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不同生境条件下西藏原始冷杉林凋落物分解特征与土壤养分的关系
代松家1,2,3, 段斐2,4,3, 方江平2,4,3, 龙春林1, 周晨霓2,4,3
1.中央民族大学 生命与环境科学学院, 北京 100081;2.西藏农牧学院 高原生态研究所, 西藏 林芝 860000;3.西藏自治区生态安全联合实验室, 西藏 林芝 860000;4.西藏农牧学院 西藏高原森林生态教育部重点实验室, 西藏 林芝 860000
摘要:
[目的] 研究不同生境条件下(林内、林外、林缘)藏东南急尖长苞冷杉林(Abies georgei var.smithii)凋落物分解特征与土壤养分特征之间的关系,为深入了解高寒高山森林生态系统物质循环过程提供依据。[方法] 采用野外分解袋法和室内分析相结合,在林内、林外、林缘3种不同生境条件下对藏东南急尖长苞冷杉林凋落物进行了原位分解试验。[结果] 分解速率总体上呈现出:林内 > 林缘 > 林外的特点,逐月分解率的变异系数表现为:林内(34.83%) < 林缘(57.35%) < 林外(72.09%);Olson指数衰减模型的模拟结果显示不同生境条件下(林内、林缘、林外)凋落物分解50%需要的时间为2.11,2.52,2.34 a,分解95%需要的时间为8.96,10.01,10.84 a;3种不同生境土壤养分在空间上差异显著,林内生境中与凋落物分解速率呈现极显著相关的土壤养分因子有土壤总有机碳(TOC)含量、N含量、土壤微生物量碳(SMBC)含量、土壤微生物量氮(SMBN)含量以及WCWN值;林外、林缘生境中与凋落物分解速率相关性最大的为土壤TOC含量,其次为WCWN值。[结论] 生境条件的差异对凋落物分解速率有显著影响,在不同的生境条件下对凋落物分解影响起主导作用的土壤养分因素不同,凋落物—土壤生物地化循环紧密联系,相互作用关系复杂,生境作用效应突出。
关键词:  凋落物分解  土壤养分  西藏  急尖长苞冷杉
DOI:10.13961/j.cnki.stbctb.2020.03.009
分类号:S718.52;Q149
基金项目:西藏自治区重大科技专项“藏东南典型林分可燃物空间分布格局及潜在火行为研究”(XZ201901-GA-03);西藏自治区科学技术厅—西藏农牧学院厅校联合基金(XZ2019ZR-G-70)
Relationship Between Decomposition Characteristics of Litters and Soil Nutrients in Tibetan Fir Forest Under Different Habitat Conditions
Dai Songjia1,2,3, Duan Fei2,4,3, Fang Jiangping2,4,3, Long Chunlin1, Zhou Chenni2,4,3
1.College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China;2.Institute of Tibet Plateau Ecology, Tibet Agriculture&Animal Husbandry University, Nyingchi, Tibet 860000, China;3.United Key Laboratories of Ecological Security, Tibet Autonomous Region, Nyingchi, Tibet 860000, China;4.Key Laboratory of Forest Ecology in Tibet Plateau, Ministry of Education, Tibet Agriculture&Animal Husbandry University, Nyingchi, Tibet 860000, China
Abstract:
[Objective] The relationship between litter decomposition characteristics and soil nutrient characteristics of Abies georgei var. smithii forest in Southeastern Tibet under different habitat conditions, i.e., in forest (IF), outside forest (OF), and beside forest (BF) was studied to provide basic data for further understanding the material circulation process of the alpine forest ecosystem.[Methods] Based on field decomposition bag method and indoor analysis, in situ decomposition experiments were conducted on A. georgei forest litters in Southeast Tibet under three different habitats.[Results] The decomposition rate showed the characteristics of IF > BF > OF, and the variation coefficient of the monthly decomposition rate represented the characteristics of IF (34.83%) < BF(57.35%) < OF (72.09%). According to the simulation results of the Olson exponential decay model, the decomposition times of litters in different habitat conditions (IF, BF, and OF) were 2.11, 2.52, and 2.34 years, respectively, and 95% of decomposition times were 8.96, 10.01, and 10.84 years, respectively. Soil nutrients in the three different habitats were significantly different in space. The soil nutrient factors in the forest habitats with significant correlation with the litter decomposition rate were soil total organic carbon (TOC) content, N content, soil microbial biomass carbon content, soil microbial biomass nitrogen content, and WC:WN value. The soil TOC content was maximum correlated with the decomposition rate of litter in the habitats outside and at forest margins, followed by WC:WN value.[Conclusion] The difference of habitat conditions had a significant impact on the decomposition rate and nutrient release rate of litters, and different soil nutrient factors played a leading role in the decomposition of litters under different habitat conditions. The litter-soil biogeochemical cycle was closely related to complex interaction and a prominent habitat effect.
Key words:  litter decomposition  soil nutrients  Tibet  Abies georgei var. smithii