ALBERT

Notes: Books reviewed in this article: Perspectives on Biodiversity: Case Studies of Genetic Resource Conservation and Development. Christopher S. Potter, foci 1. Cohen, and Dianne Janczewski, editors

Notes: To evaluate reclamation success on the Wooley Valley phosphate mine in southeastern Idaho, we compared vegetation structure and soil physical, chemical, and elemental properties of several different reclamation treatments with those of a nearby reference area (a native Artemisia tridentata vaseyana/Festuca idahoensis association) after 14 years. Vegetation data had been collected four years after reclamation, and we were able to compare differences in biomass and species composition between dates on the reclaimed area. Four years after reclamation there were no differences in total biomass between topsoil or spoil or between seed only, seed + mulch, or control treatments on the different soil types. Most treatments were dominated by seeded perennial grasses. Fourteen years after reclamation there were no differences in biomass or cover between spoil and topsoil plots, but on spoil plots the seeded and mulched treatment had higher total biomass and vegetation cover than on control or seed-only treatments. The seeded perennial legume Medicago sativa was codominant with the seeded forage grasses on all of the treatments. High initial fertilization rates probably facilitated the early establishment and dominance of the forage grasses; once nutrient levels, especially nitrogen, began to decline, the legume increased in abundance. Similarity between the reclaimed area and the reference or native area was low. Reclaimed treatments had higher biomass but lower species richness. The topsoil and spoil plots had similar soil texture, bulk density, pH, cation exchange capacity, electrical conductivity, and phosphorus. Differences in organic carbon, total nitrogen, carbon: nitrogen ratios, and available moisture were related more to treatments than to soil type. High biomass and, thus, litter input on the seed + mulch treatment on spoil plots resulted in both higher OC and TN than any on other soil/treatment combination. The reclaimed area had lower OC, TN, and available moisture than did the reference area on all but seed + mulch spoil plots. Bulk density was higher on reclaimed plots. The long-term differences observed between the reclaimed and reference areas parallel those obtained for other western reclamation sites. Although successional trajectories depend on the attribute measured, similarity to native reference areas depends on the initial reclamation methods. We discuss reclamation methods that would increase the structural and functional similarity of reclaimed and reference areas on the Wooley Valley phosphate mine.

Notes: In land restoration it is imperative to study the potential role of disturbances, biotic or abiotic, that may provide sites for colonization by specific plants. Disturbances can alter community composition by removing species or allowing others to become established. In communities where animal-generated disturbances open sites for seedling establishment, animals may have important indirect effects on several aspects of plant community structure. Animal disturbances in Quercus havardii communities of western Texas appear to open sites for colonization by herbaceous species. These animal disturbances vary in spatial distribution, density, and abiotic and biotic characteristics. The abundance of herbaceous plant seedlings is positively related to bare ground and the number of distinct disturbances. Thus, the density and the spatial distribution of these disturbances may be expected to have an important influence on the abundance and dispersion of plant species. Therefore, successful restoration efforts of sand shinnery oak communities and other similar habitats must consider the effects of animal disturbances and the role of plant-animal and plant-soil microbe interactions on plant community composition and the maintenance of plant species diversity.

Notes: The rates of seston elimination by zooplankton and primary production were measured in Funada-ike Pond, typical of human-made impoundments in Japan, from April to September in order to evaluate various treatments of the pond aimed at improving water quality by reducing seston abundance. The treatments included draining the pond water, dredging the bottom mud, eliminating the wastewater inflow, and biomanipulation through removal of all fish. After the treatment, seston abundance was reduced from more than 10 to 0.4–2.5 mg C/liter, and large daphnid species, Daphnia similis and D. magna, occurred and predominated in the zooplankton community. Seston abundance remained at a relatively low level from June to August but increased markedly in late August, while the biomass of zooplankton became high from June to mid-August and then decreased. A decrease in seston abundance was found when the elimination rate exceeded the primary production rate. The results indicate that the development of daphnid populations was effective in keeping seston abundance at a low level. The relationship between the rate of primary production and the zoo-plankton biomass required to offset this rate, however, suggests that biomanipulation aimed at increasing zooplankton biomass alone is less effective in a pond with a high primary production. The success in improving water quality in this pond seems to depend not only on the increase in biomass of large daphnid species that resulted mainly from the removal of fish, but also on the decrease in nutrient load that was realized by the other treatments.

Notes: Livestock have been excluded from riparian zones along many streams in western North America in an effort to restore aquatic and riparian habitat degraded by livestock grazing. Within these exclosures, channel adjustment to elimination of grazing pressure may lag behind plant recovery because of the time required to deposit sediment along the vegetated banks of the stream channel. Moreover, unless grazing is eliminated from the watershed, the channel within the exclosure must still accommodate increased runoff and sediment loads from upstream. This hydrologic regime may prevent a return to predisturbance channel morphology. Cross sections of the North Fork Cottonwood Creek in the White Mountains of California showed no significant difference in channel width within and downstream of a 24-year-old exclosure, despite a lush growth of stream bank vegetation that gives the impression of a narrower channel within the exclosure.

Notes: Many felids are threatened by loss of habitat, lack of genetic diversity, and over-exploitation. The reintroduction of bobcats (Felis rufus) to Cumberland Island, Georgia provided an opportunity to reintroduce a mid-sized felid without the concern for species survival that is paramount with endangered species. We captured bobcats from the coastal plain region of Georgia, briefly held them in captivity, and released them on Cumberland Island. We describe and evaluate the protocols and techniques used to accomplish the reintroduction. Future reintroductions of felids should consider the problem of post-release dispersal, although our island was relatively isolated and inhibited dispersal. Also, any reintroduction effort should invest effort and resources into post-release monitoring of the population. Empirical knowledge about the effects of spatial distribution, genetics, population dynamics, especially mechanisms of population regulation, behavior, and environmental conditions on the viability of populations is critical to the conservation of endangered species. Future research of the bobcats on Cumberland Island will be able to address aspects of the population and genetic dynamics of a small, insular felid population.

Notes: We studied the use of mineland wetlands by birds and the relationship between avian communities and wetland characteristics. Data were collected from 20 wetlands in Pike County, Indiana, and included wetland size, depth, water conductivity and salinity, aquatic macroinvertebrate abundance, vegetation, and bird use. Principal component analysis showed that physical variables could be explained by two principal component scores and that wetlands could be grouped on the basis of size and conductivity. Principal component analysis could not reduce vegetation variables to fewer principal component scores, meaning that wetland vegetation characteristics were independent of one another and did not show any trend. Most wetlands had low invertebrate density, and wetlands with higher invertebrate density had low invertebrate diversity. Wetlands with similar habitat characteristics (physical, vegetative, and invertebrate) did not necessarily show similarities in bird assemblages. Bird similarity index values ranged from 0 to 59%, implying that each wetland has its own bird community. Stepwise multiple regression analysis (α= 0.05) relating bird use and habitat characteristics showed that bird species richness increased with the species richness of submergent vegetation and was correlated negatively with the species richness of emergent vegetation. There was no significant relationship between bird species richness or bird species diversity and wetland size. The number of species within different avian guilds correlated with different habitat characteristics. The species richness of submergent plants was a factor that correlated positively with the number of species of several guilds (dabblers, wading birds, and plunge divers). Wetland age was not a factor that determined bird use.

Notes: Grass seeding is widely used for erosion control, but its consequences for soil and regeneration following fire have been measured only infrequently. This study investigates the effect of grass seeding on the type and extent of plant cover; soil moisture percentage; and moisture stress, survival, growth, and root-tip and mycorrhiza formation of Pinus lambertiana (sugar pine) seedlings in a clearcut intensely burned by wildfire. One-year-old containerized sugar pine seedlings were planted in seeded and nonseeded areas in Spring 1988 and 1989 in the Longwood Fire area of southwest Oregon. In 1988, tree seedlings in grass-seeded plots experienced intense competition from the grass, reduced root-tip and mycorrhiza formation, low levels of soil moisture to meet evapotranspirational demand, high levels of mortality, and reduced growth. In 1989, however, the opposite was true: tree seedlings in nonseeded plots experienced competition from invading native annuals and perennials, low levels of soil moisture in summer, and higher levels of mortality. The studies we report here further indicate that, in an area characterized by extended summer drought, annual ryegrass impeded regeneration of sugar pine during the first season following the fire. Native species cover and richness have been significantly reduced in the seeded area and may affect long-term soil stability, productivity, and conifer restoration. Seeding of annual ryegrass at high rates under these conditions would seem ill advised.

Notes: Books reviewed in this article: Reintegrating Fragmented Landscapes towards Sustainable Production and Nature Conservation. R. J. Hobbs and D. A. Saunders. editors Restoring Acid Waters: Loch Fleet 1984–1990. G. Howels, and T.R.K. Dalziel, editors

Notes: In prairie restoration, use of seeds from nonlocal sources has been of concern to restorationists. We examined the specificity between vesicular-arbuscular mycorrhizal fungi obtained from a single location and little bluestem obtained from three localities. Seed was obtained from three sources: (1) a commercial seed supplier in Nebraska, (2) Sand Ridge State Forest (SRSF), Mason County, Illinois, the site from which the experimental soil containing the mycorrhizal inoculum was obtained, and (3) Sand Prairie Scrub Oak Nature Preserve (SPSO), 32 km southwest of SRSF. Plants were grown in three substrates: (1) autoclaved soil, (2) autoclaved soil to which a mycorrhizal fungal-free sieving of nonautoclaved soil was added, and (3) nonautoclaved soil. All plants grown in nonautoclaved soil were colonized by mycorrhizal fungi, whereas none of those grown in other substrates were colonized. Plants grown from SRSF seeds produced significantly (p 〈 0.05) more biomass than those grown from Nebraska seeds (X̄± SE, SRSF = 0.54 ± 0.04 g, SPSO = 0.49 ± 0.03 g, Nebraska = 0.37 ± 0.03 g). Plants grown in nonautoclaved soil, regardless of seed source, produced less biomass (0.27 ± 0.02 g) than plants grown in autoclaved soil (0.58 ± 0.03 g) or autoclaved soil plus sievings (0.59 ± 0.03 g).The results provide no clear indication of a host-endophyte specificity. However, the data suggest that the local genotypes of S. scoparium are better adapted to their native soil environment than are genotypes from other localities.

