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

在1970年代之前的几十年里，安大略省中南部的森林开发导致森林构成向落叶、耐荫物种的强烈转变。虽然现代森林管理做法的目的是可持续的，但从长远来看，也可能改变这些森林，对生物多样性产生重要影响。若干长期研究表明，该区域主要的森林管理活动--单木选择对森林的构成和结构产生了长期影响。重要的是，尽管保持了让人想起未经管理的林分的树木直径分布，但在收获期间形成的均匀分布的小间隙导致了成分转变，有利于耐荫物种，失去了中等耐荫物种和针叶物种。此外，对林分改良和木材价值的重视意味着大树、病树和垂死的树木、倒下的原木和直立的枯死树木的数量减少。不幸的是，尚未开展对生物多样性影响的多轮换研究。对第一轮轮换影响的研究表明，一些成熟的森林分类群即使在轮换结束时也保持在较低的丰度，在多次轮换后，种群可能会进一步减少。此外，结构变化预计只有在几次轮回之后才能达到平衡，这对关键的动物群群具有重要影响。我的总体目标是测试安大略省中南部的单木选择是否在多次轮作中维持生物多样性。具体目标是：1)比较采伐1-2次、3-4次或未经管理的林分之间的生境结构和关键指标分类群(小型哺乳动物、昆虫和真菌)的丰度；2)通过检查邻近林分组成和结构对反应的影响，包括林间视角。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；真菌采样将包括子实体的区域搜索和基于DNA的林木采样；景观水平评估将利用森林资源调查信息和遥感ADS40和LiDAR图像。早期演替物种预计将在采伐后的年轻林分中最常见和多样化，而晚期系列、木质碎屑和与针叶树相关的物种的丰富度将随着轮伐量的增加而下降，特别是在附近的针叶林盖度和未管理的林分稀有和孤立的情况下。昆虫和真菌群落之间的功能转移预计将导致腐植酸和弱分散物种多样性的减少。这将是第一次研究多次轮作后单木选择对生物多样性的影响。

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.