Evaluation of anti-sheep tree-stem-protection products in silvopastoral agroforestry

Direct herbivore damage to trees in temperate silvopastoral agroforestry systems is a major management consideration. Individual plastic tree-shelters may sometimes cause poor tree development and they have limited life span. Therefore, some alternative tree-shelter products were tested on four year old Acer pseudoplatanus and Fraxinus excelsior. Damage to the main stem was assessed by determining the area of bark removed by sheep browsing. Wobra^®, a paint-on abrasive substance applied to the main stem, was effective in reducing sheep damage. However, some damage did occur due to breach of the protective barrier as a result of stem diameter increases and its removal through rubbing by animals. Anipel^®, a systemic bittering agent supplied through the root system, was not effective in preventing significant damage compared to no-treatment controls, possibly because of poor uptake of the active ingredient into the tree. Within treatments, there were significant differences in damage incurred. Most notably Fraxinus suffered more damage than Acer, an effect which may be related to differences in tree size and/or relative palatability.