EGI OpenIR
塔里木河下游地下水位埋深对植被 NPP 的影响
Alternative TitleInfluence of groundwater depth on vegetation NPP in the lower reaches of Tarim River
秦景秀
Subtype硕士
Thesis Advisor郝兴明
2020-06-30
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline理学硕士
Keyword地下水位埋深 CASA 模型 NPP NEP 塔里木河下游 Groundwater depth CASA model NPP NEP lower reaches of Tarim river
Abstract塔里木河下游地区,气候干旱,生态环境脆弱,植被生长所需水分条件主要来源于浅层地下水,地下水位埋深对植被生长具有重要的影响。 在以往对地下水位埋深如何影响植被的研究中,仅仅停留在彼此之间线性关系的一种解释。 但在实际中,地下水是影响植被生长的内在因子,在将地下水位作为影响植被 NPP重要因素方面的研究,目前依然处于空白。 因此,本研究基于 CASA 模型,利用遥感数据、气象数据以及地下水位数据, 以生态系统的基本功能之一(植被NPP)为研究对象,探究地下水位埋深对植被 NPP 和 NEP 的影响。全文的主要结论如下:(1) 通过借鉴史建康等(2008)模拟地下水位的方法并与之结果进行对比显示,本文模拟的结果与之一致,说明本研究成功的借鉴了这一方法进行地下水位的模拟。 CASA 模型中的水分胁迫系数是关于地下水位埋深的一个分段函数,地下水位埋深在小于 2m 和大于 10m 时分别取到了最大值(W=1)和最小值(W=0.5);地下水位埋深在 2-10m 范围之间,水分胁迫系数是关于地下水位埋深的一个指数函数,且随着地下水位埋深的增加,水分胁迫系数(W)逐渐减小。基于改进后的 CASA 模型能够较好的估算植被生产力,估算值与实测值之间误差较小(R2=0.7935),平均误差为 2.8 g C/m2m。 经验证, 改进后的 CASA 模型能够较好的估算塔里木河下游地区的植被生产力。(2)塔里木河下游植被 NPP 和 NEP 在空间分布上存在显著的差异,均在靠近河道和河道的上游地区植被 NPP 和 NEP 值较高,在远离河道和河道的下游地区植被 NPP 和 NEP 值较低。从时间变化整体趋势上,植被 NPP 和 NEP 均呈现出缓慢的增加趋势。 以胡杨为主的乔木、 柽柳为主的灌木和草本这三种植被中,胡杨的植被 NPP 和 NEP 值最大。塔里木河下游平均植被 NEP 为-18.4 g C/m2m,即为碳源,且只有胡杨的 NEP 值为正值。植被覆盖度与植被 NEP 之间存在显著的正相关关系;塔里木河下游生态系统呈现碳源的主要原因是植被覆盖度较低,即单个像元内裸地面积较大。(3)从 2005-2009 年,塔里木河下游平均地下水位呈下降趋势,尤其从 2007塔里木河下游地区,气候干旱,生态环境脆弱,植被生长所需水分条件主要来源于浅层地下水,地下水位埋深对植被生长具有重要的影响。 在以往对地下水位埋深如何影响植被的研究中,仅仅停留在彼此之间线性关系的一种解释。 但在实际中,地下水是影响植被生长的内在因子,在将地下水位作为影响植被 NPP重要因素方面的研究,目前依然处于空白。 因此,本研究基于 CASA 模型,利用遥感数据、气象数据以及地下水位数据, 以生态系统的基本功能之一(植被NPP)为研究对象,探究地下水位埋深对植被 NPP 和 NEP 的影响。全文的主要结论如下:(1) 通过借鉴史建康等(2008)模拟地下水位的方法并与之结果进行对比显示,本文模拟的结果与之一致,说明本研究成功的借鉴了这一方法进行地下水位的模拟。 CASA 模型中的水分胁迫系数是关于地下水位埋深的一个分段函数,地下水位埋深在小于 2m 和大于 10m 时分别取到了最大值(W=1)和最小值(W=0.5);地下水位埋深在 2-10m 范围之间,水分胁迫系数是关于地下水位埋深的一个指数函数,且随着地下水位埋深的增加,水分胁迫系数(W)逐渐减小。基于改进后的 CASA 模型能够较好的估算植被生产力,估算值与实测值之间误差较小(R2=0.7935),平均误差为 2.8 g C/m2m。 经验证, 改进后的 CASA 模型能够较好的估算塔里木河下游地区的植被生产力。(2)塔里木河下游植被 NPP 和 NEP 在空间分布上存在显著的差异,均在靠近河道和河道的上游地区植被 NPP 和 NEP 值较高,在远离河道和河道的下游地区植被 NPP 和 NEP 值较低。从时间变化整体趋势上,植被 NPP 和 NEP 均呈现出缓慢的增加趋势。 以胡杨为主的乔木、 柽柳为主的灌木和草本这三种植被中,胡杨的植被 NPP 和 NEP 值最大。塔里木河下游平均植被 NEP 为-18.4 g C/m2m,即为碳源,且只有胡杨的 NEP 值为正值。植被覆盖度与植被 NEP 之间存在显著的正相关关系;塔里木河下游生态系统呈现碳源的主要原因是植被覆盖度较低,即单个像元内裸地面积较大。(3)从 2005-2009 年,塔里木河下游平均地下水位呈下降趋势,尤其从 2007
Other AbstractIn the lower reaches of the Tarim River, with arid climate and fragile ecologicalenvironment, the water conditions required for vegetation growth mainly come fromshallow groundwater and the depth of groundwater level has an important impact onvegetation growth. In previous studies on how groundwater affects vegetation, it wasonly an explanation of the linear relationship between groundwater and vegetation.However, in practice, the groundwater depth is an internal factor affecting the growthof vegetation, and the research on taking the groundwater depth as the driving factoraffecting vegetation productivity is still in a blank. Therefore, based on remotesensing data, meteorological data, and groundwater data, this study takes one of thebasic functions of the ecosystem (NPP) as the research object to research the impactof groundwater depth on vegetation NPP and NEP by using the CASA model. Themain conclusions of the full text are as follows:(1) By referring to the method of simulating groundwater by Shi Jiankang et al.