ISWC OpenIR  > 水保所知识产出(1956---)
黄土高原小流域土壤有机碳 、 氮时空变异 与动态模拟 研究
李明明
Subtype博士
Thesis Advisor张兴昌
2013-10
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword黄土高原 土壤有机碳 影响因子 Gis 时空变异 Century 模型
Abstract

土壤是全球重要的碳库和氮库。在全球碳、氮循环中具有重要地位,直接影响着
陆地生态系统的温室气体排放和全球气候变化。正确估算区域土壤有机碳、氮水平以
及动态变化是全球气候变化研究的重要内容,也是近年来国际地学和生态学界的研究
热点领域。黄土高原是我国主要生态区,随着退耕还林草政策的实施,其土壤有机碳
和氮分布特征、储量估算以及未来的发展趋势研究是环境效应评价的重要内容之一。
本文以黄土高原典型小流域纸坊沟流域为研究对象,借助GPS对全流域进行均匀布点,
结合传统统计学、地统计学及 GIS,探寻黄土高原纸坊沟流域不同土地利用类型下土
壤有机碳、氮含量的空间变异性、分布特征及其影响因素,揭示了 20 年来该流域土壤
碳、氮的时空变化特性,并利用有机碳动态模型进行流域尺度的土壤有机碳模拟和预
测。得到以下主要研究成果:
1、0-100cm 土壤有机碳、氮含量均值分别为 3.08 g·kg -1 和 0.32g·kg -1 。土壤有机碳、
氮含量随土壤深度的增加而减小,与土层深度的关系均可用幂函数表示。各层土壤有
机碳、氮含量均属于中等变异强度,并符合对数正态分布,并且可用不同的半方差理
论模型拟合。土壤有机碳含量在 40cm 以上具有中等空间相关性,受随机因素和结构
性因素共同作用。40cm 以下具有强烈的空间相关性,主要受结构性因素影响。土壤全
氮含量在 0-10cm、40-60cm 具有强烈空间相关性,主要受结构性因素影响。其余四层
具有中等空间相关性,受随机因素和结构性因素共同作用。流域空间分布上的差异与
地形、土地利用和一些人类活动等因素有密切关系。普通 Kriging 插值能直观地反映出
该流域土壤有机碳空间分布的情况。
2、0-100cm 土壤有机碳、氮含量和密度均表现为:灌木>林地>草地>农地;土壤
容重依次为:农地>草地>林地>灌木。农地的土壤容重在各层均明显高于其它土地利用
方式,深度对土壤容重影响并不明显。土壤容重和有机碳含量之间可用幂函数关系来
表示。不同土地利用类型下,土壤有机碳与全氮均存在极显著线性相关关系(p<0.01),
C/N 从大到小依次为:林地>灌木>草地>农地。草地、林地和农地的土壤 C/N 随土壤深度的增加而减小,灌木则不明显。坡度在 8-15°之间土壤有机碳含量显著高于其他坡
度(p>0.05),而<5°显著低于其他坡度,15-25°土壤全氮含量显著低于其他坡度范围,
其他坡度范围差异不显著。土壤有机碳、氮含量在坡向上的差异表现为:阴坡>阳坡>
半阳坡>半阴坡。土壤有机碳、氮含量随海拔的变化呈现出相似的变化趋势:随着海拔
的增加,呈先增加后降低趋势。在垂直方向上,土壤有机碳、氮含量的剖面分布在 60cm
以上较高,随深度增加而减少的趋势明显;60cm 以下,土壤有机碳、氮平均含量较低
且稳定。
3、纸坊沟流域 0-100cm 平均有机碳、氮密度分别为 2.63kgC·m -2 和 0.267kgN·m -2 ,
有机碳、氮储量分别为 21.62×10 6 kgC、2.20×10 6 kgN。土壤有机碳密度具有强烈的空间
相关性,受结构性因素影响。而土壤氮密度具有中等空间相关性,受随机因素和结构
性因素共同作用。土壤有机碳、氮密度半方差函数的拟合曲线分别符合指数,球状模
型的变化趋势,在空间分布上表现出阶梯状和环状的空间分布格局。土地利用类型、
地形和土壤质地是土壤有机碳氮密度分布的主要影响因子。土层深度与土壤有机碳、
氮储量之间的关系可用幂函数关系式表示。土壤有机碳、氮密度小于平均值的土壤面
积约占总面积的 65.58%和 59.75%,说明流域大部分土壤的有机碳、氮含量较低,流域
土壤总储量较小。
4、近二十年来,纸坊沟流域 0-20cm 土壤有机碳、氮含量分别增加 2.37g·kg -1 和
0.12g·kg -1 。储量较 1992 年分别增加了 78%和 30%。两期数据均属于中等变异性并符
合对数正态分布。2010 年土壤有机碳、氮的变异系数与空间相关程度均高于 1992 年。
变程数据表明近 20 年来研究区域空间分布均一性减弱,小范围内变异增强,整体分布
较复杂。空间分布表明,高值区从地势较高的流域外围转向地势较为平坦的低洼地区。
退耕还林(草)引起的土地利用变化及一些人类活动是时空变化的主要原因。
5、Century 模型可以模拟黄土高原小流域土壤有机碳的动态变化。在 Century 模型
运行达到平衡状态时,研究区土壤总有机碳为 1.792kgC·m -2 ,活性有机碳库、慢性有
机碳库和惰性有机碳库分别占总有机碳库的 3%,68%和 29%。在研究区平衡状态被破
坏后,土壤总有机碳经历了“增加—减少—增加”变化趋势,最终土壤总有机碳超过
了原始自然平衡状态下的土壤有机碳水平。各组分土壤碳库的变化与土地利用方式和
农业管理模式有密切关系。应用 Century 模型模拟 2110 年土壤有机碳(0-20cm)为
1.86kgC/m 2 ,有机碳储量为 15.4×10 6 kgC,不同土地利用方式下土壤有机碳均有不同程
度的提高,显示出明显的土壤“碳汇”效应。土地利用和地形因素会在很长一段时间
内影响研究区土壤有机碳的空间分布格局。
关键词:黄土高原;土壤有机碳、氮;影响因子;GIS;时空变异;Century 模型

Other Abstract

As the important carbon and nitrogen stock, soil has the important status in the global
carbon and nitrogen cycle, which affect directly the greenhouse gas emissions of terrestrial
ecosystem and global climate change. Correct Estimating the soil organic carbon (SOC) and
