Hengduan Mountains offer land space for a variety of ecological services. However, the sustainable development and management of land space has been challenged by increased human activities in recent years. This paper...Hengduan Mountains offer land space for a variety of ecological services. However, the sustainable development and management of land space has been challenged by increased human activities in recent years. This paper performs the spatial pattern analysis of the quantitative and structural changes of various landscapes at different altitudes, and uses the land use data in 1990, 2000, 2010 and 2015 to reveal how various land patterns have changed. The results show that, within the production-living-ecological space schema, the ecological space dominates Hengduan Mountains, while the production and living space was mainly distributed in south region. During 1990-2015, the production-living-ecological spatial changes had been gradually accelerated and the regional differences had become more prominent. The agricultural production space had continuously decreased by 1132.31 km^2, and the industrial and mining production space had rapidly increased by 281.4 km^2 during 1990-2015. The living space had steadily increased, and the ecological space had increased with fluctuations. The land space pattern in Hengduan Mountains was greatly restricted by the terrain, such as altitude and slope. The implementations of China Western Development Strategy and the Returning Farmland to Forest Program had favorably promoted the changes of land spatial pattern in Hengduan Mountains.展开更多
In this study,we employed a number of geospatial techniques to examine the spatiotemporal patterns and changes of environmental attitudes and place attachment values in the Gauteng province of South Africa.The data we...In this study,we employed a number of geospatial techniques to examine the spatiotemporal patterns and changes of environmental attitudes and place attachment values in the Gauteng province of South Africa.The data were obtained from the Gauteng City Region Observatory’s Quality of Life Survey collected at three separate points in time,namely 2013,2015,and 2017.Results indicated that wards(smallest administrative and analysis units)located on the urban periphery of Gauteng,which are generally less affluent,largely held more negative environmental attitudes and place attachment values during the three time periods.In contrast,centrally located wards,which are generally more affluent,expressed more positive environmental attitudes but less place attachment values,especially in 2017.The findings of this research not only highlight the complex spatio-temporal distribution of environmental attitudes and place attachment values throughout Gauteng but also empha-size the need for spatially targeted state interventions for future environmental planning within the province.展开更多
Rice is one of the most important grain crops in Northeast China （NEC） and its cultivation is sensitive to climate change. This study aimed to explore the spatio-temporal changes in the NEC rice planting area over t...Rice is one of the most important grain crops in Northeast China （NEC） and its cultivation is sensitive to climate change. This study aimed to explore the spatio-temporal changes in the NEC rice planting area over the period of 1980-2010 and to analyze their relationship to climate change. To do so, the CLUE-S （conversion of land use and its effects at small region extent） model was ifrst updated and used to simulate dynamic changes in the rice planting area in NEC to understand spatio-temporal change trends during three periods： 1980-1990, 1990-2000 and 2000-2010. The changing results in individual periods were then linked to climatic variables to investigate the climatic drivers of these changes. Results showed that the NEC rice planting area expanded quickly and increased by nearly 4.5 times during 1980-2010. The concentration of newly planted rice areas in NEC constantly moved northward and the changes were strongly dependent on latitude. This conifrmed that climate change, increases in temperature in particular, greatly inlfuenced the shift in the rice planting area. The shift in the north limit of the NEC rice planting area generally followed a 1＆#176;C isoline migration pattern, but with an obvious time-lag effect. These ifndings can help policy makers and crop producers take proper adaptation measures even when exposed to the global warming situation in NEC.展开更多
