Summary

Description

Benton Lake refuge has nearly 6,000 acres of native western wheatgrassgreen needlegrass prairie uplands. This pilot study was designed to assess the condition of refuge prairie, assess the effects of recent prescribed burns, assess the structural integrity of refuge prairie for nesting birds and create a pilot dataset from which to design longterm monitoring. We established 25 random transects across burn treatments timesinceburn throughout the refuge. We documented 39 of an estimated 53 refuge plant species with these pilot transects. We found that although the refuge prairie is generally healthy, the data suggest native cool season grasses are being replaced with nonnative, cool season grasses such as Japanese brome, cheatgrass and Kentucky bluegrass. The recent early spring prescribed fires on the refuge did not appear to influence the native plant composition of our prairie. The pilot data suggest that there is a decrease in litter, plant height and plant vigor measured by VOR immediately after an early season prescribed fire, but this effect disappears by 2 years postfire. Except for litter, which after the initial reduction, continues to increase each year after fire. In general, the structure of our native prairie meets the needs of many of our priority upland nesting birds. When litter depths are 6, it becomes less desirable for priority breeding birds and may be a good guideline for determining when to burn. Currently, refuge grasslands are short, sparse and lacking a significant litter layer, which is not ideal nesting habitat for several species of waterfowl. Precipitation is likely to have the largest influence on the structure of our prairie. Recent prescribed fires appear to reduce litter, but do not seem to have had any other significant, lasting effects. Grazing might increase plant vigor, but until we have several more years of data, especially from wet years, it is not clear if the benefits would outweigh the costs. Chemical treatment of nonnatives may be possible and could be explored further. The data from this pilot study should be used to help set specific goals and objectives during the CCP process. Once these have been defined, this pilot data can be used to design an effective monitoring plan that will provide feedback on health of refuge grasslands and whether or not objectives are being met.