Research team
Expertise
Anthropogenic environmental change is often described in terms of its effects on biodiversity: species disappear, populations decline and ecosystems become increasingly homogenized. Understanding the underlying causal chains has been the central ambition of my research. My work therefore asks why are species or ecosystems lost, which ecological processes are set in motion following environmental degradation that causes biodiversity decline, at which organizational level do those processes operate, and how can they be modified to enable recovery and restoration. Biodiversity does not respond directly to an abstract environmental pressure such as atmospheric nitrogen deposition, soil phosphorus enrichment, soil acidification or climate change. These pressures first alter the physical and chemical conditions under which organisms live and interact. The resulting changes in resource availability, competition, mutualisms, trophic interactions and ecosystem processes then propagate through biological systems. This perspective has provided the conceptual continuity underlying a research program that includes semi-natural grasslands, heathlands, forests, peatlands and (semi-aquatic) freshwater habitats, and encompasses a wide taxonomic breadth from plants to fungi, from microorganisms to arthropods and human health. The apparent diversity of these systems reflects not a succession of unrelated research topics, but a deliberate progression towards understanding increasingly complex ecological interactions at multiple levels of biological organization because effects of environmental change is rarely confined to one level. At the level of individual organisms, I study plant fitness, resource quality and interactions with fungi and arthropods. At the population level, I investigate constraints on threatened species, including habitat quality, small population size and reproductive limitation. At the community level, I investigate interactions among plant communities and fungal and bacterial assemblages. At the ecosystem level, I examine carbon sequestration, nutrient availability, hydrological functioning and ecosystem properties that underpin human health. This highly integrated research is particularly important for understanding biodiversity conservation and restoration from local populations all the way to the landscape level. A threatened plant population may decline because its local habitat has become biogeochemically unsuitable, because regional hydrology has changed, because mycorrhizal mutualisms have been disrupted, because pollination has become unreliable, or because demographic constraints prevent recovery. Effective conservation therefore requires identifying the whole suite of actual limiting mechanism rather than assuming that generic measures for habitat protection alone will be sufficient.