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Review of studies on land use and land cover change in Nepal

Journal of Mountain Science 2016年第4期13卷 643-660页

作者： Basanta PAUDEL ZHANG Yi-li LI Shi-cheng LIU Lin-shan WU Xue Narendra Raj KHANAL Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBering 100101China University of Chinese Academy of Sciences Beijing 100049China CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China Central Department of Geography Tribhuvan UniversityKirtipurKathmandu 44613Nepal

Land use and land cover(LULC) in Nepal has undergone constant change over the past few decades due to major changes caused by anthropogenic and natural factors and their impacts on the national and regional environment and *** comprehensive review of past and present studies of land use and land cover change(LUCC) in Nepal concentrates on cropland, grassland, forest, snow/glacier cover and urban areas. While most small area studies have gathered data from different sources and research over a short period, across large areas most historical studies have been based on aerial photographs such as the Land Resource Mapping Project in 1986. The recent trend in studies in Nepal is to focus on new concepts and techniques to analyze LULC status on the basis of satellite imagery, with the help of geographic information system and remote sensing tools. Studies based on historical documents, and historical and recent spatial data on LULC, have clearly shown an increase in cropland areas in Nepal,and present results indicating different rates and magnitudes. A decrease in forest and snow/glacier coverage is reported in most studies. Little information is available on grassland and urban areas from past research. The unprecedented rate of urbanization in Nepal has led to significant urban land changes over the past 30 years. Meanwhile, long term historical LUCC research in Nepal is required for extensive work on spatially explicit reconstructions on the basis of historical and primary data collection, including LULC archives and drivers for future change.

关键词： Land use Land cover Geographic information system Remote sensing Nepal

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Accuracy assessment of approaches to spatially explicit reconstruction of historical cropland in Songnen Plain,Northeast China

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Journal of Geographical Sciences 2016年第2期26卷 219-229页

作者：姜蓝齐张丽娟臧淑英张学珍 Key Laboratory of Remote Sensing Monitoring of Geographic Environment Harbin Normal University Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchCAS Jiangsu Collaborative Innovation Center for Climate Change

To understand historical human-induced land use/cover change （LUCC） and its climatic effects, it is essential to reconstruct historical land use/cover changes with explicit spatial information. In this study, based on the historically documented cropland area at county level, we reconstructed the spatially explicit cropland distribution at a cell size of 1 km × 1 km for the Songnen Plain in the late Qing Dynasty （1908 AD）. The reconstructions were carried out using two methods. One method （hereafter, referred to as method 1） allocated the cropland to cells ordered from a high agricultural suitability index （ASI） to a low ASI, but they were all within the domain of potential cropland area. The potential cropland area was created by excluding natural woodland, swamp, water bodies, and mountains from the study area. The other method （hereafter, method II） allocated the cropland to cells in the order from high ASI to low ASI within the domain of cropland area in 1959. This method was based on the hypothesis that the cropland area domain in 1959 resulted from enlargement of the cropland area domain in 1908. We then compared these two reconstructions. We found that the crop- land distributions reconstructed by the two methods exhibit a similar spatial distribution pat- tern. Both reconstructions show that the cropland was mostly found in the southern and eastern parts of the Songnen Plain. The two reconstructions matched each other for about 68% of the total cropland area. By spatially comparing the unmatched cropland cells of the two reconstructions with the settlements for each county, we found that unmatched cropland cells from method I are closer to settlements than those from method I1. This finding suggests that reconstruction using method I may have less bias than reconstruction with method I1.

关键词： comparison of methods cropland cover late Qing Dynasty Songnen Plain, Northeast China

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Analysis of spatio-temporal features of a carbon source/sink and its relationship to climatic factors in the Inner Mongolia grassland ecosystem

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Journal of Geographical Sciences 2016年第3期26卷 297-312页

作者：戴尔阜黄宇吴卓赵东升 Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research CAS School of Planning Faculty of Environment University of Waterloo University of Chinese Academy of Sciences

