The Role of Riparian Zone Modifications in Interrupting Terrestrial Inputs to Lake Ecosystems

EPA Grant Number: F07E10850
Title: The Role of Riparian Zone Modifications in Interrupting Terrestrial Inputs to Lake Ecosystems
Investigators: Francis, Tessa
Institution: University of Washington
EPA Project Officer: Michaud, Jayne
Project Period: January 1, 2007 through January 1, 2010
RFA: STAR Graduate Fellowships (2007) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Aquatic Ecology , Aquatic Ecology and Ecosystems


Mediation of the dynamics occurring at the terrestrial-aquatic interface by intact riparian habitats is a key ecosystem function, as terrestrial-aquatic linkages are important for maintaining sustainable freshwater ecosystems. This research aims to determine some of the impacts of riparian habitat alteration on lake ecosystems, and in particular the consequences of reductions of terrestrial inputs to aquatic habitats as a result of watershed urbanization.

The consequences of urbanization for terrestrial-aquatic linkages will be investigated through two alternate hypotheses: Hypothesis 1: Urban development of riparian zones reduces terrestrial organic inputs to lakes. The degree to which terrestrial inputs are reduced varies according to the intensity of shoreline alteration and the extent of basin-wide development. Hypothesis 2: Shoreline development bears little on terrestrial inputs, relative to watershed urbanization. Terrestrial organic inputs decrease with watershed development independent of shoreline characteristics.


Paleolimnological methods will be used to test the proposed hypotheses, with three major goals: (1) Establish pre-European settlement baselines of terrestrial organic inputs, (2) create a chronology of changes in terrestrial inputs to each lake since initial deforestation, and (3) compare these limnological changes with historical data on catchment use and urban development. These hypotheses will be investigated through a survey of 12-15 lowland temperate lakes in western Washington State with varying levels of lakeshore and watershed development. Patterns of terrestrial organic inputs to each lake since initial deforestation by Europeans at the turn of the 20th Century will be determined by extracting sediment cores representing 200-400 years of sediment deposition, and geochemical analyses will determine terrestrial soil inputs, terrestrial plant inputs, and sediment ages and deposition rates.

Expected Results:

This research will demonstrate the degree to which critical coupling between terrestrial and aquatic ecosystems is disrupted by modification of the riparian zones of lakes. These results will point to the relative importance of lakeshore versus watershed disturbance in maintaining pathways for key terrestrial organic inputs.

Supplemental Keywords:

riparian, lakes, habitat coupling, subsidies, sediments, urban ecology, allochthonous inputs,

Progress and Final Reports:

  • 2007
  • 2008
  • Final