Notes: This essay reviews the recent attempts by the Northwest Power Planning and Conservation Council (NPPC) to conserve and restore wild salmon lost to hydroelectric development along the Columbia River and its tributaries. The restoration of the wild salmon is predicated on cooperation between myriad stakeholders in a planning process that includes the NPPC, 11 state and federal agencies, 13 Indian tribes, 8 utilities, and numerous interest groups. The two goals of the essay are (1) to review the recent amendments to the NPPC's fish and wildlife program, and (2) to describe the political barriers to restoration versus restocking of wild salmon in the Columbia River. The failure of political and administrative entities to deal with the problem of restoring wild salmon may result in drastic requirements being imposed by the imperatives of the Endangered Species Act.

Notes: An environmental revolution is urgently needed that will lead to a post-industrial symbiosis between man and nature. This can be realized only if the present unrestrained biological impoverishment and neotechnological landscape degradation are replaced by the creation of healthy and attractive landscapes. Restorationists can fulfill a vital role in this process. They must broaden their scales from biodiversity restoration in small, protected nature islands to the large-scale restoration of natural and cultural landscapes. To achieve this they must restore not only the patterns of vegetation but also the processes that create these patterns, including human land uses. Their goal should be to restore the total biological, ecological, and cultural landscape diversity, or “ecodiversity,” and its intrinsic and instrumental values of highly valuable, endangered seminatural, agricultural and rural landscapes. For this purpose it is essential to maintain and restore the dynamic flow equilibrium between biodiversity, ecological, and cultural landscape heterogeneity, as influenced by human land uses, which occur at different spatial and temporal scales and intensities. Recent advances in landscape ecology should be utilized for broader assessment of ecodiversity, including proposed indices of ecodiversity, new techniques such as Intelligent Geographical Information Systems (IGIS), and Green Books for the holistic conservation and restoration of valuable endangered landscapes. Restoration ecology can make an important contribution to an urgently needed environmental revolution. This revolution should lead to a new symbiosis between man and nature by broadening the goal of vegetation restoration to ecological and cultural landscape restoration, and thereby to total landscape ecodiversity.

Notes: A study of spider (Araneae) communities was conducted in rehabilitated bauxite mines at the Jarrahdale mine site of Alcoa of Australia Ltd. and in the nearby native jarrah (Eucalyptus marginata) forest in southwest Western Australia. The study was conducted from March to August 1993 in five rehabilitated sites of different age and method of rehabilitation and in two forest sites. A variety of collection methods was used, including pitfall trapping, litter sampling, sweep netting, tree beating, and visual searching. These methods were the same as those carried out in a previous study of some of these areas in 1983. We collected 151 spider species belonging to 102 genera and 34 families. We examined the relationship between various habitat features, including the age and method of rehabilitation, of the spider communities present. It was found that leaf litter depth and cover and vegetation density had a significant positive influence on recolonization by the various spider guilds. The age and method of rehabilitation were found to influence different vegetational and habitat features; these, in turn, influenced the spider communities. Thus, the older a rehabilitated site the greater the species richness of both plants and spiders. We compared these results with those of the 1983 study to determine the spider succession of the aging rehabilitation. The spider communities and guild composition were found to change as the vegetation matured, from a dominance of pioneer species to a community of species requiring less harsh conditions. By comparison with the pre-1983 rehabilitation, the latest method of rehabilitation increased the rate of recolonization by both plants and spiders.

Notes: Peak flowering activity among woody species in the tropical dry forests of St. John, U.S. Virgin Islands, coincided with the brief spring rainy season but continued at moderate levels for six months, abating with the autumn rains. Fruit maturation showed a major peak in the long winter dry season and a minor crest during the summer dry season. Seeds of wind-dispersed species disseminated mainly during the winter dry season, while animal dispersal of seeds (74% of all woody species) followed the bimodal pattern (for wet and dry seasons) described for the community as a whole. Under shadehouse conditions, most dry forest tree species germinated well (〉 80%) and emerged promptly (within four weeks of planting) and synchronously (90% emergence within a four-week interval). Nine of 29 species tested in the shadehouse manifested dormancy of at least six weeks. Seed germinability varied among tree species, and the viability of most species began to decline following six months of dry storage. Few species retained high germinability after nine months of dry storage. The species composition of soil seed banks did not correspond closely with above-ground communities on three forested sites of varying stand age. In the youngest stand (35 years old), dominated by the weedy, arborescent legume Leucaena leucocephala, the soil seed bank was also dominated by this species, but no seeds of any other tree species were found in the soil samples. Seeds of native trees were scarcely encountered (only one indigenous species) in soil seed bank samples of three forest sites. Local seed rain from less disturbed forest may not be sufficient for prompt recovery of the dry forest community on degraded sites.

Notes: Glasshouse trials, using trickle irrigation and increasing levels of NaOH-induced alkalinity, identified species that could be expected to tolerate the high-pH conditions of bauxite processing waste residue sites. Of 29 taxa tested, the most tolerant were Casuarina obesa, Melaleuca lanceolata, M. armillaris, M. nesophila, Eucalyptus loxophleba, E. halophila, E. platypus, Tamarix aphylla, and a particular clone of E. camaldulensis; E. spathulata, E. tetragona, E. preissiana, E. gomphocephala, E. diptera, and E. occidentalis proved to be relatively sensitive to severe alkaline conditions. Tolerance appeared to relate to an ability to maintain root membrane function, nutrient uptake balance, and ultimately root tissue structure while under increasing levels of alkalinity stress. Species normally inhabiting alkaline soils tended to have increased growth rates in nutrient irrigation conditions between pH 8 and 10 compared with control plants irrigated with nutrient solutions of pH values near 7.4. However, once the irrigation solutions reached pH 12 and the buffering capacity of the soil appeared to be exceeded, the condition of susceptible plants rapidly declined and death followed. Sensitive plants initially showed symptoms related to nutrient deficiency, followed by wilting and death as the root systems failed. Field trial conditions in the bauxite residue impoundments at Kwinana, Western Australia, include soils with pH values as high as 11.00. In general, the relative survival and growth of seedlings after eight months were predicted by the response under glasshouse trial conditions. Appropriately designed stress trials can be important ecological techniques in choosing species most capable of surviving difficult environmental conditions in the rehabilitation of damaged landscapes.

Notes: In ecological restoration, nonindigenous species can pose a major problem because they are often aggressive and can overwhelm native species, thus altering ecosystem structure. This article identifies the circumstances in which prospects for use of restoration technology in controlling invaders are favorable or unfavorable, the factors that make certain species good colonizers, and the characteristics that make ecosystems susceptible to invasion. It discusses prospects for using restoration technology in controlling nonindigenous species by influencing hydroperiod, photo-period, thermoperiod, edaphic conditions, and availability of biological control agents so as to produce ecological conditions that are inhospitable to invaders. The limitations of restoration are discussed, as well as specific ecological situations in which it is likely to be the method of choice for control of nonindigenous species. Use of fire, flooding, manual removal, shading, substrate removal, and herbicide application as control techniques in conjunction with restoration efforts are considered. Specific examples, including the techniques employed, indicate the potential for controlling nonindigenous species in the process of ecosystem restoration.

Notes: Adequately evaluating the success of coastal tidal marsh restoration has lagged behind the actual practice of restoring tidally restricted salt marshes. A Spartina-dominated valley marsh at Barn Island Wildlife Management Area, Stonington, Connecticut, was tidally restricted in 1946 and consequently converted mostly to Typha angustifolia. With the re-introduction of tidal flooding in 1978, much of the marsh has reverted to Spartina alterniflora. Using a geographical information system (GIS), this study measures restoration success by the extent of geographical similarity between the vegetation of the restored marsh and the pre-impounded marsh. Based on geographical comparisons among different hydrologic states, pre-impounded (1946), impounded (1976), and restored (1988) tidal marsh restoration is a convergent process. Although salt marsh species currently dominate the restored system, the magnitude of actual agreement between the pre-impounded vegetation and that of the restored marsh is only moderate. Further restoration of the salt marsh vegetation may be limited by continued tidal restriction, marsh surface subsidence, and reduced accretion rates. General trends of recovery are identified using a gradient approach and the geographic pattern’ of vegetation change. In the strictest sense, if restoration refers only to vegetation types that geographically replicate preexisting types, then only 28% of the marsh has been restored. Restoration in a broader sense, however, representing the original salt marsh vegetation regardless of spatial position, amounts to 63% restored. Unrestored marsh, dominated by Typha angustifolia and Phragmites australis, remains at 37%. By emphasizing trends during vegetation recovery, this evaluation technique aims to understand the restoration process, direct future research goals, and ultimately aid in future restoration projects.

Notes: Books reviewed in this article: The Earth in Transition: Patterns and Processes of Biotic Impoverishment. A collection of papers from a symposium held in Woods Hole, Massachusetts, October 1986. George M. Woodwell, editor Restoration of Aquatic Ecosystems: Science, Technology, and Public Policy. National Research Council.