total nitrogen (TN) level and its change,is the important content of studying global climate
change, is also the hot fields of international geological and ecological community in recent
years. The Loess Plateau is the main ecological regions. Along with the implementation of
returning farmland to forest and grass, it is one of the important contents of environment
effect evaluation that studying the distribution characteristics, stock estimation and future
development trend of SOC and TN. In this paper, Zhi Fanggou is taken as the study area,
where belongs to typical small catchment in the Loess Plateau. The area is studied to explore
its spatial variation, distribution characteristics and influencing factors of soil organic carbon
content (SOCC) and total nitrogen content (TNC) under the condition of different land use
types, by using GPS to even the stationing of the whole catchment, combined with the
traditional statistics, geostatistics and GIS. Through study, it is revealed that the
Spatial-Temporal Variability of SOC and TN in the catchment during 20 years. And,
catchment-scale SOC is simulated and predicted with Century model, which is one dynamic
model of SOC. The main research results as follows:
1. The average SOCC and TNC in depth of 0-100cm are 3.08 g·kg -1 , 0.32 g·kg -1
respectively. SOCC and TNC decreases with the increase of soil depth, the relationship of
which can be expressed by power function. Every layer’s SOCC and TN belong to medium
intensity variation, and conform to logarithmic normal distribution, which can be fitted with
different theoretical model. SOCC has medium spatial correlation above 40 cm, affected by
random and structural factors together. And it has strong spatial correlation under 40 cm,
mainly affected by structural factors. TNC has strong spatial correlation in the two layers of  0-10cm, 40-60cm, mainly affected by structural factors. And it has medium spatial
correlation in the remained 4 layers, affected by random and structural factors together.
These spatial distribution differences about the catchment have a close relationship with
factors such as the terrain, land use and human activity. The situation of SOC spatial
distribution can be directly reflected by ordinary Kriging interpolation.
2. In depth of 0-100cm, the content and density of SOC and TN are as follows: shrub >
forest > grassland > farmland, and the soil bulk density is in the order: farmland > grassland >
forest > shrub. The soil bulk density of farmland in each layer is significantly higher than
that of other land use type. The depth is not obvious effect on soil bulk density. The
relationship between the soil bulk density and SOCC can be represented by a power function.
