Effects of multiple rotations of uneven-age forest management on mammal, insect, and fungus biodiversity in central Ontario

在20世纪70年代之前的几十年里，安大略中南部的森林开发导致了森林组成向落叶、耐荫物种的强烈转变。现代森林管理做法虽然旨在实现可持续性，但也可能长期改变这些森林，对生物多样性产生重大影响。若干长期研究表明，该区域主要的森林管理活动-选择单一树木-正在对森林的组成和结构产生长期影响。重要的是，尽管树木直径分布的维护让人联想到未管理的立场，均匀分布，小的差距，在收获过程中产生的，导致了成分的转变，有利于不耐荫的物种，与损失的中间宽容的物种和针叶树种。此外，对林分改良和木材价值的重视意味着大树、病树和死树、倒木和立死树的数量减少。遗憾的是，尚未开展对生物多样性影响的多轮研究。对第一轮伐影响的研究表明，一些成熟的森林分类群即使在轮伐期结束时也仍然处于低丰度状态，在多次轮伐后，种群可能会进一步减少。此外，结构变化预计只有在几次轮换之后才能达到平衡，这对关键的动物群有重要影响。我的总体目标是测试是否单树选择在中南部安大略维持生物多样性的多次轮换。具体目标是：1）比较已采伐1 - 2次、3 - 4次或未管理的林分之间的栖息地结构和关键指示类群（小型哺乳动物、昆虫和真菌）的丰度; 2）通过检查相邻林分组成和结构对响应的影响，包括林分-林分视角。小型哺乳动物研究将利用活体诱捕;昆虫研究将侧重于飞行拦截和陷阱诱捕的群落;真菌取样将包括对子实体的区域搜索和对倒下的木材进行基于DNA的取样;景观水平评估将利用森林资源清单信息和遥感ADS40和激光雷达图像。早期演替的物种预计是最常见的和多样化的年轻的收获后的立场，而丰富的晚演替系列，木质残体，针叶树相关的物种将下降与旋转的数量，特别是在附近的针叶树覆盖和未管理的立场是罕见的和孤立的。昆虫和真菌群落之间的功能转移预计将导致减少的多样性的sacetylicandweakly-dispersing物种。这将是第一项研究，以探讨生物多样性的影响，单树选择后，多次轮换。

In the decades prior to the 1970s, forest exploitation in south-central Ontario resulted in strong shifts in forest composition towards deciduous, shade-tolerant species. Although intended to be sustainable, modern forest management practices also may be altering these forests over the long term, with important implications for biodiversity. Several long-term studies indicate that single tree selection, the predominant forest management activity in the region, is having long-term effects on forest composition and structure. Importantly, despite the maintenance of tree diameter distributions reminiscent of unmanaged stands, the evenly distributed, small gaps created during harvesting have led to a compositional shift favouring shade-intolerant species, with a loss of mid-tolerant species and coniferous species. In addition, the emphasis on stand improvement and timber values has meant reductions in the abundances of large trees, diseased and dying trees, downed logs, and standing dead trees. Unfortunately, multi-rotation studies of effects on biodiversity have not been undertaken. Studies of first-rotation impacts indicate that some mature forest taxa remain at low abundances even at the end of the rotation, with the possibility that populations will be further reduced after multiple rotations. In addition, structural changes are expected to equilibrate only after several rotations, with important implications for key faunal groups. My overall objective is to test whether single-tree selection in south-central Ontario sustains biodiversity over multiple rotations. Specific objectives are to: 1) compare habitat structure and abundances of key indicator taxa (small mammals, insects, and fungi) among forest stands that have been harvested 1-2 times, 3-4 times, or are unmanaged and 2) include an among-stand perspective by examining the effects of neighbouring stand composition and structure on responses. Small mammal research will make use of live trapping; insect research will focus on communities from flight interception and pitfall traps; fungal sampling will include both area searches of fruiting bodies and DNA-based sampling of downed wood; and landscape level assessments will make use of forest resource inventory information and remotely-sensed ADS40 and LiDAR imagery. Early-successional species are expected to be most common and diverse in young post-harvest stands, whereas abundances of late seral, woody debris, and conifer associated species will decline with the number of rotations, especially where nearby conifer cover and unmanaged stands are rare and isolated. Functional shifts among insect and fungal communities are expected to result in reductions in the diversity of saproxylic and weakly-dispersing species. This will be the first study to examine biodiversity implications of single tree selection after multiple rotations.