Contrasting changes in taxonomic, phylogenetic and functional diversity during a long‐term succession: insights into assembly processes

Abstract

Summary1. Theory predicts that the processes generating biodiversity after disturbance will change during succession. Comparisons of phylogenetic and functional (alpha and beta) diversity with taxonomic diversity can provide insights into the extent to which community assembly is driven by deterministic or stochastic processes, but comparative approaches have yet to be applied to successional systems. 2. We characterized taxonomic, phylogenetic and functional plant (alpha and beta) diversity within and between four successional stages in a > 270-year-long arable-to-grassland chronosequence. Null models were used to test whether functional and phylogenetic turnover differed from random expectations, given the levels of species diversity. 3. The three facets of diversity showed different patterns of change during succession. Between early and early-mid succession, species richness increased but there was no increase in functional or phylogenetic diversity. Higher than predicted levels of functional similarity between species within the early and early-mid successional stages, indicate that abiotic filters have selected for sets of functionally similar species within sites. Between late-mid and late succession, there was no further increase in species richness, but a significant increase in functional alpha diversity, suggesting that functionally redundant species were replaced by functionally more dissimilar species. Functional turnover between stages was higher than predicted, and higher than within-stage turnover, indicating that different assembly processes act at different successional stages. 4. Synthesis. Analysis of spatial and temporal turnover in different facets of diversity suggests that deterministic processes generate biodiversity during post-disturbance ecosystem development and that the relative importance of assembly processes has changed over time. Trait-mediated abiotic filtering appears to play an important role in community assembly during the early and early-mid stages of arable-to-grassland succession, whereas the relative importance of competitive exclusion appears to have increased towards the later successional stages. Phylogenetic diversity provided a poor reflection of functional diversity and did not contribute to inferences about underlying assembly processes. Functionally deterministic assembly suggests that it may be possible to predict future post-disturbance changes in biodiversity, and associated ecosystem attributes, on the basis of species' functional traits but not phylogeny.

Tree phylogenetic diversity promotes host–parasitoid interactions

“…Estimates of the evolutionary divergence among different lineages within a community may be good surrogates for niche differences, assuming that changes in PD are proportional to changes in niche space or ecological function, i.e. that functionally relevant plant traits are phylogenetically conserved ( [20,21]; but see [25]). Consequently, the PD of a plant community is expected to be a comprehensive predictor for ecosystem processes, as demonstrated in experimental grasslands: more productive and stable plant communities had more evolutionary diverse lineages; PD was superior in predictive power compared with species richness or traits [20].…”

Classification of Grassland Successional Stages Using Airborne Hyperspectral Imagery

“…For SLA, previous grassland studies have shown that imputation methods based on multiple imputation by chained equations may be used for filling gaps in functional trait databases [54]. Following Taugourdeau et al [54], estimates for missing values (approximately 9% of the species) were obtained using the multivariate imputation by chained equation (MICE) method [33,55,56]. Ellenberg indicator values were extracted from the JUICE database [57]: values for the four species that were not found in the database were extracted from Ellenberg et al [58].…”

“…Previous studies have shown that grassland plant communities representing different stages in the arable-to-grassland succession are characterized by different habitat conditions and plant community characteristics [33,34]. Old grasslands have lower community-weighted mean values for Ellenberg indicators for nutrient and moisture availability than young grasslands [34].…”

“…In addition, old grasslands are typically characterized by lower community-weighted mean values for specific leaf area (SLA), canopy height, and leaf size, and by higher mean values for leaf dry matter content (LDMC) than young grasslands [33]. Because SLA is associated with the assemblage of leaf chemicals that control photosynthesis, positive relationships between SLA, nutrient availability, chlorophyll content and leaf water content can be expected [33,[35][36][37][38][39].…”

Species richness and phylogenetic structure in plant communities: 20 years of succession

“…In the context of the simple idea that at the beginning of the succession the arrival of propagules is important, we expect a clustered or random structure of phylogenetic diversity and with the increasing importance of competition a trend towards overdispersion (e.g. Purschke et al, 2013).…”