Under different land use types, there are extremely significant linear correlation (p < 0.01)
between SOC and TN. From big to small, The C/N is in the order: forest > shrub > farmland >
grassland. C/N of grassland, forest and farmland decreases with the increase of soil depth,
but that of shrub is not obvious. SOCC of 8° -15° slope is significantly higher than that of
other slope (p > 0.05), while < 5° slope significantly lower than other slope. TNC of 15°-25°
slope is significantly lower than that of other slope, and the difference between other slopes
is not significant. SOCC and TNC in different aspects are shown as: cloudy slope > sunny
slope > half sunny slope > half cloudy slope. It is showed the similar trends that SOCC and
TNC vary with the change of altitude: with the increase of altitude, first increased, and then
decreased. In vertical direction, the average level is higher for the profile distribution of
SOCC and TNC above 60 cm, and the trend reduced with the increase of the depth is
obvious. The average SOCC and TNC below 60 cm are low and stable.
3. In 0-100cm depth of Zhi Fanggou catchment, the average soil organic carbon density
(SOCD) and total nitrogen density (TND) are 2.63 kgC·m -2 and 0.267 kgC·m -2 respectively,
and soil organic carbon stock (SOCS) and total nitrogen stock (TNS) are 21.62 ×10 6 kgC,
2.20×10 6 kgN respectively. SOCD has strong spatial correlation, affected by structural
factors. And TND has medium spatial correlation, affected by random and structural factors
together. SOCD and TND are fitted with semivariance function, whose curve tendency
accords with the index and spherical model respectively. They show the ladder-like and
annular pattern in the spatial distribution. The different land use type、landforms and soil
texture is important influence factor to distribution characteristics of SOCD and TND. It
can be expressed by power function that the relationship between soil depth and SOCS and
TNS. The soil area account about 65.58% and 59.75% of the total area, whose SOCD and
TND are less than average value. These show that SOCC and TNC of most area is low in the
catchment, and soil total SOCS and TNS are small.  4. In recent two decades, SOCC and TNC of 0-20 cm are increased 2.37 g·kg -1 and 0.12
g·kg -1 respectively. SOCS and TNS compared to 1992 increase by 78% and 30%
respectively. Two phase data belong to medium variability and conform to logarithmic
normal distribution. In 2010, the variation coefficient and spatial correlation degree of SOC
and TN are higher than ones in 1992. Range data shows that the spatial distribution
uniformity is abated in the study area, small scale variation is enhanced, and the overall
distribution is more complex during the past 20 years. Spatial distribution show that the high
value area from the catchment periphery of higher terrain to low-lying area of relatively flat
terrain. It is the main reason for spatial-temporal variation that the land use change and
human activity caused by returning farmland to forest and grass.
5. In this paper, the Century model is first used in the Loess Plateau, with which the
simulation and prediction in catchment scale are made. The results show that the Century
model can be applied to simulate the SOC dynamic changes of the catchment in the Loess
Plateau. In the balance status of Century model running, the total SOC pool in the study area
is 1.792 kgC·m -2 , and the active, slow and passive SOC pool are respectively 3%, 68% and
29% of the total. After the balance was destroyed, the total SOC has the change trend of
“increasing-reduction-increasing”, and final more than the original natural state of
equilibrium. the change of each component SOC pool has a close relationship with the land
use type and agricultural management mode. Simulated with Century model, in 2110, SOCD
and SOCS in depth of 0-20 cm are 1.86kgC/m 2 , 15.4×10 6 kgC respectively. Under varied
land use types, SOC increase in different degree, which shows obvious soil "carbon sink"
effect. In the study area, land use and landform will affect the spatial distribution of SOC for
a long time.
Key Words:The Loess Plateau; Soil organic C,N; Environmental variables;GIS;
Spatial-temporal variability; Century model

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/9018
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
李明明. 黄土高原小流域土壤有机碳 、 氮时空变异 与动态模拟 研究[D]. 北京. 中国科学院研究生院,2013.
Files in This Item:
File Name/Size DocType Version Access License
黄土高原小流域土壤有机碳 、 氮时空变异(15722KB)学位论文 开放获取CC BY-NC-SAApplication Full Text
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[李明明]'s Articles
Baidu academic
Similar articles in Baidu academic
[李明明]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[李明明]'s Articles
Terms of Use
No data!
Social Bookmark/Share
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.