Long-term dynamics of functional traits in abandoned agricultural fields

A fundamental question of plant succession is whether species within different successional stages differ in terms of functional traits as changes in community-level traits reflect changes in plant strategies over time.  Although there are many studies that focus on that question, researchers have not studied the long-term dynamics of those traits within plant communities in depth.  We used data from a 49-year study of old-field succession (the Buell-Small Succession Study) to assess the dynamics of important functional traits (height, seed mass, specific leaf area) and compared their dynamics among life forms and between native and non-native species.  We assessed community-level trait dynamics by determining trait values weighted by the relative abundance of each species.  Species were grouped into life history functional groups (forbs, graminoids, shrubs/vines, trees).  Overall, the relative height and seed mass of the community increased over time.  Although SLA decreased during earlier successional stages, it increased in later stages as the exotics Microstegium and Alliaria invaded the forest understory.  Native and non-native species exhibited significantly different dynamics, though they only differed in height.  In addition, trait dynamics were significantly different among functional groups.  However, groups were not consistently different across all three traits.  These results offer insight into how changes in community-level functional traits reflect fundamental shifts in plant strategies as succession proceeds.  These results also suggest a largely similar role for native and non-native species in community-level trait dynamics and succession.

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