Biodiversity, Stability, and Productivity in Competitive Communities

Abstract

Three markedly different models of multispecies competition-one mechanistic, one phenomenological, and one statistical-all predict that greater diversity increases the temporal stability of the entire community, decreases the temporal stability of individual populations, and increases community productivity. We define temporal stability as the ratio of mean abundance to its standard deviation. Interestingly, the temporal stability of entire communities is predicted to increase fairly linearly, without clear saturation, as diversity increases. Species composition is predicted to be as important as diversity in affecting community stability and productivity. The greater temporal stability of more diverse communities is caused by higher productivity at higher diversity (the "overyielding" effect), competitive interactions (the "covariance" effect), and statistical averaging (the "portfolio" effect). The relative contribution of each cause of temporal stability changes as diversity increases, but the net effect is that greater diversity stabilizes the community even though it destabilizes individual populations. This theory agrees with recent experiments and provides a degree of resolution to the diversity-stability debate: both sides of the longstanding debate were correct, but one addressed population stability and the other addressed community stability.

Biodiversity, Habitat Area, Resource Growth Rate and Interference Competition

“…4). This finding complements the statement made by Lehman and Tilman (2000) that greater diversity increases community productivity. Observe that if the direct interference strength constants m i are small, then (3.7) fails.…”

“…This novel result suggests that resource growth rates may play even greater roles than habitat area in promoting coexistence of consumer species. We note here that our result is complementary to the work of Lehman and Tilman (2000) where the authors show through several models that greater diversity increases the temporal stability of the entire community and increases community productivity.…”

Resilience, reactivity and variability: A mathematical comparison of ecological stability measures

“…Instead, empirical stability is typically expressed as the inverse of temporal variability, directly measured on time series data. This has inspired theoretical studies to consider variability-based stability measures [4,14,15], yet these approaches remain largely disconnected from the large body of resilience-based stability theory. Indeed, several obstacles stand in the way to establish a clear link between empirically motivated and purely theoretical views on stability (see Table II):…”

“…[10][11][12][13]. Although theoretical studies have also considered stability measures based on variability [14][15][16], the link with resilience is not obvious. Indeed, in contrast with resilience, variability is caused by persistent perturbations, depends on the direction and intensity of these perturbations, and on the ecosystem variable that is observed, such as total biomass.…”

Divergence in Forest-Type Response to Climate and Weather: Evidence for Regional Links Between Forest-Type Evenness and Net Primary Productivity

“…However, most previous studies typically fall short of assessing the consequences of anticipated reductions in aspects of biodiversity at spatial scales relevant to land management. For example, evidence for a positive relationship between species richness and either overall ecosystem function or stability in ecosystem function is derived primarily from studies of extremely small-scale manipulative experiments (Tilman and Downing 1994;Hooper and Vitousek 1997; or theoretical models (Tilman and others 1997b;Yachi and Loreau 1999;Lehman and Tilman 2000). As a consequence, conclusions from these experiments are difficult to separate from experimental design and challenging to relate to un-manipulated systems (Huston 1997;Naeem 2002;Naeem and Wright 2003).…”