remnant longleaf pine sandhill patches in the suburbs of Gainesville, Florida. Density and composition of hardwoods were surveyed pre-burn and 1 and 9 months post-burn. Woody stem density decreased in the burn plots, predominantly in the smaller size classes. Flowering responses of forbs and small shrubs were surveyed six times post-burn for 1 year. Overall, the burns did not yield greater densities of flowering stems, but burn patches had higher species richness and diversity than control patches. In addition, there were consistently greater numbers of “showy flowered” sandhill species in flower in burn patches relative to controls. The results of this research demonstrate that prescribed fire can be used for restoration and management of small remnants of longleaf pine sandhill in suburban neighborhoods. It is also clear that although a single prescribed burn can be effective, it will take more than one burn to attain desired restoration goals in degraded longleaf remnants.

Notes: Abstract Efficient and accurate vegetation sampling techniques are essential for the assessment of wetland restoration success. Remotely acquired data, used extensively in many locations, have not been widely used to monitor restored wetlands. We compared three different vegetation sampling techniques to determine the accuracy associated with each method when used to determine species composition and cover in restored Pacific coast wetlands dominated by Salicornia virginica (perennial pickleweed). Two ground-based techniques, using quadrat and line intercept sampling, and a remote sensing technique, using low altitude, high resolution, color and color infrared photographs, were applied to estimate cover in three small restoration sites. The remote technique provided an accurate and efficient means of sampling vegetation cover, but individual species could not be identified, precluding estimates of species density and distribution. Aerial photography was determined to be an effective tool for vegetation monitoring of simple (i.e., single-species) habitat types or when species identities are not important (e.g., when vegetation is developing on a new restoration site). The efficiency associated with these vegetation sampling techniques was dependent on the scale of the assessment, with aerial photography more efficient than ground-based sampling methods for assessing large areas. However, the inability of aerial photography to identify individual species, especially mixed-species stands common in southern California salt marshes, limits its usefulness for monitoring restoration success. A combination of aerial photography and ground-based methods may be the most effective means of monitoring the success of large wetland restoration projects.

Notes: Abstract Possible constraints on the passive recovery of bare areas in the Karoo, a semiarid region in South Africa, include inadequate supply of seed, availability of suitable microsites for plant establishment, altered soil properties, and the truncation of key soil biotic processes. Here we investigate the possibility of initiating the restoration of bare areas by soil surface treatments with gypsum (CaSO4) and/or organic mulch. We also apply an exogenous seed source to test the hypothesis that seed availability limits autogenic recovery. Both gypsum and mulch improved rain water infiltration, gypsum more so than mulch, and both treatments resulted in significantly higher numbers of reseeded seedlings compared with controls. Gypsum also improved the survival of the cohorts of seedlings of the larger seeded Tripteris sinuata. Tripteris showed the highest number of seedlings (maximum count of 150 seedlings/1,000 viable seeds sown) and surviving plants of the three reseeded species, which included two small-seeded species, Ruschia spinosa and Chaetobromus dregeanus. Throughout the study period significantly higher plant volumes of naturally seeded annuals and perennials were recorded in the gypsum and/or mulch treatments compared with the controls. Germination and emergence of reseeded and naturally seeded plants appears to be determined by the availability of cool season (autumn to spring ) soil moisture, whereas follow-up rainfall during this time is important for plant survival. Mulching of bare areas in the Succulent Karoo has the potential to re-create vegetated areas that will further capture and conserve water, soil, and nutrients. Gypsum also showed positive results but might not be a cost-effective option because of transport costs to these remote arid areas.

Notes: Abstract Spring burning of sedge-grass meadows in the Slave River Lowlands (SRL), Northwest Territories, Canada was applied between 1992 and 1998 to reduce shrub encroachment and enhance Bison bison (bison) habitat, although the impact of fire on preferred bison forage was unknown before management. In the summer of 1998 we conducted a study in the Hook Lake area of the SRL to test the effect of burn frequency (unburned, burned once, or burned three times since 1992) on herbaceous plant community composition and Salix spp. L. (willow) shrub vigor. Plant species abundance, litter biomass, soil pH, and depth of the organic soil horizon were measured in 300 1-m2 quadrats nested within 30 1,000-m2 plots in both burned and unburned dry meadows. To test the relationship between frequency and willow vigor, all willow shrubs within the plots were assigned a vigor score from I (dead) to IV (flourishing). The spring burns appear to have reduced willow vigor; however, shrub survival remained high (76%) on the most frequently burned meadows. Ordination plots resulting from canonical correspondence analysis suggest that multiple spring burns influenced plant community composition in dry meadow areas and that less palatable bison forage species (e.g., Carex aenea Fern. and Juncus balticus L.) were correlated with a regime of three spring burns. Our results suggest that frequent spring fires in the Hook Lake area have only a small negative effect on willow cover but may reduce the abundance of primary bison forage plants compared with less frequently burned meadows.

