黑河中游生态土地面积的变化

黑河干流水量统一调度和近期治理,使中游地区生活、生产、生态环境用水结构发生了重大变化。应用遥感技术对植被覆盖地、农业用地、水体、沙地、裸地、裸岩、盐碱地等进行读判,按照1987-2000年各类土地面积发展趋势,预测的2004年各类土地面积与实际面积进行比较分析,表明黑河水量调度和近期治理对提高中游林草覆盖度、减缓土地沙化等均有一定的积极作用。

Analysis of ecological effects of comprehensive treatment in the Tarim River Basin using remote sensing data

Based on multi-type,multi-temporal remote sensing data,we have monitored recent changes in cultivated land use and vegetation,in sandy areas and salinized desertification in the Green Corridor zone of the main channel of the Tarim River Basin.The results of our investigation show that the ecological environment in the Green Corridor of the main channel of the Tarim River Basin has conspicuously improved from 2002 to 2004.These improvements show up largely in such aspects as an increase in the rate of vegetation cover,a reduction in desertification land areas and a weakening in the intensity of sandy and the salinized land.On the other hand,the cultivated area in the Tarim River Basin significantly increased from 2002 to 2004.The rate of growth in cultivated areas during this period was significantly higher than that from 1999 to 2002.The increase in the use of irrigation resulting from the substantial increase in cultivated areas has a long-term potential restraining effect on the restoration of ecological functions of the Tarim River.

Changes in Land Use and Agricultural Production Structure Before and After the Implementation of Grain for Green Program in Western China–Taking Two Typical Counties as Examples

Soil erosion becomes a serious environmental problem in the world, especially in western China. An effective management practice called the Grain for Green Program(GGP), which was launched in 1999, aims to reduce soil and water loss and alleviate the ecological environment problem in western China. Two typical counties in western China, the Zhongxian(in Chongqing Municipality) and Ansai(in Shaanxi Province) were chosen to evaluate the dynamic changes of land use and agricultural production structure before and after the implementation of the Program in this paper. The results showed that the cultivated land area was reduced by 7.08% from 1989 to 2003. The cultivated land per person was decreased by 8.42% during 1999-2003. Moreover, the stability index of the secondary sector of the economy was increased from 0.91 in the period 1990-1999 to 0.94 in the following ten years. In addition, the stability index of tertiary economic sector increased from 0.88 to 0.92 in Zhongxian county. Meanwhile, the cultivated land area was reduced by 15.48% from 1990 to 1999. The soil erosion modulus was decreased by 33.33% from 1999 to 2006. Also, the stability index of secondary and tertiary economic sectors was 0.86 in the period 1998-2002. However, it decreased by 77% during 2002 to 2007 in Ansai County. These results imply that the Grain for Green Program had different impact on the two regions. Several effective strategies of soil and water conservation have been carried out to ameliorate the sustainable development of ecological environment and economy in these two counties of western China.

Preliminary analysis of spatiotemporal pattern of global land surface water

Land surface water(LSW) is one of the most important resources for human survival and development, and it is also a main component of global water recycling. A full understanding of the spatial distribution of land surface water and a continuous measuring of its dynamics can support to diagnose the global ecosystem and environment. Based on the Global Land 30-water 2000 and Global Land 30-water 2010 products, this research analyzed the spatial distribution pattern and temporal fluctuation of land surface water under scale-levels of global, latitude and longitude, continents, and climate zones. The Global Land 30-water products were corrected the temporal inconsistency of original remotely sensed data using MODIS time-series data, and then calculated the indices such as water area, water ration and coefficient of spatial variation for further analysis. Results show that total water area of land surface is about 3.68 million km2(2010), and occupies 2.73% of land area. The spatial distribution of land surface water is extremely uneven and is gathered mainly in mid- to high-latitude area of the Northern Hemisphere and tropic area. The comparison of water ratio between 2000 and 2010 indicates the overall fluctuation is small but spatially differentiated. The Global Land 30-water products and the statistics provided the fundamental information for analyzing the spatial distribution pattern and temporal fluctuation of land surface water and diagnosing the global ecosystem and environment.

Cropland expansion facilitated the outbreak of cereal aphids during 1951–2010 in China

Landscape-scale pattern could affect ecosystem service such as biocontrol of agricultural pests. Additionally, pest outbreak has been shown to be interwoven with land-use intensity. In the present research, we collected and analysed the 60-year data of cereal aphids and wheat area during 1951–2010 in China. Regression model was applied to analyse the relationship between pest damage and cropland expansion. Results showed that the percentage of cereal aphid outbreak area in wheat area increased rapidly during 1951–2010. It was 9 % during 1951–1960, while it was above 60 % during 2001–2010. In addition, effect of cropland expansion on damage of cereal aphids was significantly positive, which indicated that cropland expansion in agricultural landscape may enhance pest damage greatly.Finally, we concluded that cropland expansion was one of the most important drivers of increasing pest outbreak,which should be considered in sustainable management of cereal aphids combined with other factor(e.g. climate changes and resistant variety) at large spatiotemporal scale.