Climate change interactions at the edge: Wildfire and subsistence in the Boreal Forest, and sea-level rise and nitrogen loads at the California land-sea margin
Dates
Year
2011
Citation
Nelson, Joanna L., 2011, Climate change interactions at the edge: Wildfire and subsistence in the Boreal Forest, and sea-level rise and nitrogen loads at the California land-sea margin: University of California, Santa Cruz.
Summary
My dissertation furthers work in ecosystem resilience and social-ecological resilience to global change, in the systems of a) the northern boreal forest of interior Alaska, where climate change drives a changing wildfire regime; and b) a central Californian estuary, where N pollution and sea-level rise (due to climate change) converge at the land-sea interface, impacting rare salt marsh habitats and their provision of ecosystem services. The first study explores impacts of a changing wildfire regime on a suite of wild species important for subsistence livelihoods, including game animals, furbearers, fish, and plants. Fire is a primary determinant of landscape pattern in the boreal forest. My review of 17 species indicated highly varied [...]
Summary
My dissertation furthers work in ecosystem resilience and social-ecological resilience to global change, in the systems of a) the northern boreal forest of interior Alaska, where climate change drives a changing wildfire regime; and b) a central Californian estuary, where N pollution and sea-level rise (due to climate change) converge at the land-sea interface, impacting rare salt marsh habitats and their provision of ecosystem services. The first study explores impacts of a changing wildfire regime on a suite of wild species important for subsistence livelihoods, including game animals, furbearers, fish, and plants. Fire is a primary determinant of landscape pattern in the boreal forest. My review of 17 species indicated highly varied post-fire habitat requirements, implying that mosaics of differing stand ages best support a diversity of subsistence species. Obstacles to realizing a mosaic of different stand ages include a) increases in frequency of large-fire years due to climate change, producing homogeneous landscapes of younger trees, and b) fire suppression, producing homogeneous landscapes of older trees. Neither of these scenarios provides the heterogeneous habitats necessary to maintain subsistence livelihoods; I conclude that integrating local knowledge with agency management could improve resilience to a changing fire regime. The following two studies investigate coastal salt marshes' function as a "coastal filter" in central California, intercepting watershed-derived nitrogen (N) pollution and thereby buffering the major coastal problem of eutrophication. Nitrogen pollution and sea-level rise both impact coastal ecosystems, yet their interacting effects are poorly understood. In an experiment crossing simulated sea-level change and N addition, N addition had a significant, positive effect on plant growth, tissue quality, and total N sequestered. Simulated sea-level rise did not significantly affect biomass before a threshold of extreme sea-level rise simulation and subsequent plant death. Results suggest that coastal salt marsh plants serve as a robust N-trap and coastal filter in an experiment at one site, and that this function is not saturated despite extremely high background annual N inputs from agriculture. Findings at the landscape scale, in contrast, suggested that plants were saturated in their capacity to take up additional N in the estuary.
