Botanical composition of goat diets in thinned and cleared deciduous woodland in northeastern Brazil

Abstract

Clearing and thinning of caatinga vegetation in northeastern Brazil are viewed as methods of optimizing forage and wood production. Our study compared the botanical composition of goat diets relative to forage availability in undisturbed, cleared and 2 levels of thinned (25% and 55% canopy cover) stands of tropical woodland. 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. At the end of the growing season, available herbaceous biomass was generally 7 to 8 times higher on the treated pastures than on the control; biomass of available browse was about 4 times greater. After leaf fall, total available forage was similar for all 4 treatments but about 90% of the available forage on the control was leaf litter. Diet composition differed among the treatments only in February and May; at this time, goats on the treated pastures were selecting higher amounts of herbaceous vegetation than those on the control pastures. Even though browse availability was high throughout the wet season on the treated pastures, herbaceous vegetation was the primary dietary constituent. Only during the mid to late dry season, when herbaceous vegetation was dead and leafistem ratios were low, was browse consistently selected at high levels. We concluded that clearing and thinning increases the amount and diversity of available forage; thereby, improving foraging conditions. Moreover, production of herbaceous vegetation declines towards control levels only at some canopy cover higher than 55%.