Speaker
Description
Global biodiversity loss threatens a multitude of ecosystem functions. However, not only the diversity of communities drives their functioning, but also the identity and abundance of their members. While arthropods are key indicators of biodiversity and ecosystem functioning declines – e.g. the transfer of energy; often studied through their biomass – it remains unexplored whether such declines are caused by species loss per se, or by the identity and abundances of lost species.
Here, we use the ecological Price equation to investigate how temporal changes in arthropod biomass across grasslands of varying diversity and land use intensity can be assigned to the community assembly components of species richness, identity and abundance. Arthropods were sampled over ten years in an experimental grassland site (“Jena Experiment”) and in land use observatories (“Biodiversity Exploratories”). We put a special focus on comparing primary consumers (herbivores) and secondary consumers (predators).
Our preliminary results show that decreases in arthropod biomass over time are strongly driven by species richness and abundance losses. Species identity, however, causes counteracting effects, as lightweight species are rather lost than heavyweight species, which persist or even increase in communities over time. These effects are particularly pronounced under high grassland diversity and low management intensity, especially for predators.
We conclude that BEF relationships based on species richness account for large proportions of temporal changes in arthropod functioning (biomass), but species identity and abundance complete the picture. While lightweight species diminish, few heavyweight species take over, reducing the functional complexity of the community. Little temporal turnover under low grassland diversity and high land use intensity indicates that these homogenized communities have limited adaptation capacities. Untangling the community (dis-)assembly processes driving temporal arthropod biomass loss, we show that as communities get less diverse and abundant, the heavy members persist, leading to simplified and potentially less adaptable communities.
| Status Group | Postdoctoral Researcher |
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