Vegetation responses to an animal-generated disturbance (bison wallows) in tallgrass prairie

TitleVegetation responses to an animal-generated disturbance (bison wallows) in tallgrass prairie
Publication TypeJournal Article
Year of Publication2011
AuthorsMcMillan, BR, Pfeiffer, KA, Kaufman, DW
JournalAmerican Midland Naturalist
Pagination60 -73
Accession NumberKNZ001350

Bison (Bos bison) were a keystone species in the tallgrass prairie region of the Great Plains of North America. Cattle (Bos taurus) have been described as a functional equivalent to bison and have replaced bison in most of the grassland that remains intact. However, non-grazing behaviors influence grassland dynamics and are dissimilar between bison and cattle. Wallowing behavior (a non-grazing behavior by bison, but not cattle) creates disturbances (wallows) that were a common feature (may have numbered more than 100 million) of tallgrass prairie prior to extirpation of bison and conversion of most land to row-crop agriculture. We hypothesized that wallows are a unique disturbance that significantly influence both the structure and function of tallgrass prairie. We examined the response of plants to wallowing disturbances on Konza Prairie Biological Station, Kansas, where a herd of approximately 200 bison had year-round access to 1000 ha of native tallgrass prairie. We determined the influence of this disturbance type on aboveground net primary production (ANPP), plant species richness and diversity, and plant life form richness and diversity. The ANPP at the edge of wallowing disturbances was double the production in wallows and in adjacent prairie, which were not different from year to year. Plant species richness and diversity were significantly lower in wallows than at the edge of wallows and in adjacent prairie during all years of the study. However, composition of species were dissimilar among locations (e.g., 16% of all plant species samples were found only in the wallows); and, therefore, wallows increased the local and likely regional diversity of plant species. Likewise, wallowing disturbances increased local richness and diversity of plant life forms. It appears that these once common wallowing disturbances increase the diversity of tallgrass prairie beyond that of prairie that is grazed only (i.e., prairie with cattle).