B51B-0428
Investigating Ecosystem Pattern and Process Across a Land-Sea Gradient: A New Coastal Margin Observatory in the Pacific Coastal Temperate Rainforest

Friday, 18 December 2015
Poster Hall (Moscone South)
Ian Giesbrecht1, Ken P Lertzman1,2, Allison A Oliver1,3, Suzanne E Tank1,3, Bill C Floyd1,4, Gordon W Frazer1,5, Brian PV Hunt1,6, Colleen Kellogg1,7, Thierry Heger1,7, David Levy-Booth1,7, William H Mohn1,7, Steven J. Hallam1,7, Patrick Keeling1,7 and Paul Sanborn1,8, (1)Hakai Institute, Calvert Island, BC, Canada, (2)Simon Fraser University, Burnaby, BC, Canada, (3)University of Alberta, Edmonton, AB, Canada, (4)Vancouver Island University, Nanaimo, BC, Canada, (5)GWF LiDAR Analytics, Sidney, BC, Canada, (6)University of British Columbia, Department of Earth, Ocean, and Atmospheric Sciences, Vancouver, BC, Canada, (7)University of British Columbia, Vancouver, BC, Canada, (8)University of Northern British Columbia, Prince George, BC, Canada
Abstract:
Terrestrial organic matter exported from coastal watersheds influences marine ecosystems and carbon budgets across the globe, yet much is unknown about the fundamental processes of land-sea carbon cycling or system response to climate change. On two outer-coast islands near the center of the Pacific Coastal Temperate Rainforest (PCTR), the Hakai Institute has established a coastal margin observatory to examine the flux of terrestrial organic matter from land to sea – the origins, pathways, processes and marine consequences – in the context of long-term environmental change. The outer-coast PCTR is characterized by an ocean-moderated climate, subdued terrain, extensive wetlands and lower forest productivity than the mountainous mainland coast. Here we give an overview of, and initial results from, a new long-term multi-disciplinary investigation of processes that link PCTR watersheds with the carbon balance and food web of northeastern subarctic Pacific coastal waters.

Beginning in 2013, we established year-round sampling and a sensor network to quantify – at high temporal resolution – the amount and character of terrestrial exports from seven focal watersheds on Calvert and Hecate Islands, British Columbia. Early results show that freshwater dissolved organic carbon concentrations are high on average, fluctuate temporally and vary spatially across watersheds. A real-time hydrological sensor network shows rapid responses of stream stages and soil water tables to rainfall inputs. Carbon export can vary greatly with stream discharge in these flashy systems. We use paired marine monitoring stations at stream outlets to concurrently track ocean conditions and to trace terrestrial organic matter. Across a larger set of watersheds, we examine the role of catchment topography, hydrology and composition in controlling biogeochemical exports. On land, we use airborne LiDAR data to evaluate landscape controls on vegetation height – a proxy for forest productivity and biomass. We use field plots to characterize ecosystem pattern and process across a landscape gradient. Finally, we investigate the role of microbial communities in the processing of organic matter across multiple scales and interfaces: within soil profiles, across a soil drainage gradient and across the broader land-sea gradient.

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