The source regions of the Yangtze and Yellow rivers are important water conservation areas of China. In recent years, ecological deterioration trend of the source regions caused by global climate change and unreasonab...The source regions of the Yangtze and Yellow rivers are important water conservation areas of China. In recent years, ecological deterioration trend of the source regions caused by global climate change and unreasonable resource development increased gradually. In this paper, the spatial distribution and dynamic change of vegetation cover in the source regions of the Yangtze and Yellow rivers are analyzed in recent 10 years based on 1-km resolution multi-temporal SPOTVGT-DN data from 1998 to 2007. Meanwhile, the cor- relation relationships between air temperature, precipitation, shallow ground temperature and NDVI, which is 3x3 pixel at the center of Wudaoliang, Tuotuohe, Qumalai, Maduo, and Dari meteorological stations were analyzed. The results show that the NDVI values in these two source regions are increasing in recent 10 years. Spatial distribution of NDVI which was consistent with hydrothermal condition decreased from southeast to northwest of the source regions. NDVI with a value over 0.54 was mainly distributed in the southeastern source region of the Yellow River, and most NDVI values in the northwestern source region of the Yangtze River were less than 0.22. Spatial changing trend of NDVI has great difference and most parts in the source regions of the Yangtze and Yellow rivers witnessed indistinct change. The regions with marked increasing trend were mainly distributed on the south side of the Tongtian River, some part of Keqianqu, Tongtian, Chumaer, and Tuotuo rivers in the source region of the Yangtze River and Xingsuhai, and southern Dari county in the source region of the Yellow River. The regions with very marked increasing tendency were mainly distributed on the south side of Tongtian Rriver and sporadically distributed in hinterland of the source re- gion of the Yangtze River. The north side of Tangula Range in the source region of the Yangtze River and Dari and Maduo counties in the source region of the Yellow River were areas in which NDVI changed with marked decreasing tendency. The NDVI change was positively correlated with average temperature, precipitation and shallow ground temperature. Shallow ground temperature had the greatest effect on NDVI change, and the second greatest factor influencing NDVI was average temperature. The correlation between NDVI and shallow ground temperature in the source regions of the Yangtze and Yellow rivers increased significantly with the depth of soil layer.展开更多
The aim of this paper was to research the spatio-temporal changes in total soluble salt content （TS） in a typical arid region of South Xinjiang, China, where the climate is arid and soil salinization happens easily....The aim of this paper was to research the spatio-temporal changes in total soluble salt content （TS） in a typical arid region of South Xinjiang, China, where the climate is arid and soil salinization happens easily. The total soluble salt content was interpreted by measurements made in the horizontal mode with EM38 and EM31. The electromagnetic induction （EM） surveys were made three times with the apparent soil electrical conductivity （ECa） measurements taken at 3 873 locations in Nov. 2008, 4 807 locations in Apr. 2009 and 6 324 locations in Nov. 2009, respectively. For interpreting the ECa measurements into total soluble salt content, calibtion sites were needed for EM survey of each time, e.g., 66 sites were selected in Nov. 2008 to measure ECa, and soils-core samples were taken by different depth layers of 0-10, 10-20 and 20-40 cm at the same time. On every time duplicate samples were taken at five sites to allevaite the local-scale variability, and soil temperatures in different layers through the profiles were also measured. Factors including TS, pH, water content, bulk density were analyzed by lab experiments. ECa calibration equations were obtained by linear regression analysis, which indicated that soil salinity was one primary concern to ECa with a determination coefficient of 0.792 in 0-10 cm layer, 0.711 in 10-20 cm layer and 0.544 in 20-40 cm layer, respectively. The maps of spatial distribution were predicted by Kriging interpolation, which showed that the high soil salinity was located near the drainage canal, which validated the trend effect caused by the irrigation canal and the drainage canal. And by comparing the soil salinity in different layers, the soluble salt accumulated to the top soil surface only in the area where the soil salinization was serious, and in the other areas, the soil salinity trended to increase from the top soil surface to 40 cm depth. Temporal changes showed that the soil salinity in November was higher than that in April, and the soil salinization trended to aggravate, especially in the top soil layer of 0-10 cm.展开更多
