02081nas a2200241 4500008004100000245008200041210006900123300001500192490000700207520135700214100001801571700001401589700001801603700002401621700001801645700001701663700001901680700001601699700001601715700001701731700001701748856007401765 2014 eng d00aBiotic mechanisms of community stability shift along a precipitation gradient0 aBiotic mechanisms of community stability shift along a precipita a1693 -17000 v953 a
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 data sets 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.
1 aHallett, L.M.1 aHsu, J.S.1 aCleland, E.E.1 aCollins, Scott., L.1 aDickson, T.L.1 aFarrer, E.C.1 aGherardi, L.A.1 aGross, K.L.1 aHobbs, R.J.1 aTurnbull, L.1 aSuding, K.N. uhttps://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/13-0895.1