Wood for firewood, fence posts and construction material and forage for domestic livestock are key resources in the caatinga vegetation zone of northeastern Brazil. This experiment was designed as a preliminary assessment of thinned caatinga as the basis of a production system which optimizes forage and wood production. Two levels of thinning (25% and 55% tree canopy cover) were compared to cleared (0% tree canopy cover) and undisturbed (95% tree canopy cover) caatinga in terms of forage and wood production and goat nutrition. Clearing and thinning of caatinga vegetation resulted in higher amounts of available forage through the wet ·season and up to the time of leaf fall. After leaf fall, total available forage was similar for all four treatments. Dietary selection differed among the treatments only in February and May, when goats on treated pastures selected higher amounts of herbaceous vegetation than those on control pastures. Herbaceous vegetation was the primary dietary constituent on treated pastures throughout the wet season. During mid to late dry season, when herbaceous vegetation was dead and leaf:stem ratios were low, browse was consistently selected at high levels. Nutrient content of diets were not different among treatments, but forage and digestible energy intakes were higher (P<.OS) on treated pastures than on control. Due to lack of wood production on cleared plots from an intact tree component, total aboveground biomass production for the cleared treatment was 30% less than that for the control and about 25% less than that for the two thinned treatments. Overall, cleared and thinned treatments had similar positive forage and animal responses but thinned treatments had the added benefit of an intact tree canopy producing valuable wood. The dry season has been identified as the most critical time of the year for livestock due to low forage availability and quality resulting in weight losses and mortality. Results of this study indicated that either supplementation or increased availability of nutritious forage would be necessary for goats to continue to grow beyond the first half of the dry season. Thinning may be a means of increasing the availability of nutritious forage.

Clearing of trees from the so-called caatinga woodland that characterizes the vegetation of the semi-arid region of northeast Brazil offers possibilities for increasing forage production. This research analyzed the first-year effects of clearing caatinga on dry season forage for goats and sheep. In addition, factors affecting litter decomposition on cleared and uncleared caatinga were assessed to evaluate the viability of deferring grazing of forages during the wet season for use later in the dry season. Removing the trees resulted in a sixfold increase in production of herbaceous vegetation, however, 88 percent of the increased yield on the cleared areas was in the form of stems from herbaceous vegetation. Seventy-two percent of the stems were unpalatable to goats and sheep because of the massive size of those stems. Leaf litter from trees was an important component of the diets of goats and sheep during the dry season and clearing reduced production of this forage threefold. Clearing resulted in increased decomposition of leaf litter. Changes in microclimate played only a minor role in this difference. The reduction in the amount of leaf litter from trees relative to litter from herbs had the greatest effect on decomposition rates of dry season forage because tree litter decomposed less rapidly than did herbaceous litter. The slow decomposition of leaf litter during the dry season suggests that deferment. of cleared or uncleared caatinga for use as forage in the latter part of the dry season is feasible. An analysis of the diets of esophageally fistulated goats and sheep indicated that clearing may be a viable alternative for improving the amount and the in vitro dry matter digestibility of the forage consumed during the dry season the first-year post-treatment. These increases were attributed to an absolute greater abundance of preferred herbaceous forages (i.e., foliage and leaf litter) and to the persistent green foliage on coppicing woody plants. Dietary nitrogen appeared to limit intake, and clearing did not improve availability of this nutrient to sheep and goats at the higher levels of grazing pressure applied in this study. Other ecosystem considerations such as watershed protection and long-term community stability must also be considered in decisions to remove the tree canopy of the caatinga.