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海拔和坡向对色季拉山高山杜鹃凋落物分解的影响
侯卓男1,2,李欣彤2,张新军1*,马恬恬2,李傲2,赵金月2,王瑞红1,魏雨泉1,2,3
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(1.西藏农牧学院 高原生态研究所/西藏高原森林生态教育部重点实验室,西藏 林芝 860000;2.中国农业大学 资源与环境学院,北京 100193;3.中国农业大学 有机循环研究院(苏州),江苏 苏州 215000)
摘要:
为探究高寒森林凋落物在不同海拔和坡向的分解动态,以西藏色季拉山的高山杜鹃(Rhododendron simsii)凋落物为研究对象,在色季拉山设置3 500、3 700、3 900、4 100 m等4个梯度海拔以及西北坡(阴坡)和东南坡(阳坡)2个坡向,开展为期2年的凋落物掩埋试验,采用Olson模型明晰凋落物的降解规律,并结合木质纤维素的质量损失和土壤理化性质探究影响凋落物分解的因素。结果表明:不同海拔和坡向凋落物质量残留率均随分解时间增加而下降,分解2年后不同海拔的质量残留率为36.65%~75.99%;凋落物分解速度基本呈阴坡大于阳坡的趋势,其中海拔3 700 m阳坡处分解速度最快、半衰期和周转期最短;木质纤维素的质量损失也基本呈阴坡大于阳坡的趋势,且木质素分解程度最大,对凋落物质量损失的贡献超过50%;土壤中碳氮磷钾营养元素含量主要受坡向和凋落物分解时间的影响,在不同海拔间差异较小;海拔、坡向、分解时间及其交互作用均对凋落物分解有显著影响(P<0.01),土壤含水率和碳氮比也是影响凋落物分解的重要因素。本研究可为高寒森林凋落物分解规律及影响因素提供理论依据。
关键词:  海拔  坡向  凋落物  分解  高寒森林
DOI:10.11841/j.issn.1007-4333.2024.04.23
投稿时间:2023-10-06
基金项目:国家自然科学基金项目(31960013);西藏高原森林生态教育部重点实验室开放课题(XZA-JYBSYS-2020-02);西藏自治区科技创新基地自主研究项目(XZ2022JR0007G)
Effects of elevation and slope orientation on litter decomposition of Rhododendron simsii in Mount Segrila
HOU Zhuonan1,2, LI Xintong2, ZHANG Xinjun1*, MA Tiantian2, LI Ao2, ZHAO Jinyue2, WANG Ruihong1, WEI Yuquan1,2,3
(1.Institute of Tibet Plateau Ecology, Tibet Agricultural & Animal Husbandry University, Nyingchi 860000, China;2.College of Resources and Environment, China Agricultural University, Beijing 100193, China;3.Organic Recycling Research Institute, China Agricultural University, Suzhou 215000, China)
Abstract:
Litter is an important source of organic matter in forest ecosystems, and its decomposition process is driven by many abiotic factors. In order to investigate the decomposition dynamics of litter at different elevations and slope directions in alpine forest, a two-year litter burial experiment was conducted with Rhododendron simsii litter at 4 gradient elevations (3 500, 3 700, 3 900 and 4 100 m) and 2 slope directions of northwestern and southeastern slopes in in Mount Segrila. The Olson model was used to clarify the degradation pattern of litter, and the factors affecting the litter decomposition were investigated in the mass loss of lignocellulose and the physicochemical properties of the soil. The results showed that: The mass residual rate of litter at different elevations and slope directions decreased with the increase of decomposition time, ranging from 36.65% to 75.99%. The decomposition speed of litter and lignocellulose were generally greater on negative slopes than that on positive slopes. The degree of lignin decomposition was the highest, contributing more than 50% to the litter mass loss; decomposition rate was the fastest and the half-life and turnover period was the shortest on the positive slope at 3 700 m. The nutrient content of carbon, nitrogen, phosphorus, and potassium in soil was mainly affected by slope direction and litter decomposition time, with relatively small differences among different elevations. Elevation, slope direction, decomposition time, and their interactions all had a significant effect on litter decomposition (P<0.01), and the soil moisture and the carbon to nitrogen ratio were also important factors affecting litter decomposition. This study provides a theoretical basis for the decomposition pattern and influencing factors of litter in alpine forests.
Key words:  elevation  aspect of slope  litter  decomposition  apline forest