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凋落物是森林生态系统物质循环和能量流动的纽带,在土壤改良、幼苗更新以及水源涵养等方面具有十分重要的作用,凋落物的碳、氮、磷化学计量特征更是其中的关键。本研究比较了青海高寒地区立地条件和林龄基本相同的华北落叶松(Larix principis-rupprechtii)、青海云杉(Picea crassifolia)、青海云杉-华北落叶松混交林、青海云杉-白桦(Betula platyphylla)混交林、白桦林等5种林分凋落物的养分状况及化学计量特征。结果表明:随着凋落物分解层次加深,5种林分中凋落物的有机碳含量、速效磷含量、碳氮比和碳磷比均呈减小趋势。青海云杉纯林凋落物的铵态氮、硝态氮、速效磷3种速效养分含量均高于其他4种林分类型。阔叶林与针阔混交林地表凋落物的氮含量均显著高于针叶林及针叶混交林,阔叶林地表凋落物氮含量是针叶林的1.23倍,而磷含量则相反,针叶林凋落物磷含量是阔叶林的1.26倍。通过青海高寒区5种林分地表凋落物的化学计量特征比较,可以得出,该地区阔叶林与针阔混交林的凋落物在分解过程中主要受磷元素限制,而针叶林与针叶混交林则受氮、磷两种元素共同限制。
Litter is a link between material circulation and energy flow in forest ecosystem. It plays a very important role in soil improvement, seedling renewal and water conservation. The stomatal characteristics of carbon, nitrogen and phosphorus in litter are the key points. In this study, Larix principis-rupprechtii, Picea crassifolia, Picea crassifolia-Larix principis-rupprechtii mixed forest, Betula platyphylla) mixed forest, birch and other forest litter nutrient status and stoichiometric characteristics. The results showed that with the deepening litter decomposition level, the organic carbon content, available phosphorus content, C / N ratio and carbon to phosphorus ratio of litter all showed a decreasing trend. The available nutrient contents of ammonium, nitrate nitrogen and available phosphorus in litter of Picea crassifolia stand were higher than those of the other four stands. The nitrogen content of surface litter in broad-leaved forest and coniferous-broad-leaved forest was significantly higher than that in coniferous forest and coniferous mixed forest. The surface litter nitrogen content in broad-leaved forest was 1.23 times that of coniferous forest, while the phosphorus content was opposite Phosphorus content in leaf litter is 1.26 times of that in broadleaf forest. Through the comparison of the stoichiometric characteristics of surface litter in five types of forests in the alpine region of Qinghai, it can be concluded that the litter in the mixed forest of broad-leaved forest and coniferous-broad-leaved forest in this area is mainly limited by phosphorus during the decomposition process, Leaf mixed forest is subject to nitrogen and phosphorus two common constraints.