ALBERT

Description: Coral bleaching events threaten coral reef habitats globally and cause severe declines of local biodiversity and productivity. Related to high sea surface temperatures, bleaching events are expected to increase as a consequence of future global warming. However, response to climate change is still uncertain as future low latitude climatic conditions have no present-day analogue. Sea surface temperatures during the Eocene epoch were warmer than forecasted changes for the coming century, and distributions of corals during the Eocene may help to inform models forecasting the future of coral reefs. We coupled contemporary and Eocene coral occurrences with information on their respective climatic conditions to model the thermal niche of coral reefs and its potential response to projected climate change. We found that under the RCP8.5 climate change scenario, the global suitability for coral reefs may increase up to 16% by 2100, mostly due to improved suitability of higher latitudes. In contrast, in its current range, coral reef suitability may decrease up to 46% by 2100. Reduction in thermal suitability will be most severe in biodiversity hotspots, especially in the Indo-Australian Archipelago. Our results suggest that many contemporary hotspots for coral reefs, including those that have been refugia in the past, spatially mismatch with future shifts in coral reef habitat suitability, posing even more challenges to conservation actions under climate change. This article is protected by copyright. All rights reserved.

Description: 29 Si NMR shielding tensors of a series of triphenylsilanes Ph 3 Si R with R = Ph, Me, F, Cl, Br, OH, OMe, SH, NH 2 , SiPh 3 , C≡CPh were determined from 29 Si CP/MAS spectra recorded at low spinning rates. In addition the principal components of the shielding tensor were calculated employing the DFT-IGLO method. For most silanes experimental and calculated values are in good accordance. Larger differences were observed for systems with hydrogen bridge forming substituents and the halides bromide and chloride. In some of the spectra the shielding information interfered with residual dipolar couplings. The different contributions of the various substituents to the principal components of the shielding tensor and the orientation of the tensor within the molecules are discussed and compared for the compounds under investigation.

Description: Abstract Global deep‐time plate motion models have traditionally followed a classical rigid plate approach, even though plate deformation is known to be significant. Here we present a global Mesozoic–Cenozoic deforming plate motion model that captures the progressive extension of all continental margins since the initiation of rifting within Pangea at ~240 Ma. The model also includes major failed continental rifts and compressional deformation along collision zones. The outlines and timing of regional deformation episodes are reconstructed from a wealth of published regional tectonic models and associated geological and geophysical data. We reconstruct absolute plate motions in a mantle reference frame with a joint global inversion using hot spot tracks for the last 80 million years and minimizing global trench migration velocities and net lithospheric rotation. In our optimized model, net rotation is consistently below 0.2°/Myr, and trench migration scatter is substantially reduced. Distributed plate deformation reaches a Mesozoic peak of 30 × 106 km2 in the Late Jurassic (~160–155 Ma), driven by a vast network of rift systems. After a mid‐Cretaceous drop in deformation, it reaches a high of 48 x 106 km2 in the Late Eocene (~35 Ma), driven by the progressive growth of plate collisions and the formation of new rift systems. About a third of the continental crustal area has been deformed since 240 Ma, partitioned roughly into 65% extension and 35% compression. This community plate model provides a framework for building detailed regional deforming plate networks and form a constraint for models of basin evolution and the plate‐mantle system.

Description: Black leaf mold caused by Pseudocercospora fuligena is an important fungal disease of tomato in Southeast Asia. The objective of this study was to evaluate the control of this disease using high manganese (Mn) applied to the root substrate and to evaluate the role of the leaf apoplast in plant response to fungal infection. In a nethouse experiment in Thailand, Mn above the optimum for plant growth but below toxicity increased resistance of tomato plants to black leaf mold. Enhanced resistance caused by Mn was also obtained when tomato plants were grown under controlled conditions in a mist chamber and artificially inoculated with the fungus. Manganese significantly increased plant peroxidases in the leaf apoplast. The highest peroxidase activity was measured when plants were inoculated with Pseudocercospora fuligena. Defense-related proteins in the leaf apoplast increased when plants were inoculated with Pseudocercospora fuligena but not when treated with high Mn. It is concluded that Mn above the optimum level for plant growth can contribute to the control of Pseudocercospora fuligena in tomato. The Mn effect on disease resistance is associated with the activation of plant peroxidases in the leaf apoplast. A systemic response, possibly mediated by NADH peroxidase activity, also seems to trigger disease resistance in leaves with low Mn concentrations.

