Coastal Margins

Up or Out? Links Between Lateral and Vertical Carbon Fluxes

Coastal temperate rainforests exhibit some of the largest lateral water and dissolved carbon exports globally. Over the last decade, estimates of lateral carbon fluxes from terrestrial ecosystems in general have been revised upwards repeatedly, fundamentally altering ecosystem carbon budgets. To date, however, little work has explored coupled temporal dynamics, such as trade-offs or synchronicities, between surface emissions and these newly recognized lateral carbon fluxes.

The McNicol Lab collaborates with 11 collaborating institutions within the NSF Coastal Margin Research Coordination Network focused on building an icefield-to-ocean perspective on biogeochemistry and ecology in the temperate rainforests of the N. Pacific coast. These coastal margin ecosystems are understudied relative to tropical rainforests yet are estimated to contain similarly large carbon stocks in soils and biomass. To date, we have used machine learning to conduct a regional soil carbon assessment, identifying that moisture is the dominant control on the distribution of carbon stocks.

With RCN and USFS collaborators, we plan to establish the first wetland flux tower in the wettest, per-humid, zone of the N. Pacific coastal temperate rainforest, near Juneau, Alaska. This site will function as a high flux hydrologic end-member, while a second wetland site within Illinois would capture water flows with longer residence times. With these contrasting wetland systems, we are exploring how hydrologic flow dynamics, including storm events, impacts total carbon flux partitioning between surface emissions and lateral export, as well as speciation between carbon dioxide and methane. These data will also function as the first long term flux measurements from the per-humid coastal temperate rainforest.