Floristic Quality of Native Tallgrass Pastures in Eastern South Dakota

View the project final report

• 2008 annual report
• 2009 annual report

Commodities

• Additional Plants: native plants

Practices

• Animal Production: grazing management
• Education and Training: extension
• Natural Resources/Environment: biodiversity
• Pest Management: chemical control
• Production Systems: agroecosystems

Historic herbicide use and grazing have influenced natural diversity and quality of native pasturelands in the Great Plains. Floristic quality assessments are useful to assist agencies in prioritizing conservation practices to enhance native grasslands. The objective of this study was to determine the effects of past land use practices on the floristic quality of remnant native pastures in eastern South Dakota and southwestern Minnesota. Floristic quality assessments were conducted on 30 native pastures and categorized by past management practices (herbicide application and grazing intensity). Mean coefficient of conservatism and floristic quality index (FQI) were calculated for each site. Results showed that increased herbicide use and grazing intensity resulted in a lower species richness, mean forb coefficient of conservatism, and FQI. However, grass and grasslike plants were minimally affected. Pastures that were infrequently sprayed with herbicides and lightly grazed consistently had the highest species richness, mean coefficient of conservatism, and FQI. Pastures with no grazing produced similar values to those with moderate grazing. Pastures managed as preserves/wildlife habitat areas had higher FQI than those managed for livestock grazing. The implications of this study should further help ecologists and managers understand the positive and negative effects of grazing practices and herbicide application on tallgrass prairie remnants.

Introduction:

The natural landscape of the eastern Great Plains has been immensely altered since pre-European settlement. Large areas of land have been put into agricultural production and as a result less than 1% native tallgrass prairie remains. Remnant tallgrass prairies display varying degrees of quality due to habitat disturbance and invasion by exotic species. Long-term use of herbicides that control broadleaf species has resulted in decreased forb diversity. Exotic cool-season grasses such as smooth bromegrass and Kentucky bluegrass have increased greatly in the Great Plains. Anthropogenic additions of nitrogen deposition have contributed to the competitiveness of exotic cool-season grasses. It is likely that remnant grasslands of the eastern Great Plains have experienced greater grazing intensities since the removal of the bison, fencing of pastures, and introduction of domestic livestock. Grazing intensity has been shown to decrease the vigor of pasture forage species and increase weedy species. Therefore, tallgrass prairie remnants are a high priority for conservation by natural resource agencies. The objectives of this study were to determine the effects of past management practices, involving varying levels of herbicide application and grazing intensity, and whether the primary land use (either nature preserve/wildlife production or livestock grazing) has had an impact on floristic quality of native prairies pastures in the Prairie Coteau of eastern South Dakota and southwestern Minnesota. The literature suggests that herbicide use and grazing intensity decrease the floristic quality of native pastures and that prairies managed as nature preserves/wildlife areas should have higher floristic quality than pastures managed for livestock grazing.

1) Determine floristic quality inventory and effects of past management history on at least 16 privately owned native pastures.
2) Educate producers, extension and NRCS personnel about past management influences on floristic quality of native pastures.
3) Assist NRCS personnel in the development of ecological site descriptions and plant community models for MLRA 102A in eastern SD.