西藏东南部色季拉山土壤有机碳含量与呼吸作用特征

发布时间：2018-02-13 00:09

本文关键词： 色季拉山有机碳枯落物基础呼吸 Q_(10)　出处：《中国农业大学》2017年博士论文　论文类型：学位论文

【摘要】：青藏高原是地球陆地生态系统极为独特的地理单元,有"地球第三极"之誉。平均海拔4 000m以上,面积约290余万平方公里,是世界上最年轻,面积最大,海拔最高的高原。在亚洲乃至全球均具有极为重要的生态地位。但在全球气候变化和人为活动加剧背景下,青藏高原生态系统已发生显著变化,影响到土壤有机碳循环,并可能进一步加剧气候变化。为阐明西藏不同海拔高度土壤有机碳含量特征及土壤呼吸对温度变化的敏感性响应,为科学评估西藏高原土壤有机碳分布与动态及未来可能的变化趋势提供基础。以西藏东南部色季拉山海拔3 000-4 600 m之间不同类型植被为研究对象,开展土壤有机碳含量与主要影响因素研究,定量评价不同类型森林枯落物呼吸对土壤总呼吸碳排放的贡献,探索不同海拔高度土壤基础呼吸的温度敏感性特征,主要得到以下结果:(1)色季拉山森林0-10 cm和10-20 cm 土壤有机碳平均含量分别为(8.15±3.17)%和(5.01±2.21)%,具有较高的有机碳密度,分别为(4.44±0.61)kgnT2和(3.51±0.88)kg m-2;在海拔3 550-4 300 m之间森林土壤有机碳含量随海拔高度的升高而增加;土壤有机碳含量同时受到林下植被、微地形条件等因素的影响;不同植被类型下土壤有机碳含量表现为:森林温性草地农田亚高山草灌。(2)森林和草地土壤中,CH3和CH2官能团及酰胺-C=O官能团,均表现为随土壤层次的加深而降低;各有机碳官能团的相对含量均表现为森林温性草地亚高山草灌;在表层0-10 cm,土壤主要碳官能团相对含量均表现为:变形振动脂肪族-C伸缩振动脂肪族-C酰胺-C=O。(3)森林枯落物显著的影响着土壤呼吸,相同植被类型下,土壤总呼吸(RT)、枯落物呼吸(RL)和去除枯落物后的土壤呼吸(Rs)之间均有显著差异;针叶林RL小于阔叶林,即针叶林枯落物具有相对较低的分解速率;不同类型森林RL/RT表现为:杜鹃林云杉林高山栎林冷杉林;平均值分别为59.3%,33.3%,20.0%和17.6%;阔叶混交林不同层次土壤呼吸速率表现为,随着土壤层次的加深而降低,表层0-10 cm 土壤呼吸占总呼吸量的45.6-75.2%,但5 cm以下层土壤呼吸温度敏感性(Q10)较强;(4)海拔高度3 800 m,3 990 m和4 090 m区,表层0-5 cm和5-10 cm 土壤基础呼吸,表现为随海拔高度的升高而降低,即R3800mR3990mR4090m,但10-20cm并未表现出一致的变化规律;随着培养时间的延长,土壤基础呼吸速率快速下降,尤其在培养的前7天;土壤基础呼吸速率与培养时间之间呈极显著指数函数关系;基础呼吸速率随土壤层次的加深而降低,随着培养温度的升高而增加;5-10 cm和10-20 cm层次土壤基础呼吸的温度敏感性Q10值表现为低温阶段高于高温阶段,在15-25 ℃范围内,表层0-5 cm 土壤Q10表现为随着海拔高度的升高而增大;(5)基于大气温度和降水对土壤呼吸速率的模拟,结果表明,高海拔区土壤呼吸速率小于低海拔区,在海拔3 300-4 400 m之间,土壤年均呼吸速率值为1.26 g C m-2 d-1,年均呼吸排放量为4.60 Mg C ha-1;通过大气温度和降水进行土壤呼吸的模拟可以较好估算3 700 m高海拔区土壤呼吸,但对于低海拔区的估算结果则偏低。
[Abstract]:The Tibetan Plateau is terrestrial ecosystem is extremely unique geographical unit, "the third pole of the earth" reputation. The average altitude of more than 4 000m, an area of about 290 square kilometers, is the world's most young, the largest, highest elevation of the plateau. In Asia and the world are extremely important ecological. In the global climate change and human activities intensified under the background of ecosystem on the Qinghai Tibetan Plateau has changed significantly affect soil organic carbon cycle, and may further exacerbate climate change. In order to elucidate the different altitudes in Tibet characteristics of soil organic carbon content and soil respiration response sensitivity to temperature change, provide the basis for the distribution of soil organic carbon in Tibet plateau with the dynamic and possible future trends of scientific assessment. In Southeast Tibet between Shergyla Mountain at an altitude of 3000-4600 m of different vegetation types as the research object, to carry out soil Study on organic carbon content and the main influencing factors, quantitative evaluation of different types of forest litter respiration to total soil respiration contribution of carbon emissions, explore the characteristics of temperature sensitivity in different altitude soil basal respiration, the main results are as follows: (1) the average content of Shergyla Mountain Forest 0-10 cm and 10-20 cm respectively (soil organic carbon 8.15 + 3.17)% and (5.01 + 2.21)%, organic