Evolutionarily distinct amphibians are disproportionately lost from human‐modified ecosystems

Humans continue to alter terrestrial ecosystems, but our understanding of how biodiversity responds is still limited. Anthropogenic habitat conversion has been associated with the loss of evolutionarily distinct bird species at local scales, but whether this evolutionary pattern holds across other clades is unknown. We collate a global dataset on amphibian assemblages in intact forests and nearby human‐modified sites to assess whether evolutionary history influences susceptibility to land conversion. We found that evolutionarily distinct amphibian species are disproportionately lost when forested habitats are converted to alternative land‐uses. We tested the hypothesis that grassland‐associated amphibian lineages have both higher diversification and are pre‐adapted to human landscapes, but found only weak evidence supporting this. The loss of evolutionarily distinct amphibians with land conversion suggests that preserving remnant forests will be vital if we aim to preserve the amphibian tree of life in the face of mounting anthropogenic pressures.     

Patchwork, Pastoralists, and Perception: Dune Sand as a Valued Resource Among Herders of Inner Mongolia

Scholars have rarely reflected upon dune sand in any context other than that of environmental hazard. Yet recent anthropological research conducted among ethnic Mongol herders in the Keerqin Sandy Lands of Northeast China indicates that native inhabitants exhibit a surprising degree of tolerance, appreciation, and even preference for dune sand at specific spatio-temporal scales. Survey data, gathered primarily through the use of photographic prompts and pile sort exercises during household interviews, reveal that many residents even regard dune sand as the constituent element of a distinctive home environment and cherished way of life. This research underscores the relevance of perception to the policies and practices of human resource management. It also calls into question the authority with which officials and scholars in China and elsewhere indiscriminantly depreciate the various social utilities of dune sand in stock-herding populations.     

Grasshopper (Orthoptera: Acridoidea) species diversity in the Pampas, Argentina

Abstract.  A study was conducted to describe the major features of geographical and temporal variation in the diversity of grassland grasshopper species (Orthoptera: Acridoidea) in different sites of the Pampas, Argentina. Species richness and relative abundance were assessed at 12 sites in eastern La Pampa and western Buenos Aires provinces, from 1994 through 1999. Mean species richness at the regional level was 10, and 34 grasshopper species were collected throughout of the study. Comparison with grasshopper species diversity from the Great Plains of North America is discussed. An evaluation of the proportions of species in each of the three distribution groups (broad, intermediate and narrow) revealed that, over all sites, broadly distributed species made up 14.7% of species composition and intermediately and narrowly distributed species made up 26.5% and 58.8%, respectively. The three top-ranked species in the studied sites were Dichroplus elongatus , D. pratensis and Staurorhectus longicornis . Results showed that, contrary to what was expected, one of the widely distributed species in the region (i.e. Baeacris punctulatus ) does not always constitute one of the most abundant species. Finally, the loss of one of the historically most common species in the Pampas, D. maculipennis , is also discussed.     

Fusarium Species From Plant Debris Associated With Soils From Maize Production Areas in the Transkei Region of South Africa

Fusarium species were isolated from plant debris in soil samples collected from cultivated maize fields and from undisturbed grasslands in two areas of the Transkei region. A total of 1205 Fusarium isolates were recovered from 27 soil samples. Fifteen Fusarium species were recovered from plant debris from Bizana soils and 13 Fusarium species from plant debris from Centane soils. The two dominant Fusarium species in both areas were F. oxysporum and F. equiseti. Very few isolates of F. moniliforme and F. subglutinans were recovered, but both of these species had significantly higher relative densities in cultivated soils than in undisturbed soils. This revised version was published online in June 2006 with corrections to the Cover Date.     

Tropical grassy biomes: linking ecology,human use and conservation

Tropical grassy biomes (TGBs) are changing rapidly the world over through a coalescence of high rates of land-use change, global change and altered disturbance regimes that maintain the ecosystem structure and function of these biomes. Our theme issue brings together the latest research examining the characterization, complex ecology, drivers of change, and human use and ecosystem services of TGBs. Recent advances in ecology and evolution have facilitated a new perspective on these biomes. However, there continues to be controversies over their classification and state dynamics that demonstrate critical data and knowledge gaps in our quantitative understanding of these geographically dispersed regions. We highlight an urgent need to improve ecological understanding in order to effectively predict the sensitivity and resilience of TGBs under future scenarios of global change. With human reliance on TGBs increasing and their propensity for change, ecological and evolutionary understanding of these biomes is central to the dual goals of sustaining their ecological integrity and the diverse services these landscapes provide to millions of people.This article is part of the themed issue ‘Tropical grassy biomes: linking ecology, human use and conservation’.     

Climate change alters plant biogeography in Mediterranean prairies along the West Coast,USA

Projected changes in climate are expected to have widespread effects on plant community composition and diversity in coming decades. However, multisite, multifactor climate manipulation studies that have examined whether observed responses are regionally consistent and whether multiple climate perturbations are interdependent are rare. Using such an experiment, we quantified how warming and increased precipitation intensity affect the relative dominance of plant functional groups and diversity across a broad climate gradient of Mediterranean prairies. We implemented a fully factorial climate manipulation of warming (+2.5–3.0 °C) and increased wet‐season precipitation (+20%) at three sites across a 520‐km latitudinal gradient in the Pacific Northwest, USA. After seeding with a nearly identical mix of native species at all sites, we measured plant community composition (i.e., cover, richness, and diversity), temperature, and soil moisture for 3 years. Warming and the resultant drying of soils altered plant community composition, decreased native diversity, and increased total cover, with warmed northern communities becoming more similar to communities further south. In particular, after two full years of warming, annual cover increased and forb cover decreased at all sites mirroring the natural biogeographic pattern. This suggests that the extant climate gradient of increasing heat and drought severity is responsible for a large part of the observed biogeographic pattern of increasing annual invasion in US West Coast prairies as one moves further south. Additional precipitation during the rainy season did little to relieve drought stress and had minimal effects on plant community composition. Our results suggest that the projected increase in drought severity (i.e., hotter, drier summers) in Pacific Northwest prairies may lead to increased invasion by annuals and a loss of forbs, similar to what has been observed in central and southern California, resulting in novel species assemblages and shifts in functional composition, which in turn may alter ecosystem functions.     

The influence of nematodes on below-ground processes in grassland ecosystems

This review summarises recent information on beneficial roles that soil nematodes play in the cycling of carbon and other plant nutrients in grassland ecosystems. In particular, we focus on the role of the two dominant functional groups of nematodes, namely the microbial- and root-feeders, and how their activities may enhance soil ecosystem-level processes of nutrient cycling and, ultimately, plant productivity in managed and unmanaged grassland ecosystems. We report recent experiments which show that low amounts of root herbivory by nematodes can increase the allocation of photoassimilate carbon to roots, leading to increased root exudation and microbial activity in the rhizosphere. The effects of these interactions on soil nutrient cycling and plant productivity are discussed. Evidence is presented to show that the feeding activities of microbial-feeding nematodes can enhance nutrient mineralization and plant nutrient uptake in grasslands, but that these responses are highly species-specific and appear to be strongly regulated by higher trophic groups of fauna (top-down regulation). We recommend that future studies of the roles of nematodes in grasslands ecosystems should consider these more complex trophic interactions and also the effects of species diversity of nematodes on soil ecosystem-level processes. This revised version was published online in June 2006 with corrections to the Cover Date.