Ecosystem services (ES) are the physical goods and associated benefits that are provided to humans by ecological systems. Assessment of ES requires knowledge of ecology and ecosystem processes, and ES estimates can be improved when they include knowledge of nonlinearities, feedbacks, and interactions within ecosystems. A variety of assessment tools have been proposed to estimate the provision of ES. However, they fail to acknowledge interconnectedness of services or connections between ecosystem processes and services.
This dissertation examines connections of ecosystem processes and ES with the assumption that knowledge of ecosystem ecology and ecosystem processes can be applied to improve estimates of ES capacity over time and under a variety of management scenarios. To investigate this connection, I modified the ecosystem process model Biome-BGC to simulate the provision of ES in exurban Southeastern Michigan. The modification resulted in a new version of the model, Biome-BGC-Ex, and involved detailed changes to the source code. The modified model included the ability to model competition between turfgrass and open grown trees in a single grid cell, to incorporate residential management practices, and to translate model outputs into well-defined, quantitative estimates of ES.
My research was conducted as part of a larger collaboration, the SLUCE (Spatial Land Use Change and Ecological Effects) project and addresses the exurban residential landscape as a coupled human-natural system. It references and builds on previous elements of the SLUCE project including an empirical ecological field study, developer and homeowner interviews, web-based surveys, and modeling in a coupled human-natural system framework. My contributions to the project, specifically modifying Biome-BGC and linking it to ES, can be applied to future research on coupled human-natural systems in exurban residential landscapes.
Chapter two describes how Biome-BGC was modified for the exurban landscape and then calibrated and parameterized for Southeastern Michigan. It examined which yard management practices have the greatest effect on carbon sequestration and model results suggested N fertilization was the strongest driver across three major vegetation types. Chapter three describes how Biome-BGC-Ex was modified to estimate ES capacity of ten services and evaluated the impact of yard management practices on ES capacity. Model simulations showed trade-offs between ES relating to high amounts of carbon or biomass and freshwater recharge. Chapter four took a broader approach and evaluated ecosystem process models as a potential tool for ES assessment and discussed how the integration of Biome-BGC-Ex with other tools could improve ES assessment. I found that while process models can improve understanding of interconnected ecosystem processes and biophysical feedbacks that affect the production of ES, they require more detailed data and complex knowledge to run. These chapters also discuss limitations of Biome-BGC-Ex and its ability to adequately address ecological complexities of exurban landscapes. One major limitation was accurately modelling N dynamics of exurban tree cover and model simulations likely overestimating C sequestration under high levels of fertilization.
My dissertation research is the first to modify Biome-BGC to measure ES in a residential ecosystem. It is also novel because the work focuses on how human management of the landscape affects ES production as opposed to land use or land cover change. My dissertation research can likely be replicated in similar ecosystems to inform more complex ES modelling frameworks that rely on ES production modelling grounded in the understanding of ecosystem processes and their feedbacks.PHDResource Ecology & Mgt PhDUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/169753/1/sekiger_1.pd