Notes: Abstract Although there is no one correct technique for sampling vegetation, the sampling design chosen may greatly influence the conclusions researchers can draw from restoration treatments. Considerations when designing vegetation sampling protocol include determining what sampling attributes to measure, the size and shape of the sampling plot, the number of replicates and their location within the study area, and the frequency of sampling. We installed 20 point-intercept transects (50-m long), 8 belt transects (10 × 50 m), 10 adapted Daubenmire transects (four 0.5 × 2-m plots), and 4 modified-Whittaker plots (20 × 50 m with smaller nested plots) in treatment and control units to measure understory herbaceous response in a forest restoration experiment that tested different treatments. Point-intercept transects on average recorded at least twice as much plant cover as did adapted Daubenmire transects and modified-Whittaker plots taken at the same location for all control and treatment units. Point-intercept transects and adapted Daubenmire plots on average captured fewer rare and exotic species in the control and treatment units in comparison with the belt transects and modified-Whittaker plots. Modified-Whittaker plots captured the highest species richness in all units. Early successional understory response to restoration treatments was likely masked by the response of the herbaceous community to yearly climatic variation (dry vs. wet years). Species richness and abundance were higher in wet years than dry years for all control and treatment units. Our results illustrate that sampling techniques can greatly influence perceptions of understory plant trajectories and therefore the interpretation of whether restoration goals have been achieved. In addition, our results suggest that restoration monitoring needs to be conducted for a sufficient length of time so that restoration treatment responses can be detected.

Notes: Abstract A comparison of a composted organic amendment, a controlled-release fertilizer, and induced mycorrhizal inoculation as affecting the establishment and nutrition of bareroot Jeffrey pine (Pinus jeffreyi Grev. & Balf.) was conducted on a Sierra Nevada surface mine. The soil amendments were applied at outplanting to the backfill of augered planting holes, with a low rate of 8 g and a high rate of 16 g per seedling for the fertilizer, Gromax 21-6-2 + Minors, whereas a single rate of 2.0 L was used for organic matter. Colonization by Pisolithus tinctorius (Pers.) Coker & Couch was induced by coating the root systems with basidiospores suspended in a gel carrier. The organic amendment especially, but also mycorrhizal inoculation, caused substantial seedling mortality, whereas survival was unaffected by controlled-release fertilization. Gromax applied at the high rate produced a 74% increase in shoot volume after three growing seasons, whereas the organic amendment reduced volume by 28%. Growth was unaffected by mycorrhizal treatment. The growth response to the 16-g Gromax application probably reflected enhanced N, P, and K nutrition and decreased concentrations of potentially toxic metallic elements, including Mn and Al among others, as revealed through foliar analysis. Because they were accompanied by growth reduction, nutritional responses to the organic amendment, which involved both macronutrients and trace elements, were of little consequence. Impaired water relations may account for the poor response to this amendment. Likewise, nutritional responses to mycorrhizal inoculation produced no discernible benefit in terms of seedling performance. An inoculation procedure that failed to induce substantially greater P. tinctorius colonization in inoculated than uninoculated seedlings, and that may have also impaired water relations, likely explains this result. Overall, these findings indicate that further research is needed before either the organic amendment or the mycorrhizal inoculation procedure used here can be used in forest restoration efforts on dry sites.

