磨盘山天然次生林凋落物数量及动态

以磨盘山5.76hm2天然次生林群落固定监测样地为平台,均匀布设144个凋落物收集器,于2006年每月末(4—11月)连续收集其凋落物,用以分析群落尺度上的凋落物产量、组成及时空变化。结果表明,天然次生林年凋落量为3039.6 kg/hm2,以凋落叶(2499.2 kg/hm2)所占的比例最大,占年凋落量的82.22%,而凋落枝仅占年凋落量的9.92%,花果皮等所占比例更小,占总量的5%以下。1a内,凋落物收集器内共收集到42种树木的凋落叶,占样地内树种总数(46种)的91.30%,其中花曲柳(Fraxinus rhynchophylla)、核桃楸(Juglans mandshurica)和蒙古栎(Quercus mongolica)3个树种的凋落叶占落叶总量的82.97%,为叶凋落量的主要来源。不同收集器之间凋落量存在较大差异,99个收集器的年凋落量在200—400 g,2个收集器超过600 g;单个收集器全年最多可收集到19种树种的凋落叶,收集到凋落叶种数12种的收集器最多(29个)。凋落量月动态呈单峰型,69.78%的凋落量产生于9—10月份,叶凋落量月动态与凋落总量变化相同。落叶以秋季为主,但树种间叶凋落节律存在差异,其中核桃楸叶的凋落高峰集中在8—9月,花曲柳和春榆(Ulmus japonica)集中在9—10月,色木槭(Acer mono)为10月,蒙古栎叶为10—11月。

The amount and dynamics of litterfall in the natural secondary forest in Mopan Mountain

This study investigated the composition and spatiotemporal dynamics of litterfall at the community scale, on the basis of 144 square traps distributed uniformly in a 5.76 hm² permanent plot located in the deciduous broad-leaved forest of Mopan Mountain. The litterfall samples were collected monthly from April to November in 2006. The results showed that the annual litter production was 3039.6 kg/hm². The proportion of leaves (2499.2 kg/hm²) was 82.22%, and that of branches was 9.92%. The combination of flowers, fruits and barks was less than 5%. The leaf litters were from 42 tree species, accounting for 91.30% of the total number (46) of the tree species in the plot. The main sources of leaf litterfall were Fraxinus rhynchophylla, Juglans mandshurica and Quercus mongolica, accounting for 82.97% of the overall amount. The litterfall exhibited evident spatial heterogeneity, with 200-400g litters in 99 traps and >600g litters in 2 traps. Some traps collected as many as 19 species, but most (29 traps) did only 12 species. A single-peaked curve described the dynamic of monthly litterfall, and 69.78% of litterfall occurred in September and October. Leaf litterfall peaked in autumn and exhibited the same temporal trend as the overall litterfall. However, different species peaked in a different manner, with Juglans mandshurica at August and September, Ulmus japonica at September and October, Acer mono at October, and Quercus mongolica at October and November, respectively.