Description: This study used stream gage records to assess the impact of levees on flood levels, providing an empirical test of theoretical and model predictions of the effects on local flood response. Focusing upon a study area in Illinois and Iowa for which levee records were available, we identified 203 gages with ≥50 years hydrologic record, including 15 gages where a levee was constructed during the period of record. At these sites, step-change analysis utilizing regression residuals tested levee-related stage changes, levels of significance, and quantified the magnitudes of stage increases. Despite large differences in stream sizes, levee alignments, and degree of floodplain constriction, the post-levee rating-curve adjustments showed consistent signatures. For all of the study sites, stages for below-bankfull (non-flood) conditions were unaffected by levee construction. For above-bankfull (flood) conditions, stages at sites downstream of their associated levees also were statistically indistinguishable before vs. after levee construction. At all sites upstream of levees or within leveed reaches, however, stages increased for above-bankfull conditions. These increases were abrupt, statistically significant, and generally large in magnitude – ranging up to 2.3 m (Wabash River at Mt. Carmel, IL). Stage increases began when discharge increased above bankfull flow, and generally increased in magnitude with discharge until the associated levee(s) were overtopped. Detailed site assessments and supplementary data available from some sites helped document the dominant mechanisms by which levees can increase flood levels. Levee construction reduces the area of the floodplain open to storage of flood waters and reduces the width of the floodplain open to conveyance of flood flow. Floodplain conveyance is often underestimated or ignored, but ADCP measurements analyzed here confirm previous studies that up to 70% or more of total discharge during large floods (~3% chance flood) can move over the floodplain. Upstream of levees and levee-related floodplain constriction, back-water effects reduce flow velocities relative to pre-levee conditions and thus increase stages for a given discharge. The empirical results here confirm a variety of theoretical predictions of levee effects, but suggest that many 1D-model-based predictions of levee-related stage changes may underestimate actual levee impacts. Copyright © 2011 John Wiley & Sons, Ltd.

Description: Reforestation of formerly cultivated land is widely understood to accumulate above- and below-ground detrital organic matter pools, including soil organic matter. However, during 40 years of study of reforestation in the subtropical southeastern USA, repeated observations of above- and belowground carbon documented that significant gains in soil organic matter (SOM) in surface soils (0-7.5 cm) were offset by significant SOM losses in subsoils (35-60-cm). Here, we extended the observation period in this long-term experiment by an additional decade, and used soil fractionation and stable and radio-isotopes to explore changes in soil organic carbon and soil nitrogen that accompanied nearly 50 years of loblolly pine secondary forest development. We observed that accumulations of mineral soil C and N from 0 to 7.5 cm were almost entirely due to accumulations of light fraction SOM. Meanwhile, losses of soil C and N from mineral soils at 35 to 60 cm were from SOM associated with silt and clay-sized particles. Isotopic signatures showed relatively large accumulations of forest-derived carbon in surface soils, and little to no accumulation of forest-derived carbon in subsoils. We argue that the land use change from old field to secondary forest drove biogeochemical and hydrological changes throughout the soil profile that enhanced microbial activity and SOM decomposition in subsoils. However, when the pine stands aged and began to transition to mixed pines and hardwoods, demands on soil organic matter for nutrients to support aboveground growth eased due to pine mortality, and subsoil organic matter levels stabilized. This study emphasizes the importance of long-term experiments and deep measurements when characterizing soil C and N responses to land use change and the remarkable paucity of such long-term soil data deeper than 30 cm. This article is protected by copyright. All rights reserved.

Description: Chalcogenidotetrelates show a rich and complex chemistry encompassing intricate structures and useful materials. A step-wise coordination chemistry approach allows the sequential formation of multinary M/T/E anions (M = transition metal, T = tetrel, E = chalcogen) from simple T/E building blocks in solution. This way, a range of compounds displaying different structure types of molecular as well as extended multinary anions were obtained. To allow for even further variety, the approach can be extended to organo-functionalized chalcogenidotetrelates. Here, the organic shell of the inorganic cages plays a decisive role in reactivity and resulting structures. The formation structures and properties of these compounds will be discussed in detail in this perspective article.

Description: Previous thermomechanical modeling studies indicated that variations in the temperature and strength of the crystalline crust might be responsible for the juxtaposition of domains with thin-skinned and thick-skinned crustal deformation along-strike the foreland of the Central Andes. However, there is no evidence supporting this hypothesis from data-integrative models. We aim to derive the density structure of the lithosphere by means of integrated 3D density modeling, in order to provide a new basis for discussions of compositional variations within the crust and for future thermal and rheological modeling studies. Therefore, we utilize available geological and geophysical data to obtain a structural and density model of the uppermost 200km of the Earth. The derived model is consistent with the observed Bouguer gravity field. Our results indicate that the crystalline crust in northern Argentina can be represented by a lighter upper crust (2800 kg/m 3 ) and a denser lower crust (3100kg/m 3 ). We find new evidence for high bulk crustal densities 〉3000kg/m 3 in the northern Pampia terrane. These could originate from subducted Puncoviscana wackes or pelites that ponded to the base of the crystalline crust in the late Proterozoic, or indicate increasing bulk content of mafic material. The precise composition of the northern foreland crust, whether mafic or felsic, has significant implications for further thermomechanical models and the rheological behavior of the lithosphere. A detailed sensitivity analysis of the input parameters indicates that the model results are robust with respect to the given uncertainties of the input data.