Biodiversity patterns along environmental gradients

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Biodiversity patterns are commonly studied along environmental gradients to elucidate factors driving species assemblages and build predictions on how communities will adapt under anthropogenic disturbances. However, approaches centered on species diversity are limited by the fact that species taxonomy is relatively information-poor regarding the ecological mechanisms underlying observed patterns. The integration of functional traits into biodiversity studies should increase our ability to understand and predict species patterns, simply because species respond to ecological filters through biological attributes that define individual fitness. Recent developments in comprehensive trait-databases have enabled the use of functional traits along extensive environmental gradients for understanding biological patterns. In that regard, functional diversity, representing the value and range of functional traits in a community, has been shown to vary non-linearly with species diversity. I believe that studying the relationship between species and functional diversity along natural gradients first, and then looking at how this relationship is modified under anthropogenic disturbances, could dramatically improve our capacity to understand factors governing communities and predict their fate in the long term. Under my current discovery grant, I use wetlands to 1) investigate the link between species and functional diversity along extensive natural gradients, 2) assess the response of both species and functional diversity to anthropogenic disturbances in different contexts, and 3) evaluate how restoration using late successional species favours the recovery of both species and functional diversity of understory plant communities. I will use a vast vegetation database to study the latitudinal and minerotrophic (acidity) gradients in peatlands. I will investigate how species and functional diversity co-vary along these natural gradients and identify whether particular functional groups of species have a narrower distribution than others. In addition, I will study how anthropogenic disturbances modify the relationship between species and functional diversity by looking at 1) vegetation change in peatlands over time, in landscapes with different levels of anthropogenic development, as well as 2) vegetation changes in riparian forests when flooding regime is controlled by dams versus when a natural regime is maintained. Finally, I will investigate the resilience of the riparian forest understory after restoration by studying plant succession in riparian plantations of different ages, from 2 to 17 years, compared to reference natural riparian forests. Traits are the vehicle on which environmental drivers act to control species distribution. By studying both species and functional trait diversity in natural, disturbed and restored environments, my research program will increase our capacity to understand community patterns along environmental gradients and help us predict the resilience of our ecosystems to disturbances. Global change may modify environmental filters at all scales, and studying patterns along extended latitudinal gradients should provide valuable insight into changes in vegetation that could be expected under shifting climate. In addition, increasing our knowledge of how communities respond to disturbances and recover after restoration is of great concern, as the world Strategic Plan for Biodiversity 2011-2020 sets as an objective the restoration of 15% of degraded ecosystems by 2020.