Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2004
Publication Date: 7/1/2004
Citation: Sanderson, M.A., Goslee, S.C., Tracy, B.F. 2004. Vegetation changes in grazing lands of the northeastern USA during the 20th century [Abstract]. Pasture Ecology Abstracts. p. 14.
Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Livestock producers in the northeastern USA have intensified their grazing land management (e.g., rotational stocking, higher stocking densities, and increased nutrient inputs) as an alternative to confinement feeding. It is not clear how this intensified management may affect the plant species diversity at landscape and regional scales. During 1998 to 2003, we surveyed 126 pastures on 36 farms in nine northeastern states for plant species richness. We related these new survey results to historical data on plant species composition in northeastern pastures to assess landscape and regional scale changes in plant diversity. Diversity theory predicts that increased resource input will decrease species diversity. We hypothesized that plant species richness would be lower in the current survey and that species composition would differ from that earlier in the 20th century. Results indicate a wide range in plant species richness (19 to 42 species per pasture in the modern survey and 12 to 13 species per pasture in the historical surveys); however, two or three cool-season grasses and legumes dominated most grazing land. Our analysis indicated striking differences in pasture species composition in the early and late 20th century. Pasture surveys in the 1920's and 1930's revealed that bluegrass (Poa pratensis L.) and white clover (Trifolium repens L.) were among the most abundant plant species across the northeast. In early surveys, however, povertygrass (Danthonia spicata L.), sweet vernalgrass (Anthoxanthum odoratum L.), and Agrostis species were more abundant than in our modern surveys. The results were contrary to our hypothesis and may reflect improved soil fertility management on farms, abandonment of marginal agricultural land, or improved grazing land management. We conclude that improvements in pasture and grazing management along with the availability of improved cultivars and species of forages contributed to the increase in species richness.