Ecosystem Function in Watershed Meta-Ecosystems

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Ecosystems are intrinsically connected to each other, through movements as small as insects emerging from waterbodies to die on land, to those as distant as dust from the Sahara blowing across the Atlantic Ocean to fertilize the Amazon rainforest. Meta-ecosystem theory was developed to account for flows of organisms, resources, and energy across ecosystem boundaries. By combining community ecology (the dispersal of organisms) and ecosystem ecology (resource fluxes), it presents the opportunity to better understand the functioning of ecosystems that humans rely on: how important are they, and can changes in the functioning of one ecosystem have cascading effects across a landscape because of these connections? Unfortunately, the promise of meta-ecosystem ecology has not yet been fulfilled in empirical and applied settings. One reason for this is that theoretical work has largely been spatially implicit, neglecting the ways that the configuration of different ecosystems in a landscape shape the connections between them. The long-term goal of my research program is to develop and use spatially-explicit meta-ecosystem approaches for understanding the functioning of whole ecosystems, watersheds, and landscapes. Objective 1. We will develop spatially-explicit theoretical models to examine how animal movement influences ecosystem function by redistributing resources. While largely unaddressed in meta-ecosystem research so far, the movement of resources across ecosystem boundaries by foraging and migratory animals is a unique mechanism transporting resources against passive gradients such as gravity and currents. Our modeling work will show how human impacts on animal population sizes and habitat connectivity could affect resource flows, landscape heterogeneity, and ecosystem function. Objective 2. My research group will explore how the spatial configuration of watersheds can be used to predict ecosystem functions such as respiration and decomposition across stream and river networks. We will draw on classic theories of watershed structure, such as the River Continuum Concept, and use new geostatistical methods to model spatial covariance in decomposition and ecosystem respiration. We will thus disentangle the roles of network structure and terrestrial land cover on these key ecosystem functions. Our research will benefit management by developing new ways to estimate the functioning of entire watersheds. My proposed research will accelerate meta-ecosystem ecology by identifying how landscape and watershed structure mediates ecosystem function. It has direct relevance for the management by revealing how habitat fragmentation and other human impacts may alter animal contributions to the functioning of ecosystems. This research program will produce a new modeling framework to understand and predict ecosystem function at scales that are relevant for human interaction and management, such as watersheds and their subcatchments.