carbon density is higher, respectively (4.44 + 0.61) kgnT2 and (3.51 + 0.88) kg m-2; an elevation of between 3550-4300 m forest soil organic carbon content increased with altitude increase; soil organic carbon content at the same time by forest effect of vegetation, topography and other factors; soil organic carbon content under different vegetation types: Forest temperate grassland farmland subalpine shrub and grass. (2) forest and grassland soils, CH3 and CH2 functional groups and amide -C=O functional groups were performed with soil The soil depth decreased; the relative content of organic carbon functional groups showed temperate subalpine forest grassland grass shrub; on the surface of 0-10 cm, the relative content of the main soil carbon functional groups are as follows: the deformation vibration of aliphatic -C stretching aliphatic amide -C=O. -C (3) of forest litter affects soil respiration significantly the same, vegetation type, soil respiration (RT), litter respiration (RL) and the removal of litter after the soil respiration (Rs) showed significant difference between coniferous forest; broad-leaved forest is less than RL, coniferous forest litter decomposition rate is relatively low; different types of forest is RL/RT Rhododendron forest: Quercus forest spruce fir forest; the average values were 59.3%, 33.3%, 20% and 17.6%; broad leaved mixed forest in different levels of soil respiration rate was decreased, with the increase of soil layers and the surface, 0-10 cm soil respiration rate 45.6-7 5.2%, but below 5 cm layer temperature sensitivity of soil respiration (Q10) is strong; (4) the altitude of 3800 m, 3990 m and 4090 m, 0-5 cm and 5-10 cm of surface soil basal respiration, as altitude increases, that is R3800mR3990mR4090m, but 10-20cm did not show the consistent change; with prolonged incubation time, soil respiration rate decreased rapidly, especially in the first 7 days of training; significant exponential relationship between soil basal respiration rate and incubation time; basal respiration rate decreased with soil depth increased with the increase of culture temperature; the temperature sensitivity of Q10 5-10 cm and 10-20 cm level soil basal respiration value is higher than that in the low temperature stage at a high temperature is 15-25 DEG C, 0-5 cm surface soil Q10 was increased with the increase of altitude; (5) based on the atmospheric temperature and precipitation on Soil The simulation results show that, the respiration rate in high altitude area, soil respiration rate is less than the low altitude area, an elevation of between 3300-4400 m, average annual soil respiration rate was 1.26 g C m-2 D-1, the average annual emissions of 4.60 Mg C respiratory HA-1; soil respiration simulation can be used to estimate soil respiration in high altitude area m by 3700 the temperature and precipitation, but low estimates of low altitude area.

【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S714.2

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