A darkling beetle population in West Texas during the 1997–1998 El Niño

We examined the abundance and distribution of Eleodes extricata (Tenebrionidae) in a semi-arid region of West Texas. During the 2-year study, climatic conditions were extreme but opposite, with 1997 being unusually wet and mild, and 1998 being unusually dry and hot. These conditions were associated with striking differences in the population structure of the beetles. Under identical pitfall-sampling efforts, we captured 1562 and 671 individuals in 1997 and 1998, respectively. Capture rates were lowest in grassland, and highest in sand shinnery oak, and within the latter, they were lowest in blowouts, intermediate along the edges of blowouts, and highest under vegetative cover. Sex ratios were consistently female-biased, and the degree of bias increased from spring through fall in both years. These increases were more pronounced in 1998, with the sex ratios of early and late sampling periods differing by over four-fold, from 1·15 to 5·00. Females were heavier than males, and the dry masses of both sexes increased from spring though fall in both years. As with sex ratios, these increases were more pronounced in 1998. Only the largest beetles survived the drought, illustrating how extreme conditions can exert especially strong directional selection, and affect sex ratios in populations with sexual size dimorphism.     

Implications of model uncertainty for the mapping of hillslope‐scale soil erosion predictions

An integrated modelling approach (MIRSED) which utilizes the process‐based soil erosion model WEPP (Water Erosion Prediction Project) is presented for the assessment of hillslope‐scale soil erosion at five sites throughout England and Wales. The methodology draws upon previous uncertainty analysis of the WEPP hillslope soil erosion model by the authors to qualify model results within an uncertainty framework. A method for incorporating model uncertainty from a range of sources is discussed as a first step towards using and learning from results produced through the GLUE (Generalized Likelihood Uncertainty Estimation) technique. Results are presented and compared to available observed data, which illustrate that levels of uncertainty are significant and must be taken into account if a meaningful understanding of output from models such as WEPP is to be achieved. Furthermore, the collection of quality, observed data is underlined for two reasons: as an essential tool in the development of soil erosion modelling and also to allow further constraint of model uncertainty. Copyright © 2001 John Wiley & Sons, Ltd.     

Seasonal Forecasting for Climate Hazards: Prospects and Responses

One of the most promising developments for early warning of climate hazards is seasonal climate forecasting. Already forecasts are operational in many parts of the tropics and sub-tropics, particularly for droughts and floods associated with ENSO events. Prospects for further development of seasonal forecasting for a range of climatichazards are reviewed, illustrated with case studies in Africa, Australia, the U.S.A. and Europe. A critical evaluation of the utility of seasonal forecasts centres on vulnerability, communicationchannels, and effective responses. In contrast to short-term prediction, seasonal forecasts raise new issues of preparedness and the use of information.     

An experimental study of the effect of iron on magnesiochloritoid-talc-clinochlore-kyanite stability

The influence of Fe on the reaction clinochlore+kyanite&ding3F;magnesiochloritoid+talc (1) was determined experimentally as a function of pressure (1.6-2.6 GPa) and composition at 600 and 540 °C. Analytical electron microscopy (AEM) was used to determine the compositions of the coexisting phases in these complex multiphase run products. Within the compositional range studied (x_Fe^bulk=0.12-0.34), chlorite solid solutions were always richer in magnesium than the coexisting chloritoid solid solutions. Fractionation of Fe into the chloritoid extends the stability field of the assemblage chloritoid plus talc towards lower pressures. However, the extent of the stability field for increasing x_Fe is less than one would expect for ideal mixing behaviour in chloritoid and chlorite, and indicates a moderate positive deviation from ideality for chloritoid solid solutions. The thermodynamic data for magnesiochloritoid given in two earlier studies are in good agreement with the present experiments, those of a third study yield pressures which are much too high, at least compared with the experiments at 600 °C.     

Use of GIS mapping and modeling approaches to examine the spatial distribution of seagrasses in Barnegat Bay, New Jersey

Due to the ecological importance of seagrasses and recent indications of disease and dieback, we have synthesized existing mapped survey information concerning the spatial and temporal distribution of seagrass beds (primarily eelgrass,Zostera marina) in Barnegat Bay, New Jersey. Mapped surveys from the 1960s, 1970s, 1980s, and 1990s were digitized and compiled in a geographic information system to facilitate analysis. Comparison of the earlier maps with the 1990s survey shows an overall decrease of approximately 2,000 to 3,000 ha in the area of seagrass beds. While there are indications of seagrass decline, due to the great difference in mapping methods used for each of the surveys, we are cautious in directly attributing the decrease in mapped eelgrass acreage to a large-scale dieback. We examined the extent to which light could be used to predict the distribution of seagrass in Barnegat Bay. Data on Secchi depth throughout the bay were combined with a modification of an existing model (Duarte 1991) of the relationship betweenZ. marina compensation depths and light attenuation coefficients to predict the distribution of seagrasses in Barnegat Bay. When compared with mapped seagrass distribution in the bay, the model correctly predicts seagrass presence-absence over two-thirds of the time. The majority of the model error is due to errors of commission, i.e., the model predicts seagrass occurrence where it was not observed to occur. Most of this commission error is located in specific geographic areas (i.e., southern third of Little Egg Harbor and the western shoreline of the bay).