Primary cilia function as critical sensory organelles that mediate multiple signaling pathways,including the Hedgehog(Hh)pathway,which is essential for organ patterning and morphogenesis.Disruptions in Hh signaling ha...Primary cilia function as critical sensory organelles that mediate multiple signaling pathways,including the Hedgehog(Hh)pathway,which is essential for organ patterning and morphogenesis.Disruptions in Hh signaling have been implicated in supernumerary tooth formation and molar fusion in mutant mice.Cilk1,a highly conserved serine/threonine-protein kinase localized within primary cilia,plays a critical role in ciliary transport.Loss of Cilk1 results in severe ciliopathy phenotypes,including polydactyly,edema,and cleft palate.However,the role of Cilk1 in tooth development remains unexplored.In this study,we investigated the role of Cilk1 in tooth development.Cilk1 was found to be expressed in both the epithelial and mesenchymal compartments of developing molars.Cilk1 deficiency resulted in altered ciliary dynamics,characterized by reduced frequency and increased length,accompanied by downregulation of Hh target genes,such as Ptch1 and Sostdc1,leading to the formation of diastemal supernumerary teeth.Furthermore,in Cilk1^(-/-);PCS1–MRCS1^(△/△)mice,which exhibit a compounded suppression of Hh signaling,we uncovered a novel phenomenon:diastemal supernumerary teeth can be larger than first molars.Based on these findings,we propose a progressive model linking Hh signaling levels to sequential changes in tooth patterning:initially inducing diastemal supernumerary teeth,then enlarging them,and ultimately leading to molar fusion.This study reveals a previously unrecognized role of Cilk1 in controlling tooth morphology via Hh signaling and highlights how Hh signaling levels shape tooth patterning in a gradient-dependent manner.展开更多
Land use and its dynamics have attracted considerable scientific attention for their significant ecological and socioeconomic implications.Many studies have investigated the past changes in land use,but efforts explor...Land use and its dynamics have attracted considerable scientific attention for their significant ecological and socioeconomic implications.Many studies have investigated the past changes in land use,but efforts exploring the potential changes in land use and implications under future scenarios are still lacking.Here we simulate the future land use changes and their impacts on ecosystem services in Northeast China(NEC) over the period of 2000–2050 using the CLUE–S(Conversion of Land Use and its Effects at Small regional extent) model under the scenarios of ecological security(ESS),food security(FSS) and comprehensive development(CDS).The model was validated against remote sensing data in 2005.Overall,the accuracy of the CLUE–S model was evaluated at 82.5%.Obtained results show that future cropland changes mainly occur in the Songnen Plain and the Liaohe Plain,forest and grassland changes are concentrated in the southern Lesser Khingan Mountains and the western Changbai Mountains,while the Sanjiang Plain will witness major changes of the wetlands.Our results also show that even though CDS is defined based on the goals of the regional development plan,the ecological service value(ESV) under CDS is RMB 2656.18 billion in 2050.The ESV of CDS is lower compared with the other scenarios.Thus,CDS is not an optimum scenario for eco-environmental protection,especially for the wetlands,which should be given higher priority for future development.The issue of coordination is also critical in future development.The results can help to assist structural adjustments for agriculture and to guide policy interventions in NEC.展开更多
Underground coal fires are one of the most common and serious geohazards in most coal producing countries in the world. Monitoring their spatio-temporal changes plays an important role in controlling and preventing th...Underground coal fires are one of the most common and serious geohazards in most coal producing countries in the world. Monitoring their spatio-temporal changes plays an important role in controlling and preventing the effects of coal fires, and their environmental impact. In this study, the spatio-temporal changes of underground coal fires in Khanh Hoa coal field(North-East of Viet Nam) were analyzed using Landsat time-series data during the 2008-2016 period. Based on land surface temperatures retrieved from Landsat thermal data, underground coal fires related to thermal anomalies were identified using the MEDIAN+1.5×IQR(IQR: Interquartile range) threshold technique. The locations of underground coal fires were validated using a coal fire map produced by the field survey data and cross-validated using the daytime ASTER thermal infrared imagery. Based on the fires extracted from seven Landsat thermal imageries, the spatiotemporal changes of underground coal fire areas were analyzed. The results showed that the thermalanomalous zones have been correlated with known coal fires. Cross-validation of coal fires using ASTER TIR data showed a high consistency of 79.3%. The largest coal fire area of 184.6 hectares was detected in 2010, followed by 2014(181.1 hectares) and 2016(178.5 hectares). The smaller coal fire areas were extracted with areas of 133.6 and 152.5 hectares in 2011 and 2009 respectively. Underground coal fires were mainly detected in the northern and southern part, and tend to spread to north-west of the coal field.展开更多