(2008) and comparing with the results, we found that the results of the simulation inthis paper are consistent, which showed that this study successfully borrowed thismethod to simulate the groundwater. The water stress coefficient in the CASA modelis a piecewise function of the groundwater depth. When the groundwater depth is lessthan 2m and greater than 10m, the maximum value (W= 1) and minimum value (W=0.5) are taken. In the range of 2-10m, the water stress coefficient is an exponentialfunction of the buried depth of the groundwater level, and as the depth of thegroundwater increases, the water stress coefficient (W) gradually decreases. Based onthe improved CASA model, vegetation productivity can be better estimated, and theerror between the estimated value and the measured value is small (R2 = 0.7935), andthe average error is 2.8 g C/m2m. The improved CASA model can better estimate thevegetation productivity in the lower reaches of the Tarim River.(2) There are significant differences in the spatial distribution of vegetation NPPand NEP in the lower reaches of the Tarim River. Both NPP and NEP values are higher in the areas near the river and upstream, and lower in the areas farther from theriver and downstream. Both vegetation NPP and NEP showed a slowly increasingtrend in time. Among the three vegetations, populus euphratica has the largest NPPand NEP values. The average vegetation NEP of the lower reaches of Tarim River is-18.4 g C/m2m, which is the carbon source, and only the NEP value of populuseuphratica is positive. There is a significant positive correlation between vegetationcover and vegetation NEP. The main reason for the carbon source in the lower reachesof Tarim River is the low vegetation cover, or the large bare land area in a singlepixel.(3) From 2005 to 2009, the average groundwater depth in the lower reaches ofTarim River has shown a downward trend, especially since 2007. The main reason forthis is that the ecological water conveyance time is subject to artificial control.Nevertheless, the average groundwater depth is still within 7m, and the groundwaterdepth at 4-6m occupied the largest areas. There is a weak negative correlationbetween groundwater depth and vegetation NPP, NEP. Among the two plants ofpopulus euphratica and tamarix, the vegetation NPP and NEP of Populus euphraticawere more affected by changes in groundwater depth.
Subject Area自然地理学
Language中文
Document Type学位论文
Identifierhttp://ir.xjlas.org/handle/365004/15443
Collection中国科学院新疆生态与地理研究所
研究系统
Affiliation中国科学院新疆生态与地理研究所
First Author Affilication中国科学院新疆生态与地理研究所
Recommended Citation
GB/T 7714
秦景秀. 塔里木河下游地下水位埋深对植被 NPP 的影响[D]. 北京. 中国科学院大学,2020.
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