降水及融雪驱动下古尔班通古特沙漠南缘梭梭(Haloxylon ammodendron)群落动态与水分关系研究
文献类型：学位论文
| 作者 | 杨与广 |
| 学位类别 | 博士 |
| 答辩日期 | 2015 |
| 授予单位 | 中国科学院大学 |
| 授予地点 | 北京 |
| 导师 | 赵成义 |
| 关键词 | 梭梭 群落动态 古尔班通古特沙漠 降水 融雪 |
| 学位专业 | 理学博士 |
| 中文摘要 | 古尔班通古特沙漠广泛分布着以梭梭(Haloxylon ammodendron)为优势种的固沙植被。其群落结构和功能稳定性受到许多学者的关注。水分是干旱区诸多生态过程的关键控制因素，对梭梭群落结构和功能的稳定性起重要作用。特别是在降水和融雪驱动下，因水分条件变化梭梭群落稳定性具有不同机制。阐明梭梭群落动态与水分之间的关系对揭示梭梭群落保持稳定的内在机理具有重要意义。本文基于野外监测和数值模拟，研究了梭梭群落土壤水分时、空动态特征，分析了梭梭群落结构和功能特征及其影响因素，构建了梭梭群落系统动力学模型，模拟了梭梭群落动态和水分的相互作用关系，初步计算了梭梭群落的生态需水量，确定了引起梭梭群落动态变化的土壤水分阈值。主要结论如下：（1）在降水和融雪量驱动下，梭梭群落土壤含水量较低，水分下渗深度在100cm左右；在融雪驱动下土壤水分下渗深度要大于降水驱动下。土壤水分按固定沙区、半固定沙区、流动沙区呈递减趋势。不同坡位土壤水分存在明显的空间差异，丘间地的土壤水分要高于其余三个坡位。整个土壤层分为0-100cm土壤水分活跃带和100cm以下土壤水分稳定带两层。降水和融雪是梭梭群落水分的主要来源，大部分以土壤蒸发和植物散发的方式被消耗，分别占到总水分输入量的81.5%和16.1%，仅有2.4%用于补充土壤水分。（2）梭梭群落结构随固定沙区、半固定沙区和流动沙区立地条件变化而表现出差异性，各项指标呈降低趋势。梭梭种群结构在立地条件变化下基本趋于一致，均呈现出增长型。群落结构在同一沙区不同坡位存在差异，各项指标均表现出不同程度的空间异质性。梭梭对于群落功能的发挥起着主导性优势，7月梭梭生物量占总生物量比例在固定沙区、半固定沙区和流动沙区分别为98%、82%和85%。在不同时间尺度上，植物群落动态与降水存在显著的正相关关系，与气温关系不明显。（3）构建的梭梭群落动态与水分系统动力学模型，基本能够反映梭梭群落动态和水分之间的相互关系。梭梭群落年生长量为125.83g/m2。植物生长对水分的利用如 “脉冲-储存”的模式，下层土壤水分和梭梭生长之间存在负反馈。系统动力学模拟结果分析表明，在140.4mm降水条件下，降低降水量对梭梭群落生物量影响不显著，增大降水量到421.2mm之间，能够显著提高梭梭群落生物量；融雪量在88mm以下时，改变融雪量能够显著影响梭梭群落生物量；大降水脉冲的时间和强度变化能显著影响梭梭群落生物量。（4）初步计算出固定沙区、半固定沙区和流动沙区的生态需水量分别为58.5mm、17.8mm和11.1mm。固定沙区与半固定沙区、流动沙区梭梭群落处于两种不同稳定状态，状态转变的土壤水分阈值带为0.016-0.028cm3/cm3，梭梭生长的土壤水分阈值带为0.026-0.028 cm3/cm3。 |
| 英文摘要 | Sand fixing vegetation which dominated by Haloxylon ammodendron is widely distributed in the Gurbantunggut Desert. The structure and function stability of Haloxylon ammodendron community was widely concerned. Water is the mainly control factor for various ecological process in arid area, it palys a important role in keeping the structure and function stability of Haloxylon ammodendron community. Under the driving condition of precipitation and snowmelt, there were different stability mechanism for water variation. It’s useful for revealing the mechanism for the Haloxylon ammodendron community keeping it’s stability to illuminating the relationship between the Haloxylon ammodendron community dynamic and water. After analyzing the spatial-temporal variation characteristic of soil water and the structure and function characteristic of Haloxylon ammodendron community, we structured a system dynamics model to discuss the relationship between Haloxylon ammodendron community dynamic and water. Based on the simulation results and survey data, the Haloxylon ammodendron community’s ecological water demand was calculated and the soil water threshold for the state transition was determined. The main conclusion were displayed as fellows: (1) Under the driving condition of precipitation and snowmelt, the Haloxylon ammodendron community had low soil water content, the depth of the water infiltrated to soil was about 100cm. the snowmelt could infiltrated into deeper soil layer than precipitation. Soil water content maintained a decreasing trend from fixed sand to moving sand. There was a significant variance among the soil water content at different slope position, the soil water content at the bottom of dune was higher than the other three slope positions. The soil layer stored water about 113.78mm from 0 to 400cm. The whole