Soil contributions to watershed functions: Influence of basin characteristics on carbon and nutrient inputs to southeast Alaska streams

Project ID: PNW05JV11261933030

Federal Agency: U.S. Forest Service

Partner Institution: University of Alaska Southeast

Fiscal Year: 2005

Initial Funding: $40,000

Total Funding: $40,000

Project Type: Research

Project Disciplines: Biological

Abstract: Land managers are increasingly called upon to manage at watershed scales but few integrative tools have been developed to assist managers in assessing management effects on whole basins. Dissolved organic matter (DOM) is abundant in southeast Alaskan watersheds. DOM supports secondary production, alters nutrient availability and controls ultraviolet penetration in aquatic ecosystems and is responsive to changes in hydrology, vegetation, soil and climate, yet we know little of how major DOM source pools and catchment hydrology interact to control the quantity and quality of DOM reaching surface waters. Nearly 30% of the land area in southeast Alaska is classified as wetlands, which are thought to provide substantial DOM to surface waters. Understanding wetland-stream carbon interactions is particularly important in watersheds where changes in landcover, management, and/or climate are altering the vital soil processes. However, there is little information on how natural and human-induced changes in forest structure throughout watersheds in southeast Alaska are altering carbon cycling in soils and streams, and there are no methods to evaluate these changes over large scales in a very diverse landscape. This research will establish a template for watershed nutrient research on important representative geomorphic landforms that can be applied to other important catchment types within the region. Soils research has become well integrated into watershed research over the last few years. Despite this recent work, few studies have attempted to characterize DOM in streams influenced by wetlands or to determine the sources of allochthonous DOM in these wetlands. The proposed research will use DOM characterization as a tool to explore the role of wetland soils in influencing the quantity and quality of stream DOM concentrations in southeast Alaskan watersheds. This type of analysis will provide information about how the export of DOM from wetlands influences DOM in surface waters. Due to the ecological importance and the role DOM fills as a component of a systems carbon budget, it is important to grasp how changes in climatic conditions will affect its chemical quality and export from terrestrial systems. Extrapolations from both laboratory and field studies will be useful in predicting how ecosystems in wetland and peatland dominated systems will respond to the expected rising temperatures and precipitation associated with climate change. This research will contribute to our understanding of how climate change is affecting carbon dynamics in wetland regions and will further provide insight into future roles of these areas in the global carbon cycle.