Notes: Results are presented using vegetative shoots and bryophyte sods to restore floristically impoverished high arctic wet sedge-moss meadows that had suffered intense damage from vehicle activity during the period 1960–1967. Clonal transplants of Carex aquatilis var. stans, a native sedge, were planted with and without bryophyte sods in vehicle ruts in 1972. After nearly two decades, there was less Carex cover in the planted ruts with flowing water than in the contiguous controls. This pattern was slightly reversed in planted plots with standing water. Reinvasion of Eriophorum angustifolium occurred in treated ruts, but cover was less in both treatments than in controls in 1990. The unexpected recruitment of Eriophorum scheuchzeri from the seed bank in moss-sodded plots is discussed in terms of its local and regional importance. Total plant cover in restored ruts was nearly equal to that of controls, but biomass was somewhat less than that in control plots. Plots with bryophytes were environmentally distinct, due primarily to increases in organic mat depth relative to controls. After 18 years, restoration efforts resulted in increased plant cover in treated ruts compared to naturally recovering ruts.〈blockFixed type="quotation"〉The composition of no two patches of vegetation is precisely the same [and] neither are the seed banks. Successsion on different patches of disturebed ground in the same locality frequently proceeds quite differently because of such differences.—J. Miles, Vegetation Dynamics, 1979

Notes: Fire is a common but poorly understood disturbance in the forested ecosystems of the Sierra Madre Occidental of Mexico. In this study, fire history, forest structure (density, species composition, regeneration, forest floor fuels, herbaceous cover, and age of pines), and the dendrochronological tree-ring record were measured at two unharvested 70-ha pine-oak sites near Ojito de Camellones, Durango, Mexico. Study sites were matched in slope, aspect, elevation, slope position, and plant composition, but they differed in fire history since 1945 and in forest structure. The long-term mean fire intervals (MFI) for all fires at both sites up to 1945 were similar—4.0 years at Site 1 (1744–1945) and 4.1 years at Site 2 (1815–1945)—but Site 1 burned only three times at the site margins since 1945 while Site 2 had 9 fires that scarred two or more sample trees and 15 total fires since 1945. Density measurements and age and diameter distributions showed that Site 1 was dominated by numerous, younger, smaller trees (mean total basal area of 23.4 m2/ha and 2730 trees/ha), while Site 2 had fewer, older, larger trees (basal area of 37.2 m2/ha, 647 trees/ha). Large, rotten fuel loading and duff depth were also greater at Site 1. Because regeneration averaged 6200 stems/ha at Site 1 and 8730 stems/ha at Site 2 (no significant difference), forest density at Site 2 was not limited by regeneration capability. The distributions of overstory diameter and pine age at both sites indicate that tree establishment occurred in pulses, with the largest cohort of trees establishing at Site 1 following the 1945 fire. The dense regeneration and heavy fuel accumulation at Site 1 are likely to support a switch from the former low-intensity fire regime to a high-intensity, stand-replacing fire across the site when the next suitable combination of ignition and weather occurs. Baseline quantitative information on fire frequency and ecological effects is essential to guide conservation or restoration of Madrean forests and may prove valuable for restoration of related fire-dependent ecosystems that have experienced extended fire exclusion elsewhere in North America.

Notes: Books reviewed in this article: Directing Ecological Succession. James O. Luken Soil Restoration: Advances in Soil Science, vol. 17. Rattan Lai and B. A. Stewart, editors

Notes: The Pinelands National Reserve and UNESCO Biosphere encompass a large portion of southern New Jersey's Pine Barrens. Within the core preservation zone of these Reserves lies the Warren Grove Weapons Range, a military installation where exercises during the past 50 years have devastated portions of the indigenous pygmy pine-oak forest. In 1987, restoration efforts were initiated to identify materials and techniques that promote a diverse and productive native plant community atop drastically disturbed portions of the range. We used trial plantings to examine fertilizer and sewage compost fertility amendments, the effect of different native plant mixtures (including the dwarfed race of pitch pine, Pinus rigida), the influence of the ectomycorrhizal fungus Pisolithus tinctorius on the growth of pines and associated species, and mulch applications to conserve moisture and add organic matter. Following two growing seasons, test plantings exhibited 25% of the vegetation production found in the surrounding pine-oak community, 50% canopy closure, and levels of diversity comparable to the reference site. Maximum biomass and cover were achieved following the application of 16 Mg/ha compost and the establishment of pitch pine seedlings. Pitch pine was the dominant species in all plots where it was planted, with herbaceous species comprising the balance of the developing vegetation. Amendments of seeded grasses, P. tinctorius, and mulch influenced species composition but failed to enhance total plant production. We recommend restoring drastically disturbed sites in the pine plains with cultural input of compost to the spoils and planting of pitch pines and other woody species to accelerate the structural blending of reforested sites with the surrounding native vegetation.

Notes: A general model is presented describing ecosystem degradation to help decide when restoration, rehabilitation, or reallocation should be the preferred response. The latter two pathways are suggested when one or more “thresholds of irreversibility” have been crossed in the course of ecosystem degradation, and when “passive” restoration to a presumed predisturbance condition is deemed impossible. The young but burgeoning field of ecological restoration, and the older field of rehabilitation and sustainable range management of arid and semiarid lands (ASAL), are found to have much in common, especially compared with the reallocation of lands, which is often carried out without reference to pre-existing ecosystems. After clarifying some basic terminology, we present 18 vital ecosystem attributes for evaluating stages of degradation and planning experiments in the restoration or rehabilitation of degraded ecosystems. Finally, we offer 10 hypotheses concerning ecological restoration and rehabilitation as they apply to ASAL and perhaps to all terrestrial ecosystems.

Notes: Experiments were conducted in the field and the greenhouse to determine whether vesicular-arbus-cular mycorrhizae affect growth and competition between the native perennial Stipa pulchra and the introduced annual Avena barbata. Soils in the greenhouse were steam-sterilized, and in the field they were treated with the fungicide benomyl. Stipa pulchra showed decreased shoot dry mass and increased root mass when inoculated, while A. barbata showed the opposite response, increased shoot mass and decreased root mass. Mycorrhizal A. barbata also produced more seeds. Mycorrhizae did not alleviate the negative effects of competition of A. barbata on S. pulchra, as has been demonstrated for other pairs of weedy and nonweedy species. The same three species of mycorrhizal fungi were present in annual and perennial grasslands, but their relative composition was different. When inoculum from the two grassland types were tested in the field, the fungal species began to revert within five months to the species composition found in grasslands of the host plant. This indicates that, once annual grassland has been revegetated with the native S. pulchra, the original fungal species composition may return relatively quickly. Where A. barbata dominates, inoculation with mycorrhizal fungi alone will not suffice for establishing S. pulchra, and the usual practices for control of weed competition need to be employed.

Notes: Herbaria are potentially important repositories of living seeds that could be useful for recovery of rare plant species. To examine this capacity, we tested seed germination of rare milkweed (Asclepias) and milkvetch (Astragalus) species representing different collection dates and different herbaria. These groups have contrasting seed characteristics, with greater potential for longevity in the nonpermeable hard-coated milkvetch seeds. Twelve-year-old Asclepias lanuginosa seeds failed to germinate. However, we achieved 45% germination from three-year-old Asclepias meadii seeds, but germination dropped to 0% after ages of four to five years. Astragalus neglectus seeds germinated from 97-, 48-, and 28-year-old herbarium specimens, and Astragalus tennesseensis seeds germinated from a four-year-old collection. Seedlings produced from these experiments were incorporated into ex situ garden populations for recovery or restoration of rare species populations. Different herbarium pest control techniques may have significant bearing on the viability of seeds stored on herbarium specimens. Microwaving can cause precipitous loss of seed viability, while deep-freezing appears to allow some seeds to remain viable. Potentially live seeds of rare species should be stored under conditions that enhance their long-term viability.

Notes: The microbial community in a soil stripped and stored during opencast coal mining was analyzed. There were significant effects of soil disturbance on the microbial community: in particular, there were large decreases in the total microbial biomass, as determined by ATP analysis, and numbers of fungal propagules as a result of the store construction process, but there was no significant effect on the numbers of bacteria. During the subsequent months of storage there was a flush in the numbers of bacteria, with gram-negative bacteria showing an increase of nearly 700% in comparison to the control. During this time there was a steady accumulation in the amount of ammonium in the deepest part of the soil store, indicating the onset of anaerobiosis. These changes may be interpreted in terms of lifestyle strategy theory (Grime 1979). The bacteria exhibit behavior typical of R-strategists, or ruderal species, taking advantage of the nutrients made available by the death of fungal biomass during store construction. Fungi respond as C-strategists, or competitors, and they are severely affected by store construction-and unable to persist deep in the anaerobic part of the store. In contrast, anaerobes, S-strategists or stresstolerators, are able to survive under the same conditions. These changes have serious implications for the restoration of systems using stored topsoil as a resource. The microbial population has been altered in terms of its size and composition. Many of the fungi required for adequate breakdown and incorporation of organic matter will be absent, and the soils will be generally poor in microbial biomass. This will lead to inadequate nutrient cycling and poor soil structural stability, two factors essential for the restoration of a self-sustaining ecosystem.

Notes: In order to extend quarrying near Thrislington Plantation, County Durham, England, 8.5 ha of magnesian limestone grassland was relocated over a period of eight years from October 1982. The effects of this on the flora and invertebrate fauna were examined within the Festuca-Helianthemum community at five plots relocated at different times. Plants were sampled with a point-quadrat, and invertebrates by pitfall trapping. Comparisons were made between age of the relocation, numbers of species and individuals, and diversity of flora and invertebrates. The plots were examined using the percentage similarity measure. The plots showed an initial change in some aspects of community structure for flora and invertebrate fauna, followed by a “recovery” period. This was particularly evident in the numbers of species and species diversity of plants and in the numbers of individuals and species diversity of invertebrates. Bare ground, left by the relocation process, was still evident between relocated turfs in the early plots, but it was successfully colonized by resident species in later plots. These results have implications for the future management of this and similar sites, particularly with respect to the emphasis placed on subsequent monitoring and the need to consider invertebrate faunas when implementing management strategies.

Notes: 〈blockFixed type="quotation"〉We now recognize that humans have the power to alter the planet irreversibly, on a global scale. Humans must be concerned with the condition of the planet that is passed to future generations./〉

Notes: The objective of this study was to evaluate seven woody plant species on four growth media for their potential contribution to moose habitat and establishment of viable plant communities on a proposed mine site in southcentral Alaska. Populus balsamifera (balsam poplar), Salix alaxensis (feltleaf willow), S. barclayi (Barclay willow), S. bebbiana (Bebb willow), Alnus tenuifolia (thinleaf alder), Betula papyrifera (paper birch), and Picea glauca (white spruce) were selected for their functions in moose habitat, ease of propagation, and presence in the existing native vegetation. Three native soils were selected for biological characteristics such as different potential to form mycorrhizae and to regenerate local plant species, both of which are governed partly by existing vegetation. The fourth growth medium, glacial till or overburden, was expected to have little or no biological activity. A mining disturbance was simulated on three sites by removing existing vegetation from the plots, stripping the native soils, and then spreading these soil materials over the respective study plots. Rooted cuttings of the Salicaceae and nursery seedlings of the other species were planted in each of the four growth media. Height and survival of all plant species were greater on the three soil media than on the glacial till during the second and third years. Percentage of ectomycorrhizal infection on transplants was similar among growth media, although lower ectomycorrhizal infection occurred on volunteers in grassland soils than in the other growth media. Browsable plants were produced within three years on the disturbed native soils but not on the glacial till.