soil layer can be divided into two sub-layars, the first one named polytropic layer which from surface to 100cm and the other one named steady layer which below 100cm. Precipitation and snowmelt were the primary sources for soil water input, while evaporation and transpiration were the main way for soil water dissipation. About 81.5% of water input was dissipated by evaporation and about 16.1% was dissipated by transpiration and only 2.4% was used for soil water supply within the year. (2) The Haloxylon ammodendron community structure presented difference in fixed sand, semi-fixed and moving sand and indicators used to represent Haloxylon ammodendron community dynamic were decreasing along the site condition gradient. The Haloxylon ammodendron population structure appeared growth form at every site conditions. The community structure also presented difference at different slope position of the same site condition and the community indexes appeared spatial heterogeneity at different extent. Haloxylon ammodendron play a dominating role in the full play of community function, because the proportion of the biomass of Haloxylon ammodendron to total biomass was 98%、82% and 85% for the fixed sand, semi-fixed sand and moving sand, respectively. Precipitation was significant correlated with community dynamic at different time scales, while similar relationship was not significant between air temperature and community. (3) The system dynamic model was built to simulate the relationship between Haloxylon ammodendron community dynamic and water was considered to be reasonable and the mainly simulated result was considered to be useful. Yearly growth of Haloxylon ammodendron biomass was 125.83g/m2. The water utilization strategy of vegetation like “pulse-reserve” model and Haloxylon ammodendron growth and under-layer soil water content appeared negative feedback relationship. Simulation result showed that decreasing precipitation had little effect on biomass when precipitation less than 140.4mm but increasing precipitation had remarkable effect on biomass when precipitation greater than 140.4mm and less than 421.5mm. Snowmelt variation appeared significantly influence on biomass when snowmelt less than 88mm. The timing and intensity variation of large precipitation events influence on biomass significantly. (4) The ecological water demand of fixed sand, semi-fixed sand and moving sand were preliminary estimated and they were 58.5mm, 17.8mm and 11.1mm, respectively. Based on the survey data, the Haloxylon ammodendron community at fixed sand was considered to be one steady state and the semi-fixed sand and moving sand were considered to be another steady state, the soil water content threshold zone of the state transition was 0.016-0.028cm3/cm3. Based on the numerical simulation result, the threshold for the growth of Haloxylon ammodendron was 0.026-0.028 cm3/cm3. |
| 学科主题 | 自然地理学 |
| 语种 | 中文 |
| 源URL | [http://ir.xjlas.org/handle/365004/14937]  |
| 专题 | 新疆生态与地理研究所_研究系统_荒漠环境研究室 |
| 作者单位 | 中科院新疆生态与地理研究所 |
| 推荐引用方式 GB/T 7714 | 杨与广. 降水及融雪驱动下古尔班通古特沙漠南缘梭梭(Haloxylon ammodendron)群落动态与水分关系研究[D]. 北京. 中国科学院大学. 2015. |
入库方式： OAI收割
来源：新疆生态与地理研究所
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