Yang Dan-Li, Luo Ji, Jia Long-Yu, Shi Wen-Bo
Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China.
College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China.
Ying Yong Sheng Tai Xue Bao. 2021 May;32(5):1699-1708. doi: 10.13287/j.1001-9332.202105.009.
In this study, seven sampling sites (glaciers retreated for 0, 10, 30, 40, 50, 80 and 127 years) were chosen along a primary succession sequence in the Hailuogou glacial retreat area in the eastern margin of the Tibetan Plateau, China. The accumulation and cycling characteristics of N and P under different succession stages were analyzed by measuring biomass and N and P contents in surface soil and each vegetation layer. The N and P contents in leaves, branches and roots of tree layers decreased along the succession sequence, whereas the N and P contents in stems were higher in the late succession stage. The changes of N and P contents in litter and soil O layer were consis-tent with those in the leaves and branches of tree layers. Ecosystem N and P storage increased along the succession sequence. Ecosystem N accumulation was mainly dependent on the vegetation layer in the early succession stage. After the community reached the climax, soil became the main N pool of the ecosystem. Vegetation P storage was higher than that in the surface soil after 80 years of glacial retreat. The nutrient accumulation rate in each layer of the ecosystem was rapid in the middle succession stage, with an order of surface soil > tree layer > understory vegetation layer. The nutrient cycling coefficients of N and P in broadleaved forest in the middle stage were higher than those in coniferous forest in the late stage, whereas the N and P utilization efficiency was lower than that in coniferous forest. Therefore, the mechanism of low nutrient cycling and high utilization efficiency of coniferous trees was conducive to the their competition with other species, thus finally forming the climax community.
在本研究中，沿着中国青藏高原东缘海螺沟冰川退缩区的一个原生演替序列选择了7个采样点（冰川退缩0、10、30、40、50、80和127年）。通过测量表层土壤和各植被层的生物量以及氮和磷含量，分析了不同演替阶段氮和磷的积累与循环特征。乔木层叶片、树枝和根系中的氮和磷含量沿演替序列降低，而茎中的氮和磷含量在演替后期较高。凋落物和土壤O层中氮和磷含量的变化与乔木层叶片和树枝中的变化一致。生态系统氮和磷储量沿演替序列增加。在演替早期，生态系统氮积累主要依赖于植被层。群落达到 climax 后，土壤成为生态系统的主要氮库。冰川退缩80年后，植被磷储量高于表层土壤。生态系统各层养分积累速率在演替中期较快，顺序为表层土壤＞乔木层＞林下植被层。中期阔叶林氮和磷的养分循环系数高于后期针叶林，而氮和磷的利用效率低于针叶林。因此，针叶树养分循环低、利用效率高的机制有利于其与其他物种竞争，最终形成 climax 群落。
