Research

I am an ecosystem and community ecologist focusing on the factors that control patterns of biodiversity, food-web structure, and the functioning of ecosystems. I work primarily in freshwater systems (rivers and lakes) but my expertise also spans riparian and floodplain forests and grasslands. My research program encompasses three broad themes:

1. My fundamental research seeks to understand the mechanisms of bottom-up effects in food webs. I test theoretical predictions of how changes in the quantity, quality or diversity of basal resources (e.g. plants or detritus) influence invertebrate communities at higher trophic levels. Currently, I am assessing how changes in plant diversity influence the structure and stability of arthropod food-webs in a grassland biodiversity experiment (see The Jena Experiment for more).

2. This general knowledge informs my applied work, where I determine the impacts of climate and land-use change on community structure and the flow of energy through food webs and across landscapes. I am particularly interested in how altered hydrology and terrestrial organic matter inputs to aquatic ecosystems influence ecological processes such as primary production and respiration. I have experimentally demonstrated these effects with manipulations of the water column in large in-lake enclosures (the LakeLab facility, Lake Stechlin, Germany). I showed that wind-induced mixing of a deep lake altered phytoplankton community composition and initiated an algal bloom that conspicuously enhanced whole-lake metabolism.

3. Finally, I evaluate whether management and restoration actions meet their aims within anticipated spatial extents and timeframes. This is central to my ultimate goal of informing effective environmental stewardship and policy. My honours and doctoral work focused on how the condition of riparian vegetation influenced aquatic invertebrate communities and organic matter dynamics in Australian agricultural streams. An important outcome of this work for management was ascertaining whether stream ecosystem function could be improved by replanting riparian vegetation at relatively small scales (i.e. 300-1000 m stretches of streams). I hypothesised that replanting could restore the balance of in-stream primary production and respiration in two ways: increasing shading of phytoplankton and biofilms, and providing more organic matter substrates for microbial and invertebrate decomposers. I confirmed these hypotheses in Australian agricultural streams that had riparian vegetation replanted 10-20 years previously. This indicated that management actions on a scale that can be implemented by a single land owner can have positive effects on the functioning of adjacent waterways within decadal timescales.

Research outlook. Predicting and mitigating the impact of environmental change is critical to maintaining ecosystem services. This requires knowledge of both the direct functional roles of species and how they influence multi-trophic dynamics. However, the relationships between community composition, interaction structure, and the resultant ecosystem processes remains one of the biggest challenges in ecology. Accordingly, the driving theme of my future research will be to develop a more holistic and mechanistic understanding of how human actions impact ecosystems. I will achieve this by using trait and network approaches to bridge levels of ecological organisation (i.e. populations, communities and ecosystems).

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