亚高山森林林窗对凋落物分解过程中半纤维素动态的影响  

Effects of forest gap on hemicellulose dynamics during foliar litter decomposition in an subalpine forest

作　　者：李晗[1] 吴福忠[1] 杨万勤[1] 徐李亚 倪祥银[1] 何洁[1] 胡义[1] 

机构地区：[1]四川农业大学生态林业研究所林业生态工程四川省重点实验室、高山森林生态系统定位研究站,成都611130

出　　处：《植物生态学报》2015年第3期229-238,共10页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(31170423和31270498);国家“十二五”科技支撑计划(2011BAC-09B05);四川省杰出青年学术与技术带头人培育项目(2012JQ0008和2012JQ0059);中国博士后科学基金(2012T50782)资助

摘　　要：亚高山森林林窗可能通过改变冬季雪被格局和生长季水热环境影响林窗内凋落物中半纤维素的分解动态,但目前对此还缺乏研究。采用凋落物分解袋法,以亚高山森林5种典型物种岷江冷杉(Abies faxoniana)、红桦(Betula albosinensis)、四川红杉(Larix mastersiana)、方枝柏(Sabina saltuaria)和高山杜鹃(Rhododendron lapponicum)凋落物为研究对象,研究雪被形成期、雪被覆盖期、雪被融化期和生长季节从林窗中心、林冠林窗、扩展林窗到郁闭林下物种凋落物的半纤维素变化特征。经历一年分解后,5种凋落物的半纤维素均呈现净累积现象。针、阔叶凋落物半纤维素分别在雪被覆盖期和融化期表现出相对较高的损失率。在雪被覆盖期和融化期,凋落物半纤维素在林窗中心和林冠林窗具有相对较高的损失率;而在生长季节,林窗中心呈现相对较低的凋落物半纤维素累积率。统计分析结果表明凋落物分解过程中半纤维素损失率与环境因子和凋落物质量因子均显著相关。这些结果表明亚高山森林林窗对凋落物分解过程中半纤维素损失率具有显著影响,分别促进了半纤维素在冬季的损失以及抑制了半纤维素在生长季节的累积,意味着亚高山森林林窗的形成有利于凋落物半纤维素的降解。Aims As part of fiber structures, the hemicellulose degrades and transforms during foliar litter decomposition along with other components of leaf tissue. Forest gaps and crown canopies may regulate hemicellulose dynamics during foliar litter decomposition by redistributing winter snow cover and altering the temperature, precipitation and solar radiation during the growing season, but little information is available concerning those effects and the consequences. Therefore, our objective was to study the effects of forest gap on hemicellulose dynamics during foliar litter decomposition in an subalpine forest. Methods A field litterbag experiment was conducted in an subalpine fir（Abies faxoniana） forest in a transitional area located in the upper reaches of the Yangtze River and the eastern Qinghai-Xizang Plateau. Litterbags containing cypress（Sabina saltuaria）, red birch（Betula albosinensis）, larch（Larix mastersiana）, azalea（Rhododendron lapponicum） and fir（Abies faxoniana） were placed on forest floor from the gap center to under the closed canopy. Samples of litterbags were retrieved at the stages of snow formation, snow cover, and snowmelt as well as during the growing season. Hemicellulose contents of the remaining litter were measured. Important findings After one-year decomposition, all five types of foliar litter exhibited a tendency of hemicellulose accumulation. The needle-leaved litter and broad-leaved litter showed greater hemicellulose losses at the snow cover and snowmelt stages, respectively. Greater hemicellulose losses in the gap center and under the canopy were observed at both snow cover and snowmelt stages. In contrast, there was less litter hemicellulose accumulation in the gap center during the growing season. Statistical analysis of the resulting data indicated that both environmental factors and litter quality were significantly correlated with the litter hemicellulose losses. Our results suggested that forest gap enhanced the hemicellulose losses in winter and constra

关 键 词：林窗 凋落物 半纤维素 季节性雪被 亚高山森林 

分 类 号：S714.3[农业科学—林学]