Global climate change has become a major concern worldwide. The spatio-temporal characteristics of net ecosystem productivity(NEP), which represents carbon sequestration capacity and directly describes the qualitative and quantitative characteristics of carbon sources/sinks(C sources/sinks), are crucial for increasing C sinks and reducing C sources. In this study, field sampling data, remote sensing data, and ground meteorological observation data were used to estimate the net primary productivity(NPP) in the Inner Mongolia grassland ecosystem(IMGE) from 2001 to 2012 using a light use efficiency model. The spatio-temporal distribution of the NEP in the IMGE was then determined by estimating the NPP and soil respiration from 2001 to 2012. This research also investigated the response of the NPP and NEP to the main climatic variables at the spatial and temporal scales from 2001 to 2012. The results showed that most of the grassland area in Inner Mongolia has functioned as a C sink since 2001 and that the annual carbon sequestration rate amounts to 0.046 Pg C/a. The total net C sink of the IMGE over the 12-year research period reached 0.557 Pg C. The carbon sink area accounted for 60.28% of the total grassland area and the sequestered 0.692 Pg C, whereas the C source area accounted for 39.72% of the total grassland area and released 0.135 Pg C. The NPP and NEP of the IMGE were more significantly correlated with precipitation than with temperature, showing great potential for C sequestration.

关键词： Inner Mongolia grassland ecosystem NPP NEP carbon source carbon sink

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Spatio-temporal variation of spring phenology in Tibetan Plateau and its linkage to climate change from 1982 to 2012

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Journal of Mountain Science 2016年第1期13卷 83-94页

作者： DING Ming-jun LI Lan-hui NIE Yong CHEN Qian ZHANG Yi-li Key Laboratory of Poyang Lake Wetland and Watershed Research Ministry of Education and School of Geography and EnvironmentJiangxi Normal UniversityNanchang 330022China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of SciencesBeijing 100101China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China

The influence of climate change on vegetation phenology is a heated issue in current climate change *** used GIMMS-3g NDVI data to detect the spatio-temporal dynamics of the start of the growing season(SGS) over the Tibetan Plateau(TP) from 1982 to 2012 and to analyze its relationship with temperature and *** significant trend was observed in the SGS at the regional scale during the study period(R^2 = 0.03,P = 0.352).However,there were three time periods(1982-1999,1999-2008 and 2008-2012) with identifiable,distinctly different *** with a significant advancing trend were mainly scattered throughout the humid and semi-humid areas,whereas the regions with a significant delaying trend were mostly distributed throughout the semi-arid *** analysis showed that the response of the SGS to climate change varies *** SGS was significantly correlated with the spring temperature and the start of the thermal growth season(STGS) in the relatively humid *** increasing aridity,theimportance of the spring temperature for the SGS gradually ***,the influences of precipitation and winter temperature on the SGS were complicated across the plateau.

关键词： Spring phenology Spatial pattern Temporal variation Climate change CorrelationTibetan Plateau （TP）

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Effects of rural–urban migration on vegetation greenness in fragile areas: A case study of Inner Mongolia in China

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Journal of Geographical Sciences 2016年第3期26卷 313-324页

作者：李仕冀孙志刚谈明洪李秀彬 Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research CAS University of Chinese Academy of Sciences Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research CAS

Different government departments and researchers have paid considerable atten- tion at various levels to improving the eco-environment in ecologically fragile areas. Over the past decade, large numbers of people have emigrated from rural areas as a result of the rapid urbanization in Chinese society. The question then remains： to what extent does this migra- tion affect the regional vegetation greenness in the areas that people have moved from？ Based on normalized difference vegetation index （NDVI） data with a resolution of 1 km, as well as meteorological data and socio-economic data from 2000 to 2010 in Inner Mongolia, the spatio-temporal variation of vegetation greenness in the study area was analyzed via trend analysis and significance test methods. The contributions of human activities and natural factors to the variation of vegetation conditions during this period were also quantita- tively tested and verified, using a multi-regression analysis method. We found that：（1）the vegetation greenness of the study area increased by 10.1% during 2000-2010. More than 28% of the vegetation greenness increased significantly, and only about 2% decreased evi- dently during the study period. （2） The area with significant degradation showed a banded distribution at the northern edge of the agro-pastoral ecotone in central Inner Mongolia. This indicates that the eco-environment is still fragile in this area, which should be paid close at- tention. The area where vegetation greenness significantly improved showed a concentrated distribution in the southeast and west of Inner Mongolia. （3） The effect of agricultural labor on vegetation greenness exceeded those due to natural factors （i.e. precipitation and tempera- ture）. The emigration of agricultural labor improved the regional vegetation greenness sig- nificantly.

