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Biotic mechanisms of community stability shift along a precipitation gradient.

Hallett, L. and Hsu, J. and Cleland, E.E. and Collins, S.L. and Dickson, T.L. and Farrer, E.C. and Gherardi, L.A. and Gross, K.L. and Hobbs, R.K. and Turnbull, L. and Suding, K.N. (2014) 'Biotic mechanisms of community stability shift along a precipitation gradient.', Ecology., 95 (6). pp. 1693-1700.


Understanding how biotic mechanisms confer stability in variable environments is a fundamental quest in ecology, and one that is becoming increasingly urgent with global change. Several mechanisms, notably a portfolio effect associated with species richness, compensatory dynamics generated by negative species covariance and selection for stable dominant species populations can increase the stability of the overall community. While the importance of these mechanisms is debated, few studies have contrasted their importance in an environmental context. We analyzed nine long-term datasets of grassland species composition to investigate how two key environmental factors - precipitation amount and variability - may directly influence community stability and how they may indirectly influence stability via biotic mechanisms. We found that the importance of stability mechanisms varied along the environmental gradient: strong negative species covariance occurred in sites characterized by high precipitation variability, whereas portfolio effects increased in sites with high mean annual precipitation. Instead of questioning whether compensatory dynamics are important in nature, our findings suggest that debate should widen to include several stability mechanisms and how these mechanisms vary in importance across environmental gradients.

Item Type:Article
Keywords:Compensatory dynamics, Dominant species, LTER, Mean–variance scaling, Negative covariance, Portfolio effect, Taylor's power law.
Full text:(AM) Accepted Manuscript
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Publisher statement:© 2014 by the Ecological Society of America
Date accepted:No date available
Date deposited:14 April 2014
Date of first online publication:June 2014
Date first made open access:No date available

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