Search

Habitat filtering, species interactions and neutral colonization as well as extinction dynamics govern the sequence of community assembly and functional diversity (FD) during primary plant succession. To study the factors that influence changes in FD we here use data on plant seed size, seed numbers and specific leaf area from 107 study plots along a 7 year sequence of primary succession (2005–2011) in a 6 ha German artificial catchment. We show that the temporal variability in functional diversity can be partitioned into the effects of trait expression, species richness and plant cover. We observed a dominant role of species richness and community composition on FD. Trade-offs in the influence of species richness and plant cover tended to decrease the change in FD. Average FD steadily increased during the first 4 years of succession (2005–2008). The degree of annual changes in FD were highly plot specific. Average change in FD was comparatively low during the first 4 years and later high. Soil characteristics and light conditions did not significantly influence the detectable change in functional diversity. We conclude that the high plot-specific spatial variability of the annual changes in FD transformed the initially catchment-wide homogeneous distribution of plant species 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. [ABSTRACT FROM AUTHOR]

Understanding the causes of the generally positive relationship between biodiversity and ecosystem function (BEF) is a major research focus in ecology. Early analyses of BEF used a modification of the evolutionary Price equation to partition effects of biodiversity into components of complementarity (species richness) and dominance (species composition). However, early experiments and data on BEF did not use information on species traits or relative abundances. Here we extend the Price partition of the total expression of a single trait (such as leaf area) between two communities into five additive components: 1) species richness; 2) average species trait expression; 3) relative abundance; 4) the combined effects of relative abundance and trait expression; 5) absolute abundance. When applied to presence–absence data with no trait variation, the method yields a result that is identical to the original Price partition into two components of complementarity and dominance. When applied to an analysis of relative abundance itself as a trait, our method quantifies the strength of species co‐occurrences as a difference in Simpson diversity between the communities. We tested the new partition with artificial data sets and null model comparisons, and applied it to a long‐term data set on plant succession. A key finding is that the effects of total abundance might be very important when comparing two communities, and possibly could account for results from previous studies in which complementarity emerged as an important contributor to BEF. [ABSTRACT FROM AUTHOR]

Aims Probabilistic models of species co-occurrences predict aggregated intraspecific spatial distributions that might decrease the degree of joint species occurrences and increase community richness. Yet, little is known about the influence of intraspecific aggregation on the co-occurrence of species in natural, species-rich communities. Here, we focus on early plant succession and ask how changes in intraspecific aggregation of colonizing plant species influence the pattern of species co-existence, richness and turnover. Methods We studied the early vegetation succession in a six ha constructed catchment within the abandoned part of a lignite mine in NE Germany. At two spatial scales (1- and 25-m2 plots), we compared for each pair of species the intraspecific degree of aggregation and the pattern of co-occurrence and compared observed relationships with temporal changes in important species functional traits. Important Findings The majority of species occurred in an aggregated manner, particularly in the first 2 years of succession. In pairwise comparisons, we found an excess of segregated species occurrences leading to a positive link between intraspecific aggregation and pairwise species segregation as predicted by the aggregation hypothesis, particularly at the lower spatial resolution. The degree of intraspecific aggregation was negatively correlated with the community-wide level of species spatial turnover and with plot species richness. Our results are the first direct confirmation that increasing intraspecific aggregation and interspecific competitive interactions counteract in shaping plant community structure during succession. The respective effects of aggregation were strongest at intermediate states of early succession. [ABSTRACT FROM AUTHOR]