Species richness

About: Species richness is a research topic. Over the lifetime, 61672 publications have been published within this topic receiving 2183796 citations.

Influence of past land use on the vegetation and soils of present day forest in the vosges mountains, france

Abstract: 1 Afforestation has been widespread in western Europe over the past 200 years. In France, nearly half of the current forested area has previously been used for agricultural purposes. 2 The impact of previous land use on vegetation (physiognomy, species richness and Ellenberg's indicator value) and soil (carbon, nitrogen, phosphorus contents and pH) in the Vosges mountains (north-eastern France) was studied. Previous land uses were classified into four categories (old forest, pasture, cropland, garden) based on historical records. The potential bio-indicative value of &5N as a marker of these previous land uses was also tested. 3 Previous croplands and gardens displayed a higher species richness than old forests (24, 27 and 16 species per plot, respectively), higher Ellenberg's indicator values for nitrogen, humidity and pH and higher vegetation cover. Vegetation of previous pastures was very similar to old forest. 4 Soils under previous agricultural lands displayed a higher phosphorus content, higher pH values and lower C/N ratios than old forests. &5N was the lowest, at any depth, in old forests. 5 These differences could be interpreted as consequences of the fertility transfer which occurred from pastures to croplands or gardens, through the spread of animal manures on tilled areas. The persistence of such landscape differentiation, even a century later, should be taken into account in forest management.

Evolutionary diversification in stickleback affects ecosystem functioning

Abstract: Explaining the ecological causes of evolutionary diversification is a major focus of biology, but surprisingly little has been said about the effects of evolutionary diversification on ecosystems. The number of species in an ecosystem and their traits are key predictors of many ecosystem-level processes, such as rates of productivity, biomass sequestration and decomposition. Here we demonstrate short-term ecosystem-level effects of adaptive radiation in the threespine stickleback (Gasterosteus aculeatus) over the past 10,000 years. These fish have undergone recent parallel diversification in several lakes in coastal British Columbia, resulting in the formation of two specialized species (benthic and limnetic) from a generalist ancestor. Using a mesocosm experiment, we demonstrate that this diversification has strong effects on ecosystems, affecting prey community structure, total primary production, and the nature of dissolved organic materials that regulate the spectral properties of light transmission in the system. However, these ecosystem effects do not simply increase in their relative strength with increasing specialization and species richness; instead, they reflect the complex and indirect consequences of ecosystem engineering by sticklebacks. It is well known that ecological factors influence adaptive radiation. We demonstrate that adaptive radiation, even over short timescales, can have profound effects on ecosystems.

Species richness declines and biotic homogenisation have slowed down for NW-European pollinators and plants

Abstract: Concern about biodiversity loss has led to increased public investment in conservation. Whereas there is a widespread perception that such initiatives have been unsuccessful, there are few quantitative tests of this perception. Here, we evaluate whether rates of biodiversity change have altered in recent decades in three European countries (Great Britain, Netherlands and Belgium) for plants and flower visiting insects. We compared four 20-year periods, comparing periods of rapid land-use intensification and natural habitat loss (1930–1990) with a period of increased conservation investment (post-1990). We found that extensive species richness loss and biotic homogenisation occurred before 1990, whereas these negative trends became substantially less accentuated during recent decades, being partially reversed for certain taxa (e.g. bees in Great Britain and Netherlands). These results highlight the potential to maintain or even restore current species assemblages (which despite past extinctions are still of great conservation value), at least in regions where large-scale land-use intensification and natural habitat loss has ceased.

Measuring ectomycorrhizal fungal dispersal: macroecological patterns driven by microscopic propagules.

Abstract: Dispersal plays a prominent role in most conceptual models of community assembly. However, direct measurement of dispersal across a whole community is difficult at ecologically relevant spatial scales. For cryptic organisms, such as fungi and bacteria, the scale and importance of dispersal limitation has become a major point of debate. We use an experimental island biogeographic approach to measure the effects of dispersal limitation on the ecological dynamics of an important group of plant symbionts, ectomycorrhizal fungi. We manipulated the isolation of uncolonized host seedlings across a natural landscape and used a range of molecular techniques to measure the dispersal rates of ectomycorrhizal propagules and host colonization. Some species were prolific dispersers, producing annual spore loads on the order of trillions of spores per km 2 . However, fungal propagules reaching host seedlings decreased rapidly with increasing distance from potential spore sources, causing a concomitant reduction in ectomycorrhizal species richness, host colonization and host biomass. There were also strong differences in dispersal ability across species, which correlated well with the predictable composition of ectomycorrhizal communities associated with establishing pine forest. The use of molecular tools to measure whole community dispersal provides a direct confirmation for a key mechanism underlying island biogeography theory and has the potential to make microbial systems a model for understanding the role of dispersal in ecological theory.

Immigration and the Maintenance of Local Species Diversity

Abstract: Explaining the maintenance of high local species diversity in communities governed by competition for space has been a long‐standing problem in ecology. We present a simple theoretical model to explore the influence of immigration from an external source on local coexistence, species abundance patterns, and ecosystem processes in plant communities. The model is built after classical metapopulation models but is applied to competition for space between individuals and includes immigration by a propagule rain and an extinction threshold for rare species. Our model shows that immigration can have a huge effect on local species diversity in competitive communities where competition for space would lead to the exclusion of all but one species if the community were closed. Local species richness is expected to increase strongly when immigration intensity increases beyond the threshold required for the successful establishment of one or a few individuals. Community structure and species relative abunda...