Season of grazing and stocking rate interactively affect fuel loads in a Baikiaea plurijuga Harms woodland in northwestern Zimbabwe

Abstract

Wildfire is a major disturbance in Baikiaea plurijuga Harms woodland savannas. We tested the hypothesis that the timing and intensity of herbivory influence fuel loads. We used three stocking rates namely light (three cows and four goats ha)1), medium (six cows and eight goats ha)1) and heavy (eleven cows and sixteen goats ha)1) and three times of grazing namely early-, middle- and late-growing seasons. Season of grazing and stocking rate influenced herbaceous phytomass. Phytomass was generally the highest (53.5 g DM m)2) in paddocks grazed during the early growing season and the lowest (27.8 g DM m)2) in those grazed during the late growing season. Phytomass was also generally the highest (40.4 g DM m)2) in lightly stocked paddocks and the lowest (32.7 g DM m)2) in heavily stocked ones. Litter mass was the lowest (160.8 g DM m)2) in paddocks grazed during the early season whereas there were no differences in ungrazed paddocks and those grazed during either mid- or late growing seasons (205.4 g DM m)2). There was a negative relationship between litter mass and stocking rate. Baikiaea Benth. woodlands should be grazed during either the mid- or lategrowing season at stocking rates greater than 0.1 LU ha)1 to reduce grass fuel loads.