Based on the satellite remote sensing TM/ETM images of Xuzhou city, basic data about land use of the city from 1994 to 2000 are obtained with the neural network classification module of PCI software, and the dynamic c...Based on the satellite remote sensing TM/ETM images of Xuzhou city, basic data about land use of the city from 1994 to 2000 are obtained with the neural network classification module of PCI software, and the dynamic con- version matrix of land use is thus calculated. The areas of construction land and water body have increased by 1833.93 hm2 and 804.87 hm2, respectively. On the contrary, the area of cropland has decreased by 3207.24 hm2. The area of cropland converted into construction land makes up 26.84%, and that converted into water body amounts for 8.17% of the total area of cropland in 1994. The variation index of land use degree and the dynamic degree index of land use computed are 1.38 and 57.81%, respectively, which demonstrate that land use in Xuzhou is in a development period and the changes are drastic. The frequency index and importance index of the form in which cropland converted into con- struction land are 29.91% and 68.93% respectively. The results indicate that the change is not only widespread in space but a major form of spatial change of land use in the area.展开更多
A socio-economic data set on China＇s historical flood losses for the period 1984--2012 was compiled to analyze the exposed population, economy, and crop area as well as the vulnerabilities of the population and econo...A socio-economic data set on China＇s historical flood losses for the period 1984--2012 was compiled to analyze the exposed population, economy, and crop area as well as the vulnerabilities of the population and economy to floods. The results revealed that the exposed population was approximately 126 persons km-2 per year when taking China as a whole; in terms of the economy, potential losses due to floods were estimated to be approximately 1.49 million C/W4 km 2 and the crop area exposed to floods covered 153 million hm2 per year. China＇s total exposure to floods significantly increased over the analysis period. The areas that showed the higher exposure were mainly located along the east coast. The population＇s vulnerability to floods showed a significantly increasing trend, however, the economic vulnerability showed a decreasing trend. The populations and economies that were most vulnerable to floods were in Hunan, Anhui, Chongqing, Jiangxi, and Hubei provinces. The municipalities of Shanghai, Beijing, and Tianjin showed the lowest vulnerabilities to floods.展开更多
Forests play a central role in the global carbon cycle.China's forests have a high carbon sequestration potential owing to their wide distribution,young age and relatively low carbon density.Forest biomass is an e...Forests play a central role in the global carbon cycle.China's forests have a high carbon sequestration potential owing to their wide distribution,young age and relatively low carbon density.Forest biomass is an essential variable for assessing carbon sequestration capacity,thus determining the spatio-temporal changes of forest biomass is critical to the national carbon budget and to contribute to sustainable forest management.Based on Chinese forest inventory data(1999–2013),this study explored spatial patterns of forest biomass at a grid resolution of 1 km by applying a downscaling method and further analyzed spatiotemporal changes of biomass at different spatial scales.The main findings are:(1)the regression relationship between forest biomass and the associated infuencing factors at a provincial scale can be applied to estimate biomass at a pixel scale by employing a downscaling method;(2)forest biomass had a distinct spatial pattern with the greatest biomass occurring in the major mountain ranges;(3)forest biomass changes had a notable spatial distribution pattern;increase(i.e.,carbon sinks)occurred in east and southeast China,decreases(i.e.,carbon sources)were observed in the northeast to southwest,with the largest biomass losses in the Hengduan Mountains,Southern Hainan and Northern Da Hinggan Mountains;and,(4)forest vegetation functioned as a carbon sink during 1999–2013 with a net increase in biomass of 3.71 Pg.展开更多
