锐齿栎森林生态系统主要营养元素的层次分布

应用标准地 -标准木 -分层切割法和破坏性取样化学分析法 ,在林分器官、个体、群体和系统 4个水平上测定了秦岭锐齿栎林的生物量、营养含量和积累量。结果显示 :光合器官N、P、K和 Mg含量季节变化是从展叶到落叶逐渐下降 ,Ca则相反。枝内 N、P、K含量随枝径增加明显下降 ,Ca、Mg含量变化有所不同。树干木质部和树皮 N、P、K、Ca和 Mg含量与树干圆盘高度呈显著的正相关或正相关。根系 N、P、K、Ca和 Mg含量随根径的增加呈显著的降低趋势。 69年生锐齿栎林木生物量为 1 2 35.782 kg,营养积累量为 1 4.498kg,林木不同器官的生物量、营养含量和积累量存在较大的差异 ;叶和皮在林分营养积累和分配中具有重要意义。2 6年生锐齿栎林生态系统生物量为 1 95.7998t· hm- 2 ,营养总贮量达 390 .1 739t· hm- 2 (包括 0～ 60 cm土壤 ) ,土层占总量的 99.39% ,各层次营养积累量排序为 :土壤层 乔木层 枯枝落叶层 >灌木层 >草本层。 2 6年生锐齿栎林营养年吸收量、存留量和归还量分别为 334、374、1 38.870和 1 95.50 2 kg· hm- 2 ,且各元素的循环情况各不相同 ;林分平均归还率为0 .585,各元素的归还率不同 ,林分吸收的营养元素多一半归还予林地。

Distribution of main nutrient elements at different layers for the sharptooth oak forest ecosystem in Mt.Qinling

By the standard site-standard tree-stratification breakage andbreaking sampling determination,the biomass,nutrient percentage and accumulation contents were determined at the four levels of organs，individuals，associations and ecosystems for the sharptooth oak forests in Mt.Qinling.The results show as follow:The percentage contents of N,P,K and Mg in the photosynthetic organ decrease from foliage spreading to falling,whereas increases Ca.The percentage contents of N,P,K in branches remarkably decrease with branch diameter,but there is different trend for Ca and Mg.There are marked positive or positive relativity between the percentage contents of N,P,K,Ca and Mg and the disc height to the bole xylem.The percentage contents of N,P,K,Ca and Mg in roots evidently decrease with root diameter.The biomass and nutrient accumulation contents of the sharptooth oak individual at age 69 are 1 235.782 and 14.498 kg respectively,and there are much difference of biomass,nutrient percentage and accumulation contents among the different organs for the individual.The biomass and nutrient accumulation contents of the sharptooth oak stand (including 0～60 cm soil) at age 26 are 195.7998 and 390.1739 t·hm-2 respectively,soil is 99.39% among them,the nutrient accumulation at different levels put in order:soil layersarbor layerslitter layers＞shrub layers＞grassy layers.The annual nutrient uptake,storage and return of the sharptooth oak ecosystem at age 26 are 334.374,138.870 and 195.502 kg·hm-2.The average return ratio of the stand is 0.585 shows that more than half nutrient matter returns to woodland,and there are different cycling ratio among the different nutrient elements