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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]

Ecosystems with highly pulsed water supply must be better understood as climate change may increase frequency and severity of intense storms, droughts and floods. Here we collected data over 3 years (2016–2018) in the episodic wetland outflow channel (Aluize), Banhine National Park, in which the system state changed from dry to wet to dry. Field sampling included vegetation records, small‐scale vegetation zoning, the seed bank and water and soil quality. The same main plant species were found in both dry and wet conditions across the riverbed of the outflow channel. We found only very few diaspores of plants in the soil after prolonged drought. In the subsequent flooded state, we examined very dense vegetation on the water surface, which was dominated by the gramineous species Paspalidium obtusifolium. This species formed a compact floating mat that was rooted to the riverbed. The Cyperaceae Bolboschoenus glaucus showed high clonal growth in the form of root tubers, which likely serve as important food reservoir during drought. Soil and water analyses do not indicate a limitation by nutrients. We outline how resident people may change the plant community structure with an increasing practice of setting fire to the meadows in the dried‐up riverbed to facilitate plant regrowth as food for their livestock. [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]