Notes: Abstract We compared the floristic composition and structure of restoration areas of eucalypt woodland with untreated pasture (control) and remnant vegetation (reference) in western Sydney. The restored areas comprised over 1,000 ha of abandoned pasture, which had been treated to reduce weeds and planted with seedlings of 26 native plant species raised from seed obtained locally from remnant vegetation. Plantings were carried out 0–9 years ago. Floristic composition was measured in quadrats using frequency scores and cover abundance. As far as possible treatments and restoration ages were replicated across sites. Ordination and analyses of similarity failed to distinguish the composition of restored vegetation from that of untreated pasture, which were both significantly different from that of remnant vegetation. There was a weak compositional trend with age of restored vegetation, but this was not in the direction of increasing resemblance to remnant vegetation. There was some evidence for convergence in structural features of restored with remnant vegetation, but this was at least partly attributed to plant growth. Subject to constraints imposed by the sampling design, environmental factors, and spatial variation were discounted as explanations for the results. The results therefore suggest either failure of restoration treatments or a restoration trajectory that is too slow to detect within 10 years of establishment. Our conclusions agree with those of similar studies in other ecosystems and support: (1) the need to monitor restoration projects against ecological criteria with rigorous sampling designs and analytical methods, (2) further development of restoration methods, and (3) regulatory approaches that seek to prevent damage to ecosystems rather than those predicated on replacing losses with reconstructed ecosystems.

Notes: Abstract Landslides result in the loss of vertical vegetative structure, soil nutrients, and the soil seed bank. These losses impede timely recovery of tropical forest communities. In this study we added bird perches to six Puerto Rican landslides with three types of surfaces (bare, climbing fern, grass) in an effort to facilitate inputs of forest seeds through bird dispersal and to accelerate plant succession. Numbers of bird-dispersed forest seeds were significantly higher in plots beneath introduced perches than in control plots. Perches did not increase forest seedling densities compared with control plots. Seven different species of birds were observed on introduced perches. Because 99% of the seed inputs to controls and perch plots in the six landslides were wind-dispersed seeds (mostly graminoids), perches can improve landslide restoration if woody plants establish and shade out the dominant graminoid and climbing fern ground cover. Although increasing seed inputs from forest species is a critical step in accelerating revegetation of landslides, we suggest that supplemental restoration techniques be applied in addition to bird perches to promote forest recovery.

Notes: Abstract The effects of seasonal drought, belowground competition, and low soil fertility on the survival and growth over 2 years of four native tree species planted on a degraded hillside grassland in Hong Kong were studied in a field transplant experiment using three-way analysis of variance. The tree species were Schima superba (Theaceae), Castanopsis fissa (Fagaceae), Schefflera heptaphylla (Araliaceae), and Sapium discolor (Euphorbiaceae), and the treatments were dry season irrigation, herbicide, and fertilizer. Each species responded differently to the treatments. Sapium had a very low survival rate as a result of wind damage at the exposed study site. All three treatments significantly reduced the survival rate of Castanopsis seedlings, whereas herbicide reduced it for Sapium but increased it for Schefflera. The significant effects on seedling growth were all positive, except for a strong negative effect of herbicide on Castanopsis growth. Overall, the results suggest that all three factors—seasonal drought, belowground competition, and low soil nutrients—can significantly impair seedling growth on a degraded hillside site in Hong Kong but that their relative importance differs among species. The growth benefits of the three treatments were largest and most consistent for Schima, which as a mature forest dominant would be expected to be particularly sensitive to the environmental conditions on degraded open sites. This study highlights the fact that more systematic planting trials are needed to identify suitable native tree species for cost-effective reforestation on degraded hillsides in Hong Kong and South China.

Notes: Abstract Prescribed fire is often used to restore grassland systems to presettlement conditions; however, fire also has the potential to facilitate the invasion of exotic plants. Managers of wildlands and nature reserves must decide whether and how to apply prescribed burning to the best advantage in the face of this dilemma. Herbicide is also used to control exotic plants, but interactions between fire and herbicides have not been well studied. Potentilla recta is an exotic plant invading Dancing Prairie Preserve in northwest Montana. We used a complete factorial design with all combinations of spring burn, fall burn, no burn, picloram herbicide, and no herbicide to determine the effects of fire, season of burn, and their interaction with herbicide on the recruitment and population growth of P. recta over a 5-year period. Recruitment of P. recta was higher in burn plots compared with controls the first year after the fire, but this did not lead to significant population growth in subsequent years, possibly due to drier than normal conditions that occurred most years of the study. Effect of season of burn was variable among years but was higher in fall compared with spring burn plots across all years. Herbicide effectively eliminated P. recta from sample plots for 3–5 years. By the end of the study density of P. recta was greater in herbicide plots that were burned than those that were not. Results suggest that prescribed fire will enhance germination of P. recta, but this will not always lead to increased population growth. Prescribed fire may reduce the long-term efficacy of herbicide applied to control P. recta and will be most beneficial at Dancing Prairie when conducted in the spring rather than the fall. Results of prescribed fire on exotic plant invasions in semiarid environments will be difficult to predict because they are strongly dependent on stochastic climatic events.

