Understanding the stability and diversity of an ecosystem
Experiments in aquatic ecosystems have also shown that large-scale processes play a significant role in stabilizing ecosystems. Dynamical stability refers to stability across time.
This is often termed the resistance of a system. All rights reserved. Species differ from one another in their resource use, environmental tolerances, and interactions with other species, such that species composition has a major influence on ecosystem functioning and stability.
Diversity stability relationship
Schindler, D. Forest Diversity and Function , — Note that when the environmental and demographic variances of the two species are not equal, each of the terms in eqn 12 becomes a sum of effects due to each species. This makes selection effects possible, that is, effects due to dominance by species with either high or low environmental or demographic variance see Discussion , but no qualitatively new mechanism of stabilisation of ecosystem properties arises from differences in environmental or demographic variances. Such species could buffer the system against the loss of other species. Middle d—f : environmental component of CVNT2 A in eqn 12 when environmental responses are perfectly asynchronous. In a year study of naturally assembled Inner Mongolia grassland vegetation, Bai et al. This in turn decreases the magnitude of summed species variances and covariances eqns , but it increases the strength of the effects of demographic stochasticity, thereby increasing the variability of total biomass eqn 5. The most striking feature of asymmetry in intrinsic rates of natural increase is probably the fact that it can generate situations where both the strength and asymmetry of interspecific competition have stabilising effects on ecosystem properties. Figure 1 shows how having multiple species present in a plant community can stabilize ecosystem processes if species vary in their responses to environmental fluctuations such that an increased abundance of one species can compensate for the decreased abundance of another. This article is somewhat dated given that a considerable amount of new research has since been published. Furthermore, the dependence of these aggregate measures of population variability on the strength of interspecific competition is complex.
These experiments found that species diversity conferred spatial and temporal stability on several ecosystem functions. Although asymmetry in intrinsic rates of natural increase stabilises total biomass compared with a system in which both rates are either high i.
Factors affecting ecosystem stability
These findings demonstrate that local species richness — both within and among functional groups — confers stability on ecosystem processes in naturally assembled communities. Looking at all possible combinations of communities containing 1, 2 or 3 species, we see that, as the number of species goes up, the probability of containing the blue species also goes up. In contrast, in the community containing both green and blue individuals, the decrease in one species is compensated for by an increase in the other species, thus creating stability in ecosystem productivity between years. Resistance and inertia persistence [ edit ] Resistance and inertia deal with a system's inherent response to some perturbation. Forest Diversity and Function , — Biodiversity and Conservation 19, — When and how can biodiversity be expected to enhance ecosystem stability? Observational studies of ecosystems use constancy to describe living systems that can remain unchanged. Resistance is a measure of how little the variable of interest changes in response to external pressures. Ecologists should turn the question on its head, the researchers believe: rather than focusing on how diversity affects stability, scientists might make faster progress by focusing on stability first. Thus, our analysis does not support the intuitive hypothesis that interspecific competition stabilises aggregate ecosystem properties through compensatory dynamics between species in symmetrical communities. This difference in when species are active leads to complimentary resource utilization and can increase total productivity of the ecosystem. This in turn decreases the magnitude of summed species variances and covariances eqns , but it increases the strength of the effects of demographic stochasticity, thereby increasing the variability of total biomass eqn 5. This fundamental metric of ecosystem function has relevance for global food supply and for rates of climate change because primary production reflects the rate at which carbon dioxide a greenhouse gas is removed from the atmosphere.
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