• A Rapid Method for Assessing Rates of Soil Erosion from Rangeland: An Example from Botswana

      Abel, N.; Stocking, M. (Society for Range Management, 1987-09-01)
      The erosion of rangeland soils is a widespread problem in Africa. Yet, there are few methods for estimating its rate. Using data from 2 catchments in Botswana, a technique for estimating erosion and sediment yield is demonstrated. It involves low level photographic sampling of vegetation cover, kriging to interpolate percentage cover from sample points, and the application of a simplified soil loss estimation procedure called SLEMSA. This modelling approach gives gross soil loss and allows the estimation of sediment yield. It is easy and cheap to apply and gave results in line with field experience.
    • Clearcutting Brazilian Semiarid Tropics: Observations on Its Effects on Small Ruminant Nutrition during the Dry Season

      Kirmse, R. D.; Provenza, F. D.; Malechek, J. C. (Society for Range Management, 1987-09-01)
      Small ruminant production in northeast Brazil is limited by prolonged nutritional stress during the dry season. Our study assessed the effects of clearcutting woody vegetation on the nutrition of goats and sheep during the initial dry season following clearing. Dry matter intake g day-1 was higher for animals on cleared than on uncleared areas (818 vs. 627; P<0.05). Extrusa from esophageally fistulated animals grazing cleared, as opposed to uncleared, areas was more digestible (52 vs. 47%; P<0.05), was similar in crude protein (7.1 vs. 7.1%; P<0.05), and was lower in neutral detergent fiber (49 vs. 51%; P<0.05) and lignin (14 vs. 16%; P<0.05). Intake and diet quality declined on both cleared and uncleared areas as forage availability declined. Animals on cleared areas benefitted from increased availability of herbs and of biomass from palatable trees that coppiced and retained green leaves throughout much of the dry season. Animals on uncleared areas relied heavily on leaf litter from trees, which provided a poorer quality, but persistent, source of forage throughout the dry season.