scispace - formally typeset
Search or ask a question
Topic

Species richness

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


Papers
More filters
Journal ArticleDOI
02 Apr 2009-Nature
TL;DR: It is found that the stability of the net ecosystem denitrification in the face of salinity stress was strongly influenced by the initial evenness of the community, therefore, when communities are highly uneven, or there is extreme dominance by one or a few species, their functioning is less resistant to environmental stress.
Abstract: Owing to the present global biodiversity crisis, the biodiversity-stability relationship and the effect of biodiversity on ecosystem functioning have become major topics in ecology. Biodiversity is a complex term that includes taxonomic, functional, spatial and temporal aspects of organismic diversity, with species richness (the number of species) and evenness (the relative abundance of species) considered among the most important measures. With few exceptions (see, for example, ref. 6), the majority of studies of biodiversity-functioning and biodiversity-stability theory have predominantly examined richness. Here we show, using microbial microcosms, that initial community evenness is a key factor in preserving the functional stability of an ecosystem. Using experimental manipulations of both richness and initial evenness in microcosms with denitrifying bacterial communities, we found that the stability of the net ecosystem denitrification in the face of salinity stress was strongly influenced by the initial evenness of the community. Therefore, when communities are highly uneven, or there is extreme dominance by one or a few species, their functioning is less resistant to environmental stress. Further unravelling how evenness influences ecosystem processes in natural and humanized environments constitutes a major future conceptual challenge.

866 citations

Journal ArticleDOI
TL;DR: This review seeks to synthesise information on the responses of insects and allied groups to increasing altitude and provide a platform for future research by considering how montane insect species will respond to climate warming.
Abstract: The literature on the response of insect species to the changing environments experienced along altitudinal gradients is diverse and widely dispersed. There is a growing awareness that such responses may serve as analogues for climate warming effects occurring at a particular fixed altitude or latitude over time. This review seeks, therefore, to synthesise information on the responses of insects and allied groups to increasing altitude and provide a platform for future research. It focuses on those functional aspects of insect biology that show positive or negative reaction to altitudinal changes but avoids emphasising adaptation to high altitude per se. Reactions can be direct, with insect characteristics or performance responding to changing environmental parameters, or they can be indirect and mediated through the insect's interaction with other organisms. These organisms include the host plant in the case of herbivorous insects, and also competitor species, specific parasitoids, predators and pathogens. The manner in which these various factors individually and collectively influence the morphology, behaviour, ecophysiology, growth and development, survival, reproduction, and spatial distribution of insect species is considered in detail. Resultant patterns in the abundance of individual species populations and of community species richness are examined. Attempts are made throughout to provide mechanistic explanations of trends and to place each topic, where appropriate, into the broader theoretical context by appropriate reference to key literature. The paper concludes by considering how montane insect species will respond to climate warming.

865 citations

Journal ArticleDOI
17 Apr 2003-Nature
TL;DR: Here a long-term data set is used, from an estuarine fish community, to show how an ecological community can be separated into two components: core species, which are persistent, abundant and biologically associated with estuarist habitats, are log normally distributed andOccasional species, who occur infrequently in the record, are typically low in abundance and have different habitat requirements; they follow a log series distribution.
Abstract: The observation that a few species in ecological communities are exceptionally abundant, whereas most are rare, prompted the development of species abundance models Nevertheless, despite the large literature on the commonness and rarity of species inspired by these pioneering studies, some widespread empirical patterns of species abundance resist easy explanation Notable among these is the observation that in large assemblages there are more rare species than the log normal model predicts Here we use a long-term (21-year) data set, from an estuarine fish community, to show how an ecological community can be separated into two components Core species, which are persistent, abundant and biologically associated with estuarine habitats, are log normally distributed Occasional species occur infrequently in the record, are typically low in abundance and have different habitat requirements; they follow a log series distribution These distributions are overlaid, producing the negative skew that characterizes real data sets