Notes: Abstract Boating activities are an increasing source of physical damage to coral reefs worldwide. The damage caused by ship groundings can be significant and may result in a shift in reef structure and function. In this study we evaluate the status of two restoration projects established in 1995, 6 years after two freighters, the M/V Maitland and the M/V Elpis, ran aground on reefs of the Florida Keys National Marine Sanctuary. Our approach includes field monitoring in support of simulation model development to assess the effectiveness of the restoration efforts. A population model was developed for the coral Porites astreoides to project the convergence rates of coral abundance and population size structure between the restored and surrounding reference habitats. Coral communities are developing rapidly on the restoration structures. Species richness and abundance of the dominant coral, P. astreoides, were nearly indistinguishable between the restoration structures and reference habitats after only 6 years. However, although abundance and size structure of P. astreoides populations are rapidly approaching those of the reference habitats (a convergence in size structure within 10 years was simulated), maximum coral size will take twice as long to converge for this species. The sensitivity of the model to maximum recruitment rates highlights the importance of recruitment on the recovery rates of restored habitats, suggesting that special attention should be afforded to provide coral recruits with appropriate recruitment substrate at the time of restoration. Finally, the rates of convergence and, hence, the level of success of a restoration effort were shown to be influenced not only by the recruitment and survivorship rates of corals on the restoration structures but by the characteristics of the reference population as well. Accordingly, reference populations ought to be considered a “moving target” against which restoration success has to be measured dynamically. The simple, cost-effective, monitoring–modeling approach presented here can provide the necessary tools to assess the current status of a restoration effort and to project the time required for coral populations to resemble those found on undamaged reference habitats

Notes: Abstract Uniola paniculata (sea oats) rhizomes uprooted by hurricanes and deposited as wrack could be salvaged and replanted in dune restoration. To test this unexplored technique, percent tiller emergence was observed for 4 years from U. paniculata rhizomes replanted after submersion in seawater; air exposure of 0, 1, 3, 5, 7, and 11 days; freshwater rinse; and reburial in pots (watered) or on the beach (with or without supplemental water). In addition, U. paniculata rhizomes uprooted by Hurricane Georges were experimentally planted, and effects of soil salinity and moisture on emergence were tested in the greenhouse. Tiller emergence declined with increasing length of air exposure and decreasing size of rhizome. Tiller survival was enhanced by rainfall, rinsing with salt or fresh water during exposure and immediately after planting or supplemental beach watering. Although emergence was not reduced by soil salinity of 1,800 μS/cm, emergence was reduced by soil salinity of 5,800 μS/cm. Across the 4 years of the study tiller emergence from treated rhizomes varied considerably. U. paniculata rhizomes lost bud viability after 3–5 days of beach exposure, unless fresh water from rainfall, wet burlap storage, or watering was applied within 3 days. Bud viability was extended through 11 days when supplied with water. Thus, reburial within 3–11 days after a storm is a viable restoration technique.

Notes: Abstract Annual grasslands in California are often managed with seasonal grazing and prescribed burning on the assumption that such practices have long-term benefits for native species. Mature native perennial bunchgrasses, particularly Nassella pulchra (purple needlegrass), are often the focal species, although very little is known about responses at different life history stages. Thus, important questions remain about long-term population dynamics of both mature plants and seedling recruitment. In plots receiving repeated grazing and burning events over 7 years, mortality of mature plants was threefold higher on mounds than on intermounds and likely reflected increased competition intensity associated with increased resource availability in deeper soil. Burning and grazing treatments had strong positive effects on basal area of mature N. pulchra. However, plants in grazed plots that were not burned contained considerable standing dead biomass. Topographic location strongly influenced growth as intermound plants grew relatively more than mound plants, but the effects on growth of burning and grazing did not vary with topographic location. In mapped plots N. pulchra recruitment was very low, and overall density dropped an average of 31%. However, a significant time-by-burning effect indicated that survival was significantly higher in burned plots. After 7 years of repeated treatments, effects of burning and grazing management on mature N. pulchra were positive but not for all phenological stages. Understanding long-term influence of management on bunchgrass populations may not be easy to determine because short-term results may not reflect long-term responses and some life cycle dynamics may be observed only over very long periods.

