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This paper reports field observational evidence on the diversity-biomass production relationship from eastern Mediterranean shrublands dominated by Cistus salviifolius. The main results are: (1) plant diversity and ecosystem primary production are positively correlated in the Cistus shrublands, which are multigrowth form systems; (2) the taxonomic and growth form diversity in Cistus shrublands...
Water-column mixing is known to have a decisive impact on plankton communities. The underlying mechanisms depend on the size and depth of the water body, nutrient status and the plankton community structure, and they are well understood for shallow polymictic and deep stratified lakes. Two consecutive mixing events of similar intensity under different levels of herbivory were performed in...
For unicellular organisms, a lack of effects of local species richness on ecosystem function has been proposed due to their locally high species richness and their ubiquitous distribution. High dispersal ability and high individual numbers may enable unicellular taxa to occur everywhere. Using our own and published data sets on uni- and multicellular organisms, we conducted thorough statistical analyses...
We compared the parasitoid communities associated with grass-feeding herbivores in Germany and Britain to examine geographical consistency in community composition and to test ecological characteristics of the plants and host insects that may explain variability in parasitoid community structure. The parasitoid communities of 16 chalcid wasps feeding on ten grass species were sampled between 1986...
Abstract. The relationship between biodiversity and individual ecosystem processes is often asymptotic, saturating at relatively low levels, with some species contributing more strongly than others. This has cast doubt on arguments for conservation based on maintenance of the functioning of ecosystems. However, we argue that the link between biodiversity and ecosystem functioning is an important additional...
Abstract. In a recent study, Troumbis and Memtas [Oecologia (2000) 125:101128] demonstrated that plant diversity and productivity were correlated in a Mediterranean grassland, and presented this as observational evidence that diversity may positively influence productivity. However, the hump-backed model between biomass or productivity and diversity predicts that productivity and diversity should...
In a recent study, Troumbis and Memtas [Oecologia (2000) 125:101–128] demonstrated that plant diversity and productivity were correlated in a Mediterranean grassland, and presented this as observational evidence that diversity may positively influence productivity. However, the hump-backed model between biomass or productivity and diversity predicts that productivity and diversity should be positively...
The relationship between biodiversity and individual ecosystem processes is often asymptotic, saturating at relatively low levels, with some species contributing more strongly than others. This has cast doubt on arguments for conservation based on maintenance of the functioning of ecosystems. However, we argue that the link between biodiversity and ecosystem functioning is an important additional...
Several components of the diversity of plant communities, such as species richness, species composition, number of functional groups and functional composition, have been shown to directly affect the performance of exotic species. Exotics can also be affected by herbivores of the native plant community. However, these two possible mechanisms limiting invasion have never been investigated together...
. The impact of regional factors (such as speciation or dispersal) on the species richness in local communities (SL) has received increasing attention. A prominent method to infer the impact of regional factors is the comparison of species richness in local assemblages (SL) with the total number of species in the region (SR). Linear relations between SR and SL have been interpreted as an indication...
. Microsites that prevent seed germination are critical for slowing the invasion of native plant communities by aggressive, clonal species. A suitable model for study is the clonal grass, Phalaris arundinacea, which reproduces prolifically from seed and is spreading into wetlands across temperate North America. Knowing that light conditions control its seed germination in the laboratory and that...
. Earthworms are a major component of many terrestrial ecosystems. By modifying decomposition processes and soil structure, they function as driving factors of the soil microbial community. Using microcosms, we investigated the effects of the presence and community composition of earthworms on the in situ respiratory response of a microbial community to an array of organic substrates including carbohydrates,...
Availability and heterogeneity of resources have a strong influence on plant community structure in undisturbed systems, as well as those recovering from disturbance. Less is known about the role of resource availability and heterogeneity in restored communities, although restoration provides a valuable opportunity to test our understanding of factors that influence plant community assembly. We altered...
Animals aid population growth and fitness in tropical forest communities through dispersal and negatively impact populations through seed predation. The interaction between dispersal and seed predation can produce distance- or density-dependence; powerful mechanisms for maintaining species diversity incorporated in the JanzenConnell model. Large mammals, the highest biomass seed predators of intact...
Ice is a major structuring force in marine and freshwater environments at high latitudes. Although recovery from scouring has been quantified in time, the frequency of scouring in the Antarctic has not. We placed grids of markers at 917m depth at two sites, to study ice-scouring over 2years at Adelaide island (Antarctic Peninsula). We quantified the time scale of scour frequencies, and linked this...
Reducing the biological diversity of a community may decrease its resistance to invasion by exotic species. Manipulative experiments typically support this hypothesis but have focused mainly on one trophic level (i.e., primary producers). To date, we know little about how positive interactions among species may influence the relationship between diversity and invasibility, which suggests a need for...
Mammals are hypothesized to either promote plant diversity by preventing competitive exclusion or limit diversity by reducing the abundance of sensitive plant species through their activities as browsers or disturbance agents. Previous studies of herbivore impacts in plant communities have focused on tree species and ignored the herbaceous community. In an experiment in mature-phase, tropical moist...
Variation in plant species performance in response to water availability offers a potential axis for temporal and spatial habitat partitioning and may therefore affect community composition in tropical forests. We hypothesized that short dry spells during the wet season are a significant source of mortality for the newly emerging seedlings of pioneer species that recruit in treefall gaps in tropical...
Despite the development of diversity indices in community ecology that incorporate both richness and evenness, pollination biologists commonly use only pollinator richness to estimate generalization. Similarly, while pollination biologists have stressed the utility of pollinator importance, incorporating both pollinator abundance and effectiveness, importance values have not been included in estimates...
Increasing temperatures due to climate change were found to influence abundance and timing of species in numerous ways. Whereas many studies have investigated climate-induced effects on the phenology and abundance of single species, less is known about climate-driven shifts in the diversity and composition of entire communities. Analyses of long-term data sets provide the potential to reveal such...
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