Notes: Seagrass transplanting experiments were conducted in Back Sound, Carteret County, North Carolina, and Tampa Bay, Pinellas County, Florida. In Florida, we compared three planting methods (cores, stapled bare root, and peat-pot plugs) for shoot addition rate coverage, and labor cost (harvest, fabrication, and deployment) using Halodule wrightii. Only planting methods and development rates were recorded for Syringodium filiforme. Fertilizer additions were made to peat-pot plantings of H. wrightii and Zostera marina in both North Carolina and Florida. Exclosure cages were tested to attempt to minimize bioturbation of H. wrightii and Z. marina in both North Carolina and Florida. Recovery from harvesting impacts to existing, natural beds of S. filiforme and H. wrightii were assessed in Florida. The peat-pot method was about 35% and 63% less expensive in work time than staples and core tubes, respectively. Response to fertilizer additions was masked by inconsistent release properties of the fertilizer, although some indication of positive response to phosphorus fertilizer in sediments with low carbonate content, and nitrogen in general, was detected. Complete loss of peat pots, largely ascribed to bioturbation, occurred in a large planting (Tampa Bay) but not in nearby smaller ones where exclosure cages were used. Cages did not affect planting unit survival in North Carolina but did improve number of shoots per planting unit in one of three experiments. No detrimental effects of cages were noted. Existing natura beds used to harvest transplanting stock in Tampa Bay recovered from excavations as large as 0.5 m2 in one year. Significant cost savings were found to be possible through methodological improvement, including planting techniques, bioturbation exclusion, and possibly fertilizer additions.

Notes: Land rehabilitation is proposed as a management strategy to reverse the negative consequences of tropical deforestation and land degradation. We first define the concepts associated with ecosystem modification—conversion, damage, and degradation—and those associated with ecosystem repair—restoration, rehabilitation, and reclamation. We then present a scheme of sustainable land use in the tropics, with illustrations of how rehabilitation and restoration activities fit into the overall scheme of the use of land. Because damaged lands cannot contribute effectively to sustained economic development, land rehabilitation is a necessary step for increasing the chances of attaining sustainability. Approaches for rehabilitating ecosystems are discussed, including the management of stressors and subsidies in relation to their point of interaction in the ecosystem. Finally, we illustrate the concepts of ecosystem rehabilitation of damaged, degraded, and derelict lands with examples of case studies from dry to humid life zones in island and continental situations throughout the tropics. The case studies demonstrate that opportunities for success exist, even with severely degraded lands, but a considerable amount of research remains to be done before we have a full understanding of the complexity of the task facing us.

Notes: The foundation of a successful revegetation or restoration program is quality native seed. This requires careful collection, processing, and storage. Mature seed should be collected from healthy, local stands with a sufficiently broad genetic base. Careful identification of the site characteristics and seed-lot tracking are essential. Yearly variation in seed production and seed quality can be very high, and an early determination of seed quality can prevent expensive failures. Nondestructive evaluation using X-rays is effective and economical, but techniques such as staining, inspection, and germination tests can also be helpful. Cleaning, dewinging, and upgrading seed before storage can (1) reduce weight and bulk, (2) improve storage life, (3) increase germination, and (4) make greenhouse production and field planting easier and more economical. The seeds of many native plants can lose their viability quickly if they are not stored under controlled conditions. Seeds in storage must also be protected from rodents, pests, and disease. Dormancy is common in the seeds of many native species, and experimentation is often necessary to determine the best way to break seed dormancy. This can be complicated by year-to-year and plant-to-plant variation.

Notes: The performance of woody plants was analyzed in 15 successional seres starting at bare ground in central European manmade habitats. The total cover of woody species after 10 years of succession was significantly related neither to initial soil moisture nor to nitrogen (expressed using Ellenberg indicator values). But the comparison of seres indicates that establishment of woody plants was easier under moderate environmental conditions and retarded in extreme habitats (dry, nutrient-poor, or acid). The arrival of the first woody plants was delayed in dry sites. No significant differences were found between primary and secondary seres, either with respect to the total cover of woody plants reached after 10 years of succession or considering the time of their arrival. In total, 24 woody species (10 shrubs and 14 trees) appeared in the series investigated. Their successional performance (in terms of the number of seres in which the species occurred and maximum cover reached in any sere) was not related to species traits (life strategy, type of mycorrhizae, mode of dispersal, diaspore weight), except for the regeneration strategy, species with seasonal regeneration by seeds were capable of creating higher cover. Betula pendula (European birch) was the most successful species in spontaneous succession, especially on moist sites. Practical suggestions for the management of particular habitats (sites disturbed by mining, sites reclaimed after acid rain deforestation, urban sites, abandoned fields) are provided regarding the establishment of woody plants.

Notes: Books reviewed in this article: Semiarid Lands and Deserts: Soil Resources and Reclamation J. Skujins, editor

Notes: Several landscape restoration alternatives were evaluated in the Gorecht area, a cultivated river plain in the northern part of the Netherlands. A landscape analysis was performed to investigate the hydrological functioning of this area. Groundwater composition in the area was assessed by using distribution patterns of indicative plant species. Results proved to be consistent with an interpolation of actual data of the groundwater composition. Groundwater flow was simulated with hydrological models to explain the observed patterns in water chemistry. It appeared that upwelling Ca-rich groundwater is now absent in the area, contrary to the past situation. Because a constant supply of Ca-rich water is an essential condition for mesotraphent fen vegetation, we concluded that under the present conditions the regeneration prospects for these vegetation types are poor. We suggest that the plan to regenerate groundwater-fed fens be abandoned for a plan to create surface-water-fed marshes.

Notes: Restoration of an abandoned 16-ha Nike missile base site located on a former wetland in the lower Detroit River (Michigan, U.S.A.) was investigated with an emphasis on wetland restoration. The site included a 2.7-ha abandoned missile base, a 1.3-ha lake, 10.4 ha of emergent and submersed wetlands, and 1.8 ha of uplands. Aquatic beds in the shallow bay connected to the river supported floating leaved and submersed aquatics including Nymphaea tiiberosa, Vallisneria antericana, Elodea canadensis, and Heteranthera dubia, with mats of green, filamentous algae. A 10-ha diked wetland adjacent to the site was dominated by Typha spp., Salix spp., Nymphaea tuberosa, Myriophyllum spicatum, Elodea canadensis, Chara sp., and Juncus effusus. Restoration objectives included a nature preserve, an outdoor recreation area, an experimental wetland complex, and an environmental education center. Ten alternative designs were suggested, including four with wetlands open to the bay, three with diked wetlands, and the rest involving island construction, a reconstructed upland site, or a wetland research facility. Alternatives were evaluated for their contribution to local ecology, research, education and wildlife, ease of maintenance, and probability of success. Construction of a wetland resembling conditions before construction of the base was recommended for its low maintenance and opportunity for research on non diked wetland design and construction in protected bays in the Laurentian Great Lakes. Recreational and educational opportunities were also recommended as part of the site restoration.

Notes: The recent publication of Restoration of Aquatic Ecosystems: Science, Technology, and Public Policy has generated much scientific, public, and political discussion. Although the book emphasizes the restoration of entire aquatic ecosystems, discussion of senescent dams and human-made reservoirs is absent. The important societal and ecological roles of reservoirs warrant a closer examination of the potential ecological restoration of aging reservoirs. Problems with long-term reservoir management include lack of long-term management strategies, sedimentation, hazardous waste accumulation, impacts of recreational use, and the creation of new aquatic and riparian habitats. Policy conflicts may arise when habitats created in the reservoir are destroyed to restore the downstream habitats or when created habitats upstream undergo successional changes that impact the commercial or recreational value of the reservoir. Rare or endangered species may also create similar conflicts. The establishment of an ecological restoration bonding program that includes environmental education and conservation prior to new dam construction may aid in resolving potential conflicts in the future.

Notes: Books reviewed in this article: The Uses of Ecology: Lake Washington and Beyond W. T. Edmonson

Notes: Sagittaria latifolia Willd. is commonly used for wetland enhancement, restoration, and creation. It is a C3 species that is widely distributed in southeastern Canada and the eastern half of the United States. It provides habitat and food benefits to waterfowl and improves water quality in wetlands. Monoecious and dioecious varieties occur in the U.S. that exhibit different life history characteristics. Clonal spread occurs through growth of rhizomes and tubers. S. latifolia grows in a wide range of fresh water and soil conditions. It persists in stabilized water levels at depths of less than 50 cm and few drawdowns. The species tolerates and assimilates high levels of nutrients and heavy metals. There is a limited data base on the installation and management of the species. Tubers and plants are preferred plant materials for field establishment. Herbivory by insects, waterfowl, and other animals may greatly reduce planting success. Future studies relevant to improvement of propagule storage, planting conditions, and management of mature plants for wetland projects are suggested.

Notes: A model of ecosystem degradation and three possible responses to it—restoration, rehabilitation, and real-location—is applied to ongoing projects in the arid mediterranean region of southern Tunisia, the subhumid mediterranean region of central Chile, and the semiarid tropical savannas of northern Cameroon. We compare both nonhuman and human determinants of ecosystem degradation processes in these contrasted regions, as well as interventions being tested in each. A number of quantifiable “vital ecosystem attributes” are used to evaluate the effects of ecosystem degradation and the experimental responses of rehabilitation on vegetation, soils and plant-soil-water relations. We argue that attempts to rehabilitate former ecosystem structure and functioning, both above- and below ground, are the best way to conserve biodiversity and insure sustainable long-term productivity in ecosystems subjected to continuous use by people in arid and semi-arid lands of “the South.” The success of such efforts, however, depends not only on elucidating the predisturbance (or slightly disturbed) structure and function of the consciously selected “ecosystem of reference,” but also on understanding and working with the socioeconomic, technical, cultural, and historical factors that caused the degradation in the first place.

