检索结果-南通市图书馆

Change of surface cover greenness in China between 2000 and 2010

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2012年第22期57卷 2835-2845页

作者： LIU Shuang1,4. GONG Peng1,2,3.State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Institute of Remote Sensing Applications of chinese academy of Sciences,and beijing Normal University, beijing 100101, China 2Institute for Global Change studies & Center for Earth System Science, Tsinghua University, beijing 100084. China 3.epartment of Environmental Science, Policy and Management, University of California, Berkeley, CA94.20, USA 4.raduate University of chinese academy of Sciences, beijing 10004., China State Key Laboratory of Remote Sensing Science Jointly Sponsored by Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing China Graduate University of chinese academy of Sciences Beijing China Institute for Global Change studies & Center for Earth System Science Tsinghua University Beijing China Department of Environmental Science Policy and Management University of California Berkeley USA

Surface greenness reflects the situation of vegetation *** index calculated from the Red and Near Infrared bands of remote sensing images,whose values indicate the level of photosynthetic activity,is monotonically related to surface greenness when vegetation canopy does not fully cover the background *** for desert regions,vegetation index is positively correlated with vegetation ***,vegetation index can be used to study the change in greenness of desert *** study collected MODIS Normalized Difference Vegetation Index (NDVI) data from 2000 to 2010 and analyzed their change over China in this *** results showed that an increasing trend of NDVI occurred over 66.84. (OLS fitting) or 64.27% (LAD fitting) of China,indicating that China's greenness is increasing ***,desertification of China *** showing large increase in greenness are found in Shaanxi,Shanxi,Ningxia,Henan,Shandong,Qinghai,and Gansu while regions with large decrease in greenness are found in Northeast Inner Mongolia,South Tibet,Jiangsu,and *** of Qinghai,Gansu,Xinjiang and South Tibet could probably be driven by climate *** of greenness in Northeast Inner Mongolia was related to agricultural *** of greenness in Jiangsu and Shanghai was related to rapid *** factors did not exhibit obvious correspondence to the large increase in greenness in Shaanxi,Shanxi,Ningxia and Gansu,indicating that the changes might have been caused by human *** reduction of desert areas in China could probably have been caused by human management and protection at the national scale.

关键词：中国地表覆盖归一化植被指数植被覆盖度沙漠地区 NDVI 西藏南部气候因素

A case study of spatial heterogeneity of soil moisture in the Loess Plateau,western China:A geostatistical approach

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2009年第1期24卷 63-73页

作者： BI Huaxing1,2,LI Xiaoyin3.LIU Xin3.GUO Mengxia3.and LI Jun3.1 Prof., College of Soil and Water Conservation, {4. forestry University, {4. 100083. China, Key Laboratory of Soil and Water Conservation and {3. Combating, Ministry of Education, {4. 100083. China 2 Researcher, Ji-xian National Ecological Station of China, {4. 100083. China 3.Graduate student, College of Soil and Water Conservation, {4. forestry University, {4. 100083. China [a]Prof. College of Soil and Water Conservation Beijing Forestry University Beijing 100083 China Key Laboratory of Soil and Water Conservation and Desertification Combating Ministry of Education Beijing 100083 China [b]Researcher Ji-xian National Ecological Station of China Beijing 100083 China [c]Graduate student College of Soil and Water Conservation Beijing Forestry University Beijing 100083 China

Soil moisture distribution shows highly variation both spatially and temporally. This study assesses the spatial heterogeneity of soil moisture on a hill-slope scale in the Loess Plateau in West China by using a geostatistical approach. Soil moisture was measured by time-domain reflectometry(TDR) in 3.3.samples. Two kinds of sampling scales were used(2 x 2 m and 20 x 20 m) at two soil layers(0-3. cm and 3.-60 cm). The general characteristics of soil moisture were analyzed by a classical statistics method,and the spatial heterogeneity of soil moisture was analyzed using a geostatistical approach. The results showed that the spherical model is the best-fit model to simulate soil moisture on the experimental hill-slope. The parameters of this model indicated that the spatial dependence of soil moisture in the selected hill-slope was moderate. Even the 2 x 2 m sampling scale was too coarse to show the detailed spatial variances of soil moisture in this area. The dependent distance increased from 27.4.m to 4.4.16 m as the sampling scale became coarse(from 2 x 2 m to 20 x 20 m). A map of soil moisture was generated by using original soil moisture data and interpolated values determined by the Kriging method. The average soil moisture(area weighted) in the different layers of soil was calculated on the basis of this map(10.94. for the 0-3. cm soil layer,11.88% for the 3.-60 cm soil layer). This average soil moisture is lower than the corresponding average effective soil moisture,which suggests that the soil moisture is not sufficient to support vegetation in this area.

