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高山森林河流中凋落叶元素释放动态不仅是生态系统物质循环和能量流动的重要组成部分,而且是森林养分流失的主要过程,并可能与冬季雪被和冻融导致的水环境变化密切相关.以岷江上游高山森林4种代表性植物康定柳(Salix paraplesia)、高山杜鹃(Rhododendron lapponicum)、方枝柏(Sabina saltuaria)和四川红杉(Larix mastersiana)凋落叶为对象,采用凋落叶分解袋法,研究冬季不同冻融时期(冻结初期、冻结期、融化期)河流中凋落叶碳(C)、氮(N)和磷(P)元素动态特征.康定柳、方枝柏和四川红杉凋落叶C(14.6%-47.7%)、N(22.3%-58.5%)和P(4.8%-20.5%)元素在整个冬季均表现为明显的释放现象,而高山杜鹃凋落叶C(-7.3%)和N(-62.7%)表现为明显的负释放(富集)现象,P(0.7%)表现为微量的释放现象.整体而言,凋落叶分解过程中C、N和P元素在冬季的冻结初期、冻结期和融化期整体表现为释放—富集—释放的模式,但康定柳和方枝柏凋落叶N表现为富集—富集—释放模式,方枝柏凋落叶P表现为释放—富集—富集模式.同时,凋落叶C、N和P元素的释放率受河流水温、p H、电导率和C、N、P营养元素等水体环境因子的显著影响.这些结果表明高山森林河流水环境特征显著影响了凋落叶分解过程中元素动态及其相关的物质循环过程,但影响程度受到凋落叶种类和基质质量的控制.
The dynamics of elemental release from litter in alpine forest is not only an important part of ecosystem circulation and energy flow, but also the main process of forest nutrient loss and may be closely related to the change of water environment caused by freezing and thawing in winter. Four representative plants of Salix paraplesia, Rhododendron lapponicum, Sabina saltuaria and Larix mastersiana litter in the upper reaches of the Minjiang River were used as litter-leaf decomposition bags, The dynamic characteristics of carbon (C), nitrogen (N) and phosphorus (P) in leaf litter in different freezing and thawing periods (initial freezing, freezing and thawing) in winter were studied. C (14.6% -47.7%), N (22.3% -58.5%) and P (4.8% -20.5%) showed obvious release throughout the winter while C (4.73%) and N (-62.7%) showed obvious negative release (enrichment) phenomenon, P (0.7%) showed a trace release phenomenon.Overall, litter decomposition of C, N and P elements in the early winter freeze , Freezing and thawing period overall performance for the release - enrichment - release mode , But the litter N of Kangdingliu and Fangdebai showed enrichment-enrichment-release patterns and the litterfall P of the branches and shoots showed a pattern of release-enrichment-enrichment.At the same time, the contents of C, N and P in litter Were significantly affected by environmental factors such as river water temperature, p H, conductivity, and nutrients such as C, N and P. These results indicated that the water environment characteristics of the alpine forest rivers significantly affected the element dynamics and their correlation in litter decomposition Of the material cycle, but the degree of influence by litter types and matrix quality control.