红椿凋落叶全碳释放的林窗效应

为了调整低山丘陵区低效林林分结构,探明马尾松人工林不同林窗下凋落物的全碳释放规律,论文以长江上游低山丘陵区人为采伐形成的马尾松（Pinus massoniana）人工林7种不同大小林窗（G1：100 m²,G2：225 m²,G3：400 m²,G4：625 m²,G5：900 m²,G6：1 225 m²,G7： 1 600 m²）为研究对象,以林下为对照,研究了乡土阔叶树种红椿（Toona ciliata）凋落叶近1 a的全碳释放率和全碳释放速率（每30 a）。结果表明：1）相对小型（100~200 m²）和大型（1 225~ 1 600 m²）林窗以及林下,中型（400~625 m²）林窗更能促进凋落叶全碳的释放;2）全碳释放速率表现出先快后慢的变化趋势,在分解中后期（90~270 d）,出现碳的富集现象;3）凋落物全碳的释放受林窗大小、位置、分解时间的交互作用,分解时间对红椿凋落叶的全碳释放率影响极显著（P < 0.01）,林窗大小对全碳释放有显著影响（P < 0.05）,而林窗内不同位置（中心和边缘）对凋落叶碳释放无显著影响;4）凋落物分解温度、含水率和全碳释放率、质量损失速率表现出极显著正相关（P < 0.01）。

Effect of Forest Gap on Carbon Release of Toona Ciliata Leaf Litter

In order to readjust the structure of pine forest and explore the regularity of litter carbon release in forest gaps of Pinus massoniana plantation, a field litterbag experiment was set up in thinning Pinus massoniana plantation with seven different sizes of forest gaps (G1: 100 m², G2: 225 m², G3: 400 m², G4: 625 m², G5: 900 m², G6: 1 225 m², G7: 1 600 m²). The effect of the sized of forest gap on carbon release rate of Toona ciliata leaf litter was studied. The results indicated that: 1) Compared with the small size (100-200 m²) and the large size (1 225-1 600 m²) of forest gaps, the medium sized (400-625 m²) forest gaps promoted the carbon release. 2) The carbon release rate in early period of the first 30 days is higher than in the following periods. The carbon release rate shows that after a decomposition of 90 days, there is a phenomenon of carbon concentration enrichment. 3) The carbon release is affected by the gap size, within-gap location, and decomposition time as well. Decomposition time has extremely significant effect on carbon release (P < 0.01), and gap size also has significant effect on carbon release (P < 0.05). However, there is no significant effect of within-gap location on carbon release. 4) The temperature and moisture have extremely significant positive correlation (P < 0.01) with carbon release rate and mass loss rate.