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作 者 ：孙秀云,王传宽

期 刊 ：生态学报 2007年 27卷 12期 页码：5130~5137

关键词：倒木；CO2通量；粗木质残体；分解；呼吸；温带森林；

Keywords:downed log, carbon dioxide flux, coarse woody debris, decomposition, respiration, temperate forest,

摘 要 ：在倒木丰富的森林生态系统中，倒木分解释放的CO2通量（RCWD）是生态系统碳收支中不容忽视的一个组分。采用红外气体分析法（Li-6400 IRGA）测定东北东部山区典型温带天然次生林中11个主要树种的RCWD及其相关环境因子。主要研究目标包括：比较11个树种的RCWD、倒木温度（TCWD）和倒木含水量（WCWD）；量化RCWD与TCWD和WCWD的关系；量化RCWD的季节动态。研究结果表明：白桦、山杨、紫椴、胡桃楸、蒙古栎、色木槭、春榆、红松、黄菠萝、落叶松和水曲柳在测定期间RCWD的平均值分别为：10.64、8.38、7.85、6.59、6.01、4.07、3.88、2.55、2.29、1.96μmolCO2•m^-2•s^-1和1.90μmolCO2•m^-2•s^-1。软阔叶树种的RCWD最高；针叶树种的RCWD总体上低于阔叶树种的。在整个测定期间，不同树种的TCWD虽然没有显著性差异（p > 0.1），但是其WCWD差异极显著（p < 0.001）。树种、倒木个体、倒木所处的立地状况及其交互作用均显著地影响RCWD，但其影响程度因树种而异。所有树种的TCWD、WCWD及其交互作用显著地（p < 0.01）影响RCWD；包括了这些作用的RCWD模型解释了39.9 %~72.9 %的RCWD变异。不同树种RCWD的季节变化呈现基本一致的单峰曲线格局，主要受TCWD的驱动；而WCWD主要影响RCWD的季节内变化和树种间的差异。

Abstract:Downed log is a conspicuous and important component of forest ecosystems. The CO2 flux from downed logs (RCWD) is an important component of carbon budgets in forest ecosystems with moderate to large amounts of downed logs. In this study, we used an infrared gas exchange analyzer (LI-6400 IRGA) to measure the RCWD of 11 major tree species in natural secondary temperate forests in northeastern China and related environmental factors. Our specific objectives were to (1) compare RCWD, temperature (TCWD) and water content of downed logs (WCWD) for the 11 tree species；(2) quantify the relationships of RCWD against TCWD and WCWD for the species; and (3) examine seasonal dynamics of RCWD. The measured RCWD for Betula platyphylla, Populus davidiana, Tilia amurensis, Juglans mandshurica, Quercus mongolica, Acer mono, Ulmus propinqua, Pinus koraiensis, Phellodendron amurense, Larix gmelinii, and Fraxinus mandshurica averaged 10.64, 8.38, 7.85, 6.59, 6.01, 4.07, 3.88, 2.55, 2.29, 1.96 μmolCO2•m^-2•s^-1 and 1.90μmolCO₂•m^-2•s^-1, respectively. The RCWD for the softwood tree species was greater than that for the hardwood tree species, and the RCWD for the coniferous species tended to be less than that for the broadleaved species. During the measuring period, the TCWD did not differ significantly among tree species (p > 0.1), but the WCWD did (p < 0.001). The RCWD was significantly affected by tree species, dimension of downed logs, site conditions, and their interactions, but the degree of these effects depended on tree species. The TCWD, WCWD and their interactions significantly (p < 0.01) influenced the RCWD, explaining 39.9%~72.9% of the variations in the RCWD data. The seasonality of RCWD was mainly driven by the TCWD and showed an overall bell-shaped curve for all the tree species, whereas the variations among tree species within a specific season were mainly influenced by WCWD.

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