ExploreNiche: Belowground and temporal niche partitioning along land-use gradients in grasslands

• Applicant: Privatdozentin Dr. Maria Májeková
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 512047507

Niche partitioning is recognized as a key mechanism by which coexistence is maintained by plant species utilizing different niches to partition resources, leading to the avoidance of competitive exclusion. However, the precise mechanisms underlying plant species' coexistence and the maintenance of biological diversity and ecosystem functioning are still one of the fundamental, yet most debated questions in both basic and applied ecology, with several important knowledge gaps to be addressed. Moreover, though recognized in theory, the empirical support for the niche partitioning under field conditions is scarce, especially in plant communities dominated by similar life forms such as grasslands.The first important knowledge gap that remains open is the relative importance of the spatial and the temporal components of niche partitioning for the maintenance of species' coexistence and diversity. Here we define the spatial component as belowground partitioning of water-uptake depths in the vertical soil profile and the temporal component as partitioning of resource uptake and growth opportunities among years caused by species specializing in particular patterns of temporal variance of water supply. In addition to the paucity of empirical evidence in general, a comprehensive empirical evaluation of the relative importance of the belowground spatial and the temporal components of niche partitioning functioning is so far missing. The second important knowledge gap that remains open is to what extent and in which direction the niche partitioning varies along gradients land-use gradients. While one hypothesis proposes that niche partitioning should operate at similar intensities at all levels of productivity, another suggests that it should be more important in highly productive environments. This question is especially relevant since such gradients do not only occur naturally but are a vital part of the semi-natural landscape created and maintained by different land use. Biodiversity Exploratories present a unique opportunity to fill both of the aforementioned knowledge gaps through a well-replicated, long-term, integrative experimental design along pronounced land-use gradients. Specifically, here I propose to: (1) quantify the belowground niche partitioning by determining the plant's water-uptake depths using a non-destructive approach of oxygen stable isotopes in a well-replicated experimental design of 150 Experimental Plots (EPs) in grasslands, (2) couple these novel data with the existing long-term temporal data on species year-to-year variability and associated relevant functional traits, (3) determine the relative importance of the two components of niche partitioning for maintaining species diversity and ecosystem functioning, and (4) assess how the extent and relative importance of niche partitioning vary along gradients of resource availability, stress, and disturbance, which are determined by differences in land-use management.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1374: Biodiversity Exploratories