关键词： Spatial heterogeneity Soil moisture Geostatistics Loess Plateau of China

A Review on Basic Research of desertification Combating in China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science Foundation in China 2003年第2期 35-37页

作者： Yu Zhenliang Gu Reisheng Chen Yue Du Shengming Liu Shirong ( Department of Life Sciences, NSFC, beijing 100085 chinese academy of forestry, beijing 100094.

China is one of the countries seriously affected by desertification in the world. Nowadays, China has desertification-affected land area of about 2.67 million square kilometers, accounting for 27.9 percent of the entire territory in China, at an average rate of about 104.0 square kilometers annually during the period of 1994.to 1999. At the same time, the area of desertification caused by wind erosion is expanding at an average rate of 3.3. square kilometers per year. China' s gov-

关键词： in have NSFC on A Review on Basic Research of desertification Combating in China of Basic

Strategies for Combating desertification and Rehabilitating Affected Lands in the Qinghai-Tibet Plateau——A Case Study of Qinghai Province

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Strategies for Combating Desertification and Rehabilitating ...

Simulated multi-scale watershed runoff and sediment production based on GeoWEPP model

作者： Lu Qi and Yang Youlin National Research and Development Centre for Combating desertification,beijing 100091,P. R. China National Bureau to Combat desertification,State {3. Administration,{4. 100714.P. R. China

The Qinghai-Tibet Plateau is located at the third pole of the world and its total land areais 2,63.,700 km,covers approximately 27.5% of the total land territory of *** Qinghai-Tibet Plareau,the highest distribution of desertification affected land in the word,covers approximately 720.9 thousand km,occupying 27.3.% of the total land territory of theQinghai-Tibet Plateau and 27.4.% of the total area of the desertiflcation affected land in *** to the classification of the root causes of desertification,there are wide distribution ofthree major patterns of the affected lands,which have been identified as the desertification causedby wind erosion and aeolian process,the frozen and melting processes at cold plateau and by soilsalinization/alkalization and *** area of each pattem of desertification affected landmentioned above is 3.4.2 thousand km,3.3.thousand km and 23.7 thousand km *** the basis of grading criteria of the severity of desertification,the desertification in the Qinghai-Tibet Plateau can be divided into three categories,***,medium and severe desertification,representing 26.5%,3..3.% and 4..16% *** effective combating and rehabilitation,some stratgic measures have been developed:l)biological-engineering preservation:biologicaland mechanical sand barriers,natural reserves,protected hunting and preservation;2)rehabilitation and restoration:shelterbelt networks for protecting ***-farm andgrazing lands,rotation grazing system and rotation cultivation;and 3.watershed management andriver valley development:integrated agricultural development,snow-capped mountain and deserttourism,encouragement of commnnity or township owned enterprises and service trade.

关键词： desertification,pattern,distributive areas,severity,combating strategy,Qinghai,Qinghai-Tibet Plateau.

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2009年第4期24卷 465-478页

The runoff and sediment yield data from the Qiaozidonggou, Qiaozixigou, and Lu’ergou watersheds, in the Loess Plateau of China are used to calibrate and validate the runoff and sediment yield simulated by GeoWEPP model of the WEPP Model at watershed scale. The indices of relative error, R, correlation coefficient, R 2 , and Nash-Suttcliffe efficiency coefficient En s are used to evaluate the model fit. The eco-hydrological responses in the Luoyugou and Lu’ergou watersheds are also forecast based on the WEPP Model. Meanwhile, the relation between vegetation pattern changes and sediment yield in the watershed is discussed, and the responses of runoff and sediment yield in the watersheds concerning forest growth stages are studied. The results show that the relative errors of simulated values of runoff and sediment yield are below 3.%, the correlation coefficients are above 0.90, and the Nash-Suttcliffe efficiency coefficients are above 0.80. The simulation results present satisfactory performance, thus, the model could be used to simulate the runoff and sediment yield in these small watersheds. It is also observed that soil erosion tended to become severe as precipitation increased in the watershed, while soil erosion has a decreasing trend as forest cover increases and vegetation pattern is optimized. When the watershed is fully covered by forest, erosion and sediment yield are minimized. When the forest cover is about 3.% and evenly distributed in the watershed, the erosion intensity is lower than if the forest cover is collectively distributed in the watershed. Erosion varies with different forest growth stages in the watershed; it is more serious at the young and near planting stage and is the smallest at the mature forest stage.