Notes: The feasibility of measuring soil salinity with electromagnetic induction (EM) for determining riparian restoration potential was investigated on a 28-hectare plot at the Bosque del Apache National Wildlife Refuge in central New Mexico. The plot was cleared of exotic Tamarix chinensis (saltcedar), surveyed and gridded into 1370.2 hectare sections. Soil samples and EM measurements were taken at each section. We compared laboratory-determined ECe values from the soil samples with ECa values calculated from the EM measurements using a model developed by Rhoades et al. (1990). Direct comparison of ECe values determined from the two methods yields a low correlation due to sample-size differences but the calculated ECa was able to accurately predict whether the measured ECe would lie above or below some threshold value. An assessment of general site suitability for riparian restoration with electromagnetic induction has proven to be a rapid, accurate, and cost-effective alternative to intensive soil sampling.

Notes: Extensive areas of the tropics have been converted into pasture for cattle ranching. Frequently, abandoned pasture does not revert to forest. The goal of this project was to identify barriers to lowland moist forest regeneration in highly degraded grasslands in the Sierra Nevada de Santa Marta, Colombia. The barriers we considered were seed source, seed predation, competition with grasses, microclimate and soil limitations on plant growth, and fire. Seed dispersal into the grasslands is limited to within 10 meters of forest fragments, but this barrier can be overcome by sowing seeds and planting seedlings and by establishing perches to attract dispersers. In these degraded grasslands, seed predation was lower than in the adjacent forest patches, and there was no evidence that grasses inhibited the establishment of woody species. The most important barrier was the severe degradation of the soils. In much of the area, the A and B horizons have been eroded away, leaving saprolite at the soil surface. Seedlings of two fast-growing pioneer species, Ochroma pyramidale and Cochlospermum vitifolium, grew to a maximum height of only 2.5 and 12 cm, respectively, during the first eight months. The slow plant growth in the degraded grassland soils compared to forest soils was associated with lower levels of cation-exchange capacity, calcium, magnesium, and potassium. Even if these barriers could be overcome, the frequent and extensive use of fire in the region must be controlled to avoid killing established woody plants.

Notes: Biological resources can be more usefully incorporated into many aspects of restoration ecology. During the planning and design stage, the wide genotypic variation in natural plant populations must be recognized and exploited. This will ensure that genotypes used on a site are best adapted to local conditions and have a greater probability of survivorship than arbitrarily chosen material. Also, certain unusual genotypes can be located using the principles of evolutionary ecology and can be installed in areas with extreme conditions, such as soils contaminated with heavy metals, in areas where rapid colonizing ability (high seed set and/or clonal growth) is particularly advantageous, or where soils are of poor quality. Similarly, where high herbivore pressure is a threat to restoration, genotypes that are well defended, chemically or mechanically, against animal enemies should be selected to initiate the restoration process. The nursery industry can be encouraged to supply an ecologically wider selection of material for restoration, originating from local biological reserves and natural habitats. During the management phase of a restoration, local natural habitats are critical as reservoirs of biological control agents, seed sources for plant species, and members of higher trophic levels and additional plant species needed during succession. Mutualists such as pollinators, seed dispersers, and mycorrhizal fungi are vital to the success of a restoration project, and these must invade from nearby natural habitats or must be deliberately introduced. During the evaluation phase of restoration, local natural areas should be used as templates of community composition and structure from which one measures success. A functioning restoration project will interact biologically with surrounding areas, the exchange of species and genes being particularly important. Analysis of the microbial and invertebrate communities that have invaded the installed plant community may be useful and accurate determinants of ecological function. For these latter stages of the restoration process, the value of preserving local habitat remnants is high and complements their usefulness as a source of ecologically precise material for installation.

Notes: Community classification has emerged from ecology textbooks into the arena of environmental impact evaluation and mitigation. This development is especially apparent in southern California, where the fate of a community called coastal sage scrub is being decided. Regional plans for development, mitigation, preservation, and restoration are being formulated that will permanently affect the natural landscape. This paper demonstrates the potential for the name of a plant community to affect tradeoffs in planning processes that are intended to offset removal of habitat by development. The discussion focuses on two types of classification systems. One system is hierarchical, with established nomenclatorial rules that allow natural variation to refine the community definitions. Names of plant associations directly reflect the dominant species in the association, as in Artemisia californica—Eriogonum fasciculatum (California sagebrush—California buckwheat). The second system is nonhierarchical, in which observations of natural landscapes are fit into established definitions of community types, such as Diegan coastal sage scrub. Advantages and disadvantages of both types of systems are discussed and illustrated by two examples of problems in classifying coastal sage scrub. The discussion concludes with the point that the name of a community has the potential to significantly affect the extent to which equal tradeoffs between community types are actually achieved in mitigation and restoration efforts.

Notes: This article contributes to the worldwide trend of using microbiological methods for bioindication of the influence of abiotic, biotic, and anthropogenic factors on the soil environment, especially on the plough layer of soils. It compares two approaches to assess microbial biomass-C: (1) chemical treatment of soil samples by CHCl3 vapor, followed by extraction, and (2) heat treatment in the range of 62–65°C for 24 hours, followed by extraction. It recommends the analysis of different forms of organic carbon, the total carbon of soil organic mass, and microbial biomass-C and other forms of organic carbon extractable with 0.5 M K2SO4 and 0.5 M (NH4)2SO4 respectively. It presents a simple mathematical model suitable for assessment of microbial recuperation of the topsoil (0–15 cm) after restoration. The relation between the measured values and the values calculated with the model expressed as percentages expresses the quality of restoration achieved and the stage of disturbance of the living microbial part of the topsoil. It indicates not only the ecological impact but also the deficit and stress situations, to which the living microbial part of the topsoil is exposed in the long term.

Notes: Books reviewed in this article: Ecological Principles of Nature Conservation. L. Hansson, editor Saltmarsh Ecology. P. Adam

Notes: Within an urban park in southern California, the relationship between the structure and floristics of vegetation and the distribution, abundance, and behavior of wildlife was studied in relatively undisturbed areas (San Luis Rey) and in contiguous areas (Guajome Park) in need of restoration. These data were used to develop recommendations for the enhancement of native animal species in the park. The abundance of amphibians and reptiles was highest in native upland scrub and willow (Salix)-riparian vegetation types, and lowest in dry, disturbed sites. Western fence lizards (Sceloporus occidentalis) were the most abundant reptile throughout both study areas. Overall, bullfrogs (Rana catesbiana), an exotic species, were the dominant amphibians; the native Pacific treefrog (Hyla regilla) was rare throughout. At both study areas, the small mammal community was dominated by western harvest mice (Reithrodontomys megalotis) and deer mice (Peromyscus maniculatus) and, to a lesser extent, by brush mice (P. boylii) and exotic house mice (Mus musculus). Negative correlations in abundance existed between house mice and harvest mice, and between house mice abundance and overall small mammal abundance. In riparian sites, cottonwood (Populus fremontii) and various height classes of willow were the dominant factors in the majority of bird abundance–habitat‘correlations and where foraging activities were concentrated. Recommendations for enhancing native animal species include reduction of marsh sedimentation, removal of feral species, and development of connections between the park and nearby natural areas. A corridor of native riparian vegetation (primarily cottonwood-willow) should be developed to replace the existing agricultural fields, thereby linking Guajome with the San Luis Rey River.

Notes: Eight individual rock iguanas (Iguana pinguis) from Anegada Island were relocated to Guana Island by Lazell, 1984–1987, in order to establish a second population reservoir for this endangered species. The species may have originally occupied the entire Puerto Rico Bank. The relocation has been successful and, in the area currently providing the best habitat, we estimate a density of 9 or 12 animals of various age classes per 19 ha. The optimal area contains a sheep exclosure with relatively dense understory vegetation and numerous exotic as well as native species of plants. Iguana activity is concentrated on east facing slopes and ridge-tops that get morning sun. Outside the exclosure most edible ground cover and shrubs have been eaten by sheep, leaving toxic or noxious species, such as Croton or Lantana, in the understory where I. pinguis adults generally forage. Removal of sheep may be critical to continued population growth of these reptiles. Views on relocation or repatriation of other endangered Antillean Iguana species are advanced, with some ideas on minimum viable population sizes and a possible explanation for the extirpation of I. pinguis from much of its former range.

Notes: Books reviewed in this article: Functions of Nature Evaluation of Nature in Environmental Planning, Management and Decision Making. Rudolf S. de Groot Landscape Restorastion Handbook D. Harker, S. Evans, M. Evans, and K. Harker

Notes: Results of a short-term study of the revegetation of illegally rock-plowed wetlands in the East Everglades are reported. Comparisons of the plant communities on a restored site, an unrestored site, and the natural control areas directly adjacent to these sites were made using line intercept transects. On the site where removal of the rock-plowed material and grading of the surface to below original elevation were required for restoration, less than 20% of plant cover was of nonwetland species, and the occurrence of exotic species was low. On the rock-plowed site where no restoration efforts were performed, 61% of plant cover was of nonwetland species, and there was a higher occurrence of exotic species compared to the restored rock-plowed and the control sites.

Notes: The extreme species richness of native shrubland vegetation (kwongan) near Eneabba, Western Australia, presents a major problem in the restoration of sites following mineral sand mining. Seed sources available for post-mining restoration and those present in the native kwongan vegetation were quantified and compared. Canopy-borne seeds held in persistent woody fruits were the largest seed source of perennial species in the undisturbed native vegetation and also provided the most seeds for restoration. In undisturbed vegetation, the germinable soil seed store (140–174 seeds · m−2) was only slightly less than the canopy-borne seed store (234–494 seeds · m−2), but stockpiled topsoil provided only 9% of the germinable seeds applied to the post-mining habitat. The age of stockpiled soil was also important. In the three-year-old stockpiled topsoil, the seed bank was only 10.5 seeds · m−2 in the surface 2.5 cm, compared to 56.1 to 127.6 seeds · m−2 in fresh topsoil from undisturbed vegetation sites. In the stockpiled topsoil, most seeds were of annual species and 15–40% of the seeds were of non-native species. In the topsoil from undisturbed vegetation, over 80% of the seeds were of perennial species, and non-native species comprised only 2.7% of the seed bank. Additional seeds of native species were broadcast on restoration areas, and although this represented only 1% of the seed resources applied, the broadcast seed mix was an important resource for increasing post-mining species richness. Knowledge of the life-history characteristics of plant species may relate to seed germination patterns and assist in more accurate restoration where information on germination percentages of all species is not available.

