Management of natural pasture increases native and exotic herbaceous biomass and biodiversity in the Caatinga of Brazil

Abstract

The objective of this study was to evaluate the ability of savanna thinning and enrichment with grasses to maintain local biodiversity and intensify biomass production in an area of Caatinga. The study was carried out in a Caatinga area thinned into savanna and an unmanipulated area during the rainy and rainy-dry transition seasons of 2016. The herbaceous biomass production, diversity, and equability of the thinned and unmanipulated areas were evaluated by calculating values of the Shannon-Weaver (H?) and Pielou (J?) indices. The establishment of massai and buffel grasses in the savanna-thinned area was also evaluated. The area thinned into savanna produced more native herbaceous forage biomass in both the rainy (1,940.55 kg ha-1) and rainy-dry transition seasons (1,918.55 kg ha-1) than that in the unmanipulated area in the same periods (78.42 and 37.40 kg ha-1, respectively), without compromising biodiversity, as the Shannon-Weaver and Pielou indices for the savanna-thinned area (H? = 1.48 and J? = 0.62, respectively) and for the unmanipulated area (H? = 1.29 and J? = 0.72) were comparable. The frequency of species with a known forage value in the area thinned into savanna was still able to increase by 141% in the rainy season and 1,700% in the rainy-dry transition season. Massai grass became better-established in the savanna-thinned area that buffel grass, where it produced up to 3 t of dry matter ha-1. The thinning and enrichment treatments promoted an increase in the biodiversity of the area, and moreover contributed to increases in forage biomass in the Caatinga.

Keywords

• Unmanipulated area, Massai grass, buffel grass, botanical composition, enrichment, savanna thinning.