Community structure of saprophagous arthropods in forestcanopies and their status in a decomposer system

森林土壤中的甲螨、跳虫等分解型微型节肢动物在森林生态系统的养分循环中起着重要作用。据了解，他们不仅栖息在土壤中，而且在树冠，因此建议，分解过程可能会开始在森林树冠。日本柳杉（Cryptomeria japonica D. Don）的枯枝落叶在林冠上的附着时间长达数年，其在林冠上的分解过程比其它树种更为重要。本研究在日本爱知县名古屋以东55 km的稻生名古屋大学实验林中进行，目的是弄清日本雪松冠层枯叶和枯枝中分解者微型节肢动物的群落结构。1999年5月至9月期间，每隔约一个月进行一次抽样。从树冠上采集了附着的枯叶和枯枝 ...更多信息 在29年生的日本雪松种植园中，在每次取样时选择三棵树。在实验室中，枯叶和枯枝样品被分离并在NaOH溶液中洗涤以提取其中的微型节肢动物。微型节肢动物在目水平上进行了计数和鉴定，而在5月取样的微型节肢动物在科水平上进行了计数和鉴定。在对流烘箱中干燥之前和之后，在微量天平上称量死叶和枝条，从日本雪松树冠上附着的死叶和枝条上取样阿卡里、弹尾目和双翅目幼虫。从个体数量上看，阿卡里占总节肢动物的50%以上，其次是弹尾目和双翅目幼虫。共记录到阿卡里9科，弹尾目5科。由于所有阿卡里螨类均为甲螨纲，且大多数为食腐或食真菌的，因此，从附着的枯叶和树枝上采集的甲螨的种类组成不同于以往报道的整个冠层的种类组成。枯叶和枯枝小型节肢动物的分类组成不同，这可能反映了它们之间的栖息地特征的差异。每单位死体干质量（g^<-1>d.wt）的阿卡里密度从5月到9月呈上升趋势。这种趋势也不同于以前报道的整个树冠。这些结果表明，附着的枯枝落叶在整个冠层中可能具有特定的栖息特征。阿卡里相对丰度在5 - 9月较高，而弹尾目和双翅目幼虫在7 - 8月温暖干燥的条件下有增加的趋势。然而，在调查期间，它们的密度几乎保持不变，表明它们的种群密度相对稳定。少

Decomposer microarthropods such as oribatid mites and springtails in forest soils play important roles in the nutrient cycle offorest ecosystems. It is known that they inhabit not only in soils but also on canopies, and it is thus suggested that ; decomposition processes may start at forest canopies. Because Japanese cedar (Cryptomeria japonica D. Don), in particular, keeps dead leaves and dead branches attached on the canopies for several years, their decomposition processes on canopies I are more important than on those of other tree species. The objective of this study is to clarify the community structure of decomposer microarthropods in dead leaves and dead branches on canopies of Japanese cedar trees.This study was carried out in the Nagoya University Experimental Forest at Inabu, located 55 km east of Nagoya, Aichi Prefecture, Japan. Sampling was carried out from May to September 1999 at intervals of about a month. Attached dead leaves and branches were sampled from the canopies … More of three trees selected on each sampling occasion at a 29 years-old : plantation of Japanese cedar. In the laboratory, dead-leaf and dead-branch samples were separated and washed in NaOH solution to extract microarthropods from them. Microarthropods were counted and identified at the order level, while those sampled on May at the family level. The dead leaves and branches were weighed on a microbalance before and after drying in a convection oven.Acari, Collembola and dipteran larvae were sampled from attached dead leaves and blanches on canopies of Japanese cedar. In terms of the number of individuals, Acari occupied more than 50% ofthe total arthropods, followed by Collembola and dipteran larvae. Nine families of Acari and five families of Collembola were recorded. Because all Acari were Oribatida, most of which were detritivorous or fungivorous, the species composition of oribatid mites from attached dead leaves and branches differed from that previously reported for the whole canopy. The taxonomic compositions of the microarthropods differed between dead leaves and dead branches, which may reflect a difference in the characteristics as habitats between them. The density of Acari per dry mass of dead parts (number g^<-1> d.wt) increased from May to September. This tendency also differed from that previously reported for the whole canopy. These results suggest that attached dead leaves and branches may have a specific feature as habitattin the whole canopy. The relative abundance of Acari to all microarthropods was high from May to September, while those of Collembola and dipteran larvae tended to increase in July and August under warm and dry conditions. Their densities, however, were almost constant during the survey period, suggesting that they have relatively stable population densities. Less