近5年青海省植被覆盖变化的遥感监测

This paper used five years （2001-2006） time series of MODIS NDVI images with a 1-km spatial resolution to produce a land cover map of Qinghai Province in China. A classification approach for different land cover types with special emphasis on vegetation, especially on sparse vegetation, was developed which synthesized Decision Tree Classification, Supervised Classification and Unsupervised Classification. The spatial distribution and dynamic change of vegetation cover in Qinghai from 2001 to 2006 were analyzed based on the land cover classification map and five grade elevation belts derived from Qinghai DEM. The result shows that vegetation cover in Qinghai in recent five years has been some improved and the area of vegetation was increased from 370,047 km^2 in 2001 to 374,576 km^2 in 2006. Meanwhile, vegetation cover ratio was increased by 0.63%. Vegetation cover ratio in high mountain belt is the largest （67.92%） among the five grade elevation belts in Qinghai Province. The second largest vegetation cover ratio is in middle mountain belt （61.80%）. Next, in the order of the decreasing vegetation cover ratio, the remaining grades are extreme high mountain belt （38.98%）, low mountain belt （25.55%） and flat region belt （15.46%）. The area of middle density grassland in high mountain belt is the biggest （94,003 km^2）, and vegetation cover ratio of dense grassland in middle mountain belt is the highest （32.62%）, and the increased area of dense grassland in high mountain belt is the greatest （1280 km^2）. In recent five years the conversion from sparse grass to middle density grass in high mountain belt has been the largest vegetation cover variation and the converted area is 15931 km^2.     

中国典型土地覆盖类型地表反照率的年内变化特征(英文)

Surface albedo is a primary causative variable associated with the process of surface energy exchange. Numerous studies have examined diurnal variation of surface albedo at a regional scale; however, few studies have analyzed the intra-annual variations of surface albedo in concurrence with different land cover types. In this study, we amalgamated surface albedo product data(MCD43) from 2001 to 2008, land-use data(in 2000 and 2008) and land cover data(in 2000); quantitative analyses of surface albedo variation pertaining to diverse land cover types and the effect of the presence/absence of ground snow were undertaken. Results indicate that intra-annual surface albedo values exhibit flat Gaussian or triangular distributions depending upon land cover types. During snow-free periods, satellite observed surface albedo associated with the non-growing season was lower than that associated with the growing season. Satellite observed surface albedo during the presence of ground snow period was 2–4 times higher than that observed during snow-free periods. Surface albedo reference values in typical land cover types have been calculated; notably, grassland, cropland and built-up land were associated with higher surface albedo reference values than barren while ground snow was present. Irrespective of land cover types, the lowest surface albedo reference values were associated with forested areas. Proposed reference values may prove extremely useful in diverse research areas, including ecological modeling, land surface process modeling and radiation energy balance applications.     

河西走廊张掖绿洲土地利用/土地覆盖变化特征

Taking two false color composite Landsat 5 TM(Thematic Mapper)images of band 4,3,2taken in 1995 and 2000 as data resources,this paper carried out study on LUCC of Zhanye oasis in recent five years by interpretation according to land resources classification system of 1∶00,000 Resources and Environmental Database of the Chinese Academy of sciences.The results show that great changes have taken place in landuse/landcover in Zhangye oasis since 1995:(1)Changes of landuse structure show that cropland and land for urban construction and built-up area increased,on the contrary,water area and grassland decreased.These changes reflect the deterionration of arrangement of water and land resources between the upper and lower reaches of the Heihe River.(2)Regional differences of landuse/landcover are evident,characterized by following aspects:in Sunan County located in Qilian Mountain area,unused land and grassland decreased,but cropland and land for urban construction and built-up area inreased.In Minle and Shandan counties located in foothills,unused land,warer area and cropland decreased,but grassland and land for urban construction and built-up area increased.In Zhangye City,Linze County and Gaotai County located in plain area of the middle reaches of the Heihe River,unused land,warer area and grassland decreased,while woodland,cropland and land for urban construction and buile-up area increased.     

