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作 者 ：邓仁菊,杨万勤*,冯瑞芳,胡建利,秦嘉励,熊雪晶

期 刊 ：生态学报 2009年 29卷 10期 页码：5730~

关键词：季节性冻融；凋落物分解；元素释放；亚高山森林；

Keywords:seasonal freeze-thaw, litter decomposition, element release, subalpine forest,

摘 要 ：季节性冻融期间的凋落物分解对季节性冻土区的森林生态系统过程可能具有重要的影响，但已有的研究报道很少。因此，采用凋落物分解袋法研究了岷江冷杉 (Abies faxoniana Rehder & E. H. Wilson)林和白桦(Betula platyphylla Sukaczev)林凋落叶的分解。一个季节性冻融期间，冷杉林和白桦林凋落物的质量损失率分别为(19.4 ±2.0)%和(21.5±3.5)%，约为1a中凋落物分解的64.5%和65.6%，表明季节性冻融对亚高山森林凋落物分解影响显著。冷杉凋落物中C、N、P、K、Ca和Mg的释放率为(15.0±1.0)%、(34.1±3.6)%、(17.0±0.9)%、(22.8±5.9)%、(20.1±0.1)%和(36.3±2.1)%，白桦凋落物中C、N、P、K、Ca和Mg的释放率为(20.7±0.1)%、(29.4±3.4) %、(15.7±1.3)%、(16.8±5.1)%、(21.3±1.8)%和(20.5±28)%。结合叶凋落物产量可以推断，冷杉林凋落物在一个季节性冻融期间释放到土壤的N、P、K、Ca、Mg为(10.17±1.14) kg·hm-2、(0.68±0.08) kg·hm-2、(4.08±0.46) kg·hm-2、(0.46±0.05) kg·hm-2、(0.09±0.01) kg·hm-2，白桦林为(5.61±112) kg·hm-2、(0.34±0.07) kg·hm-2、(1.21±0.24) kg·hm-2、(0.300±0.059) kg·hm-2、(0.051±0.010) kg·hm-2，这对于春季亚高山森林植物生长具有重要的生态学意义。

Abstract:As one of the most important forest ecosystem processes, litter decomposition is controlled by integrated biotic and abiotic factors such as climate change, species composition, litter quality, soil temperature and moisture, as a consequence of which more attentions have been given to the decomposition process of litters in different forest ecosystems and their relations with biotic and abiotic factors over the past decades. As yet, numerous experiments on litter decomposition were carried out at 3-25 ℃, far less information is available on mass loss and element releases in litters of the subalpine forest during a freezing-thawing season. A simple experiment on leaf litter decomposition was therefore carried out in fir (Abies faxoniana Rehder & E. H. Wilson) and birch (Betula platyphylla Sukaczev) forests in order to character the litter decomposition process during a freezing-thawing season and their ecological significance. Litter bags were put on the forest floor and in 10 cm soil layer beneath fir and birch forests before soil freezing in October 2006, and sampled after thawing in April and October 2007. Rates of litter decomposition and releases of carbon and nutrients were measured in different soil depths and forest stands during a freezing and following season. Over one freeze-thaw season, (19.4±2.0)% and (21.5±3.5)% leaf litters were decomposed in fir and birch forests, and accounted for 64.5% and 65.6% of the annual mass loss of the corresponding litters, respectively, implying that litter decomposition was influenced significantly by seasonal freeze-thaw cycle in the subalpine forest. During the freeze-thaw period, (15.0±1.0) % of C, (34.1±3.6) % of N, (17.0±0.9) % of P, (22.8±5.9) % of K, (20.1±0.1) % of Ca and (36.3±2.1) % of Mg were released from fir needle litter, and (20.7±0.1)% of C, (29.4±3.4) % of N, (15.7±1.3) % of P, (16.8±5.1) % of K, (21.3±1.8) % of Ca and (20.5±2.8) % of Mg released from birch leaf litter, respectively. Consequently, calculated by the leaf litter production in the corresponding forest, fresh leaf litter released (10.17±1.14) kg hm-2 and (5.61±112) kg hm-2 of N, (0.68±0.08) kg hm-2 and (0.34±0.07) kg hm-2 of P, (4.08±0.46) kg hm-2 and (1.21±024) kg hm-2 of K, (0.46±0.05) kg hm-2 and (0.300±0.059) kg hm-2 of Ca, and (0.09±0.01) kg hm-2 and (0051±0.010) kg hm-2 of Mg into soil in fir and birch forests over one freeze-thaw season, respectively. Nutrients released from litters during soil freeze-thaw period are favorable for plant nutrition and growth in the next growing season, which are of ecological importance for maintaining the subalpine forest ecosystem process.

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