By constructing evaluation indicator system of sustainable land use of Tibet from three aspects of ecological environment, economic development, resources and social advancement, this article studies the following con...By constructing evaluation indicator system of sustainable land use of Tibet from three aspects of ecological environment, economic development, resources and social advancement, this article studies the following contents respectively in two dimensions of time and space： the changes of sustainable land use of Tibet in recent 20 years and spatial characteristics of sustainable land use of Tibet in 2002. The following conclusions can be drawn from evaluation results .① With regard to com- prehensive evaluation value of sustainable land use, the trend of Tibet sustainable land use evaluation values from 1983 to 2002 are very close to the comprehensive evaluation values of ecological environment, which is up trend; ② sustainable utilization degree of land use in eastern region of Tibet is much higher than that of western region. ③ the sustainable land use evaluation value of Nyingtri County is the highest, and the counties with relatively higher land sustainable use values include Lhasa, Lhoka, Chamdo. While Nakchu, Ngari, Shigatse counties have the relatively lower evaluation values; ④ By analyzing each evaluation indicator＇s weight on sustainable land use, it can be concluded that the key limiting factors of sustainable Tibet land resource utilization are land desertification, grassland degradation and low economic level.展开更多
Detailed information on the spatio-temporal changes of cropland soil organic carbon(SOC) can significantly contribute to the improvement of soil fertility and mitigate climate change. Nonetheless, information and know...Detailed information on the spatio-temporal changes of cropland soil organic carbon(SOC) can significantly contribute to the improvement of soil fertility and mitigate climate change. Nonetheless, information and knowledge on the national scale spatio-temporal changes and the corresponding uncertainties of SOC in Chinese upland soils remain limited. The CENTURY model was used to estimate the SOC storages and their changes in Chinese uplands from 1980 to 2010. With the Monte Carlo method, the uncertainties of CENTURY-modelled SOC dynamics associated with the spatial heterogeneous model inputs were quantified. Results revealed that the SOC storage in Chinese uplands increased from 3.03(1.59 to 4.78) Pg C in 1980 to 3.40(2.39 to 4.62) Pg C in 2010. Increment of SOC storage during this period was 370 Tg C, with an uncertainty interval of –440 to 1110 Tg C. The regional disparities of SOC changes reached a significant level, with considerable SOC accumulation in the Huang-Huai-Hai Plain of China and SOC loss in the northeastern China. The SOC lost from Meadow soils, Black soils and Chernozems was most severe, whilst SOC accumulation in Fluvo-aquic soils, Cinnamon soils and Purplish soils was most significant. In modelling large-scale SOC dynamics, the initial soil properties were major sources of uncertainty. Hence, more detailed information concerning the soil properties must be collected. The SOC stock of Chinese uplands in 2010 was still relatively low, manifesting that recommended agricultural management practices in conjunction with effectively economic and policy incentives to farmers for soil fertility improvement were indispensable for future carbon sequestration in these regions.展开更多
An improved Carnegie Ames Stanford Approach model （CASA model） was used to estimate the net primary productivity （NPP） of the Northeast China Transect （NECT） every month from 1982 to 2000. The spatial-temporal d...An improved Carnegie Ames Stanford Approach model （CASA model） was used to estimate the net primary productivity （NPP） of the Northeast China Transect （NECT） every month from 1982 to 2000. The spatial-temporal distribution of NPP along NECT and its response to climatic change were also analyzed. Results showed that the change tendency of NPP spatial distribution in NECT is quite similar to that of precipitation and their spatial correlation coefficient is up to 0.84 （P 〈 0.01）. The inter-annual variation of NPP in NECT is mainly affected by the change of the aestival NPP every year, which accounts for 67.6% of the inter-annual increase in NPP and their spatial correlation coefficient is 0.95 （P 〈 0.01）. The NPP in NECT is mainly cumulated between May and September, which accounts for 89.8% of the annual NPP. The NPP in summer （June to August） accounts for 65.9% of the annual NPP and is the lowest in winter. Recent climate changes have enhanced plant growth in NECT. The mean NPP increased 14.3% from 1980s to 1990s. The inter-annual linear trend of NPP is 4.6 gC·m^-2·a^-1, and the relative trend is 1.17%, which owns mainly to the increasing temperature.展开更多
