Gravel pits support waterbird diversity in an urban landscape

We assessed the benefit of 11 gravel pits for the settlement of waterbird communities in an urbanized area lacking natural wetlands. Gravel pits captured 57% of the regional species pool of aquatic birds. We identified 39 species, among which five were regionally rare. We used the Self Organizing Map algorithm to calculate the probabilities of presence of species, and to bring out habitat conditions that predict assemblage patterns. The age of the pits did not correlate with assemblage composition and species richness. There was a positive influence of macrophyte cover on waterbird species richness. Larger pits did not support more species, but species richness increased with connectivity. As alternative wetland habitats, gravel pits are attractive to waterbirds, when they act as stepping stones that ensure connectivity between larger natural and/or artificial wetlands separated in space

What does regional studies study? From subnational to supra-national regional spaces or Grossraum of sovereign governance

This article makes a case for expanding the scope of current versions of “regional studies” to include greater emphasis upon transnational regions as of equal if not greater importance compared with an exclusive focus upon sub-national regions. The latter more restrictive approach is typically predicated on the continued centrality of state borders against which the dominant notion of regions as subnational entities is constituted and reiterated. Drawing upon a case study of the African Union our study provides a framework, a critically revised Grossraum theory, for addressing the emergence of a new pluralistic and multipolar world order characterised by supra-national regions and regional organizations. Traditional Schmittian notions of Grossraum are shown to be in need of substantial revision before they are able to adequately accommodate and explain the empirical details of our case study

Extreme drought impacts have been underestimated in grasslands and shrublands globally

Climate change is increasing the frequency and severity of short-term (~1 y) drought events-the most common duration of drought-globally. Yet the impact of this intensification of drought on ecosystem functioning remains poorly resolved. This is due in part to the widely disparate approaches ecologists have employed to study drought, variation in the severity and duration of drought studied, and differences among ecosystems in vegetation, edaphic and climatic attributes that can mediate drought impacts. To overcome these problems and better identify the factors that modulate drought responses, we used a coordinated distributed experiment to quantify the impact of short-term drought on grassland and shrubland ecosystems. With a standardized approach, we imposed ~a single year of drought at 100 sites on six continents. Here we show that loss of a foundational ecosystem function-aboveground net primary production (ANPP)-was 60% greater at sites that experienced statistically extreme drought (1-in-100-y event) vs. those sites where drought was nominal (historically more common) in magnitude (35% vs. 21%, respectively). This reduction in a key carbon cycle process with a single year of extreme drought greatly exceeds previously reported losses for grasslands and shrublands. Our global experiment also revealed high variability in drought response but that relative reductions in ANPP were greater in drier ecosystems and those with fewer plant species. Overall, our results demonstrate with unprecedented rigor that the global impacts of projected increases in drought severity have been significantly underestimated and that drier and less diverse sites are likely to be most vulnerable to extreme drought

Bottom melting on the Filchner-Ronne Ice Shelf, Antarctica, using different measuring techniques

During the 1989/90 field season on Filchner-Ronne Ice Shelf (FRIS), Antarctica, special interest was focussed on the examination of the bottom-melting rate by different measuring techniques. Access to the sea water underneath the ice shelf was gained by means of hot-water drillings. The installation of temperature cable and TDR-sensor lines yield a distinct value of the bottom mass-balance parameter after re-measurement in 1992. In addition a seasonal dependence for bottom melting is indicated. The results of the long-term observation conform with a mass-balance study performed in the same region from surface-based measurements in the same season (Determann et al., 1990 ).The influence of tidal-induced ice shelf/ocean interaction with regard to bottom melting can be derived from a continual registration of sea-water temperatures