Notes: The composition and structure of ant communities were used to assess the success of the preliminary restoration program at Ranger uranium mine in the seasonal tropics of northern Australia. Ants were surveyed at eight sites, including two relatively undisturbed control sits, within the Ranger lease. The revegetated sites represented a range of variables likely to influence restoration success: revegetation age (two, four, and eight years), proximity to undisturbed sites (which act as potential sources of recolonization), and burning treatment. Revegetation at most sites was dominated by fast-growing species of Acacia. There was a clear succession of ant species across revegetated sites. Initial colonization was by species of Iridomyrmex, but as plant cover and litter development increased these were replaced by broadly adapted, opportunist species, especially the introduced Paratrechina longicornis. Ant recolonization was very slow at isolated sites, with only 12 species present after eight years (the oldest site available). This compares with 21 species after only four years at a site located close to potential sources of recolonization. The ant community at this site, however, was very similar to that at another site located close to colonization sources, but eight years old. Ant succession therefore appeared to have stalled at this point, with species richness and composition bearing little resemblance to that at control sites. The heavy shade and litter produced by acacias were considered to be the major impediment to further change. Results from a site that had undergone a prescribed burn after two years, thereby breaking dominance by acacias and allowing for the establishment of a wide variety of plant taxa, suggest that such management practices may promote further colonization by ant species.

Notes: Soil microbial activity and soil nutrients were monitored on a revegetated coal surface mine in southwestern Wyoming from the initial planting in 1982 through 1987. Total soil nitrogen (N) and organic matter did not change during this period. However, despite no changes in available phosphorus (P) concentrations, the total P declined over 50% during the five-year period, with no apparent reduction in the loss rates. The greatest loss was in the bound inorganic P pool. Moisture appeared not to limit microbial mass-C. Microbial mass-C was higher under shrubs than in interspaces and increased with time. Total organic matter did not increase. Thus, the ratio of microbial mass-C to organic matter-C increased during the study period. This suggests that the input of readily decomposable substrate may limit microbial activity. During the study period, all above-ground litter was removed by wind. Root production in the surface soils was low and highly variable and, in this habitat, probably did not contribute largely to the organic matter status. These data suggest that despite an apparent recovery of many parameters used to indicate reclamation or restoration success, the soil-bound P pools could be undergoing a loss. Microbial-C and organic matter changes indicate a system that is not approaching equilibrium within the required monitoring period of most restoration efforts. These parameters could eventually reduce the recovery potential of restored sites.

Notes: A series of experiments designed to demonstrate the potential of using managed, attached algal production to permanently remove excess phosphorus from agricultural run-off is described. The experiments were carried out on a secondary canal in the New Hope South region of the Florida Everglades Agricultural Area from October, 1991, to May, 1992. Natural algal populations of periphyton, including species of the genera Cladophora, Spirogyra, Enteromorpha, Stigeoclonium, and a variety of filamentous diatoms such as Eunotia and Melosira, were grown on plastic screens in raceways, under a wave surge regime. Considerable biomass production of algae occurred, and the resulting algal canopy also trapped plankton and organic particulates from the water column. A seven- to eight-day harvest interval was determined to be optimal, and both hand harvesting and vacuum harvesting were employed. The vacuum device is applicable to large scale-up. In source water having total phosphorus concentrations of 0.012–0.148 ppm, mean macro-recovery dry biomass production levels of 15–27 g/m2/day were achieved. The lower rates occurred in the winter, the higher rates in the late spring. Two techniques were employed to reduce losses of fine material at harvest during the March to May period. Gravity sieving increased mean dry production levels to 33–39 g/m2/day. The mean phosphorus content of harvested biomass ranged from 0.34% to 0.43%. Total phosphorus removal rates during the spring period of average solar intensity and low nutrient supply, by methods demonstrated in this study, ranged from 104 to 139 mgTP/m2/day (380–507 kgP/ha/year). Over the incoming nutrient range studied, phosphorus removal was independent of concentration and was 16.3% of total phosphorus for 15 m of raceway. Up-stream-downstream studies of overflowing water chemistry (total P, total dissolved -P, orthophosphate -P) showed highly -significant reductions of all phosphorus species. Total phosphorus reduction closely correlated with phosphorus yield from biomass removal. Yearly, minimum phosphorus removal rates are predicted that are 100–250 times that achieved both experimentally and in long-term, large-area wetland systems. Engineering scale-up to systems of hundreds of acres is being studied.

Notes: The goal of this study was to use terrestrial arthropods to help evaluate the progress of a riparian restoration effort along the San Luis Rey River in California by comparing characteristics of the arthropod community at the reconstructed system to those of a naturally occurring riparian woodland used as a reference site. Insects and other arthropods were sampled throughout 1989–1991 using pan trapping and sweep sampling of dominant plants. Assemblages of taxa were monitored as indicators of functional groups that influence ecosystem processes: pollinators, herbivores, predators, parasites, and detritivores. Relative abundances of indicator assemblages were compared between sites to evaluate the establishment and maintenance of processes critical for the natural function of the reconstructed riparian ecosystem. A major objective of this project was to create habitat for the Least Bell's Vireo, so a group of potential prey items was designated to indicate vireo food resources. Over 230,000 arthropods were identified to order or family and by size. Insect communities developed rapidly at the restored habitat. Although the abundance of all arthropods was lower at the reconstructed site than at the reference site, the same orders were present after three years in similar proportions at both locations, and mean abundances were within an order of magnitude of each other. Abundance of certain groups, such as detritivores, suggested that arthropods had propagated rapidly at the restoration site, a possible indication of resiliency. Relatively low numbers of other arthropods, such as predators and parasites, at the reconstructed site indicated the need for continued monitoring. The decline of pollinators and herbivores by 1991 at the reconstructed site suggested that they may have immigrated or been introduced with transplanted vegetation in 1989, but have had difficulty colonizing the site. Although the Least Bell's Vireos were seen foraging at the restored site after three years, no nests were found. Nesting is anticipated, however, as the site matures.

Notes: Abstract. The impact of cattle trampling on the porosity of a representative soil (Typic Natraquoll) of the flooding Pampa of Argentina was studied from 1984 to 1987. Water content, total porosity (TP), macroporosity (〉 30 μm) and mean weight diameter of water-stable aggregates (MWD) were determined in undisturbed topsoil samples taken from adjacent continuously grazed (1.0 animal unit/ha/yr) and ungrazed (since 1976) areas. It was expected that trampling would decrease macroporosity when the soil was ponded, and that the damaged macropores would regenerate during the subsequent soil drying. This was only partly verified. The soil varied in TP from 58 to 64% in the ungrazed area, and from 53 to 78% in the grazed area. This variation resulted mainly from shrink-swell processes. Trampling decreased soil macroporosity (mainly 〉60 μm) from 8 to 5% and decreased MWD from 5.35 to 4.58 mm under dry soil conditions. The damaged soil pores regenerated and aggregate stability recovered during the subsequent period of surface water ponding, when soil swelling increased macropores in the grazed area but not in the ungrazed area. There was no evidence of poaching damage in this soil.

Notes: Book Reviewed in this article:Soils and the Environment By Alan Wild.Nitrate. Processes, Patterns and Management Edited by T.P. Hurt, A.L. Heathwaite and S.T. Trudgill.Urban Soil and Landscape Design By P.J. Craul.Bullock, P. & Gregory, P. J. 1991. Soils in the urban environment.

Notes: Abstract. Recent experiments on soils overlying sand, chalk and limestone aquifers have shown that nitrate leaching losses can be decreased by modifying crop husbandry. Green cover during winter, if established early enough, can reduce nitrate loss. Cultivations can be timed to minimize leaching, and the advantages of irrigation (increased nitrogen offtake and smaller post-harvest soil mineral nitrogen residues) outweigh the potential disadvantage of increased leaching risk during the growing season. It is important not to over-fertilize crops. Using these techniques within farm rotations has decreased nitrate losses in small plot experiments. The next step is to measure the effects on commercial farms where the scale of operation might preclude the high level of husbandry that is required for successful nitrogen management.

Notes: Book Reviewed in this article:Lysimeter Studies of the Fate of Pesticides in the Soil Edited by F. Führ and R. J. Hance.

Notes: Abstract. The effects of increasing periods of mechanical cultivation on soil properties under maize and cassava are compared with those under savanna in south-western Nigeria. Bulk density is significantly greater under cultivation and total porosity, pH, organic matter and extractable nutrients are all significantly less than under savanna. However, the amounts of nitrate-nitrogen and extractable nutrients do not show clear decreases with increasing mechanical cultivation. As the periods of mechanization increase, changes in most soil properties indicate increasing soil degradation. The implications of these results for agricultural policies in Nigeria arc discussed.

Notes: Abstract. Leaching of nitrate from a sandy loam cropped with spring barley, winter wheat and grass was compared in a 4-year lysimeter study. Crops were grown continuously or in a sequence including sugarbeet. Lysimeters were unfertilized or supplied with equivalent amounts of inorganic nitrogen in calcium ammonium nitrate (CAN) or animal slurry according to recommended rates (1N) or 50% above recommended rates (1.5N).Compared with unfertilized crops, leaching of nitrate increased only slightly when 1N (CAN) was added. Successive annual additions of 1.5N (CAN) or 1N and 1.5N (animal slurry) caused the cumulative loss of nitrate to increase significantly. More nitrate was leached after application of slurry because organic nitrogen in the slurry-was mineralized.With 1N (CAN) the leaching losses of nitrate were in the following order: continuous spring barley undersown with Italian ryegrass 〈 continuous ley of perennial ryegrass 〈 spring barley in rotation and undersown with grass 〈 perennial ryegrass grown in rotation = winter wheat grown in rotation 〈 sugarbeet in rotation 〈 continuous winter wheat 〈 continuous barley 〈 bare fallow.At recommended levels of CAN (1N), cumulative nitrate losses over the four years were similar for the crops when grown in rotation or continuously. When crops received 1.5N (CAN) or animal slurry, nitrate losses from the crops grown continuously exceeded those from crops in rotation. Including a catch crop in the continuous cropping system eliminated the differences in nitrate leaching between the two cropping systems.

