Submitted to: Grassland Science in Europe
Publication Type: Proceedings
Publication Acceptance Date: 6/20/2003
Publication Date: 6/20/2002
Citation: SANDERSON, M.A., TAUBE, F., TRACY, B., WACHENDORF, M. PLANT SPECIES DIVERSITY RELATIONSHIPS IN GRASSLANDS OF THE NORTHEASTERN USA AND NORTHERN GERMANY. GRASSLAND SCIENCE IN EUROPE. 2002. v. 7. p. 841-842. Interpretive Summary: Biodiversity is a key feature of properly functioning grazed ecosystems. Legumes are one of the keystone plant species in productive grasslands. White clover is the most widely grown legume in temperate grasslands. It is not clear if high levels of plant diversity are compatible with appropriate levels of white clover in grazed swards. Our objective was to determine the erelationship between plant species diversity and white clover content on a wide range of temperate grazing lands. Grazed swards on 33 farms in northern Germany and 40 farms in the northeastern USA were surveyed for plant species richness and white clover abundance. There was a strong negative relationship between plant species richness and the clover content of swards in northern Germany. White clover mainly displaced herb species but not grasses. There were no clear relationships among clover content and total, grass, or herb species richness in the USA.
Technical Abstract: Recent developments in grassland-based livestock production systems have created a need for new information on pasture and forage ecology and management. We determined the relationship between plant species diversity and white clover content on a wide range of temperate grazing lands. In northern Germany, as the white clover proportion of the sward dry matter increased, the total number of plant species in the sward decreased. The number of herb species decreased the most as white clover proportion increased, whereas the number of grass species in the sward decreased only slightly. With increasing proportions of white clover, Taraxacum officinale L. became dominant within the fraction of herbs as well as Lolium perenne L. did within the fraction of grasses. In the northeastern USA, there was no clear relationship between white clover content and the plant species composition of the sward. The average number of plant species identified in ngrazed swards of the northeastern USA was 32 with a range of 15 to 56 species. About 50% of the species were broadleaf herbs, 21% were grasses, and 9% were grasses. In general, a greater number of broadleaf forb and fewer grass species were present in northeastern USA swards than in grazed swards of northern Germany. The swards sampled in the USA were primarily older (20 to 100 years old) permanent pastures and the dominant plant cover was bluegrass (Poa species) and white clover. Patterns of plant species composition in grazed swards were different in northern Germany and the northeastern USA. Environmental and management differences between these grassland regions may account for some of these differences.