By using GIS, RS and landscape ecology, LandsatTM (1993 and 2009) and ETM (2001) remote sensing images of Licheng District of Ji’nan City, Shandong Province were interpreted, and dynamic changes of landscape pattern ...By using GIS, RS and landscape ecology, LandsatTM (1993 and 2009) and ETM (2001) remote sensing images of Licheng District of Ji’nan City, Shandong Province were interpreted, and dynamic changes of landscape pattern in the district were analyzed at the levels of class and landscape. The results showed that during the 16 years the landscape pattern in the district had changed significantly. (a) From the perspective of patch category, areas of arable land, woodland and grassland decreased unceasingly, and arable land accounted for the largest reduction from 488.15 km 2 in 1993 down to 324.37 km 2 in 2009, witnessing a reduction rate of 33.56%. But the patch quantity and fragmentation increased, patch connectivity reduced. Spatial pattern of construction land expanded and its area witnessed a significant increase of 147.05%. Patch cohesion index increased and connectivity grew better. (b) From the perspective of overall landscape, patch quantity, contagion and perimeter-area fractal dimension decreased, patch shape became simple, the Shannon’s diversity index, Shannon’s evenness index and splitting index increased, landscape heterogeneity rose. With the rapid social and economic development, landscape pattern will be more and more influenced by human behaviors展开更多
Based on analyzing the changes of land use in Wuzhong District, Suzhou City from 2005 to 2008, temporal and spatial changes of land use from 2008 to 2020 were analyzed by using the model CLUE-S and, from the perspecti...Based on analyzing the changes of land use in Wuzhong District, Suzhou City from 2005 to 2008, temporal and spatial changes of land use from 2008 to 2020 were analyzed by using the model CLUE-S and, from the perspective of landscape ecology, future landscape pattern changes of land use in Wuzhong District were also quantitatively discussed by utilizing landscape indices. The results indicated that there was a large variation range of land use in Wuzhong District from 2005 to 2008 and massive farmland and woodland were transformed into construction land and gardens. Guided by the policy of saving intensive land and protecting farmland, future variation range of land use will get smaller obviously. The fragmentation degree for farmland, woodland and water area will get decreased but will get increased relatively for construction land. In general, all landscapes tend to a balanced development.展开更多
Land-use/land-cover changes （LUCCs） have links to both human and nature inter- actions. China＇s Land-Use/cover Datasets （CLUDs） were updated regularly at 5-year inter- vals from the late 1980s to 2010, with stand...Land-use/land-cover changes （LUCCs） have links to both human and nature inter- actions. China＇s Land-Use/cover Datasets （CLUDs） were updated regularly at 5-year inter- vals from the late 1980s to 2010, with standard procedures based on Landsat TM／ETM＋ im- ages. A land-use dynamic regionalization method was proposed to analyze major land-use conversions. The spatiotemporal characteristics, differences, and causes of land-use changes at a national scale were then examined. The main findings are summarized as fol- lows. Land-use changes （LUCs） across China indicated a significant variation in spatial and temporal characteristics in the last 20 years （1990-2010）. The area of cropland change de- creased in the south and increased in the north, but the total area remained almost un- changed. The reclaimed cropland was shifted from the northeast to the northwest. The built-up lands expanded rapidly, were mainly distributed in the east, and gradually spread out to central and western China. Woodland decreased first, and then increased, but desert area was the opposite. Grassland continued decreasing. Different spatial patterns of LUC in China were found between the late 20th century and the early 21st century. The original 13 LUC zones were replaced by 15 units with changes of boundaries in some zones. The main spatial characteristics of these changes included （1） an accelerated expansion of built-up land in the Huang-Huai-Hai region, the southeastern coastal areas, the midstream area of the Yangtze River, and the Sichuan Basin; （2） shifted land reclamation in the north from northeast China and eastern Inner Mongolia to the oasis agricultural areas in northwest China; （3） continuous transformation from rain-fed farmlands in northeast China to paddy fields; and （4） effective- ness of the ＂Grain for Green＂ project in the southern agricultural-pastoral ecotones of Inner Mongolia, the Loess Plateau, and southwestern mountainous areas. In the last two decades, although climate change in the north affected the change in cropland, policy regulation and economic driving forces were still the primary causes of LUC across China. During the first decade of the 21st century, the anthropogenic factors that drove variations in land-use pat- terns have shifted the emphasis from one-way land development to both development and conservation. The ＂dynamic regionalization method＂ was used to analyze changes in the spatial patterns of zoning boundaries, the internal characteristics of zones, and the growth and decrease of units. The results revealed ＂the pattern of the change process,＂ namely the process of LUC and regional differences in characteristics at different stages. The growth and decrease of zones during this dynamic LUC zoning, variations in unit boundaries, and the characteristics of change intensities between the former and latter decades were examined. The patterns of alternative transformation between the ＂pattern＂ and ＂process＂ of land use and the causes for changes in different types and different regions of land use were explored.展开更多
