Evaluation of some factors involved in reducing browsing damage to eucalypt trees by sheep

Abstract

These experiments evaluated in northeastern Victoria the factors affecting the severity of browsing damage to eucalypts by sheep. We aimed to develop management options for integrating sheep grazing in agroforestry systems. One-year-old tree seedlings were planted into annual pasture and grazed at high stocking rates (44 sheep/ha) for up to 1 week when the pasture was abundant. In experiments 1 and 2, crossbred weaners almost totally defoliated Eucalyptus camaldulensis (river red gum) seedlings after 96 h grazing; damage from older Merino wethers was minimal. Of the 4 eucalypt species tested for relative acceptability or palatability to crossbred weaners, E. camaldulensis was the most heavily browsed and E. globulus spp. bicostata (southern blue gum), least. The height of the pasture immediately surrounding the seedlings, and therefore visibility of the seedling to the sheep, did not affect browsing extent. In experiment 3, potential repellents were applied either on the ground around E. camaldulensis seedlings or sprinkled on the foliage. Six repellants provided short-term protection from crossbred weaner sheep; Replex 1 and 3, and egg and paint were the most effective. After 4 days grazing, seedlings treated with Replex 3 had sustained 24% mean browsing damage compared with 90% for the control.