The Relationship Between Grazing and Plant Biodiversity in Tropical Pasture Lands A study on the implications of intermediate disturbance hypothesis S. Madigan Freedman

Introduction Understanding the relationship between cattle grazing and biodiversity in the environment is imperative to researchers’ and farmers’ developing more cost efficient, environmentally friendly methods of grazing livestock in the tropics. While most assume that higher grazing gleans higher rewards, medium disturbance hypothesis proposes that, “the highest diversity is maintained at intermediate levels of disturbance.”(Begon and Harper 1996) This suggests that the highest levels of biodiversity would be maintained when grazing occurs at moderate levels—in turn providing farmers with higher, more sustainable profits. The purpose of this study is to test the intermediate disturbance hypothesis in tropical pasturelands by analyzing the relationship between livestock grazing and plant biodiversity in Sao Paulo State, S.E. Brazil.

Hypothesis Null Hypothesis: Cattle Grazing is NOT correlated with plant biodiversity in pastures. Hypothesis II: Cattle Grazing is NEGATIVELY correlated with plant biodiversity in pastures. Hypothesis III: Cattle Grazing is POSITIVELY correlated with plant biodiversity in pastures. Hypothesis IV: In areas of INTERMEDIATE GRAZING biodiversity will be HIGHEST. Expected Outcome: GREATEST BIODIVERSITY WILL BE FOUND WITHIN AREAS OF MODERATE GRAZING.

Results The medium intensity pasture showed the highest levels of species diversity, population density, and varience of all three pastures ANOVA showed significance between the medium intensity pasture and the other two

Conclusions & Implications The intermediate disturbance hypothesis was proven correct, demonstrating that the highest levels of plant biodiversity are achieved by moderate grazing methods in tropical pasturelands. Suggested methods of moderate grazing may include: 1) Investing in other species of regional livestock more adaptable to the area. 2) Feeding livestock on Biogas products (methane, carbon) to successful help control against overgrazing.