Submitted to: Ecology Society of America Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 8, 2001
Publication Date: August 8, 2001
Citation: TRACY, B.F., SANDERSON, M.A. PRODUCTIVITY AND STABILITY RELATIONSHIPS IN CLIPPED PASTURE COMMUNITIES OF VARYING DIVERSITY. ECOLOGY SOCIETY OF AMERICA ABSTRACTS. 2001. P. 29. Technical Abstract: Recent studies have shown that plant diversity strongly affects ecosystem function in grasslands. In May 1998, we initiated a field experiment to address questions about the relationship between plant diversity and ecosystem function in pasture communities that we frequently clipped to simulate rotational grazing. The experiment consisted of 15 different cool lseason (C3) forages planted into eight mixtures of 1, 2, 3, 4, 6, 8, 10 an 15 species, respectively. The eight mixtures were seeded into small plots and clipped at four week intervals. In 1999 and 2000 growing seasons, we measured changes in aboveground production and species composition. Root biomass, microbial respiration, and nitrate concentrations were measured from soil cores. The simplest communities were 50-80% less productive than more complex mixtures. The low productivity was a result of the simple mixtures containing only grasses and no legume functional group. Functional group diversity of the mixtures similarly explained ~ 45% of th variation in aboveground production, while species diversity explained less than 1%. Root biomass, rates of microbial respiration, and soil nitrate concentrations were largely unrelated to plant diversity. Increased plant functional group diversity improved the stability of aboveground biomass production and species composition during drought conditions of 1999. We concluded that pasture communities should contain at least three different plant functional groups (perennial grasses, legumes, and broadleaf forbs) to help maximize sustainability.