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全球陆地生态系统水分利用效率及 人为用地 植被缺失热 效应
夏磊
Subtype硕士
Thesis Advisor王飞
2015-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword陆地生态系统 植被净初级生产力(npp) 水分利用效率(wue) 生物能量 固定 蒸发潜热 人工地表
Abstract

陆地生态系统的碳循环和水循环问题是全球变化研究的热点和核心问题,而水分利
用效率(Water Use Efficiency, WUE)可以描述和衡量不同生态系统的碳水关系,对预测
陆地生态系统对全球变化的响应具有重要的意义。同时,由于土地利用变化,大面积植
被覆盖区域被人工地表所取代,植被的缺乏将导致部分能量不能被植被所吸收固定,同
时部分能量不能通过植被的蒸散发作用而转化为大气潜热,这两部分能量将相对保留在
地球表层,并最终导致地表热储存增加,可能引起和加剧局地乃至全球气候变化。
基于此,本文依托 2000-2013 年 MOD17A3 NPP(净初级生产力)数据和 MOD16A3
ET(蒸散发)数据,对全球陆地生态系统 WUE 的时空变异特征进行计算分析,同时根
据 2009 年全球土地覆盖产品(GlobCover 2009),分析了全球陆地生态系统各土地覆被
类型的 WUE 值的大小和年际变化趋势。对于全球人工地表区域,估算因植被缺失而少
固定的太阳能以及对应的蒸发潜热(植被缺失热累积),同时估算由植被缺失热累积引
起的气候强迫。主要研究结果有:
(1)14 年间,全球陆地生态系统 WUE 平均值为 873.45 mg C m -2 mm -1 ,年均 WUE
在 2000-2013 年年际波动范围为 849.26-896.59 mg C m -2 mm -1 ,总体上有所增加,但无
趋势性增加。2010 年之前,WUE 呈显著减少趋势(P<0.01),2010 年之后,迅速增加
但趋势不显著。
(2)在 2000-2013 年期间,WUE 值呈显著和极显著减少的像元占全球陆地总像元
数的 7.51%,主要分布在欧亚交界区域、马来半岛、澳大利亚中部平原、亚马逊平原等
地区;WUE 值呈显著和极显著增加的区域共占 10.96%,主要分布在刚果盆地、恒河平
原、黄土高原、青藏高原等地区。
(3)各大洲的 WUE 存在明显的空间分布特征。在非洲和大洋洲自北向南递增,在
欧洲和南美洲自东向西递增,在亚洲和北美洲,在大约北纬 50 度以北,WUE 自南向北
递减。各大洲 WUE 均值大小顺序为:欧洲>大洋洲>非洲>南美洲>北美洲>亚洲,北美
洲的 WUE 平均值与全球 14 年平均值相当。
(4)全球陆地生态系统像元WUE值为600-900 mg C m -2 mm -1 之间的区域占31-36%,
其次为 900-1200 mg C m -2 mm -1 (21-25%),最少的区间为 0-300 mg C m -2 mm -1 和区间>1500 mg C m -2 mm -1 ,所占百分比均在 5-8%之间。
(5)九种土地覆被类型的 WUE 大小顺序依次为常绿针叶林>针阔混交林>落叶阔
叶林>落叶针叶林>耕地>灌木>湿地>常绿阔叶林>草地。在 2000-2013 年期间,常绿阔叶
林、落叶针叶林和耕地三种类型的 WUE 呈显著性变化(P<0.05),在 2000-2010 年时段
内,常绿阔叶林、常绿针叶林、耕地、草地和湿地均呈显著(P<0.05)或极显著(P<0.01)
变化。
(6)2009 年因全球人工地表区域存在而直接少固定的太阳能为 3.35×10 18 J,对应
的蒸发潜热为 2.05×10 20 J,植被缺失导致的热累积约为 2.08×10 20 J;植被缺失热累积在
研究区域(CF R )、陆地生态系统(CF L )和全球(CF G )引起的气候强迫值分别为 15.163、
0.0443 和 0.0129W m -2 ,其中因 NPP 形成而对应的蒸发潜热占植被缺失热累积总和的 98%
以上。
关键词:陆地生态系统;植被净初级生产力(NPP);水分利用效率(WUE);生物能量
固定;蒸发潜热;人工地表

