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

Abstract

Abstract. Secondary succession on arable fields is a popular system for studying processes influencing community assembly of plants. During early succession, the arrival and establishment of those propagules that can pass the environmental filters operating at a given site should be among the dominant processes leading to an initial increase in species richness. With ongoing succession, environmental filtering should decrease in relative importance compared to competitive interactions, which then should decrease species richness. Thereby, the phylogenetic structure of communities should change from random or clustered patterns during early succession to overdispersion. Disturbance is supposed to act as an additional filter, causing communities to be phylogenetically clustered. By analysing the species richness and phylogenetic structure of secondary succession in two different regions in Germany with three different disturbance levels each, we tested this general model. Although in one of the regions (Gimritz) we found the expected trajectory of species richness, phylogenetic structure did not follow the expected trend from random or clustered towards overdispersed communities. In the other region (Bayreuth), species richness did not follow the expected trajectory and phylogenetic structure remained clustered over the course of succession. A preliminary analysis of autecological characteristics of the species involved (Ellenberg indicator values) nevertheless showed clear contrasting trends. The idiosyncrasies of successional trajectories across sites might be due to the environmental context, the regional species pool as well as the legacy of former land use reflected in the seed bank.

Understorey phylogenetic diversity in thermophilous deciduous forests: overstorey species identity can matter more than species richness

“…In plant communities, clustering can result from various constraints among which habitat filtering driven by biotic and abiotic disturbance (e.g. fire; Verdú and Pausas 2007) (Stadler et al 2017). On the other hand, it can also result from competitive exclusion in non-restrictive, stable habitats (Mayfield and Levine 2010).…”

“…Both indices are measures of phylogenetic divergence (Tucker et al 2016) successfully used for the assessment of sustainability and health of forest ecosystems (Potter and Koch 2014) or for the impact of forest plantations on understorey phylogenetic structure (Piwczyński et al 2016). NRI measures the standardized effect size of the mean phylogenetic distance (MPD), which estimates the average phylogenetic relatedness between all possible pairs of taxa in an assemblage; this index is dominated by the deep phylogenetic relationships between taxa since its calculation considers all pairwise distances within the community (Webb 2000;Stadler et al 2017). NTI is a standardized measure of the branch-tip phylogenetic clustering of the species on the plot (usually indicated as Mean Nearest Taxon Distance, MNTD) and is independent from the arrangement of the higher-level groups in the phylogenetic tree (Webb et al 2002).…”

Detecting phylodiversity-dependent diversification with a general phylogenetic inference framework

“…Phylogenetic diversity, quantifying the genetic differences among a group of species, has been identified as a key feature of diversity [Kling et al, 2018, Scheiner et al, 2017 to be taken into account in conservation biology [Laity et al, 2015, Faith andBaker, 2006] (but see Cantalapiedra et al [2019], Mazel et al [2018]), community ecology [Stadler et al, 2017, Tucker et al, 2016, Webb et al, 2006, Violle et al, 2011, evolutionary biology [Kling et al, 2018] and the intersection of these fields. Phylogenetic diversity, or phylodiversity, provides a different perspective on diversity and ecological limits.…”