ISWC OpenIR  > 水保所2018--届毕业生论文
甘肃省天然草地生产力时空变化及气候驱动力
苗海涛
Subtype硕士
2019-05
Degree Grantor中国科学院大学
Place of Conferral中科院教育部水土保持与生态环境研究中心
Degree Name工程硕士
Keyword天然草地,生产力,时空变化,生长季气候因子,尺度效应
Abstract

不断加剧的全球气候变化严重影响草地生态系统功能,而草地生产力是草地生态系统过程和草地生态系统功能中重要的组成部分。草地生产力在气候变化的驱动下会影响草地资源的可利用性。因此,探究天然草地生产力时空动态变化特征以及其变化的气候驱动力尤为重要。

本研究以干旱半干旱区的天然草地为研究对象,通过探究30年前后气候因子变化对天然草地生产力的驱动作用,并结合多种统计方法,系统研究了天然草地生产力长期变化趋势;探究了天然草地生产力在不同草地生态系统中长期变化的气候驱动力及沿着水热梯度的空间变化趋势;阐明了尺度效应对天然草地生产力空间变化的作用,有助于深入了解气候变化对草地生态系统的影响,对陆地生态系统碳循环研究具有重要意义。研究取得了以下主要结论:

11980s-2010s,甘肃省天然草地生产力在不同草地类型呈现下降的趋势,但其下降幅度在不同草地生态系统中存在差异,高寒草地下降了13%,温带草地下降了3%。与温带草地相比,高寒草地对气候变化更加敏感,导致其生产力下降的幅度更大。

2)甘肃省天然草地生产力变化由温度、湿润度和辐射能量协同作用。当降雨量长期无显著变化时,温度(包括地温和气温)是影响草地生产力变化的主要气候驱动因子。太阳辐射是引起高寒草地生产力下降必不可少的气候驱动因子,而太阳辐射的升高将增强温度对天然草地生产力的作用。

(3)研究区从西北到东南呈现由干热到湿冷变化的趋势。从干旱区到湿润区,天然草地生产力呈显著上升的总趋势,但其在干热地区或湿冷地区内部变化趋势不显著。天然草地植物生长对降雨响应滞后性导致干热地区天然草地生产力差异不显著,而物种间竞争激烈导致湿冷地区天然草地生产力差异不显著。

(4)在不同尺度下,随湿润度增加草地生产力呈增加趋势,而区域尺度模拟天然草地生产力与气候因子关系要优于局部尺度,因此,模拟天然草地生产力与环境因子之间的关系需要考虑尺度效应。从干热地区到湿冷地区草地生产力呈先缓慢后快速增加的趋势。随着湿润度的增加,干热地区草地水分利用效率迅速降低,引起天然草地生产力缓慢增加;而湿冷地区草地水分利用效率线性增加,引起天然草地生产力快速增加。

Other Abstract

The intensification of global climate changes (such as global warming) seriously affects the grassland ecosystem functions, and grassland aboveground productivity is an important component of grassland ecosystem processes and grassland ecosystem functions. Therefore, it is particularly important to explore the spatial and temporal dynamics of aboveground net primary productivity (ANPP) as well as its climate drivers in the natural grassland.

In this study, natural grassland was studied in arid and semi-arid regions. Specifically, the ANPP change in natural grassland was explored from 1980s to 20l0s as well as the climate factors. With various statistical methods, we systematically explored the long-term variable trend of grassland ANPP in different grassland ecosystem and the climate driving force which causes the long-term ANPP changing trend in different grassland ecosystems. Moreover, we also explored the spatial variation trend of ANPP in natural grassland along the hydrothermal gradient, and explored the scale effect on spatial variation of ANPP in natural grassland. Those are contributed to understand the impact of global climate change on grassland ecosystems, and the impact of climate change on grassland ecosystems is helpful for exploring terrestrial ecosystem carbon cycle. The study has made the main conclusions:

(1) The study area is mainly located at the intersection of the Qinghai-Tibet Plateau, the Loess Plateau and the Inner Mongolia Plateau. With diverse climate types, it has evolved diverse grassland types. The ANPP in different grassland types showed a common decreasing trend, but the variation range of grassland ANPP in different grassland ecosystems was different. The ANPP decreased by 13% in alpine grassland while decrease by 3% in temperate grassland. Compared with the temperate grassland ecosystem, the ANPP in alpine grassland decreased more rapidly, mainly for the sensitive of climate change in alpine grassland.

(2) In natural grasslands, the grassland ANPP change is determined by temperature, humidity and radiant energy. When long-term precipitation changes are not significant, temperature (including ground soil temperature and atmospheric temperature) will be the main climate drivers that affect the changing ANPP in natural grassland. The increase of temperature decreases the soil moisture and causes the soil desiccation, which in turn leads to limited vegetation growth and the ANPP transfer into the ground, which ultimately reduces the grassland ANPP. Solar radiation is an essential climate driving factor for the ANPP decline in alpine grassland, and the increase in solar radiation will enhance the effect of temperature on grassland productivity.

(3) The study area a is divided into four regions, arid region, semi-arid region, semi-humid region and humid region in terms of humid index. From northwest to southeast of the study area, there is a general trend from dry-hot to wet-cold. From arid region to humid region, the grassland ANPP has increased significantly, but there is no significant variation in dry-hot regions or wet-cold regions. The difference of grassland ANPP in dry-hot regions is not significant due to the hysteresis of grassland plant growth to precipitation, while the difference in grassland ANPP in wet-cold regions is not significant due to the intense species competition with abundant resources.

(4) At local and regional scales, the grassland ANPP increases with the increase of humid index, while the coefficient of determination of linear regression model at regional scale is more than twice that of local scale, thus scale effects should be taken into consideration when exploring the relationship between grassland ANPP and surrounding environment. Specifically, the grassland ANPP from dry-hot to wet-cold region increases slowly and then rapidly. The rapid decrease of grassland water use efficiency in dry-hot region is caused by the slow increase of grassland ANPP, while the increase of grassland water use efficiency in wet-cold region is caused by the rapid increase of grassland ANPP.

MOST Discipline Catalogue农学::草学
Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8786
Collection水保所2018--届毕业生论文
Recommended Citation
GB/T 7714
苗海涛. 甘肃省天然草地生产力时空变化及气候驱动力[D]. 中科院教育部水土保持与生态环境研究中心. 中国科学院大学,2019.
Files in This Item:
File Name/Size DocType Version Access License
毕业论文-苗海涛.pdf(3962KB)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
[苗海涛]'s Articles
Baidu academic
Similar articles in Baidu academic
[苗海涛]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[苗海涛]'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.