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黄土丘陵区燕沟流域植被生态特征及其生产力 形成过程模拟
王凯博
Subtype博士
2011-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword植被净初级生产力 模型 气候变化 土地利用变化 黄土丘陵区
Abstract

黄土高原是我国水土流失治理和生态环境建设的重点区域,植被生产力在一定程
度上是评价植被恢复和生态治理成效的重要指标。气候和土地利用变化是全球变化的
主要组成部分,也是影响植被生产力改变的主要驱动因素。目前,全球气候变化已成
为不争的事实,黄土高原的土地利用格局也自国家退耕还林(草)政策实施以来发生
了很大变化。因此,研究黄土高原植被生产力形成过程及其对气候和土地利用变化响
应,对于明确黄土高原植被对全球变化的响应与适应性,指导该区植被建设具有重要
意义。
本文以黄土丘陵区燕沟流域为例,通过对流域11 种典型植物土壤理化特性、生
理生态特征和群落生长动态的连续监测,探讨了不同植被类型土壤理化特征、植物叶
片光合特性和结构性状以及C、N、P 化学计量特征的季节变化规律;在综合考虑小
流域土壤水分和地形因素对植被碳同化过程影响的基础上,以研究区DEM 为基础,
构建了景观尺度复杂地形条件下植被生产力形成过程模型(CT-VPP),估算了流域不
同生态系统的土壤水量平衡和植被净初级生产力(NPP)的空间分布,并分析了流域
不同植被类型NPP 对气候和土地利用变化的响应。论文主要研究结果如下:
不同植被类型对土壤理化性质的改善程度不同,天然植被对土壤理化性质的改善
作用明显高于人工植被。与农田相比,不同植被类型土壤容重降低,土壤养分含量增
加,土壤含水量有所降低;天然灌木林和草地群落土壤有机质和全氮含量显著高于人
工乔木和灌木林,农地和果园土壤有机质和全氮含量最低;随着土层加深,不同植被
类型土壤理化性质差异减小;土壤全磷在不同植被类型和土层深度差别不明显。
燕沟流域11 种典型植物叶片光合特性、结构性状和C、N、P 化学计量特征表现
出较大的物种间和季节变化差异。总体看来,植物的光合速率、氮素和水分利用效率
在生长中期(7 月)大于前期(5 月)和后期(9 月),蒸腾速率在生长前期大于中期
和后期,而比叶重在生长后期大于前期和中期;叶片C 含量表现为生长前期低于生
长中期和后期,而N、P 含量随季节变化规律与之相反;叶片C:N、C:P 和叶片C 含量随季节变化规律相似,叶片N:P 随季节变化趋势相对复杂;表明了植物发育过程中
前期注重投资和后期侧重防御的生长策略。
构建并验证了复杂地形条件下植被生产力形成过程模型。该模型由太阳辐射的地
形校正、土壤水分平衡模拟和植物碳同化过程模拟三个模块组成。模型运行需要输入
气象、土壤、植被和空间数据驱动,输出结果包括坡地太阳辐射、蒸散发、土壤含水
量、植被NPP 等日、月和年值的空间分布。经燕沟流域NPP 实测数据和不同NPP 模
型模拟数据的对比验证,本模型具有较好的预测效果。模拟结果表明,燕沟流域2007
年植被NPP 约7681.5 t·C,不同植被类型NPP 大小顺序为乔木林>果园>灌木林>农田
>草地;NPP 的地形分布特征为:阴坡和半阴坡大于阳坡和半阳坡,5°-15°坡大于其
他坡度。
流域植被NPP 对气候变化发生时期的响应敏感性不同。其中,全年和夏半年降
水增加显著增加植被NPP,而冬半年降水增加对植被NPP 促进作用不明显;全年、
夏半年和冬半年气温增加明显降低植被NPP,其中冬半年气温增加对NPP 降低作用
最明显。全年或夏半年降水变化对植被NPP 的影响大于温度变化,而冬半年降水变
化对植被NPP 的影响小于温度变化。不同植被类型对气温和降水变化响应敏感性差
别明显,乔、灌木NPP 对温度和降水变化的敏感性要大于草本和作物,不同坡向植
被NPP 对气候变化响应差异较小。
土地利用格局变化对流域植被NPP 影响明显。流域退耕还林后(2007 年)较退
耕还林前(1997 年)农田和草地面积分别减少了20.4%和10.5%,而乔、灌木林地和
果园面积分别增加了13.9%、3.1%和8.7%,退耕还林后流域植被NPP 约增加了10%。
若以流域2007 年土地利用格局为背景,25°以上坡地全部转变为乔木林或果园后流域
植被NPP 将分别增加11.1%或15.5%,转变为农田或草地时植被NPP 将分别减少7.8%
或18.9%,而转变为灌木林时植被NPP 变化不大。
本研究在野外试验、文献资料整理和计算机编程的的基础上初步构建了复杂地形
条件下植被生产力形成过程模型,探讨了黄土高原燕沟流域植被NPP 分布及其对气
候变化和土地利用变化的响应,研究结果有助于揭示黄土高原植被碳同化过程机制,
明确不同植被类型对全球变化的响应与适应性差异。然而,本研究只是在小流域尺度
对黄土高原植被生产力形成过程进行了模拟研究,要揭示全球变化下的黄土高原生态
系统碳循环过程与格局的变化,尚需对区域尺度的植被生产过程进行模拟研究。
关键词:植被净初级生产力;模型;气候变化;土地利用变化;黄土丘陵区

