Abstracts

Presented by Dan Smith - Email: djssmith@ucdavis.edu

The Suisun Marsh is one the largest brackish marshes in the western United States, containing both extensively managed wetlands and tidal wetlands. The managed wetlands are especially important to migratory waterfowl early in the wintering period, as they provide wetland habitat before many of the wetlands in the Central Valley receive water. Historically, the marsh supported over 300,000 wintering waterfowl as recently as the 1960s, but in the last decade that number has fallen to 60,000. To determine the carrying capacity of Suisun Marsh we collected 10 soil core samples from 45 managed wetlands (26 private, 19 Public) and 15 tidal wetlands throughout Suisun Marsh in early November and in early February for two years. To evaluate seed depletion we will use a trio of sample plots 5m in diameter, two open plots and one exclosure. Using historic telemetry data and expert opinion we will place the exclosure and one open plot in a position within five wetlands that receive high amounts of waterfowl use, while the other open plot will be placed in the same wetland in an area that receives traditionally low use. We will collect three soil cores from the plots every two weeks over winter to assess seed depletion. We will also measure the decomposition rates of the five most commonly consumed seeds by placing freshly collected mature seeds into fiberglass bags. Four replicate bags per species will be placed within the exclosures, every month a bag for each species will be removed, and seeds will be dried and weighed before their caloric content is quantified via bomb calorimetry. With estimates of seed availability, seed depletion rates, and seed decomposition, we will provide one of the first comprehensive estimates of the contemporary carrying capacity for waterfowl in Suisun Marsh under a number of different management scenarios.