As we enter the Anthropocene, vast changes to the Earth’s ecosystems threaten biodiversity and important ecological processes. Identifying how such changes will alter ecosystem services across geographic and environmental gradients is increasingly central for understanding the consequences of these global impacts. Predicting ecosystem functioning at large spatial scales, however, rests on our ability to scale up from local plots to landscapes, which is highly contingent on our understanding of how functioning varies through space. Such an understanding has been hampered by a strong experimental focus of biodiversity-ecosystem functioning research restricted to small spatial scales. To address this limitation, we investigated the drivers of spatial variation in multitrophic energy flux—a measure of ecosystem functioning in complex communities—at the landscape scale in Indonesia and Germany. We used a structural equation modelling framework based on distance matrices to test how spatial and environmental distances drive variation in community energy flux via four mechanisms: species composition, species richness, niche complementarity, and biomass.
Results/Conclusions
We found that both spatial and environmental distance were important for driving turnover in community composition, leading to clear differences among sampling sites in overall rates of energy flux in multitrophic communities of litter macroinvertebrates. Despite some differences in the relative strength of effects on various community attributes (such as α- and β-diversity) and energy fluxes, we found remarkable similarities in the potential mechanisms driving these responses between the Indonesian and German study regions. More specifically, we found that geographic and environmental distance indirectly influenced species richness and biomass, with clear evidence that these were the dominant mechanisms explaining variability in community energy flux over spatial and environmental gradients. Our results reveal that species composition and trait variability may become redundant in predicting ecosystem functioning at the landscape scale. Instead, we demonstrate that species richness and total biomass may best predict ecosystem functioning at larger spatial scales, especially when considering fluxes of energy in complex multitrophic systems.