80年来埃塞俄比亚北部高原土地利用/覆被变化（英文）

Despite many studies on land degradation in the Highlands of Northern Ethiopia, quantitative information regarding long-term changes in land use/cover(LUC) is rare. Hence, this study aims to investigate the LUC changes in the Geba catchment(5142 km2), Northern Ethiopia, over 80 years(1935–2014). Aerial photographs(APs) of the 1930 s and Google Earth(GE) images(2014) were used. The point-count technique was utilized by overlaying a grid on APs and GE images. The occurrence of cropland, forest, grassland, shrubland, bare land, built-up areas and water body was counted to compute their fractions. A multivariate adaptive regression spline was applied to identify the explanatory factors of LUC and to create fractional maps of LUC. The results indicate significant changes of most types, except for forest and cropland. In the 1930 s, shrubland(48%) was dominant, followed by cropland(39%). The fraction of cropland in 2014(42%) remained approximately the same as in the 1930 s, while shrubland significantly dropped to 37%. Forests shrank further from a meagre 6.3% in the 1930 s to 2.3% in 2014. High overall accuracies(93% and 83%) and strong Kappa coefficients(89% and 72%) for point counts and fractional maps respectively indicate the validity of the techniques used for LUC mapping.     

Desertification Reversion in Relation to Land Use Change and Climate in Naiman County, Inner-Mongolia, China

Analyses of desertified land and land use change in Naiman County of Inner-Mongolia showed that there was a fluctuated in-crease of rain-fed cropland in the period from 1951 to 1960, then decreased until the middle of the 1990＇s, then increased again, while irrigated cropland consistently increased. The woodland and build-up land consistently increased while grassland area de-creased. The area of water body increased from 1975 to 1995 and then decreased while river beach decreased. Wetland change fluctuated with a maximum of 303.53km2 in 1995 and a minimum of 62.08 km2 in 2002. Invasion of cropland into river beach does not only change land coverage on the beach, but also the hydrological process of the river systems and deeply influence wa-ter availability. The correlation between cropland and underground water table is negative and significant. Increase of irrigated cropland is the primary cause of water availability reduction. Water table reduction is negatively correlated to cropland. The total desertified land has decreased since 1975. A rapid increase occurred before 1959, but it is difficult to assess the change of deserti-fication due to lack of data from 1959 to 1975. Changes of different types of desertified lands were different. There is no signifi-cant correlation between land use and different types of desertified land, but there is a significant negative correlation between woodland and total desertified land. The correlation between grassland and total desertified land is positive and significant. There is a significant correlation between different land cover and key factors such as water body and annual precipitation, river beach and runoff, area of shifting dune and annual precipitation, and cropland and underground water table. Desertification reversion in Naiman County is fragile and will be even much more fragile due to population growth, rapid land use and climate change. This will lead to continued invasion of irrigated cropland into more fragile ecosystems and reduction of water availability.     

中国2010-2015年土地利用变化的时空格局与新特征（英文）

Land use/cover change is an important theme on the impacts of human activities on the earth systems and global environmental change. National land-use changes of China during 2010–2015 were acquired by the digital interpretation method using the high-resolution remotely sensed images, e.g. the Landsat 8 OLI, GF-2 remote sensing images. The spatiotemporal characteristics of land-use changes across China during 2010–2015 were revealed by the indexes of dynamic degree model, annual land-use changes ratio etc. The results indicated that the built-up land increased by 24.6×10~3 km~2 while the cropland decreased by 4.9×10~3 km~2, and the total area of woodland and grassland decreased by 16.4×10~3 km~2. The spatial pattern of land-use changes in China during 2010–2015 was concordant with that of the period 2000–2010. Specially, new characteristics of land-use changes emerged in different regions of China in 2010–2015. The built-up land in eastern China expanded continually, and the total area of cropland decreased, both at decreasing rates. The rates of built-up land expansion and cropland shrinkage were accelerated in central China. The rates of built-up land expansion and cropland growth increased in western China, while the decreasing rate of woodland and grassland accelerated. In northeastern China, built-up land expansion slowed continually, and cropland area increased slightly accompanied by the conversions between paddy land and dry land. Besides, woodland and grassland area decreased in northeastern China. The characteristics of land-use changes in eastern China were essentially consistent with the spatial govern and control requirements of the optimal development zones and key development zones according to the Major Function-oriented Zones Planning implemented during the 12 th Five-Year Plan(2011–2015). It was a serious challenge for the central government of China to effectively protect the reasonable layout of land use types dominated with the key ecological function zones and agricultural production zones in centraland western China. Furthermore, the local governments should take effective measures to strengthen the management of territorial development in future.     