Notes: Abstract. Changes in amounts of macro-(N, P, K) and micro-nutrients (Fe, Mn, Zn and Cu) were determined in two calcareous soils amended over an eight-month period with pig slurry applications ranging from 0 to 500 m3/ha, and planted in containers with green pepper (Capsicum annuum). Total N and exchangeable K increased after slurry applications of 300 m3/ha or more, and available P increased after the smallest application rate (100m3/ha). Maximum crop nutrient uptakes of 41, 40 and 91% for N, P and K occurred with the smallest dose of slurry. Large losses of N, ranging from 27 to 74% (mean 55%) of N added to soil, occurred with all slurry treatments. From 41 to 71% (mean 55%) of the total P added in pig slurry was fixed in non-assimilable forms. Most of the K from the pig slurry was available to the plants. Most of the micro-nutrients (Fe, Mn, Zn and Cu) from the slurry were immobilized in the soil, probably because of the high pH and the small amounts of organic matter in both the slurries and soils tested.

Notes: Abstract. Oxidation rates of pyrite in colliery spoil were measured under both field and laboratory conditions. Meld oxidation rates varied through the year, depending primarily upon temperature. Rates of acid release of 7–15 μmoles H+/day were measured in field lysimeters in the period May to November. Little oxidation of the pyrite occurred between November and May; the rates in the summer months were approximately 5–10 times those during die winter. The rate of oxidation in the summer was limited by the solubility of amorphous iron oxides. Slow oxidation during the winter is probably related to the inactivity of Thiobacillus ferrooxidans at low temperatures. The rates of acid production in the laboratory in the temperature range 0–18°C were similar to those in the field. Materials inhibiting pyrite oxidation should be added when oxidation rates are slow, so that they are not overwhelmed by large amounts of acid.

Notes: Abstract. . A soil crust, produced by applying 44 mm of distilled water at an intensity of 290 mm/h using a rainfall simulator, was sufficiently rigid to significantly decrease emergence of barley from 76 to 40% and of oil seed rape from 82 to 61%. If the crust was kept wet by regular application of water as a fine mist, its strength was significantly decreased, but emergence remained poor because of prolonged soil wetness. After mist-spraying the crusted surface just before emergence, per cent emergence was greater than uncrusted controls.Application to the soil of a static pressure after sowing but without crusting either had no effect or increased emergence, probably because of improved seed-soil contact. However, crusting of the compacted soil decreased emergence severely. If the crust was allowed to dry it became very strong (〉 300 kPa). Mist-spraying at the time of emergence only also improved seed emergence almost to that in the uncrusted controls. Repeated mist spraying after crusting decreased the strength of the crust, but the resulting waterlogging decreased emergence to less than half those of the controls and of the treatments sprayed just before emergence only. Compared with other management techniques available for amelioration of crusted seedbeds, carefully timed fine spray watering seems to offer the best opportunity for ensuring rapid seed emergence comparable to that in uncrusted soils.

Notes: Abstract. The data from the national project to monitor water erosion has mostly been treated in an aggregate form, because in many of the monitored transects in any year too few fields were eroded for the data to be split into its component parts. However, in crop year 1983 erosion affected enough fields in two localities with contrasting soils for their data to be compared. Rainfall patterns in the two localities were similar. The transects covered a sandland area in Nottinghamshire and an area of clayland in and on the margins of Bedfordshire. Compared with the clayland, rilling of the sandland was widespread, related to the greater range of crops grown there, and more severe. On clayland, rills were mainly confined to valley floors, and slopes flanking these valleys generally had lower gradients than those on the sandland. On sandland, slopes were steeper in eroded fields drilled to winter cereals than they were in fields planted to potatoes or sugarbeet. Such field- based studies hint at the complex interactions of rain falling on a cropped field. Erosional thresholds are not static. The areas of fields affected by erosion and deposition were mostly very small. This helps us understand why the farmer often considers erosion unimportant.

Notes: Abstract. The electrical conductivity of pig slurry suggests that addition of this waste to soils in arid and semi-arid areas could cause salinization. Changes in electrical conductivity and soluble salt concentration in two calcareous soils indicated a salinity risk after 24 months of pig slurry addition at rates of 400 m2/ha/yr or more. Salinity risk increased with soil water-holding capacity. Water-soluble potassium concentrations showed a greater increase than other cations in the soils because of the large amount present in the slurry. The proportion of soluble potassium in the soil depended on the soil's cation exchange capacity and on the composition of the clay fraction.

Notes: Abstract. Spatial averaging of data before or after modelling has important implications for large area land evaluation studies. Two procedures are evaluated for the spatial averaging of weather and soil moisture data before and after modelling (procedures A and B, respectively). The Thiessen polygon weighting technique is applied to a network of weather stations to derive daily weather values for the period 1955 to 1985 for 12 selected Agroecological Resource Areas (ARAs) on the Canadian prairies. These values are used in the model for procedure A. The components of the soil moisture balance for spring wheat are estimated with a budgeting model, assuming wheat is grown continuously for 30 years on soils with available water-holding capacities (AWCs) of 150 and 250 mm. In procedure B, the data from individual stations are used as input to the model and the same Thiessen polygon weighting coefficients are applied to the output variables. A comparison of the two procedures shows no significant difference for temperature-related variables such as frost dates, harvest date and cumulative potential evapotranspiration. The differences for moisture-related variables (soil moisture content at sowing, cumulative actual evapotranspiration, runoff and deep drainage) are often statistically significant, but the absolute differences are less than 10 mm at probability levels ranging from 10 to 90%. For many practical applications the two procedures give similar results.

Notes: Abstract. The area covered per unit mass (Am) of a mulch material is an important factor for controlling erosion, especially in the humid tropics. Values of Am for mulching materials commonly available in S.E. Nigeria - guinea grass, banana leaves and palm leaves - were found to be 0.00035, 0.00038 and 0.00020 haAg, respectively. These values are within the range (0.0001–0.0007 ha/kg) reported for other mulching materials elsewhere. They can be fitted into existing equations to determine the amount of mulches required to achieve any predetermined ground cover percentage.

Notes: Abstract. Information on land resources and the capacity of land to support agricultural production is a prerequisite for the formation of sound agricultural policies. This paper summarizes Canadian experiences in developing national and regional land evaluation systems. Potential users expected the system to estimate the degree to which changes in biophysical and socio-economic conditions would alter options for land use and production, and to provide a context for more detailed analysis.A broad-scale land evaluation system was designed to serve the needs identified by representative user groups. Two prototype systems were developed from available information to test the major features of the system design. Neither prototype was complete; one was national in extent and capable of addressing issues of national and provincial importance, the other covered a sub-provincial area but allowed for more detailed evaluation of the effects of soil modifying processes. A full range of applications was demonstrated using one or other of the prototype systems. As a result of this project, the broad-scale land evaluation system design was improved and verified, ongoing research and data collection activities were adjusted to ensure that they meet the needs of a macroscale land evaluation system, and approaches were developed to overcome problems of land evaluation system development.

Notes: Abstract. The influence of trampling on the soils of the St James Walkway was studied during 1985 by comparing ‘on’- and off-track sites. Trampling increased the average soil bulk density by 0.3 g/cm3 at 0–5 cm depth and by 0.1 g/cm3 at 10–15 cm depth. Trampling increased the average soil shear strength by 11 kPa at 0–5 cm depth and by 6 kPa at 5–10 cm depth. All mineral soils were compacted to some extent by trampling. The podzolized high country yellow-brown earths (Dystrochrepts) were the most affected because their organic topsoil was truncated. Their exposed subsoil was however more resistant to further damage than their topsoil. Organic soils (Medihemists) were not compacted but their very low shear strength and high moisture content make them unsuitable for tracks. Untrampled soil bulk density and soil stone content were negatively correlated with the change in bulk density by trampling, and could be used to predict the risk of soil compaction by trampling.

Notes: Abstract. Bypass flow and concurrent leaching of nitrogen were studied on a Vertisol in south-western Kenya under rangeland and bare, manually tilled cropland. Showers of 30 mm/hr were simulated, causing bypass flow of 47–62% in rangeland topsoils and 19–49% in cropland topsoils. Volumetric water contents after experimentation increased from 28 to 35% and from 24 to 38%, respectively, for the two land-use types.In rangeland samples up to 3.4 kg N/ha was found in the leachate of unfertilized soil. With a fertilizer application of 50 kg N/ha, up to 5.7 kg N/ha was lost from a pre-wetted soil, and more than 20 kg N/ha from dry soil. In cropland topsoils up to 2.2 kg N/ha was lost from unfertilized soil, and only up to 2.9 kg N/ha from both dry and prewetted fertilized soil. Although Vertisols are often linked with excess water, the phenomenon of bypass flow can cause water stress to crops in their early growth stages. Nitrogen leaching losses were large from dry grassland, but prewetting helped to decrease them. On intensively cultivated cropland there was little nitrogen leaching; the tilled topsoil was able to retain most of the supplied nitrogen.

Notes: Abstract. Soils and land use in the Atlantic Zone of Costa Rica were mapped independently at a scale of 1: 100000. At this scale, mapping units are often composite, both in terms of soil type and land utilization type. Combinations of given soil and land utilization types were produced by overlaying the soil and land use maps, on which there was 63% coincidence of unit boundaries. Each combination of land unit and land use was evaluated in terms of bio-physical potentials. From expert judgement land use was shown to be (a) in balance with the use potential, (b) exceeding the use potential (‘over-use’) or (c) less than the use potential (‘under-use’). 18% of the area is over-used, in non-sustainable forms of land use, but 51% is under-used and could be put to more demanding types of land use.

