Trait driven or neutral: understanding the change in functional trait diversity during early plant succession using Price partitions

Abstract

Habitat filtering, species interactions, and neutral colonisation and extinction dynamics govern the sequence of community assembly and functional diversity during primary plant succession. For an understanding we need to disentangle the underlying abiotic and biotic drivers behind these processes. Here we use data on plant seed size, number and specific leaf area from 107 initially homogeneous study plots along a seven year sequence of primary succession (2005–2011) in a 6 ha German artificial catchment and show that an additive partition of the temporal change in functional diversity (FD) into trait, richness, and abundance effects can according to a recently developed new Price partitioning provide insights into the relative importance of these drivers. Average FD steadily increased during the first four years of succession and reached a plateau in 2009. The annual change in FD was plot specific manifest in a highly positively skewed distribution. Average change in FD were comparatively low up to 2008 and later high. Initial soil characteristics and plant demand traits did not significantly influence the change in functional diversity. We observed trade-offs in the influence of species and abundance effects that tended to decrease the change in FD. We conclude that the high plot specific spatial variability of the annual changes in FD transform an initially homogeneous distribution of plants into a mosaic of very different local plant communities. Our partitioning results also indicate that the successional sequences in FD are in accordance with a hidden Markov series.