川滇高山栎灌丛营养元素积累与生物循环特征

Accumulation and Biological Cycling of Nutrient Elements in Quercus aquifolioides Shrublands

养分循环是森林生态系统的重要生态功能。以位于青藏高原东南缘的川西折多山东坡川滇高山栎（Quercus aquifolioides）灌丛为研究对象,分析了其营养元素的分布、积累和生物循环特征。结果显示：（1）川滇高山栎不同器官营养元素含量不同,叶片和枝条为N〉K〉Ca〉Mg〉P,树干和地下器官为Ca〉K〉N〉Mg〉P。（2）川滇高山栎灌丛生态系统各营养元素总贮量（kg/hm2）依次为：Ca（650.06）、N（252.67）、K（197.01）、Mg（51.18）、P（49.22）,其中川滇高山栎灌层储量占88.61%～96.10%,林下草本层占0.64%～4.22%,凋落物层占2.54%～9.25%。（3）川滇高山栎灌层营养元素主要储存于地下根系,占灌层的67%～81%,丰富的根系营养元素储量有利于川滇高山栎灌丛在遭受火烧、砍伐等干扰后萌生更新。（4）川滇高山栎灌丛营养元素年积累量[kg/（hm2·a）]依次为：Ca（20.82）、N（7.46）、K（6.12）、P（2.33）、Mg（1.55）;灌丛营养元素利用系数为0.09,循环系数为0.60,周转时间为22.87a。研究表明,川滇高山栎灌丛具有较低的营养元素利用率和较长的营养元素周转期。

In natural and man-made protected plantations,cycling of nutrient is an important aspect as significant amounts of nutrients are returned to the soil through litter fall and become available for reabsorption.Nutrient distribution,accumulation and cycling of Quercus aquifolioides shrublands in the eastern slope of the Zheduo mountain were studied.The results showed that：（1）Nutrient concentration differed somewhat according to components.The nutrient elements patterns were N〉K〉Ca〉Mg〉P in leaf and branch components and Ca〉K〉N〉Mg〉P in stem and belowground components.（2）The total nutrient standing stocks were estimated to be （kg/hm2）：N（252.67）,P（49.22）,K（197.01）,Ca（650.06）,and Mg （51.18）.The proportions of these nutrients distributed in the shrub component,herb component and litter component were 88.61%～96.10%,0.64%～4.22% and 2.54%～9.25%,respectively.（3）Most of the nutrients in Q.aquifolioides shrub were distributed in the belowground components （67%～81%）.The abundant nutrient reserve in roots favored for resprouting of Q.aquifolioides after fire and coppicing.（4）The nutrient annual accumulations in the shrubs were [kg/（hm2·a）]：Ca（20.82）〉N（7.46）〉K（6.12）〉P（2.33）〉Mg（1.55）.The nutrient utilization coefficient of the five elements was estimated to be 0.09,and the nutrient cycling coefficient to be 0.60,and the nutrient recycling period was also estimated.The nutrient use efficiency of Q.aquifolioides shrublands was low and the recycling period of nutrient was long.