关键词： GeoWEPP model Eco-hydrological response Watershed runoff Sediment yield Model calibration Erosion modeling

Sandstorms and desertification

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2000年第3期10卷 99-102页

作者： CHEN Zhi-qing1, ZHU Zhen-da2 (1.Institute of Geographic Sciences and Natural Resources Research, chinese academy of Sciences, beijing 100101, China 2. Institute of Dsert Research, chinese academy of Sciences, beijing 100101, China)

Sandstorm is a frequently occurred disastrous weather in northern China. The increasing occurrence frequency recently, especially the much more frequently occurred sandstorms with high intensity in the spring of 2000 have caused great loss to national economy. The combination of strong wind, exposed sandy soil on ground surface and unstable air current constitutes the necessary conditions for the sandstorms. However, the accelerated desertification process resulting from irrational human economic activities is responsible for the accelerated sandstorms. The effective measures to mitigate sandstorm lie in strengthening desertification control and eco-environmental protection.

关键词： sandstorm generating conditions desertification eco-environmental protection

Reviewing on the Development of forestry Sciences and Technology in China

在线全文

学校读者我要写书评

暂无评论

chinese forestry Science and Technology 2003年第2期2卷 54-61页

作者： ZHANG Dahua MEI Xiuyingchinese academy of forestry. beijing 100091. China

This essay reviews and sums up about the major achievement of forestry sciences-and technology in the past 50 years in China, from 8 fields including hereditary breeding of forest, silviculture, forest ecology, forest management, forest protection, combating desertification, wood sciences and technology, and forestry chemistry and technology.

关键词： China forestry development of science and technology

Estimation of Sand Transportation Rate for Fixed and Semi-Fixed Dunes Using Meteorological Wind Data

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2009年第1期19卷 129-136页

作者： HU Xia LIU Lian-You LI Shun-Jiang XIAO Bi-Lin LIU Mu-Xin Key Lab of Environment Change and Natural Disaster Ministry of Education Beijing Normal Univeristy Beijing 100875 （China） academy of Disaster Reduction and Emergency Management Ministry of Civil Affairs/Ministry of Education Beijing Normal University Beijing 100875 （China） State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 21008 （China） Institute of Plant Nutrition and Resources Beijing Academy of Agriculture and Forestry Sciences Beijing 100097 （China） Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Beijing 100081 （China）

Taibus County, Inner Mongolia, China, lies in a farming-pastoral ecotone, where severe wind erosion and various aeolian sand hazards are prevalent and fixed and semi-fixed sand dunes occur frequently. This study was conducted to investigate the relationships between sand transportation rate and wind speed for the fixed and semi-fixed sand dunes based on field measurements. The annual quantity of soil erosion by wind was estimated using meteorological wind data. The results indicated that the sand transportation rate in Taibus County in 2000 was 57.3. kg cm-1 year-1 for the semi-fixed dunes and 4.56 kg cm-1 year-1 for the fixed dunes. The total duration of erosive winds covered 12.5% of the time of the year, and spring posed the highest potential of sand transportation. Wind with low speed (≤ 17 m s-1) and high frequency plays a dominant role in sand transportation, while strong wind (≥ 17 m s-1) with low frequency significantly enhanced the sand transportation. Erosive wind speed, directions, and frequency were three crucial dynamic factors influencing sand hazards in the farming-pastoral ecotone. The dominant factors intensifying sand and dust storms in Taibus County might be related to the favorable wind condition in combination with the durable drought, which led to land desertification and vegetation degradation.

关键词： fixed and semi-fixed dunes meteorological wind data sand transportation rate wind erosion

Research on TemporaI and Spatial Patterns and Dynamic Laws of Soil Water at Eco-tope between Oasis and Desert

在线全文

学校读者我要写书评

暂无评论

chinese forestry Science and Technology 2002年第2期1卷 31-37页

作者： WANG Bing CUI Xianghui BAO YonghongThe Research Institute of Forest Ecology. Environment and Protection chinese academy of forestry. beijing 100091, China

Based on long term and stationary research, the temporal and spatial patterns and dynamic laws of soil water content in Minqin desert area were studied. Some results are as follows:(1)The change of soil water content in different years is not obviously in shrub sand dune of Nitraria sibirica and Tamarix ramosissima, but it was great in shifting sand dune, the maximum is 2.53.%; (2)The season dynamics can be divided into three stages: accumulating, consuming and stable; (3. The vertical change of soil wa...

关键词： Minqin desertification soil water content temporal and spatial pattems dynamic laws