Topic
Species richness
About: Species richness is a research topic. Over the lifetime, 61672 publications have been published within this topic receiving 2183796 citations.
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TL;DR: The results of this study demonstrate that mycorrhizal symbiosis can have large effects on plant community structure, and that differential host species response to fungal colonization is a key factor explaining the dominance of warm- season C4 grasses in tallgrass prairie and limiting plant species evenness and diversity.
Abstract: In grassland ecosystems, symbiotic associations between plants and mycor- rhizal fungi are widespread and have important influences on the life histories, demography, and species interactions of plants, and on belowground ecosystem processes. To assess the consequences of the symbiosis at the plant community level, we conducted a 5-yr field experiment in tallgrass prairie to investigate the influence of arbuscular mycorrhizal fungi on plant species composition, relative abundances, and diversity. Replicate plots in which mycorrhizal fungi were suppressed with benomyl application every two weeks during each growing season, were compared to nontreated mycorrhizal control plots on six watershed units at the Konza Prairie in northeastern Kansas. Benomyl successfully reduced mycor- rhizal colonization to <25% of mycorrhizal control plots. Mycorrhizal colonization of roots in control plots was inversely related to annual precipitation. Suppression of mycorrhizae resulted in decreases in abundances of the dominant, obligately mycotrophic C4 tall grasses, compensatory increases in abundances of many subordinate facultatively mycotrophic C3 grasses and forbs, but no change in total aboveground biomass, as estimated from canopy density. Suppression of mycorrhizal symbiosis resulted in a large increase in plant species diversity. Two possible mechanisms for mycorrhizal mediation of plant species composition and diversity are: (1) alterations in resource distribution among neighbors via hyphal con- nections, and (2) differential host species responses to mycorrhizal fungal colonization in communities in which the competitive dominants are more strongly or more weakly my- cotrophic than their neighbors. The results of this study demonstrate that mycorrhizal symbiosis can have large effects on plant community structure, and that differential host species response to fungal colonization is a key factor explaining the dominance of warm- season C4 grasses in tallgrass prairie and limiting plant species evenness and diversity. The results also underscore the importance of above- and belowground linkages in tallgrass prairie and indicate that alterations in belowground fungi and rhizosphere processes can have large effects on aboveground floristic composition and diversity in grasslands.
475 citations
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Royal Botanic Garden Edinburgh1, National Autonomous University of Mexico2, University of Edinburgh3, National Agrarian University4, Smithsonian Conservation Biology Institute5, Universidade Federal de Minas Gerais6, National University of Rosario7, Pontificia Universidad Católica del Ecuador8, Spanish National Research Council9, National Museum of Natural History10, University of Los Andes11, South Colombian University12, University of Atlántico13, Venezuelan Institute for Scientific Research14, Arizona State University15, Alexander von Humboldt Biological Resources Research Institute16, Del Rosario University17, International Institute of Minnesota18, University of Antioquia19, District University of Bogotá20, National University of Salta21, Bangor University22, University of the West Indies23, Universidad del Tolima24, National University of Colombia25, Royal Botanic Gardens26, University of Pamplona27
TL;DR: Using 835 inventories covering 4660 species of woody plants, marked floristic turnover among inventories and regions indicates that numerous conservation areas across many countries will be needed to protect the full diversity of tropical dry forests.
Abstract: Seasonally dry tropical forests are distributed across Latin America and the Caribbean and are highly threatened, with less than 10% of their original extent remaining in many countries. Using 835 inventories covering 4660 species of woody plants, we show marked floristic turnover among inventories and regions, which may be higher than in other neotropical biomes, such as savanna. Such high floristic turnover indicates that numerous conservation areas across many countries will be needed to protect the full diversity of tropical dry forests. Our results provide a scientific framework within which national decision-makers can contextualize the floristic significance of their dry forest at a regional and continental scale.
473 citations
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TL;DR: The results demonstrate that, over the long term, the loss of plant species propagates through food webs, greatly decreasing arthropod species richness, shifting a predator-dominated trophic structure to being herbivore dominated, and likely impacting ecosystem functioning and services.
Abstract: Plant diversity is predicted to be positively linked to the diversity of herbivores and predators in a foodweb. Yet, the relationship between plant and animal diversity is explained by a variety of competing hypotheses, with mixed empirical results for each hypothesis. We sampled arthropods for over a decade in an experiment that manipulated the number of grassland plant species. We found that herbivore and predator species richness were strongly, positively related to plant species richness, and that these relationships were caused by different mechanisms at herbivore and predator trophic levels. Even more dramatic was the threefold increase, from low- to high-plant species richness, in abundances of predatory and parasitoid arthropods relative to their herbivorous prey. Our results demonstrate that, over the long term, the loss of plant species propagates through food webs, greatly decreasing arthropod species richness, shifting a predator-dominated trophic structure to being herbivore dominated, and likely impacting ecosystem functioning and services.
473 citations
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TL;DR: Understanding how pollination processes are affected in such degraded landscapes can inform effective conservation and management of remaining natural areas.
Abstract: The ecological significance of spacing among plants in contributing to the maintenance of species richness, particularly in tropical forests, has received considerable attention that has largely focussed on distance- and density-dependent seed and seedling mortality. More recently it has become apparent that plant spacing is also relevant to pollination, which often constrains seed production. While seed and seedling survival is reduced at high conspecific densities, pollination success, by contrast, is positively correlated to local conspecific density. Distance-dependent mechanisms acting on pollination and seed production have now been described for a variety of plants, with relatively isolated plants or fragmented populations generally suffering reduced fecundity due to pollen limitation. Yet there is considerable variability in the vulnerability of plant species to pollination failure, which may be a function of breeding system, life history, the pollination vector, the degree of specialisation among plants and their pollinators, and other indirect effects of habitat change acting on plants or pollinators. As reduced tree densities and population fragmentation are common outcomes of anthropogenically altered landscapes, understanding how pollination processes are affected in such degraded landscapes can inform effective conservation and management of remaining natural areas.
473 citations
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TL;DR: Evaluating bat populations may be a good first step in assessing an area's conservation value, especially in rainforest regions, because bats are abundant, diverse, and easy to sample and they fulfill several of the requirements of indicator species.
Abstract: Evaluating the degree of disturbance of any region to determine its relative importance for conservation purposes requires procedures that are relatively inexpensive and that yield accurate results fast. Because bats are abundant, diverse, and easy to sample, especially in the Neotropical rainforest, they fulfill several of the requirements of indicator species as identified in the literature. For 10 months we sampled bat communities in the Selva Lacandona in Chiapas, Mexico, at 15 sites representing five habitats. We also measured 10 variables representing vegetation structure and diversity at each site. With fuzzy-set techniques we produced a gradient classification of disturbance for the 15 sites based on the vegetation data. We explored the relationship between vegetation conditions, described as the membership degrees in the construct “fuzzy forest set” (the complementary fuzzy set of “disturbance”), and four bat community variables. Bat species richness, number of rare bat species, and the bat diversity index were positively correlated with the vegetation scores, and relative abundance of the most abundant bat species was negatively correlated with vegetation scores. A high number of phyllostomine species in a community is a good indicator of low levels of disturbance. Although a single indicator group will probably not be sufficient for decision-making processes in conservation, evaluating bat populations may be a good first step in assessing an area's conservation value, especially in rainforest regions.
472 citations