Other Abstract

The Loess Plateau in China is one of the key regions of soil erosion control and
ecological environment construction. Vegetation net primary productivity (NPP) is an
important indicator in evaluating the effectiveness of vegetation recovery and ecosystem
management. Climate and land use change are the major components of global change, and
also apparently affect the NPP. Currently, global climate change has become an
indisputable fact, and the land use pattern in the Loess Plateau also has changed greatly
since the implementation of Grain for Green Project. Therefore, studying the formation of
vegetation productivity and its response to climate and land use change has great
significance in clarifying the response of NPP to global change, and in guiding the
vegetation construction in this region.
In the study, we take Yangou watershed in loess hill-gully region as a case. Base on
the continuous monitoring on soil physical and chemical properties, community features
and plant ecophysiological characteristics of the eleven typical plants, the soil physical and
chemical characteristics of different vegetation types, the seasonal variation of plant
photosynthesis and leaf structure traits and C, N, P stoichiometry were discussed.
Moreover, in considering the effects of soil moisture content and terrain factors on
vegetation carbon assimilation process and basing on the DEM of the study area, a NPP
model applied in complex terrain was constructed (CT-VPP). And then, the water balance
and NPP of different vegetation ecosystem in the watershed were simulated and the
responses of NPP of different vegetation types to climate and land use change were
analysized.
The improvement on soil physical and chemical properties of different vegetation type
was different, and the improving effect of natural vegetation was higher than artificial  vegetation. Compared with farmland, soil bulk and soil moisture decreased while soil
nutrient increased under other four vegetation types. Soil organic matter and total nitrogen
in natural shrubland and grassland were significantly higher than that in artificial woodland
and shrubland, and the lowest soil organic matter and total nitrogen content were in
farmland and orchard. With soil depth, the difference of soil physical and chemical
properties among different vegetation types gradually diminished. While the difference of
soil total phosphorus were not significant among different vegetation types and different
soil depth.
The photosynthetic characteristics, leaf physical traits, and stoichiometric parameters
of eleven typical plants varied greatly with species and seasonal change. Overall, the plant
photosynthetic rate, nitrogen and water use efficiency of different plants were higher in the
middle growth stage (July) than that in the early (May) and late (September) growth stage,
and the transpiration rate was higher in the early growth stage than that in the middle and
late growth stages, while specific leaf weight were higher in the late growth stage than that
in the early and middle growth stages. Leaf C content was lower in the early growth stage
than that in the middle and late growth stage, while the leaf N and P content had a contrast
seasonal variation. Leaf C: N, C: P had similar seasonal variation trend with leaf C content,
while the seasonal variation of leaf N: P was relatively complex. These results indicated
that plants invested more energy on productive organ in the early growth periods while
invested more energy on defensive organ in the late growth periods during their developing
process.
A NPP model applied in complex terrain was constructed and validated. The model
consisted of three modules which were solar radiation sub-model, soil water balance
sub-model and plant carbon assimilation sub-model. The model was drove by weather, soil,
vegetation, and spatial data, and the output of the model included solar radiation,
evapotranspiration, soil moisture, and NPP, etc. at daily, monthly and annual step. The
model was tested with the measured data, and also with simulated results of other similar
models. The verification results showed that the model had good prediction in the study
area. The simulated results showed that the NPP of the watershed in 2007 was about
7681.5 t·C with the order of woodland> orchard> shrubland> farmland> grassland, shady
and semi-shady slope> sunny and semi-sunny slope, and 5 ° -15 ° slope > other slope.  

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8900
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
王凯博. 黄土丘陵区燕沟流域植被生态特征及其生产力 形成过程模拟[D]. 北京. 中国科学院研究生院,2011.
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