过去百年青藏高原耕地时空变化及其对土壤保持功能的影响（英文）

Geographically explicit historical land use and land cover datasets are increasingly required in studies of climatic and ecological effects of human activities. In this study, using historical population data as a proxy, the provincial cropland areas of Qinghai province and the Tibet Autonomous Region(TAR) for 1900, 1930, and 1950 were estimated. The cropland areas of Qinghai and the TAR for 1980 and 2000 were obtained from published statistical data with revisions. Using a land suitability for cultivation model, the provincial cropland areas for the 20 th century were converted into crop cover datasets with a resolution of 1 × 1 km. Finally, changes of sediment retention due to crop cover change were assessed using the sediment delivery ratio module of the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST) model(version 3.3.1). There were two main results.(1) For 1950–1980 the fractional cropland area increased from 0.32% to 0.48% and land use clearly intensified in the Tibetan Plateau(TP), especially in the Yellow River–Huangshui River Valley(YHRV) and the midstream of the Yarlung Zangbo River and its two tributaries valley(YRTT). For other periods of the 20 th century, stability was the main trend.(2) For 1950–1980, sediment export increased rapidly in the Minhe autonomous county of the YHRV, and in the Nianchu River and Lhasa River basins of the YRTT, which means that sediment retention clearly decreased in these regions over this period. The results of this assessment provide scientific support for conservation planning, development planning, or restoration activities.     

1990–2010年中国土地覆被变化引起反照率改变的辐射强迫(英文)

Land cover change affects surface radiation budget and energy balance by changing surface albedo and further impacts the regional and global climate. In this article, high spatial and temporal resolution satellite products were used to analyze the driving mechanism for surface albedo change caused by land cover change during 1990–2010. In addition, the annual-scale radiative forcing caused by surface albedo changes in China's 50 ecological regions were calculated to reveal the biophysical mechanisms of land cover change affecting climate change at regional scale. Our results showed that the national land cover changes were mainly caused by land reclamation, grassland desertification and urbanization in past 20 years, which were almost induced by anthropogenic activities. Grassland and forest area decreased by 0.60% and 0.11%, respectively. The area of urban and farmland increased by 0.60% and 0.19%, respectively. The mean radiative forcing caused by land cover changes during 1990–2010 was 0.062 W/m2 in China, indicating a warming climate effect. However, spatial heterogeneity of radiative forcing was huge among different ecological regions. Farmland conversing to urban construction land, the main type of land cover change for the urban and suburban agricultural ecological region in Beijing-Tianjin-Tangshan region, caused an albedo reduction by 0.00456 and a maximum positive radiative forcing of 0.863 W/m2, which was presented as warming climate effects. Grassland and forest conversing to farmland, the main type of land cover change for the temperate humid agricultural and wetland ecological region in Sanjiang Plain, caused an albedo increase by 0.00152 and a maximum negative radiative forcing of 0.184 W/m2, implying cooling climate effects.     

元代前期省域耕地面积重建（英文）

Reconstructing historical land use and land cover change(LUCC) at the regional scale is an important component of global environmental change studies and of improving global historical land use datasets. By analyzing data in historical documents, including military-oriented cropland(hereafter M-cropland) area, the number of households engaged in M-cropland(hereafter M-household) reclamation, cropland area, and the number of households, we propose a conversion relationship between M-cropland area and cropland area reclaimed by each household. A provincial cropland area estimation method for the Yuan Dynasty is described and used to reconstruct the provincial cropland area for AD1290. Major findings are as follows.(1) Both the M-cropland and cropland areas of each household were high in the north and low in the south during the Yuan Dynasty, which resulted from different natural conditions and planting practices. Based on this observation, the government-allocated M-cropland reclamation area to each household was based on the cropland area reclaimed by each household.(2) The conversion relationship between M-cropland and cropland areas per household showed conversion coefficients of 1.23 and 0.65 for the south and north, respectively.(3) The cropland area in the entire study area in AD1290 was 535.4×106 mu(Chinese area unit, 1 mu=666.7 m~2), 57.8% in the north and 42.2% in the south. The fractional cropland areas for the entire study area, north, and south were 6.8%, 6.6%, and 7.1%, respectively and the per capita cropland areas for the whole study area, north, and south were 6.7, 15.6, and 4.1 mu, respectively.(4) Cropland was mainly distributed in the middle and lower reaches of the Yellow River(including the Fuli area), Huaihe River Basin(including Henan Province), and middle and lower reaches of the Yangtze River(including Jiangzhe, Jiangxi, and Huguang provinces).     