Drought, which is one of the most frequently occurring severe hazards with long time scales and cov- ering wide geographical areas, is a natural phenomenon resulting in significant economic losses in agriculture and i...Drought, which is one of the most frequently occurring severe hazards with long time scales and cov- ering wide geographical areas, is a natural phenomenon resulting in significant economic losses in agriculture and industry. Drought is caused by an imbalance between the inputs of and the demand for water which is insufficient to meet the demands of human activities and the eco-environment. As a major arid and semi-arid area and an important agricultural region in Northwest China, North Xinjiang （NX） shows great vulnerability to drought. In this paper, the characteristics of inter-annual and seasonal drought were analyzed in terms of drought occurrence and drought coverage, by using the composite index of meteorological drought and the data of daily precipitation, air temperature, wind speed, relative humidity and sunshine duration from 38 meteorological stations during the period 1961-2012. Trend analysis, wavelet analysis and empirical orthogonal function were also applied to investigate change trend, period and regional characteristics, respectively. In NX, annual and seasonal drought occurrence and drought coverage all showed a decreasing trend that was most significant in winter （with rates of-0.26 month/10a and -15.46%, respectively）, and drought occurrence in spring and summer were more frequent than that in autumn and winter. Spatially, drought was severe in eastern regions but mild in western regions of NX. Annual and seasonal drought occurrence at 38 meteorological stations displayed decreasing trends and were most significant in ＂Shi- hezi-Urumqi-Changji＂, which can help to alleviate severe drought hazards for local agricultural production and improve human livelihood. NX can be approximately classified into three sub-regions （severe drought region, moder- ate drought region and mild drought region）, which were calculated from annual drought frequencies. The cross wavelet transform suggested that SOl （Southern Oscillation Index）, AOI （Arctic Oscillation Index）, AAOI （Antarctic Oscillation Index）, PAOI （Pacific/North American Oscillation Index） and NAOI （North Atlantic Oscillation Index） have significant correlation with the variation of drought occurrence in NX. To prevent and mitigate the occurrence of drought disasters in NX, agricultural and government managers should pay more attention to those drought events that occur in spring and summer.展开更多
Agricultural landscape along the riparian zones is designated as important landscape components for partly controlling water quality, biodiversity, as well as for their aesthetic role in landscapes. Therefore, the cha...Agricultural landscape along the riparian zones is designated as important landscape components for partly controlling water quality, biodiversity, as well as for their aesthetic role in landscapes. Therefore, the change of agricultural landscape along the riparian zones is at the top of the agenda for many policy makers and landscape planners. As a basis for conservation management, sufficient information about landscape structure should be provided. In the present study, we reconstructed the former landscape structure and elucidated the changes in landscape patterns during a period of about 15 years. Two sets of maps were used： a landsat-5 TM image （1987） and landsat-7 ETM image （2002）. The frequency index, landscape diversity index and landscape fragmentation index were calculated for analyses. The results showed that： （1） the areas of the irrigated land, river, forest and beach landscape classes presented a decreasing trend while the areas of landscape classes of pool, paddy fields, dry land and construction land increased. （2） Disturbed by human activity, landscape diversity index increased but landscape fragmentation index decreased. In short, Human activities have had important influences on agricultural landscape of the riparian zones along the Yellow River in Henan Province.展开更多