859 citations

Journal ArticleDOI
TL;DR: This paper summarizes data on regeneration patterns of trees within the framework of hypotheses that (1) tree species partition gaps of different spatial distributions and sizes and (2) partitioning occurs because regeneration strategies keyed to gaps of particular size ranges involve adaptive compromises that restrict the competitive success of the species in gaps of differing sizes.
Abstract: Published observations on adaptations for seed disperal and seedling establishment are consistent with the hypothesis that rainforest trees partition forest clearings as establishment sites for offspring. Gaps vary importantly in two ways. The size of the opening affects the microclimate of the gap and therefore the conditions for seedling establishment. For any individual tree, the frequency of occurrence of gaps of a particular size range affects the probability that its propagules will reach a gap of suitable size for germination and establishment. In most rainforests large gaps (involving the death of several trees) are probably more rare than small gaps (involving single trees or branches). Interspecific competition for establishment sites has resulted in adaptive compromises in the regeneration strategies of each species. Traits that increase the probability of establishing seedlings in gaps of a particular size range appear to lower establishment in gaps outside this size range. I suggest that the coexistence of many rainforest tree species is at least partially due to their partitioning of canopy gaps by size. Therefore the size-class frequercy distribution of gaps peculiar to a given rainforest is expected to influence the types and diversity of species present. Examination of vegetation data from New and Old World rainforests reveals many patterns consistent with this hypothesis. This framework provides a mechanism for predictive and experimental studies of competitive interactions among rainforest trees. MECHANISMS PROPOSED to account for patterns of species richness within animal communities have relied heavily on resource partitioning (cf. Schoener 1974). Similar hypotheses have been less successful in accounting for plant species diversity. Different plants have similar modes of resource acquisition and share the same few essential resources (light, moistLre, minerals). It is not clear how such uniform resources could be partitioned by physiologically similar species in complex communities (e.g. Richards 1969). Although rainforest species exhibit patterns associated with variation in topography or soil (e.g. Ashton 1964a, Grieg-Smith et al. 1967, Poore 1968, Williams et al. 1969, Austin et a/. 1972, Ashton 1977), species with non-random distributions often show no association with edaphic variation (Schulz 1960, Poore 1968), and overlap along edaphic gradients is high between similar species. It remains difficult to account for high diversity in relatively uniform topographic and edaphic environments. In face of high plant species diversity unexplained by resource partitioning, theorists have invoked stochastic or historical processes to account for modern patterns (e.g. Federov 1966, Van Steenis 1969, Prance 1973, Stebbins 1974, and see Ashton 1969 for a discussion). These hypotheses assume that competitive interaction among plant species is of little importance in the determination of relative abundances of species. Here I suggest that a mechanism for resource partitioning among rainforest trees exists in their differential regeneration in treefall gaps of different sizes and spatial distributions. At a superficial level some of these differences are a well-established part of natural history lore (e.g. Richards 1964, Van Steenis 1958, Budowski 1965) and form the basis of sustained-yield forestry systems (e.g. Taylor 1962, Whitmore 1975). Several papers have emphasized that gaps are an important source of environmental heterogeneity in rainforest (Schulz 1960, Whitmore 1975, 1978, Hartshorn 1978). Nevertheless, it is evident from the literature that gap regeneration strategies have not been considered an important component of competitive interactions among trees. Few studies of rainforest vegetation include attention to the nature and distribution of natural gaps or to differential seedling establishment in them. This paper summarizes data on regeneration patterns of trees within the framework of hypotheses that (1) tree species partition gaps of different spatial distributions and sizes and that (2) partitioning occurs because regeneration strategies keyed to gaps of particular size ranges involve adaptive compromises that restrict the competitive success of the species in gaps of differing sizes. High mortality rates of seeds and seedlings (e.g. Liew and Wong 1973) suggest that selection pressures are likely to be particularly strong on factors affecting dispersal of seeds and establishment of seedlings. Gaps as establishment sites for seedlings are critical resources, and gap partitioning provides an important mechanism through which empirically to examine interspecific competitive interactions among tree species. Rainforest spatial structure and species diversity are reviewed in this light. Experimental tests of the relationships between TROPICAL SUCCESSION 47-55 1980 47 This content downloaded from 157.55.39.159 on Sun, 18 Sep 2016 06:29:01 UTC All use subject to http://about.jstor.org/terms traits described and regeneration success in gaps of different sizes are largely lacking. Support for these hypotheses is therefore based on empirical studies of forest structure and field observations accumulating over the last 50 years of ecological studies of rainforests. This framework is presented in the hope of stimulating the generation of testable hypotheses on competitive interactions among rainforest trees and experimental research on fruit, seed, and seed-

857 citations

Journal ArticleDOI
22 Jun 2007-Science
TL;DR: This work uses an experimental mycorrhizal plant system to test whether functional similarity among closely related species (phylogenetic conservatism) can drive community assembly and ecosystem functioning and suggest that phylogenetic trait conservatism can promote coexistence and enhance ecosystem function because of functional complementarity among those same lineages.
Abstract: Ecology seeks to explain species coexistence and its functional consequences, but experimental tests of mechanisms that simultaneously account for both processes are difficult. We used an experimental mycorrhizal plant system to test whether functional similarity among closely related species (phylogenetic conservatism) can drive community assembly and ecosystem functioning. Communities were constructed with the same number of fungal species, but after 1 year of growth, realized species richness was highest where the starting species were more distantly related to each other. Communities with high realized species richness also stimulated plant productivity more than those with low realized species richness. Our findings suggest that phylogenetic trait conservatism can promote coexistence because of reduced competition between distinct evolutionary lineages and enhance ecosystem function because of functional complementarity among those same lineages.

856 citations


Network Information
Related Topics (5)
Species diversity
32.2K papers, 1.2M citations
95% related
Biodiversity
44.8K papers, 1.9M citations
94% related
Habitat
25.2K papers, 825.7K citations
93% related
Ecosystem
25.4K papers, 1.2M citations
91% related
Biological dispersal
30K papers, 1.2M citations
89% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20243
20232,454
20225,118
20213,510
20203,287
20193,254