Radiative forcing over China due to albedo change caused by land cover change during 1990–2010

Land cover change affects surface radiation budget and energy balance by chang- ing surface albedo and further impacts the regional and global climate. In this article, high spatial and temporal resolution satellite products were used to analyze the driving mechanism for surface albedo change caused by land cover change during 1990-2010. In addition, the annual-scale radiative forcing caused by surface albedo changes in China＇s 50 ecological regions were calculated to reveal the biophysical mechanisms of land cover change affecting climate change at regional scale. Our results showed that the national land cover changes were mainly caused by land reclamation, grassland desertification and urbanization in past 20 years, which were almost induced by anthropogenic activities. Grassland and forest area decreased by 0.60% and 0.11%, respectively. The area of urban and farmland increased by 0.60% and 0.19%, respectively. The mean radiative forcing caused by land cover changes during 1990-2010 was 0.062 W/m2 in China, indicating a warming climate effect. However, spatial heterogeneity of radiative forcing was huge among different ecological regions. Farmland conversing to urban construction land, the main type of land cover change for the urban and suburban agricultural ecological region in Beijing-Tianjin-Tangshan region, caused an albedo reduction by 0.00456 and a maximum positive radiative forcing of 0.863 WIm2, which was presented as warming climate effects. Grassland and forest conversing to farmland, the main type of land cover change for the temperate humid agricultural and wetland ecological region in Sanjiang Plain, caused an albedo increase by 0.00152 and a maximum negative radiative forcing of 0.184 W/m2, implying cooling climate effects.     

综合地理数据与MODIS物候特征的区域土地覆盖制图(英文)

The study developed a feasible method for large-area land cover mapping with combination of geographical data and phenological characteristics, taking Northeast China (NEC) as the study area. First, with the monthly average of precipitation and temperature datasets, the spatial clustering method was used to divide the NEC into four ecoclimate regions. For each ecoclimate region, geographical variables (annual mean precipitation and temperature, elevation, slope and aspect) were combined with phenological variables derived from the moderate resolution imaging spectroradiometer (MODIS) data (enhanced vegetation index (EVI) and land surface water index (LSWI)), which were taken as input variables of land cover classification. Decision Tree (DT) classifiers were then performed to produce land cover maps for each region. Finally, four resultant land cover maps were mosaicked for the entire NEC (NEC_MODIS), and the land use and land cover data of NEC (NEC_LULC) interpreted from Landsat-TM images was used to evaluate the NEC_MODIS and MODIS land cover product (MODIS_IGBP) in terms of areal and spatial agreement. The results showed that the phenological information derived from EVI and LSWI time series well discriminated land cover classes in NEC, and the overall accuracy was significantly improved by 5.29% with addition of geographical variables. Compared with NEC_LULC for seven aggregation classes, the area errors of NEC_MODIS were much smaller and more stable than that of MODIS_IGBP for most of classes, and the wall-to-wall spatial comparisons at pixel level indicated that NEC_MODIS agreed with NEC_LULC for 71.26% of the NEC, whereas only 62.16% for MODIS_IGBP. The good performance of NEC_MODIS demonstrates that the methodology developed in the study has great potential for timely and detailed land cover mapping in temperate and boreal regions.     