Notes: Abstract Cades Cove, Great Smoky Mountains National Park, U.S.A. was historically cleared largely for pastoral purposes; it is now comprised of recently abandoned pastures dominated by non-native pasture species. To investigate the potential for reducing non-native species relative to native species, park managers initiated an experiment in 1995 that included mowing, herbicide application, planting of seed, and burning of replicate 20 × 50–m plots at each of two sites within Cades Cove. Between 1995 and 2001 we evaluated the response of the plant community (i.e., species-specific cover and frequency, biomass, diversity) to this suite of treatments and compared it with unmanipulated control plots at each site. Four years after treatment initiation abundance measures of Plantago lanceolata, Setaria geniculata, and Trifolium spp. averaged one-third lower in treated than control plots. Frequency of Festuca pratensis was lower in treated than in control plots for 2 years, but after 4 years its frequency, cover, and biomass did not differ between treated and control plots. By 2000 the cover of Sorghastrum nutans in treated plots increased to 23–47%, depending on the site. Total biomass and diversity increased in treated plots. The dominance of Lespedeza cuneata at one site apparently reduced planting success, biomass production, and diversity and evenness. Post-treatment lags in response for several species, coupled with interannual variation in response to environmental conditions, suggest that evaluations of treatment success would differ greatly depending on when the evaluation was conducted.

Notes: Abstract We compared nekton and benthos densities and community compositions in a natural mixed seagrass bed dominated by Halodule wrightii (shoalgrass) with those found in three shoalgrass transplant sites and adjoining sand habitats in western Galveston Bay, Texas, U.S.A. Quantitative drop traps and cores were used to compare communities up to seven times over 36 months post-transplant where transplant beds survived. Total densities of fishes, decapods, annelids, benthic crustaceans, and most dominant species were significantly higher in natural seagrass than in transplanted shoalgrass or sand habitats during most sampling periods. On occasion, fish and decapod densities were significantly higher in transplanted shoalgrass than in adjoining sand habitats. No consistent faunal differences were found among transplant sites before two of three sites failed. Taxonomic comparison of community compositions indicated that nekton and benthos communities in natural seagrass beds were usually distinct from those in transplanted beds or sand habitats, which were similar. We conclude that reestablishing a shoalgrass bed that resembles a natural seagrass bed and its faunal communities in the Galveston Bay system will take longer than 3 years, provided that transplants persist.

Notes: Abstract Restoration of degraded natural vegetation in parks is often complicated by the need to maintain public access. We tested whether the natural canopy species, Thuja occidentalis, can be restored to degraded cliff edges in Bruce Peninsula National Park, Ontario, Canada without reductions in visitor numbers. Eighty 10-year-old and 80 4-year-old container-grown saplings and 1,400 seeds were planted and monitored for 4 years. Eight treatments were applied that tested for effects of planting site (distance from cliff edge and pathways) and supportive measures (soil, water, cages, or signs) on survival, growth, and damage. No trees became successfully established from seed. Younger trees showed faster initial establishment and growth, but 4-year survival was the same for both age groups (39%). Supplemental soil improved the health of planted trees, and both soil and water slightly improved their survival. Cages did not affect survival and growth but decreased damage to 4-year-old trees and increased it for 10-year-olds. Signs had no effect on any measured variable. Trees planted away from the cliff edge and from pathways had the greatest establishment success, 4-year survival, and general health. Relative visitor density, as estimated from spot counts of visitors, had the largest effect on restoration success; the results suggest a threshold of visitor density above which restoration may be impossible. Planting location, especially with respect to shade, was also important. The planting of 4-year-old trees without supportive measures is suggested as the most cost-effective restoration technique at this site. The results indicate that restoration of open woodland habitats is possible without total visitor exclusion but that some restrictions on visitor numbers or activities are necessary.