Other Abstract

The carbon and water cycles are the core issue and hot topics in global change study. The
interaction between carbon and water cycles can be characterized by the Water Use Efficiency
(WUE). It is essential to study WUE across global terrestrial ecosystems to explore the
inherent relationship between the carbon and water cycles and to help predict the influences
of climate change on terrestrial ecosystems. Furthermore, due to intensive human activities,
the natural vegetation has been largely replaced by the artificial surface area. Unlike
vegetation, the artificial area can’t fix the solar energy, in addition, the impervious material
covers the land surface and prevents heat dissipation from evapotranspiration. Therefore, part
solar energy will not be directly fixed by vegetation, and some is also not taken away through
evapotranspiration in these artificial areas, that is to say, both parts of the energy are relatively
reserved in surrounding air, and will be eventually transformed into the heat and warms the
land surface and atmosphere convection layer. It may cause and aggravate the local or even
global climate change.
In this study, we calculated and analyzed the fourteen-year WUE of the global terrestrial
ecosystems using remotely sensed data from the MODIS NPP products (MOD17A3) and the
MODIS ET products (MOD16A3) from 2000 to 2013. Also, based on the global land cover
data in 2009 (GlobCover 2009), we compared the WUE of different land-cover types. For the
global artificial surface, we calculated the energy that was not fixed and taken away by
evapotranspiration in global artificial surface area because of lacking vegetation, and assessed
the climate forcing resulted from the above energy. The main results as follows:
(1) The fourteen-year average WUE was 873.45 mg C m -2 mm -1 . The annual mean WUE
fluctuated from 849.26 to 896.59 mg C m -2 mm -1  in 2000-2013, and it increased in the whole
process but non-significant. Before 2010, WUE significantly decreased (P<0.01), and rapidly
increased after that year, but the variable trend was non-significant.
(2) During fourteen years, pixels with significant and highly significant decreasing trends
accounts for 7.51% of the total global land pixels, which mainly distributed in the Eurasian
transition area, the Malay Archipelago, Australia's central plains, Amazon Plain and so forth.  Pixels with significant and highly significant increasing trends accounted for 10.96%, and
they mainly distributed in Congo Basin, Gangetic Plains, Loess Plateau and Tibet Plateau.
(3) WUE presents a clear spatial distribution on each continent. In Africa and Oceania,
the WUE gradually increased from north to south. Similarly, an obvious increase with
longitude from east to west can be observed in Europe and South America. However, the
patterns in Asia and North America are more complex, in that the WUE appears to increase in
a southern direction in areas above the latitude of 50° N. WUE decreases with an order of
Europe, Oceania, Africa, South America, North America and Asia. WUE in North America is
very nearto the fourteen-year average WUE.
(4) WUE values in the 600-900 mg C m -2 mm -1 interval accounted for 31-36% of the
entire land surface, followed by the interval of 900-1200 mg C m -2 mm -1  (21-25%), and the
least were the intervals of 0-300 mg C m -2 mm -1  and >1500 mg C m -2 mm -1 that accounted for
only 5-8%.
(5) WUE of nine land-cover types showed a decreasing order as Needleleaved evergreen
forest, Mixed forest, Broadleaved deciduous forest, Needleleaved deciduous forest, Cropland,
Shrubland, Wetland, Broadleaved evergreen forest and Grassland. During fourteen years,
WUE of broadleaved evergreen forest, needleleaved deciduous forest and cropland showed
significant variation (P<0.05). From 2000 to 2010, WUE values of five types including
broadleaved evergreen forest, needleleaved evergreen forest, cropland, grassland and wetland
varied significantly (P<0.05) or highly significantly (P<0.01).
(6) The energy which was not directly fixed was 3.35×10 18 J and the energy that was not
transformed was 2.05×10 20  J. Total energy which was relatively increased was 2.08×10 20  J,
causing climate forcing of 15.16 W m -2 on research areas, 0.0443 W m -2 on global land areas
and 0.0129 W m -2 on globe. Climate forcing induced by the heat not taken away by
evapotranspiration accounted for above 98% of the total climate forcing value.
Keywords: Global terrestrial ecosystems; Net primary production (NPP); Water Use
Efficiency (WUE); Energy fixed; Latent heat of evapotranspiration; Artificial surfaces

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/9031
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
夏磊. 全球陆地生态系统水分利用效率及 人为用地 植被缺失热 效应[D]. 北京. 中国科学院研究生院,2015.
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