COMPARATIVE FLORISTIC DIVERSITY OF SPRING CREEK AND NINE-MILE PRAIRIES, NEBRASKA

摘要

Spring Creek Prairie (SCP), in Lancaster County, Nebraska, was purchased by Audubon Nebraska in 1998 and is being restored for educational purposes and scientific study. It is a remnant tallgrass prairie of 247 ha (610 acres) that was grazed for a century but never plowed. The research was conducted to obtain baseline information about diversity and abundance of upland species, for assessment of management practices. Specimens were collected from September, 1998, through October, 2000, and an inventory was produced. These data were compared with similar data from Nine-Mile Prairie (NMP), a nearby and essentially ungrazed virgin tallgrass prairie that is now managed with prescribed burning. Seventy-eight percent of the 349 species at SCP are native and 22% are non-native. At about one-third the size, NMP contains 398 species, with 85% native and 15% non-native. Sampling data from the fall of 1999 indicated greater richness at SCP, while actual plant species inventories showed greater total richness at NMP. Ruderal and introduced species are significantly more abundant at SCP. Richness assessed using the "Chicago Method" indicated lower values at SCP than NMP, as did Simpson's diversity index. Detrended correspondence analysis, frequency, and basal cover indicated a greater propensity for warm-season grasses at NMP and for ruderal grasses and forb species at SCP.