Abstract：
Beavers are expanding into cities as they recolonize their historic range. While they increase the ecological functioning of urban green areas, human-beaver conflicts occur. Public support to deal with conflicts has shifted from population to forage control. Tree guards are becoming popular with management personnel in North America and Europe to reduce damage to valuable trees. The problem is that this management technique has not been studied. We inventoried the tree guard types in use in natural and manicured river parks in the City of Saskatoon, Canada, determined their adherence to an installation protocol by measuring guard dimensions, and assessed the relative effectiveness of guards in protecting trees from beaver cutting. The inventory revealed that four types of tree guards are in use, ranging from light gauge chicken wire to heavy gauge chain link fencing. Overall, 11% of the trees with guards that we inventoried were cut by beavers, but variation among guard types was observed. Less than 10% of trees with type i and ii guards were beaver cut whereas 17% of trees with types iii and iv guards were beaver cut. Fewer trees were cut when there was adherence to installation protocol, regardless of guard type. Cut trees with guard types i, iii and iv experienced both minor and major damage whereas cut trees with guard type ii experienced only minor damage. The study results have implications for developing effectiveness and implementation monitoring plans for tree guards as part of an overall beaver management plan.
摘要：
海狸在重新定居其历史范围时正在向城市扩展。虽然它们增加了城市绿地的生态功能，人与海狸的冲突发生。解决冲突的公众支持已经从人口转向饲料控制。树木护卫越来越受到北美和欧洲管理人员的欢迎，以减少对珍贵树木的损害。问题是这种管理技术尚未被研究。我们清点了萨斯卡通市自然和修剪整齐的河流公园中使用的树木护卫类型，加拿大,通过测量防护装置尺寸来确定他们对安装协议的遵守情况，并评估了警卫保护树木免受海狸砍伐的相对有效性。清册显示,目前使用的护树有四种,从轻型铁丝网到重型铁丝网。总的来说,我们发现的有警卫的树木中有11％被海狸砍伐，但观察到警卫类型之间的差异。少于10％的具有i型和ii型防护装置的树木被海狸砍伐，而17％的具有iii型和iv型防护装置的树木被海狸砍伐。遵守安装协议时砍伐的树木较少，无论警卫类型。用I型警卫砍伐树木，iii和iv遭受了轻微和重大损坏，而具有ii型保护的砍伐树木仅遭受了轻微损坏。研究结果对制定树木警卫的有效性和实施监控计划具有重要意义，作为整个海狸管理计划的一部分。