Notes: Abstract. Regression equations successfully allowed the calculation of water retained at—0.3 × 105 Pa and–15 × 105 Pa matric potentials from single soil characteristics, such as bulk volume or clay content, in clayey horizons derived in similar ways from a single parent material. It is possible to use these regression equations on other soils with similar clay fabrics. The fabric is expressed numerically using the pore volume associated with clay particles.

Notes: Abstract. The impact of lead shot on soils and crops was examined at a clay pigeon shooting site in northern England. Topsoil cores were collected along a 300 m transect from the shooting range, and the numbers of lead shot pellets per soil core, total and ‘plant-available’(0.5m acetic acid extractable) lead concentrations, organic matter content, pH and cation exchange capacity were determined. The number of oilseed rape plants and their stem diameters were recorded in 1 m2 quadrats placed at the soil sampling locations. Total and ‘plant-available’ lead concentrations in the soil were most but plant numbers per m2 and mean stem diameters were least in the area of greatest lead shot deposition. Total lead concentrations in the soil commonly exceeded 5000 mg/kg; these are considerably greater than threshold ‘trigger’ concentrations proposed by the Department of the Environment, above which soils are considered to be contaminated and warrant further investigation. Concentrations of lead in the oilseed rape plants themselves were also largest in the area of most intense lead shot deposition; in root samples the lead concentration exceeded 400 mg/kg. The management and remediation of contaminated soils at the clay pigeon shooting site are discussed.

Notes: Abstract. Nepal is facing a serious problem of being unable to maintain soil fertility in agriculture and forestry. Land use practices initiated over the past 10–15 years have resulted in insufficient nutrient inputs, while biomass use and production have increased. Changes in forest soil fertility have resulted from intensive use of forest biomass for animal feed and collection of forest litter for use in agriculture. The agricultural fertility changes have resulted from intensifying annual crop rotations from 1.5 to 2.5 crops and insufficient inputs. The removal of biomass from the forest has curtailed the natural organic cycle by virtually eliminating nutrient inputs.The soils are very acidic and have little C, N, P and exchangeable bases, but have large amounts of active iron. Basic nutrients are not sustained in agriculture and differences in inputs and management between irrigated and rainfed agricultural systems are becoming visible. Irrigated fields show the largest cation content because of input from irrigation water. Rainfed agricultural sites, which receive the most nutrients (fertilizers and manure), have the highest pH values and C and N contents. All soil fertility conditions are marginal and put into question the long-term sustainability of current levels of production. Alterations in the cropping intensity are needed and the introduction of nitrogen fixing trees and crops seems to be the most viable option towards sustainability.

Notes: Abstract. Estimates of winter drainage, D, are available for 82 locations in England and Wales for each winter during the 35-year period, 1940/1 to 1974/5. At each location, D is approximately normally distributed. The variability, expressed as a coefficient of variation, is approximately inversely proportional to the average drainage; it is large, ranging from 20–30% in Wales and the uplands of northern and western England to 60–70% in eastern England. Assuming a normal distribution, the probability of exceeding a given amount of drainage is easily found.The proportion, f of solute initially in the soil that is leached each winter can be calculated using these estimates of D in a simple layer model. However, f is not normally distributed, but can be fitted by the Type-1 extreme-value distribution.If there are n years of data, and m is the rank of a value in order of decreasing size, the estimation of the probability, P, of exceeding the mth largest value, fm, is P(ffm) =m/(n+1), and the return period, t, is 1/P years. Using the transform, W= In[—In P], graphs of/against W yield families of lines that, for a given location and depth in the soil, depend only on soil type, and from which extreme values likely to be encountered in a given return period can be forecast. Results are discussed for Mildenhall, Suffolk (= 99 ± 68 mm), Cockle Park, Northumberland (±= 275 ± 125 mm), Welshpool, Powis (±= 373 ± 121 mm), Carmarthen, Dyfed (±= 764 ± 196 mm) and Ambleside, Cumbria (±= 1280 ± 276 mm).

Notes: Abstract. During the four consecutive winters between 1984 and 1989 a computer simulation model was used to estimate the amounts of nitrogen in a cereal crop and available from soil to the crop after winter. The model does this by taking account of daily weather and by making simple assumptions about the starting conditions each autumn after the harvest of the previous crop. Some of the information which was given to farmers on viewdata systems is displayed, together with maps showing the average amounts of nitrogen in soil and crop in spring over 10 years in eastern England. This 10-year average is used as a baseline against which to judge the simulations in each of the four winters of our viewdata service.

Notes: Abstract. Rooting depth, watertable depth and oxygen regime were measured in plots of Sitka spruce, lodgepole pine and a 50% mixture of each species planted on a deep unflushed blanket peat. The water-table was about 10 cm deeper and roots occurred about 2 cm deeper under the pine than under the spruce or the mixture. In addition the mean concentration of oxygen at 50 cm depth was significantly larger under the pine and the mixture than under the spruce, showing that the rapid early growth of the pine had started to dry the peat. There was no evidence of any improvement in the growth of the spruce in the mixture compared to the pure Sitka spruce, suggesting that the expected nursing benefit had not occurred.

Notes: Abstract. The effect of organic matter content and other soil properties on soil erosion in the Rogate area, West Sussex, UK, was assessed using a rainfall simulator. Thirty soil samples (Podzols, Brown sands, Brown earths, Alluvial gley and Podzolized brown sands) collected from eroded and uneroded fields were exposed to 50 mm/h and 70 mm/h simulated rainfall. The results show that organic matter content influences soil erosion, through its effect on the stability of aggregates.

Notes: Abstract. Soil hydraulic conductivities are frequently required for process-based modelling of the soil water regime. Field-saturated hydraulic conductivity was measured with the Guelph permeameter in 10 soil series with a range of structures and textures. The permeameter offers a range of options for calculating conductivities depending on soil conditions, particularly homogeneity of pore distribution within each horizon. However, even horizons described as massive or apedal were not sufficiently homogeneous to satisfy the boundary conditions entirely.Hydraulic conductivities were calculated by the one head, fixed α* procedure; α* is an index of capillarity. No direct correlations were found between hydraulic conductivity and land use. However, the average hydraulic conductivity of coarse textured topsoils which were mainly under arable agriculture was less than that of the finer textured topsoils largely under grassland. Even limited structural development increased the hydraulic conductivities of fine textured, compact subsurface horizons. It is important to match the adopted procedure to the soil conditions both during the determination of flow rates in the field and in the subsequent analyses.

Notes: Abstract. In 1989–90 over 80% of the erosion on agricultural land in the South Downs was on ploughed or cultivated surfaces prepared for spring planting of cereals. This was in contrast to the pattern in previous years when most erosion was in winter cereal fields. An unusual late winter rainfall peak was the primary cause. Periods of erosion risk associated with other land uses on the South Downs are also discussed.

Notes: Abstract. Linear, exponential and power function regressions were compared for rainfall, runoff and soil loss data. The power function performed better (R2= 0.77) than exponential or linear functions for estimating runoff from daily rainfall. However, this relationship was improved (R2= 0.96) by inclusion of a random component to the deterministic part of the function. A linear relationship between runoff and soil loss data performed better (R2= 0.77) than exponential or power functions. These relationships help in designing soil and water conservation works for supplemental irrigation in the area.

Notes: Abstract. Analysis of agro-climatic conditions forms the first stage of physical land evaluation. Monthly rainfall, potential evapotranspiration and air temperature data are analysed by the agro-climatic module of the Jamaica Physical Land Evaluation System (JAMPLES). Dependable rainfall (R75), the minimum amount exceeded in a given time period in 75% of the years, ranges from 537 to 5332 mm/yr at the 141 recording stations under review, and mean potential evapotranspiration (PET) ranges from 1120 to 1580 mm/yr. Annual R75/PET ratios range from 0.3–5.0 island-wide and regional differences permit delineation of four ‘moisture availability’ zones. These are subdivided with respect to the length of the ‘dependable’ growing periods (DGP) and dry periods. The DGP is less than 2 months in the southern coastal plains and 12 months long in the north-eastern part of the island. Mean daily air temperature decreases from 26 to 13°C with elevation, permitting the delineation of five temperature classes. Suitable regions for growing particular crops can be determined with the Jamaica Geographical Information System (JAMGIS), which includes a digitized version of the 1:250000 map of agro-climatic zones. More specific land suitability assessments, taking soil conditions and feasible land management practices into account, are prepared with the physical land evaluation module of JAMPLES.

Notes: Understanding soils — the experience of an adviser By N.H. Pizer

Notes: Abstract. Crop responses to applied potassium fertilizers are erratic in many arid and semi-arid soils. The potassium supplying potential of river-bed sediments and release of interlayer potassium from eleven alkaline soils were measured in two separate experiments. Sediments from the Chenab and Ravi Rivers in Pakistan were exhausted of potassium by successively growing wheat, maize, mungbean, and wheat in them for a total of 200 days, using Hoagland solution to supply optimum amounts of other nutrients. Cumulative plant dry matter yield was significantly greater on the Chenab sediments. The quantities of potassium supplied to plants from the sediments of the two rivers were also significantly different.Interlayer potassium was extracted for 1230 minutes from a Udic Haplustalf (Pindorian series) by twelve different solutions each with the same electrolyte content (100 cmol). The sodium adsorption ratios (SAR) of the solutions were adjusted to 5, 10, 25, and 50, each with Ca: Mg ratios of 25:75, 50: 50 or 75:25, using solutions of sodium, calcium and magnesium chloride. The potassium released from the soil was inversely related to solution SAR. Increasing proportions of magnesium relative to calcium in solution favoured the release of potassium, except in the SAR 50 solution. Significantly different quantities of potassium were extracted by various solutions. Maximum potassium (442 mg/kg) was extracted by SAR 5 solution with a Ca: Mg ratio of 25:75. Interlayer potassium subsequently removed by this solution from 11 alkaline soils ranged from 407 to 499 mg/kg. The potassium released from all but three of the soils was related to their clay content (r= 0.72; n= 8). The release of potassium from the soils followed the Elovich function. The intercept (X1) and slope (X2) estimated for the function was related to potassium released (y) by the equation: y=−1.13 + 2.74X1−0.014X2 (r= 0.998; n= 8)The results imply that river sediments treated with irrigation water containing magnesium and sodium ions can contribute substantial amounts of available potassium for plant growth.