Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
Ecol Appl. 2010 Dec;20(8):2310-21. doi: 10.1890/09-0815.1.
Current clear-cutting forestry practices affect many boreal organisms negatively, and those dependent on dead wood (saproxylics) are considered as particularly vulnerable. The succession of species assemblages in managed forest habitats regenerating after clear-cutting is, however, poorly known. We compared beetle assemblages in three successional stages of managed boreal spruce forests established after clear-cutting and two types of older spruce forests that had not been clear-cut. We also assessed whether saproxylic and non-saproxylic beetle assemblages show similar biodiversity patterns among these forest types. Beetles were collected in window traps in nine study areas, each encompassing a protected old-growth forest (mean forest age approximately 160 years, mean dead wood volume 34 m3/ha), an unprotected mature forest (approximately 120 years old, 15 m3/ha), a middle-aged commercially thinned forest (53 years old, 3 m3/ha), a young unthinned forest (30 years old, 4 m3/ha), and a clearcut (5-7 years after harvest, 11 m3/ha). Saproxylic beetles, in particular red-listed species, were more abundant and more species rich in older forest types, whereas no significant differences among forest types in these variables were detected for non-saproxylics. The saproxylic assemblages were clearly differentiated; with increasing forest age, assemblage compositions gradually became more similar to those of protected old-growth forests, but the assemblage composition in thinned forests could not be statistically distinguished from those of the two oldest forest types. Many saproxylic beetles adapted to late-successional stages were present in thinned middle-aged forests but absent from younger unthinned forests. In contrast, non-saproxylics were generally more evenly distributed among the five forest types, and the assemblages were mainly differentiated between clearcuts and forested habitats. The saproxylic beetle assemblages of unprotected mature forests were very similar to those of protected old-growth forests. This indicates a relatively high conservation value of mature boreal forests currently subjected to clear-cutting and raises the question of whether future mature forests will have the same qualities. Our results suggest a high beetle conservation potential of developing managed forests, provided that sufficient amounts and qualities of dead wood are made available (e.g., during thinning operations). Confirming studies of beetle reproduction in dead wood introduced during thinning are, however, lacking.
当前的皆伐林业实践对许多北方生物产生了负面影响，而那些依赖枯木（腐生性的）的生物被认为尤其脆弱。然而，人们对皆伐后管理森林生境中物种组合的演替知之甚少。我们比较了皆伐后三种演替阶段的管理北方云杉林和两种未皆伐的较老云杉林的甲虫组合。我们还评估了腐生性和非腐生性甲虫组合在这些森林类型之间是否表现出相似的生物多样性模式。在九个研究区域中，我们使用窗式陷阱收集了甲虫，每个研究区域都包含一个受保护的古老森林（平均森林年龄约为 160 年，平均枯木量为 34 立方米/公顷）、一个不受保护的成熟森林（约 120 年，15 立方米/公顷）、一个中年商业间伐林（53 年，3 立方米/公顷）、一个年轻的未间伐林（30 年，4 立方米/公顷）和一个皆伐林（皆伐后 5-7 年，11 立方米/公顷）。腐生性甲虫，特别是红色名录物种，在较老的森林类型中更为丰富和多样，而在非腐生性甲虫中，没有发现这些变量在森林类型之间有显著差异。腐生性甲虫组合明显不同；随着森林年龄的增加，组合组成逐渐变得更类似于受保护的古老森林，但在间伐林中的组合组成无法与两个最古老的森林类型在统计上区分开来。许多适应晚熟阶段的腐生性甲虫存在于中年间伐林中，但不存在于较年轻的未间伐林中。相比之下，非腐生性甲虫通常在五种森林类型中分布更为均匀，组合主要在皆伐林和森林生境之间分化。未受保护的成熟森林的腐生性甲虫组合与受保护的古老森林非常相似。这表明当前遭受皆伐的成熟北方森林具有相对较高的保护价值，并提出了未来成熟森林是否具有相同品质的问题。我们的研究结果表明，管理森林的甲虫保护潜力很大，前提是要有足够数量和质量的枯木（例如，在间伐过程中）。然而，目前缺乏在间伐过程中引入枯木的甲虫繁殖的确认研究。
