Recent Land Degradation and Improvement in China
Recent Land Degradation and Improvement in China
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DOI：
10.1579/0044-7447-38.3.150
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发表时间：
2009-05-01
期刊：
影响因子：
6.5
通讯作者：
Dent, David
中科院分区：
文献类型：
--
作者：
Bai, Zhanguo;Dent, David
土地退化是一个全球性的发展和环境问题，在程度、经济影响和受影响的人数方面，中国比大多数国家受到的影响更大。需要最新的定量信息来支持粮食和水安全、经济发展和环境完整性的政策和行动。最近一段时期的数据使我们能够区分历史遗留的土地退化和现在正在发生的情况。我们将土地退化定义为生态系统功能和生产力的长期下降，并通过遥感归一化植被指数（NDVI）和绿色指数来衡量。NDVI可以转化为净初级生产力。如果考虑到其他可能造成土地退化的因素，偏离标准可作为土地退化和改良的替代评估。这些其他因素包括气候，气候可以通过雨水利用效率和能源利用效率来评估。对23年全球清查模型与制图研究（GIMMS）NDVI数据的分析表明，中国1981-2003年NPIP总体呈上升趋势，但经气候调整后NPP下降的地区占全国的23%，主要集中在华南地区。约35%的中国人口（4.57亿13.17亿）依赖于退化的土地。退化地区的净初级生产力损失为12 kgC ha（-1）y（-1），相当于近6 000万tC未从大气中固定;这些地区土壤有机碳的损失可能更大。土地退化与旱地之间没有关联;耕地和森林的问题更大：退化土地中有21%是耕地，40%是森林，分别占耕地的24%和森林的44%。土地退化与农村人口密度或贫困之间没有简单的统计关系。大多数已查明的土地退化发生在南部和东部，其原因是前所未有的土地使用变化。
Land degradation is a global development and environment issue that afflicts China more than most countries in terms of the extent, economic impact, and number of people affected. Up-to-date, quantitative information is needed to support policy and action for food and water security, economic development, and environmental integrity. Data for a defined, recent period enable us to distinguish the legacy of historical land degradation from what is happening now. We define land degradation as long-term decline in ecosystem function and productivity and measure it by remote sensing of the normalized difference vegetation index (NDVI), the greenness index. NDVI may be translated to net primary productivity (NPIP). Deviation from the norm serves as a proxy assessment of land degradation and improvement-if other factors that may be responsible are taken into account. These other factors include climate, which may be assessed by rain-use efficiency and energy-use efficiency. Analysis of the 23-year Global Inventory Modeling and Mapping Studies (GIMMS) NDVI data reveals that, in China over the period 1981-2003, NPIP increased overall, but areas of declining climate-adjusted NPP comprise 23% of the country, mainly in south China. About 35% of China's population (457 million out of 1 317 million) depend on the degrading land. Degrading areas suffered a loss of NPP of 12 kgC ha(-1) y(-1), amounting to almost 60 million tC not fixed from the atmosphere; loss of soil organic carbon from these areas is likely to be orders of magnitude greater. There is no correlation between land degradation and dry lands; it is more of an issue in cropland and forest: 21% of degrading land is cropland and 40% is forest, 24% of the arable and 44% of the forest, respectively. There is no simple statistical relationship between land degradation and rural population density or poverty. Most identified land degradation is in the south and east, driven by unprecedented land-use change.