Effects of long-rotation on biodiversity in plantations

研究了长轮伐期及相关生态因子对日本落叶松人工林6个甲虫科生物多样性的影响。比较了长轮伐期和中龄人工林林下和冠层甲虫多样性。确定了各甲虫科物种丰富度与24个生态变量之间的关系。我们发现，甲虫的多样性往往增加与长期轮换。尤其是冠层中的植食性增加。在所测的24个生态变量中，自然更新成熟树木的物种丰富度和多度以及粗木质材料的质量和数量对甲虫多样性的影响最大。前一个变量随着长时间的轮换而增加，尽管后者没有，因为间伐的树木被留在中年人工林作为倒下的原木。因此，发生自然再生的本地树木，已经长得足够高，达到冠层高度在长轮伐期人工林落叶松人工林的生物多样性的改善，有助于本地甲虫物种丰富度在这些林地。长时间的轮伐使人工林更加异质，特别是在树冠层，并促进更大的本地甲虫多样性。

We studied the effects of long-rotation and related ecological variables on the biodiversity of six beetle families in larch(Larix kaempferi) plantations. Beetle diversity in the forest understory & the canopy of long-rotation and middle-aged plantations was compared. The relationships between the species richness of each beetle family and 24 ecological variables were identified. We found that beetle diversity tended to increase with long-rotation. Especially, phytophagies increased in the canopy. Among the 24 measured ecological variables, the species richness & abundance of naturally regenerated mature trees and the quality & quantity of coarse woody material had the strongest influences on beetle diversity. The former variable increased with long rotation, though the latter did not because thinned trees were left in middle-aged plantations as fallen logs. Therefore, the occurrence of naturally regenerated native trees that had grown sufficiently tall to reach canopy height in long-rotation plantations underpinned the improved biodiversity in larch plantations, contributing to native beetle species richness in these woodlands. Long-rotation makes plantations more heterogeneous, particularly in the canopy, and promotes greater native beetle diversity.