Seasonal variation in leaf-litter input and leaf dispersal distances to streams: the effect of converting broadleaf riparian zones to conifer plantations in central Japan

作者：Kanasashi Tsutomu^*; Hattori Shigeaki

来源：Hydrobiologia, 2011, 661(1): 145-161.

DOI：10.1007/s10750-010-0520-4

• Riparian forest
• Stream ecosystem
• Sugi plantation
• Leaf dispersal

Sugi (Cryptomeria japonica D. Don) is one of the most important evergreen coniferous plantation species in Japan. Much of the riparian forest that was originally dominated by deciduous broadleaf trees has been converted into sugi plantations. The present study investigated the seasonality of leaf-litter input and leaf dispersal to streams to assess the effects of converting riparian forest to sugi plantations. The seasonality of leaf-litter input was assessed at three streams in Nagoya University Forest. At one stream dominated by deciduous broadleaf trees, input was limited to autumn. At two streams in a sugi plantation, input was prolonged from autumn to early spring, and was dominated by sugi needles from winter to early spring. These results suggest that sugi plantations alter the seasonality of leaf-litter input from riparian forests and affect stream ecosystems. Leaf dispersal was assessed by considering the relationship between leaf dispersal distance from three forest layers to the stream and leaf-litter input into two streams. The maximum leaf dispersal distance was 26-28 m for deciduous broadleaf trees from mid-October to November and 10-12 m for sugi needles from December to April. Leaf dispersal distance depended on the tree species. Four species of deciduous broadleaf tree showed greater leaf dispersal than that of sugi. The mean weight of individual sugi needles was higher than that of the broadleaf trees' leaves, and dispersal depended on strong winds in winter and early spring. Although the leaf dispersal distance from the understory was within 2-4 m, it could be a significant source of leaf-litter input to streams.

• 出版日期2011-2