Timing and Protocols for Estimating Seed Production in Moist-Soil and Phalaris arundinacea Dominated Areas in Rainwater Basin Wetlands

Abstract

In the Rainwater Basin region of Nebraska, seeds produced by wetland plants are an important food source for waterfowl. Seed production estimates are used to set habitat management goals and evaluate management efforts. Most seed production estimates focus on one-time sampling during peak seed production, but it is unknown how well this captures the total production of wetland seeds throughout the growing season. We evaluated seed production from throughout the growing season in Rainwater Basin wetlands to describe timing of seed production, compare seed production estimates based on one-time and season-long sampling, and quantify how seed production is affected by the invasive species Phalaris arundinacea. Mature seeds were collected from early June to mid-October. One-time sampling of seed production in moist-soil vegetation estimates were only 27% that of season-long sampling. Estimates were consistently lower in P. arundinacea invaded areas. Season-long estimates in P. arundinacea areas were 19% those in moist-soil vegetation, and one-time sampling estimates were 10% those of moist-soil vegetation. We recommend that future seed production estimates use 2-3 sampling periods to better capture the full production of an area. Sampling periods should be based on the peak seed production of the most productive species in the targeted wetland.