内蒙古农牧交错带土地利用变化对土壤碳储量的影响研究（英文）

Soil organic carbon(SOC) stocks in terrestrial ecosystems vary considerably with land use types. Grassland, forest, and cropland coexist in the agro-pastoral ecotone of Inner Mongolia, China. Using SOC data compiled from literature and field investigations, this study compared SOC stocks and their vertical distributions among three types of ecosystems. The results indicate that grassland had the largest SOC stock, which was 1.5-and 1.8-folds more than stocks in forest and cropland, respectively. Relative to the stock in 0–100 cm depth, grassland held more than 40% of its SOC stock in the upper 20 cm soil layer; forest and cropland both held over 30% of their respective SOC stocks in the upper 20 cm soil layer. SOC stocks in grazed grasslands were remarkably promoted after ≥20 years of grazing exclusion. Conservational cultivation substantially increased the SOC stocks in cropland, especially in the 0–40 cm depth. Stand ages, tree species, and forest types did not have obvious impacts on forest SOC stocks in the study area likely due to the younger stand ages. Our study implies that soil carbon loss should be taken into account during the implementation of ecological projects, such as reclamation and afforestation, in the arid and semi-arid regions of China.     

Seasonal changes in the relationship between species richness and community biomass in grassland under grazing and exclosure, Horqin Sandy Land, northern China

How species diversity–productivity relationships respond to temporal dynamics and land use is still not clear in semi-arid grassland ecosystems. We analyzed seasonal changes of the relationships between vegetation cover, plant density, species richness, and aboveground biomass in grasslands under grazing and exclosure in the Horqin Sandy Land of northern China. Our results showed that in grazed and fenced grassland, vegetation cover, richness, and biomass were lower in April than in August, whereas plant density showed a reverse trend. Vegetation cover during the growing season and biomass in June and August were higher in fenced grassland than in grazed grassland, whereas plant density in April and June was lower in fenced grassland than in grazed grassland. A negative relationship between species richness and biomass was found in August in fenced grassland, and in grazed grassland the relationship between plant density and biomass changed from positive in April to negative in August. The relationship between the density of the dominant plant species and the total biomass also varied with seasonal changes and land use (grazing and exclosure). These results suggest that long-term grazing, seasonal changes, and their interaction significantly influence vegetation cover, plant density, and biomass in grasslands. Plant species competition in fenced grassland results in seasonal changes of the relationship between species richness and biomass. Long-term grazing also affects seasonal changes of the density and biomass of dominant plant species, which further affects the seasonal relationship between plant density and biomass in grasslands. Our study demonstrates the importance of temporal dynamics and land use in understanding the relationship between species richness and ecosystem function.     

1987–2010年中国新增建设用地占用耕地格局演变研究（英文）

Over the past few decades,built-up land in China has increasingly expanded with rapid urbanization,industrialization and rural settlements construction.The expansions encroached upon a large amount of cropland,placing great challenges on national food security.Although the impacts of urban expansion on cropland have been intensively illustrated,few attentions have been paid to differentiating the effects of growing urban areas,rural settlements,and industrial/transportation land.To fill this gap and offer comprehensive implications on framing policies for cropland protection,this study investigates and compares the spatio-temporal patterns of cropland conversion to urban areas,rural settlements,and industrial/transportation land from 1987 to 2010,based on land use maps interpreted from remote sensing imagery.Five indicators were developed to analyze the impacts of built-up land expansion on cropland in China.We find that 42,822 km2 of cropland were converted into built-up land in China,accounting for 43.8% of total cropland loss during 1987–2010.Urban growth showed a greater impact on cropland loss than the expansion of rural settlements and the expansion of industrial/transportation land after 2000.The contribution of rural settlement expansion decreased;however,rural settlement saw the highest percentage of traditional cropland loss which is generally in high quality.The contribution of industrial/transportation land expansion increased dramatically and was mainly distributed in major food production regions.These changes were closely related to the economic restructuring,urban-rural transformation and government policies in China.Future cropland conservation should focus on not only finding a reasonable urbanization mode,but also solving the "hollowing village" problem and balancing the industrial transformations.     

开垦对内蒙古温带草地土壤不同有机碳组分的影响(英文)

