On the relative importance of CSR ecological strategies and integrative traits to explain species dominance at local scales

Abstract

Summary Identifying ecological strategies based on functional traits has been one of the main focuses of studies on plant community assembly. Recently, an important and timely tool, ‘StrateFy’, has been proposed for detecting plant strategies across the globe according to the CSR scheme. The CSR scheme is undeniably efficient across scales, and distinct CSR strategies among species have been proposed to explain differing degrees of dominance among species. However, in a previous study we showed that dominance ranking of woody species in a resource‐poor habitat (coastal sandy plain) was not explained by morphological traits commonly measured in functional approaches (such as those used to estimate CSR strategies), but by integrative traits (i.e. traits that are the result of different combinations of functional traits) more related to plant performance. Here, we used CSR analysis and StrateFy on a dataset collected on a coastal sandy plain to test the hypothesis that the dominance ranking would be compatible with the CSR strategies; that is, that dominant species would show a greater proportion of the stress‐tolerance strategy (S%) than subordinate species. Contrary to our hypothesis, all species exhibited an S/CS strategy, and the most dominant species had neither similar values nor the highest S%. The inability of CSR analysis (as applied using StrateFy) to predict dominance ranking suggests that it can explain relative dominance when different strategies co‐occur, but not in cases where dominant and subordinate plants share the same strategy. We argue that the relative importance of CSR and integrative traits for describing dominance ranking may depend on how CSR strategies are filtered in each environment. In environments where only a narrow range of strategy classes are viable, integrative traits may be more important for explaining variation in degrees of dominance. Thus, the ability of a given species to achieve dominance may depend on integrative traits resulting from multiple trait arrays, not necessarily captured by the specific leaf area, leaf dry mass content and leaf area measurements that are used to calculate the relative proportions of strategies in StrateFy. A lay summary is available for this article.