Notes: The central part of the Carolina terrane in western South Carolina comprises a 30 to 40 km wide zone of high grade gneisses that are distinct from greenschist facies metavolcanic rocks of the Carolina slate belt (to the SE) and amphibolite facies metavolcanic and metaplutonic rocks of the Charlotte belt (to the NW). This region, termed the Silverstreet domain, is characterized by penetratively deformed felsic gneisses, granitic gneisses, and amphibolites. Mineral assemblages and textures suggest that these rocks formed under high-pressure metamorphic conditions, ranging from eclogite facies through high-P granulite to upper amphibolite facies.Mafic rocks occur as amphibolite dykes, as metre-scale blocks of coarse-grained garnet-clinopyroxene amphibolite in felsic gneiss, and as residual boulders in deeply weathered felsic gneiss. Inferred omphacite has been replaced by a vermicular symplectite of sodic plagioclase in diopside, consistent with decompression at moderate to high temperatures and a change from eclogite to granulite facies conditions. All samples have been partially or wholly retrograded to amphibolite assemblages. We infer the following P-T-t history: (1) eclogite facies P-T conditions at ≥ 1.4 GPa, 650–730 °C (2) high-P granulite facies P-T conditions at 1.2–1.5 GPa, 700–800 °C (3) retrograde amphibolite facies P-T conditions at 0.9–1.2 GPa and 720–660 °C. This metamorphic evolution must predate intrusion of the 415 Ma Newberry granite and must postdate formation of the Charlotte belt and Slate belt arcs (620 to 550 Ma).Comparison with other medium temperature eclogites and high pressure granulites suggests that these assemblages are most likely to form during collisional orogenesis. Eclogite and high-P granulite facies metamorphism in the Silverstreet domain may coincide with a ≈570–535 Ma event documented in the western Charlotte belt or to a late Ordovician-early Silurian event. The occurrence of these high-P assemblages within the Carolina terrane implies that, prior to this event, the western Carolina terrane (Charlotte belt) and the eastern Carolina terrane (Carolina Slate belt) formed separate terranes. The collisional event represented by these high-pressure assemblages implies amalgamation of these formerly separate terranes into a single composite terrane prior to its accretion to Laurentia.

Notes: Abstract Ecological restoration enjoys widespread use as a technique to mitigate for environmental damage. Success of a restoration project often is evaluated on the basis of plant cover only. Recovery of a native arthropod fauna is also important to achieve conservation goals. I sampled arthropod communities by pitfall trapping in undisturbed, disturbed, and restored coastal sage scrub habitats in southern California. I evaluated arthropod community composition, diversity, and abundance using summary statistics, cluster analysis, and detrended correspondence analysis (DCA) and investigated influence of vegetation on arthropod communities with multiple regression analysis. Arthropod diversity at undisturbed and disturbed sites was greater than at sites that were 5 and 15 years following restoration ( p 〈 0.05). Number of arthropod species was not significantly different among undisturbed, disturbed, and restored sites, and two restoration sites had significantly more individuals than other sites. Vegetation at disturbed and undisturbed sites differed significantly; older restorations did not differ significantly from undisturbed sites in diversity, percent cover, or structural complexity. In multiple regression models, arthropod species richness and diversity was negatively related to vegetation height but positively related to structural complexity at intermediate heights. Exotic arthropod species were negatively associated with overall arthropod diversity, with abundance of the earwig Forficula auricularia best predicting diversity at comparison (not restored) sites (r2 = 0.29), and abundance of the spider Dysdera crocata and the ant Linepithema humile predicting diversity at all sites combined (r2 = 0.48). Native scavengers were less abundant at restored sites than all other sites and, with a notable exception, native predators were less abundant as well. DCA of all species separated restored sites from all other sites on the first axis, which was highly correlated with arthropod diversity and exotic arthropod species abundance. Lower taxonomic levels showed similar but weaker patterns, with example families not discriminating between site histories. Vegetation characteristics did not differ significantly between the newly restored site and disturbed sites, or between mature restoration sites and undisturbed sites. In contrast, arthropod communities at all restored sites were, as a group, significantly different from both disturbed and undisturbed sites. As found in other studies of other restoration sites, arthropod communities are less diverse and have altered guild structure. If restoration is to be successful as compensatory mitigation, restoration success standards must be expanded to include arthropods.

Notes: Abstract The Pacific islands off southern California, U.S.A. and Baja California, Mexico hold potential for the conservation and restoration of California Mediterranean coastal ecosystems. However, the presence of exotic herbivores and invasive plants pose threats to these systems. Here, we use introduced herbivore removal as a large-scale experimental manipulation to examine the importance of top-down and bottom-up processes to a large-scale restoration effort. Using a paired approach on the Todos Santos Islands, Mexico we removed herbivores from one island, while they temporarily remained on an adjacent and similar island. We augmented this experiment with smaller scale herbivore exclosures on the control island. At both scales we failed to detect an herbivore effect on the plant community; rather plant community dynamics appeared to be dominated by El Niño related precipitation and exotic annuals. A parallel experiment on the San Benito Islands, Mexico revealed a different dynamic: Top-down effects on the plant community by exotic herbivores were evident. Differences in the response from the plant communities to both exotic herbivore presence and removal between these two island groups, along with Santa Barbara Island, U.S.A., where restoration has been on-going, raise important questions in ecosystem restoration. The history of anthropogenic disturbance, exotic plant abundance, and aridity play roles in postherbivore removal recovery. Although island conservation practitioners have honed the ability to remove exotic mammals from islands, development of invasive plant removal techniques is needed to fully capitalize on the conservation potential of California island ecosystems.