关键词： rural-urban migration agricultural labor vegetation greenness NDVI Inner Mongolia

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Modern pollen assemblages from surface lake sediments in northwestern China and their importance as indicators of vegetation and climate

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Science China Earth Sciences 2015年第9期58卷 1643-1655页

作者： QIN Feng ZHAO Yan LI Quan CAI MaoTang Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Nature Resources ResearchChinese Academy of Sciences

The modern pollen assemblages of surface lake sediments and topsoils in northwestern China were studied to understand the relationship of modem pollen data with contemporary vegetation and climate, and the differences between the pollen assem- blages of surface lake sediments and topsoils. The results show that Chenopodiaceae and Artemisia are dominant elements in the pollen assemblages of northwestern China. Additionally, Ephedra, Cyperaceae, Asteraceae, Poaceae, Picea, Pinus, and Betula are also important pollen taxa. Both pollen assemblages and principal component analysis indicate that pollen data from surface lake sediments and topsoils can be used to differentiate the main vegetation types of this region （desert, steppe, mead- ow and forest）. However, differences exist between modern pollen assemblages of the two types of sediments due to the dif- ferent relevant source areas of pollen and degrees of pollen preservation. For example, the larger relevant source area of sur- face lake sediment results in a higher abundance of Betula in pollen assemblage from surface lake sediment, whereas the ten- dency to disintegrate thin-walled pollen types in topsoil leads to a higher proportion of resistant pollen, such as Asteraceae. Linear regression analysis indicates that the Artemisia/Chenopodiaceae （A/C） ratio in pollen assemblages of surface lake sedi- ments can be used to indicate humidity changes in the study area. However, the A/C ratio in topsoils should be used carefully. Our results suggest that pollen data from surface lake sediments would be better references for interpreting the fossil pollen assemblages of lake cores or lacustrine profiles.

关键词： modern pollen assemblage surface lake sediment topsoil vegetation climate northwestern China

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Distribution and transfer of Se in soil of Hainan Province

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IOP Conference Series: Earth and Environmental Science 2018年第2期199卷

作者： Zhe Hao Yonghua Li Xinqing Zou Lihong Chen School of Geographic and Oceanographic Sciences Nanjing University Nanjing 210093 China Key Laboratory of Engineering Oceanography Second Institute of Oceanography SOA Hangzhou 310012 China Collaborative Innovation Center of South China Sea Studies Nanjing University Nanjing 210093 China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Key Laboratory of Coast and Island Development (Nanjing University) Ministry of Education Nanjing 210093 China

Soil plays an important role to human health. Selenium is an essential nutrient for health. Se in soil will affect human health mainly by transferring to rice and other crops, and then to human body through the food chain .So it's necessary to analyse distribution of Se concentration in soil and its bioaccumulation ability from soil to rice. In this study, concentrations of soil Se ranged from 108.41-618.23μg/kg by counties. The average value was 343.90μg/kg, which was higher than soil background. It indicated that soil in Hainan was loaded with selenium. Soil in northeast contains more Se than that in southwest and Se content in natural soil was significant higher than cultivated soil. Positive correlations were seen between soil Se, rice Se and C/100,000. The transfer ability of Se varies in counties.

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An explanation of labor migration and grain output growth:Findings of a case study in eastern Tibetan Plateau

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Journal of Geographical Sciences 2016年第4期26卷 484-500页

作者：阎建忠张镱锂花晓波杨亮 College of Resources and Environment Southwest University Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchCAS University of Chinese Academy of Sciences Institute of Geography University of Hamburg

