The savanna vegetation under cattle grazing in Central Brazil

Abstract

The ecological impact of cattle grazing on Brazilian savannas is poorly known. This study aimed to evaluate vegetation structure, diversity, and fuel load in savannas under rotational grazing. We studied three adjacent, fire-excluded savanna fragments in Central Brazil: one subjected to rotational grazing, one excluded from grazing for 2.5 years, and one ungrazed. For vegetation sampling, we used the line-point intercept method. Fuel load was quantified by measuring the dry mass of necromass, live graminoids, and other plants with a stem diameter < 6 mm. There were no differences in vegetation cover above 2 m height among sites. Below 2 m, total cover was three times greater in the ungrazed site than in the grazed, while the short-term exclusion site showed intermediate values. Graminoids had the highest absolute cover in the ungrazed site for 2.5 years (97%), followed by the ungrazed (86%) and grazed (60%) sites. Species richness decreased from 133 species in ungrazed to 100 species in ungrazed for 2.5 years and 96 species in grazed site. Fuel load was 61% lower in the grazed site compared to the ungrazed site. These findings suggest that Cerrado savannas have the potential to be used as intermittent pastures on private farms, as they did not severely impact vegetation structure and diversity, and reduced fuel loads in fire-excluded savanna fragments. Future studies should explore varied grazing regimes and different regions to assess the feasibility of using cattle as a conservation ally.

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