A global meta-analysis of non-lethal mammal browsing control in forests

Increasing resource demand, desire to sequester atmospheric carbon, and conservation goals are driving a need for forests to be managed more effectively in the face of numerous challenges. One such challenge is damage perpetrated by browsing mammals, which can cause substantial financial and ecological impacts. Current practices focus on lethal control measures for mitigating mammal browsing damage, however stakeholder pressure is calling for a transition to non-lethal alternatives. Little is known about the relative efficacy of different non-lethal control methods for mitigating browsing damage by mammals other than deer. Using a multilevel meta-analytical framework across 1,908 effect sizes, we investigate the relative efficacy and longevity of different non-lethal control methods implemented against a broad suite of browsing mammals across different spatial scales. We found that tree guards, repellents and exclusion fencing all significantly reduce mammal browsing damage and retain their effect for long periods. There was, however, substantial variation in efficacy within individual control strategies highlighting the importance to forest managers of selecting the correct method from within the broad strategies we identified. We then discuss other factors to consider when implementing non-lethal mammal browsing control so that forest managers are well informed when implementing a control strategy.