Notes: Abstract Restoration practitioners have long been faced with a dichotomous choice of native versus introduced plant material confounded by a general lack of consensus concerning what constitutes being native. The “restoration gene pool” concept assigns plant materials to one of four restoration gene pools (primary to quaternary) in order of declining genetic correspondence to the target population. Adaptation is decoupled from genetic identity because they often do not correspond, particularly if ecosystem function of the disturbed site has been altered. Because use of plant material with highest genetic identity, that is, the primary restoration gene pool, may not be ultimately successful, material of higher order pools may be substituted. This decision can be made individually for each plant species in the restored plant community in the scientific context that ecosystem management demands. The restoration gene pool concept provides a place for cultivars of native species and noninvasive introduced plant material when use of native-site material is not feasible. The use of metapopulation polycrosses or composites and multiple-origin polycrosses or composites is encouraged as appropriate. The restoration gene pool concept can be implemented as a hierarchical decision-support tool within the larger context of planning seedings.

Notes: Abstract Willamette Valley upland prairie in western Oregon, U.S.A. has been severely degraded and fragmented in the past 150 years after European settlement, resulting in vast population reductions of endemic species. Icaricia icarioides fenderi (Fender's blue butterfly) and Lupinus sulphureus ssp. kincaidii (Kincaid's lupine) are federally listed as Endangered and Threatened Species, respectively. Both are Willamette Valley upland prairie endemics, and Kincaid's lupine is the primary host plant for the Fender's blue butterfly. Attempts to grow Kincaid's lupine have been partially successful in a greenhouse situation; however, propagating plants from field-sown seed can be tenuous and plant establishment is unpredictable. Kincaid's lupine seeds were planted in the fall 1997 at two different upland prairie sites, and the cohort was followed through the summer 2000. Based on cohort tables the most vulnerable life stages to mortality are the germinant stage and the first growing year. Mechanical scarification of Kincaid's lupine seeds yielded no significant differences in survivorship, maternal function, plant size, and the percentage of seeds germinated compared with unscarified seeds. Differential seed source performance detected at one planting site suggests that underlying differences in population genetics may affect Kincaid's lupine vigor, fitness, and establishment. Future restoration projects for Kincaid's lupine should focus on upland prairie sites with naturally occurring lupine populations because local ecological conditions are favorable for lupine establishment. Moreover, the addition of new individuals to small Kincaid's lupine colonies will buffer against the effects of inbreeding depression and increase the site carrying capacity for Fender's blue butterfly.

Notes: Abstract Rapid establishment by aggressive plants such as Phalaris arundinacea (reed canarygrass) often interferes with sedge meadow establishment in restored prairie pothole wetlands in the mid-continental United States. Introducing a cover crop during community establishment might suppress P. arundinacea invasion in restored prairie potholes by reducing resource availability. We evaluated two potential cover crops, Echinochloa crusgalli (barnyardgrass) and Polygonum lapathifolium (nodding smartweed), for suppressing P. arundinacea invasion in an experimental wetland using replacement series competition experiments. Further, we assessed the effects of E. crusgalli and P. lapathifolium on sedge meadow establishment by sowing Carex hystericina, a common wetland sedge, as a third species at a constant density in the replacement experiments. Echinochloa crusgalli, compared with no cover crop, reduced P. arundinacea biomass by more than 1,000 g/m2 (65%) after two growing seasons. Polygonum lapathifolium did not affect P. arundinacea biomass. Dense E. crusgalli canopies in the first year and thick E. crusgalli thatch in the second year substantially reduced light availability for P. arundinacea establishment. Echinochloa crusgalli also reduced C. hystericina biomass by more than 1,800 g/m2 (99%) after two growing seasons. Carex hystericina biomass was similar in plots sown with E. crusgalli to P. arundinacea monocultures. Neither E. crusgalli nor P. lapathifolium is likely to improve sedge meadow restoration success. These trends were not sensitive to initial sowing density or elevation above water level. Without methods to suppress P. arundinacea invasions, sedge meadow restorations may often fail. Thorough site preparation to remove P. arundinacea propagule sources before restoration is essential.

