色季拉山急尖长苞冷杉林不同层次土壤CO2浓度对短时降雨的响应  

Response of soil CO concentration at different depth of abies georgei var smithii forest to short-time rainfall on Sejila Mountain, southeastern Tibet

作　　者：刘合满 曹丽花 李江荣[2,3] 杨红 LIU Heman;CAO Lihua;LI Jiangrong;YANG Hong(Xinyang Agriculture and Forestry University,Xinyang 464000,China;Research Institute of Tibet Plateau Ecology,Tibet agriculture and Animal Husbandry university,Linzhi 860000,China;Tibet Key Laboratory of Forest Ecology in Plateau Area,Ministry of Education,Linzhi 860000,China;Department of Resources and Environment,Tibet Agriculture and Animal Husbandry University,Linzhi 860000,China)

机构地区：[1]信阳农林学院,信阳464000 [2]西藏农牧学院高原生态研究所,林芝860000 [3]西藏高原森林生态教育部重点实验室,林芝860000 [4]西藏农牧学院资源与环境学院,林芝860000

出　　处：《生态学报》2020年第22期8354-8363,共10页Acta Ecologica Sinica

基　　金：国家自然科学基金项目(41561052,41461055)。

摘　　要：为阐明不同层次土壤CO_(2)浓度日变化特征及对短时降雨的响应,以西藏东南部色季拉山急尖长苞冷杉(Abies georgei var. smithii)林为研究对象,在自然降雨条件下,分析短时降雨及水分再分布过程中各层次土壤CO_(2)浓度变化特征。结果表明:在0—60 cm层次内,土壤CO_(2)浓度随土壤层次的加深而显著增加(P<0.01),二者之间呈显著对数函数关系(R=0.9764,P<0.01);短时降雨脉冲使表层5 cm土壤CO_(2)浓度显著下降,而10 cm层次土壤CO_(2)浓度显著增加;在降雨和水分再分布阶段,5 cm与10 cm层次土壤CO_(2)浓度之间极显著负相关,10、20、40 cm和60 cm之间均呈极显著正相关(P<0.01);5 cm层次土壤含水量显著影响0—60 cm剖面CO_(2)浓度,降雨阶段,二者之间极显著线性正相关(P<0.001),而水分再分布阶段,二者之间符合极显著幂函数负相关(P<0.001)。即降雨引起表层土壤含水量的快速增加,显著提高土壤剖面CO_(2)浓度,而降雨停止后,有利于土壤CO_(2)向土表的释放;土壤温度和含水量对CO_(2)浓度的影响效应在各层次之间表现不一致,除40 cm均为正效应外,其他各层均表现为相反的影响效应。这些结果表明,短时降雨使各层次土壤含水量增加,减少土壤表面CO_(2)释放量,使下层土壤体系中CO_(2)浓度升高,在分析土壤CO_(2)通量时间变化时,应考虑短时降雨对不同层次土壤CO_(2)的影响。Soil respiration is an important ecological process in which CO_(2) from different depths of the soil is transported to the soil surface and released to the atmosphere. The CO_(2) production and diffusion rates at different depths in the soil significantly affect the CO_(2) flux from the soil surface. Rainfall is a frequent weather event that causes an increase in the soil water content(SWC), and temperature changes induce dramatic variations in soil CO_(2) production and transport. To clarify diurnal variations in soil CO_(2) concentrations and the response to short-term rainfall, we selected Sejila Mountain in Southeastern Tibet as a model area. Under natural rainfall conditions, the characteristics of abies georgei var smithii forest soil CO_(2) concentrations at different depths were analyzed. The results showed that the soil CO_(2) concentration increased with soil depth in the following order 60 cm > 40 cm > 20 cm > 10 cm > 5 cm. Mean values were 5365, 5304, 4990, 4335 and 4179 μmol/mol, respectively. There was a significant logarithmic relationship between the CO_(2) concentration and the soil depth, given by y=531.1 lnD + 3274(R=0.9764,P=0.004). The soil CO_(2) concentrations at 5 cm and 10 cm showed obvious diurnal variations, and could be expressed as a single-peak curve, while diurnal variations at 20 cm, 40 cm and 60 cm were very small. Short-term rainfall significantly affected the CO_(2) concentrations in the 5 cm and 10 cm soil layers;the CO_(2) concentration in the 5 cm soil layer decreased from 4196 μmol/mol to 4176 μmol/mol at the rainfall stage, and the CO_(2) concentration in the 10 cm soil layer increased significantly from 4252 μmol/mol to 4354 μmol/mol. But there was a significant increase in CO_(2) in the 5 cm soil layer and a decreased in CO_(2) in the 10 cm soil layer during soil water redistribution. Closure of the CO_(2) transport channel by water may be an important mechanism governing the increase in the CO_(2) concentration in soil layers below 5 cm. At the rainfall and water r

关 键 词：色季拉山 短时降雨 土壤CO2浓度 土壤温度 土壤含水量 

分 类 号：S714[农业科学—林学]