Cultivation is one of the most important human activities affecting the grassland ecosystem besides grazing, but its impacts on soil total organic carbon (C), especially on the liable organic C fractions have not been fully understood yet. In this paper, the role of cropping in soil organic C pool of different fractions was investigated in a meadow steppe region in Inner Mongolia of China, and the relationships between different C fractions were also discussed. The results indicated that the concentrations of different C fractions at steppe and cultivated land all decreased progressively with soil depth. After the conversion from steppe to spring wheat field for 36 years, total organic carbon (TOC) concentration at the 0 to 100 cm soil depth has decreased by 12.3% to 28.2%, and TOC of the surface soil horizon, especially those of 0-30 cm decreased more significantly (p<0.01). The dissolved organic carbon (DOC) and microbial biomass carbon (MBC) at the depth of 0-40 cm were found to have decreased by 66.7% to 77.1% and 36.5% to 42.4%, respectively. In the S.baicalensis steppe, the ratios of soil DOC to TOC varied between 0.52% and 0.60%, and those in the spring wheat field were only in the range of 0.18%-0.20%. The microbial quotients (qMBs) in the spring wheat field, varying from 1.11% to 1.40%, were also lower than those in the S. baicalensis steppe, which were in the range of 1.50%-1.63%. The change of DOC was much more sensitive to cultivation disturbance. Soil TOC, DOC, and MBC were significantly positive correlated with each other in the S. baicalensis steppe, but in the spring wheat field, the correlativity between DOC and TOC and that between DOC and MBC did not reach the significance level of 0.05.     

热带森林覆被的时空动态评价——以印度Malkangiri district of Orissa为例

Tropical forests have been recognized as having global conservation importance. However,they are being rapidly destroyed in many regions of the world. Regular monitoring of forests is necessary for an adaptive management approach and the successful implementation of ecosystem management. The present study analyses the temporal changes in forest ecosystem structure in tribal dominated Malkangiri district of Orissa,India,during 1973-2004 period based on digitized forest cover maps using geographic information system (GIS) and interpretation of satellite data. Three satellite images Landsat MSS (1973),Landsat TM (1990) and IRS P6 LISS III (2004) were used to determine changes. Six land cover types were delineated which includes dense forest,open forest,scrub land,agriculture,barren land and water body. Different forest types were also demarcated within forest class for better understanding the degradation pattern in each forest types. The results showed that there was a net decrease of 475.7 km2 forest cover (rate of deforestation = 2.34) from 1973 to 1990 and 402.3 km2 (rate of deforestation = 2.27) from 1990 to 2004. Forest cover has changed over time depending on a few factors such as large-scale deforestation,shifting cultivation,dam and road construction,unregulated management actions,and social pressure. A significant increase of 1222.8 km2 agriculture area (1973-2004) clearly indicated the conversion of forest cover to agricultural land. These alterations had resulted in significant environmental consequences,including decline in forest cover,soil erosion,and loss of biodiversity. There is an urgent need for rational management of the remaining forest for it to be able to survive beyond next decades. Particular attention must be paid to tropical forests,which are rapidly being deforested.     

黄淮海平原农区土地利用转型及其动力机制（英文）

Land use transition refers to changes in land use morphology, including dominant morphology and recessive morphology, of a particular region over a period of time driven by various factors. Recently, issues related to land use transition in China have attracted interest among a wide variety of researchers as well as government officials. This paper examines the patterns of land use transition and their dynamic mechanism in the Huang-Huai-Hai Plain during 2000–2010. First, the spatio-temporal patterns of land use transition, their characteristics and the laws governing them were analyzed. Second, based on the established conceptual framework for analyzing the dynamic mechanism of land use transition, a spatial econometric regression analysis method was used to analyze the dynamic mechanism of the five types of major land use transition in the Huang-Huai-Hai Plain at the county level. Land use pattern changes in the study area were characterized by an increase in construction land, water body and forested land, along with a decrease in farmland, unused land and grassland. The changes during 2000–2005 were much more significant than those during 2005–2010. In terms of factors affecting land use transitions, natural factors form the basis, and they have long-term effects. Socio-economic factors such as population and GDP, however, tend to determine the direction, structure, size and layout of land use transition over shorter time periods. Land law and policy factors play a mandatory guiding and restraining role in land use transitions, so as to improve the overall efficiency of land use. Land resource engineering is also an important tool to control land use transitions. In general, the five types of major land use transition were the result of the combined action of various physical, social and economic factors, of which traffic condition and location condition had the most significant effects, i.e. they were the common factors in all land use transitions. Understanding the spatio-temporal process of land use transitions and their dynamic mechanisms is an important foundation for utilizing land resources, protecting regional ecological environment and promoting sustainable regional socio-economic development.     