Although there has been rapid rural-urban migration in rural China since the 1980s, the total grain production of China saw a continuous increase. As of today, the relationship between labor migration and grain output growth remains partial and contradictory. The main aim of this empirical study is to examine some specific measures adopted by peasants to deal with labor shortage and maintain grain output growth. Using tracking survey, participatory rural appraisal methods, and land plot investigation, we investigate 274 households and 1405 arable land plots in four villages in two stages in Jinchuan county, southwestern China. The results show that continuous emigration of labor from the four villages caused the abandon- ment of a small amount of land, decreased labor intensity, and reduced multiple cropping index, shifting from ＂corn-wheat＂ multiple cropping pattern to the ＂corn＂ cropping pattern, which means labor shortage in some households. At the same time, owing to surplus labor in the villages, the peasants utilize a series of means to offset the negative impacts of labor migration on grain output, such as cropland transfer, labor exchange in the busy seasons, and the substitution of capital and technology for labor. The econometric analysis also shows that labor migration boosts grain production. This study provides a reasonable explanation of grain output growth under rural-urban migration.

关键词： labor migration land use change labor intensity capital intensity grain output

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Contributions of climate, varieties, and agronomic management to rice yield change in the past three decades in China

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Frontiers of Earth Science 2016年第2期10卷 315-327页

作者： He ZHANG Fulu TAO Dengpan XIAO Wenjiao SHI Fengshan LIU Shuai ZHANG Yujie LIU Meng WANG Huizi BAI Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China Institute of Geographical Sciences Hebei Academy of Sciences Shijiazhuang 050011 China Juncao Research Institute Fujian Agriculture and Forestry University Fuzhou 350002 China Qufu Normal University Rizhao 276826 China

The long-term field experiment data at four representative agro-meteorological stations, together with a crop simulation model, were used to disentangle the contributions of climate change, variety renewal, and fertilization management to rice yield change in the past three decades. We found that during 1981-2009 varieties renewal increased rice yield by 16%-52%, management improvement increased yield by 0-16%, and the contribu- tions of climate change to rice yield varied from - 16% to 10%. Varieties renewal and management improvement offset the negative impacts of climate change on rice production. Among the major climate variables, decreases in solar radiation reduced rice yield on average by 0.1% per year. The impact of temperature change had an explicit spatial pattern. It increased yield by 0.04%-0.4% per year for single rice at Xinbin and Ganyu station and for late rice at Tongcheng station, by contrast reduced yield by 0.2%- 0.4% per year for single rice at Mianyang station and early rice at Tongcheng station. During 1981-2009, rice varieties renewal was characterized by increases in thermal requirements, grain number per spike and harvest index. The new varieties were less sensitive to climate change than old ones. The development of high thermal require- ments, high yield potential and heat tolerant rice varieties, together with improvement of agronomic management, should be encouraged to meet the challenges of climate change and increasing food demand in future.

关键词： adaptation climate change food security,impact cultivar management

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A global moderate resolution dataset of gross primary production of vegetation for 2000-2016

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Scientific data 2017年第1期4卷 170165-170165页

作者： Zhang, Yao Xiao, Xiangming Wu, Xiaocui Zhou, Sha Zhang, Geli Qin, Yuanwei Dong, Jinwei Center for Spatial Analysis Department for Microbiology and Plant Biology University of Oklahoma Norman OK 73019 United States Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering Institute of Biodiversity Science Fudan University 200433 Shanghai China State Key Laboratory of Hydroscience and Engineering Department of Hydraulic Engineering Tsinghua University 100084 Beijing China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research CAS 100101 Beijing China

Accurate estimation of the gross primary production (GPP) of terrestrial vegetation is vital for understanding the global carbon cycle and predicting future climate change. Multiple GPP products are currently available based on different methods, but their performances vary substantially when validated against GPP estimates from eddy covariance data. This paper provides a new GPP dataset at moderate spatial (500 m) and temporal (8-day) resolutions over the entire globe for 2000-2016. This GPP dataset is based on an improved light use efficiency theory and is driven by satellite data from MODIS and climate data from NCEP Reanalysis II. It also employs a state-of-the-art vegetation index (VI) gap-filling and smoothing algorithm and a separate treatment for C3/C4 photosynthesis pathways. All these improvements aim to solve several critical problems existing in current GPP products. With a satisfactory performance when validated against in situ GPP estimates, this dataset offers an alternative GPP estimate for regional to global carbon cycle studies.

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