Notes: Abstract Interest in restoring native ecosystems is resulting in conversion of marginal agricultural lands to bottomland hardwood-dominated forests in the midwestern and midsouthern United States. Growing stock for these efforts typically consists of planted oak (Quercus spp.) and volunteer vegetation. Reports of mixed reforestation success and the lack of post-establishment tree growth data prompted this evaluation of vegetation characteristics of 5- to 7-year-old operational restorations in the Lower Cache River Watershed in southernmost Illinois, U.S.A. Fraxinus pennsylvanica (green ash), Acer negundo (box-elder), and Liquidambar styraciflua (sweetgum) together comprised 77% of all tree stems observed. Full stocking of overstory tree species can be expected to produce a closed canopy stand within 160 m of a forested edge, due primarily to the abundance of rapidly growing volunteer-origin trees. Planted oaks contributed minimally to total tree stocking but were present in sufficient numbers to eventually improve wildlife habitat, and therefore satisfied restoration objectives. Oak height was 23% greater when in the presence of a non-oak tree species. Herbaceous cover was dominated by Solidago gigantea (late goldenrod) and Juncus spp. (rushes). Solidago gigantea was associated with poor growth and low density of non-oak stems, whereas Juncus dudleyi (Dudley's rush) was associated with taller non-oak stems. These results suggest that the presence of volunteer-origin trees is crucial for the creation of full stand stocking that will result in rapid development of a closed canopy forest. Improved success of future reforestation efforts will require more intensive methods to establish adequate stocking beyond 160 m of a forest edge. Methods described here could be adapted for agricultural field to forest restorations in other regions to predict critical distances from volunteer seed sources within which supplemental planting would be unnecessary to meet tree stocking objectives.

Notes: Abstract The decline and range reduction of sage grouse populations are primarily due to permanent loss and degradation of sagebrush–grassland habitat. Several studies have shown that sage grouse productivity may be limited by the availability of certain preferred highly nutritious forb species that have also declined within sagebrush ecosystems of the Intermountain West, U.S.A. The purpose of this study was to determine the suitability of three species of forbs for revegetation projects where improving sage grouse habitat is a goal. Species suitability was determined by evaluating the emergence, survival, and reproduction of Crepis modocensis, C. occidentalis, and Astragalus purshii in response to method of establishment (seeding or transplanting), site preparation treatment (burned or unburned), and microsite (mound or interspace) in an Artemisia tridentata ssp. wyomingensis vegetation association in south central Oregon. For seeded plants A. purshii had the lowest emergence (8%) of all three species. Both seeded Crepis species had similar overall emergence (38%). Significantly more Crepis seedlings emerged from shrub mounds in unburned areas (50%) than in any other fire-by-microsite treatment (33 to 36%). Approximately 10% more Crepis seedlings survived in mounds compared with interspaces. Nearly twice as many emerging Crepis seedlings survived in the burned areas as opposed to unburned areas (p 〈 0.01). This resulted in more plant establishment in burned mounds despite higher emergence in unburned mounds. Astragalus purshii seedlings also survived better in burned areas (p = 0.06) but had no differential response to microsite. Fire enhanced survival of both Crepis and A. purshii transplants (p = 0.08 and p = 0.001). We believe additional research is needed to improve A. purshii emergence before it will become an effective plant for restoring sage grouse habitat. Conversely, we conclude that these Crepis species provide a viable revegetation option for improving sage grouse habitat in south central Oregon.

Notes: Abstract Vegetation samples from either spontaneously revegetated or technically reclaimed spoil heaps of different ages in one of the largest active brown coal mining districts in Europe were analyzed and compared. The spoil heaps are located in the northwestern part of the Czech Republic and represent ages between 0 and 45 years. Ordination analysis (detrended correspondence analysis) showed that vegetation on technically reclaimed spoil heaps developed in a different way than that on spontaneously revegetated ones. The latter exhibited much higher species diversity in the oldest stages with the number of species doubled that of technically reclaimed sites. The oldest stages were also more advanced along an expected successional gradient as indicated by the ordination. Accelerating the vegetation development by technical reclamation was only of temporal character, whereas spontaneous succession proceeded further over the longer time scale. Spontaneous succession is advocated as an inexpensive and easy alternative to technical reclamation, because it leads to a more natural and rich vegetation cover. Unfortunately, technical reclamation is still the only approach considered in the present reclamation activities for this region.