Abstract Population sizes and species distributions of wild ungulates in Europe have increased during the past decades, and continue to do so. As a result, browsing pressure in forests is increasing and concerns about the effects of increasingly common multi-species deer communities on forestry are rising. However, we currently lack an understanding of how the composition of deer communities affects browsing damage, particularly with respect to the role of species with different dietary requirements. Further, the relative importance of predictors of browsing damage in systems with multiple browsers remains elusive. Here, we used data from Swedish management, which is monitoring ungulates and their damage to forests, to test how deer densities, forage availability, and winter severity predict browsing damage on commercially important Scots pine (Pinus sylvestris) at national and regional scales. Moose (Alces alces) is the main browser of Scots pine, but competes with other deer over more preferred forage. During winter, a higher index of moose density was associated with higher browsing damage in northern Sweden, where there is low competition from other deer. In southern Sweden, competition from other deer is higher and a higher density index of roe deer (Capreolus capreolus) was associated with higher winter damage. However, there was no relationship between moose density and damage. We suggest that moose are forced to browse more pine due to interspecific competition over alternative forage resources in the south, yielding stronger relationships between densities of competing deer species and damage than between moose density and damage. Pine density, a proxy for forage availability, was an equally or more important determinant for browsing damage as deer density indices in most regions. Increasing pine density was associated with reduced browsing damage caused in winter in all regions and reduced damage caused in summer in central Sweden. Increased winter severity, as an index of snow depth, predicted increased winter damage in the northern region only. To reduce winter damage, our results suggest that management should consider deer densities and forage availability simultaneously, while adopting a multi-species approach. Results varied among regions, with densities of other deer being more relevant in the south and winter severity more relevant in the north. Management data did not predict summer damage well. Since national models did not capture regional variations, we conclude that management decisions and actions need to be tailored to the regional or local scale.

中文翻译：

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商业林浏览破坏的预测因素——一项关联全国管理数据的研究

摘要 在过去的几十年中，欧洲野生有蹄类动物的种群规模和物种分布有所增加，并且还在继续增加。因此，森林中的浏览压力越来越大，人们越来越担心多品种鹿群落对林业的影响。然而，我们目前缺乏对鹿群落组成如何影响浏览损害的了解，特别是关于具有不同饮食要求的物种的作用。此外，在具有多个浏览器的系统中，浏览器损坏预测器的相对重要性仍然难以捉摸。在这里，我们使用了瑞典管理部门的数据，该管理部门正在监测有蹄类动物及其对森林的破坏情况，以测试鹿的密度、饲料可用性、和冬季严重程度预测在国家和区域范围内对具有重要商业价值的苏格兰松（Pinus sylvestris）的浏览损害。驼鹿 (Alces alces) 是苏格兰松树的主要浏览者，但与其他鹿竞争更喜欢的草料。在冬季，较高的驼鹿密度指数与瑞典北部较高的浏览破坏有关，那里与其他鹿的竞争较少。在瑞典南部，来自其他鹿的竞争更加激烈，狍 (Capreolus capreolus) 较高的密度指数与较高的冬季损害有关。然而，驼鹿密度和损伤之间没有关系。我们建议驼鹿由于南方替代饲料资源的种间竞争而被迫吃更多的松树，在竞争鹿物种的密度和损害之间产生比驼鹿密度和损害之间更强的关系。在大多数地区，松树密度是草料可用性的代表，是与鹿密度指数同等或更重要的浏览损害决定因素。增加松树密度与所有地区冬季造成的浏览损害减少以及瑞典中部夏季造成的损害减少有关。冬季严重程度的增加，作为积雪深度的指标，仅预测北部地区的冬季损害会增加。为减少冬季损害，我们的结果表明，管理人员应同时考虑鹿密度和草料可用性，同时采用多物种方法。结果因地区而异，其他鹿的密度在南方更相关，冬季的严重性在北方更相关。管理数据并没有很好地预测夏季损害。由于国家模型没有捕捉到区域差异，我们得出结论，管理决策和行动需要根据区域或地方的规模进行调整。