清末松嫩平原耕地重建方法比较分析（英文）

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 I) 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 cropland distributions reconstructed by the two methods exhibit a similar spatial distribution pattern. 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 II. This finding suggests that reconstruction using method I may have less bias than reconstruction with method II.     

Scenarios of land cover in Eurasia under climate change

The method for surface modelling of land cover scenarios(SMLCS) has been improved to simulate the scenarios of land cover in Eurasia. On the basis of the observation monthly climatic data observed from 2127 weather stations in Eurasia during 1981–2010, the climatic scenarios data of RCP26, RCP45 and RCP85 scenarios released by CMIP5, and the land cover current data of Eurasia in 2010, the land cover scenarios of Eurasia were respectively simulated. The results show that most land cover types would generally have similar changing trends in the future, but with some difference in different periods under the three scenarios of RCP26, RCP45 and RCP85. Deciduous needleleaf forest, mixed forest, shrub land, wetlands and snow and ice would generally decrease in Eurasia during 2010–2100. Snow and ice would have the fastest decreasing rate that would decrease by 37.42% on average. Shrub land would have the slowest decreasing rate that would decrease by 5.65% on average. Water bodies would have the fastest increasing rate that would increase by 28.78% on average. Barren or sparsely vegetated land would have the slowest increasing rate that would increase by 0.76%. Moreover, the simulated results show that climate change would directly impact on land cover change in Eurasia.     

环京津贫困带土地利用变化多情景模拟与景观格局动态变化——以河北省张家口市为例（英文）

Land use/cover change has been recognized as a key component in global change and has attracted increasing attention in recent decades. Scenario simulation of land use change is an important issue in the study of land use/cover change, and plays a key role in land use prediction and policy decision. Based on the remote sensing data of Landsat TM images in 1989, 2000 and 2010, scenario simulation and landscape pattern analysis of land use change driven by socio-economic development and ecological protection policies were reported in Zhangjiakou city, a representative area of the Poverty Belt around Beijing and Tianjin. Using a CLUE-S model, along with socio-economic and geographic data, the land use simulation of four scenarios–namely, land use planning scenario, natural development scenario, ecological-oriented scenario and farmland protection scenario–were explored according to the actual conditions of Zhangjiakou city, and the landscape pattern characteristics under different land use scenarios were analyzed. The results revealed the following:(1) Farmland, grassland, water body and unused land decreased significantly during 1989–2010, with a decrease of 11.09%, 2.82%, 18.20% and 31.27%, respectively, while garden land, forestland and construction land increased over the same period, with an increase of 5.71%, 20.91% and 38.54%, respectively. The change rate and intensity of land use improved in general from 1989 to 2010. The integrated dynamic degree of land use increased from 2.21% during 1989–2000 to 3.96% during 2000–2010.(2) Land use changed significantly throughout 1989–2010. The total area that underwent land use change was 4759.14 km2, accounting for 12.53% of the study area. Land use transformation was characterized by grassland to forestland, and by farmland to forestland and grassland.(3) Under the land use planning scenario, farmland, grassland, water body and unused land shrank significantly, while garden land, forestland and construction land increased. Under the natural development scenario, construction land and forestland increased in 2020 compared with 2010, while farmland and unused land decreased. Under the ecological-oriented scenario, forestland increased dra-matically, which mainly derived from farmland, grassland and unused land. Under the farmland protection scenario, farmland was well protected and stable, while construction land expansion was restricted.(4) The landscape patterns of the four scenarios in 2020, compared with those in 2010, were more reasonable. Under the land use planning scenario, the landscape pattern tended to be more optimized. The landscape became less fragmented and heterogeneous with the natural development scenarios. However, under the ecological-oriented scenario and farmland protection scenario, landscape was characterized by fragmentation, and spatial heterogeneity of landscape was significant. Spatial differences in landscape patterns in Zhangjiakou city also existed.(5) The spatial distribution of land use could be explained, to a large extent, by the driving factors, and the simulation results tallied with the local situations, which provided useful information for decision-makers and planners to take appropriate land management measures in the area. The application of the combined Markov model, CLUE-S model and landscape metrics in Zhangjiakou city suggests that this methodology has the capacity to reflect the complex changes in land use at a scale of 300 m×300 m and can serve as a useful tool for analyzing complex land use driving factors.