Border area is not only an important gateway for inland opening-up,but also an important part of completing the building of a moderately prosperous society and optimizing national urban spatial pattern in China.Due to...Border area is not only an important gateway for inland opening-up,but also an important part of completing the building of a moderately prosperous society and optimizing national urban spatial pattern in China.Due to the location,natural resources endowment,and traffic accessibility,the urbanization speed is relatively slow in border areas.Therefore,it is a special area that needs to pay close attention to,especially under the background of the Belt and Road Initiative and China's regional coordinated development program.Based on the county-level data from 2000 to 2015,this paper tries to analyze the spatio-temporal pattern of urbanization in 134 border counties,and applies geographical detector method to study the driving forces of urbanization in border areas.Conclusions are as follows:(1)From 2000 to 2015,urbanization rate in border areas has been lower than the national average,and the gap has been widening.Some border counties in southern Xinjiang,Tibet,northeast of Inner Mongolia,and Yunnan,are even facing the problem of population loss.(2)In the same period,urbanization rate in the northwestern and southwestern border is low,while their urbanization rate grows relatively faster comparing with other border counties;urbanization rate in Tibet border is the lowest and grows relatively slowly;urbanization rate in the northeastern and northern border is slightly higher,but it grows slowly or even stagnates.(3)Transportation and industry are the important driving forces of urbanization in border areas,while the driving forces of market is relatively weak.And there are obvious mutual reinforcements among the driving forces,while the effort and explanatory power of resource force increases obviously after interaction.(4)Urbanization rate in the northwestern and southwestern border areas grows relatively fast,with industrial force and transportation force,market force and administrative force as the main driving forces respectively.Tibet border area has the lowest urbanization rate and growth rate,as the driving force of urbanization with strong contribution has not yet formed in Tibet.In the northeastern and northern border areas,the contribution of transportation force to urbanization is greater than other forces,and its interaction with market and industry has obvious effects.展开更多
基金Major State Basic Research Development Program of China,No.2015CB452706
文摘Hengduan Mountains offer land space for a variety of ecological services. However, the sustainable development and management of land space has been challenged by increased human activities in recent years. This paper performs the spatial pattern analysis of the quantitative and structural changes of various landscapes at different altitudes, and uses the land use data in 1990, 2000, 2010 and 2015 to reveal how various land patterns have changed. The results show that, within the production-living-ecological space schema, the ecological space dominates Hengduan Mountains, while the production and living space was mainly distributed in south region. During 1990-2015, the production-living-ecological spatial changes had been gradually accelerated and the regional differences had become more prominent. The agricultural production space had continuously decreased by 1132.31 km^2, and the industrial and mining production space had rapidly increased by 281.4 km^2 during 1990-2015. The living space had steadily increased, and the ecological space had increased with fluctuations. The land space pattern in Hengduan Mountains was greatly restricted by the terrain, such as altitude and slope. The implementations of China Western Development Strategy and the Returning Farmland to Forest Program had favorably promoted the changes of land spatial pattern in Hengduan Mountains.
文摘In this study,we employed a number of geospatial techniques to examine the spatiotemporal patterns and changes of environmental attitudes and place attachment values in the Gauteng province of South Africa.The data were obtained from the Gauteng City Region Observatory’s Quality of Life Survey collected at three separate points in time,namely 2013,2015,and 2017.Results indicated that wards(smallest administrative and analysis units)located on the urban periphery of Gauteng,which are generally less affluent,largely held more negative environmental attitudes and place attachment values during the three time periods.In contrast,centrally located wards,which are generally more affluent,expressed more positive environmental attitudes but less place attachment values,especially in 2017.The findings of this research not only highlight the complex spatio-temporal distribution of environmental attitudes and place attachment values throughout Gauteng but also empha-size the need for spatially targeted state interventions for future environmental planning within the province.
基金supported and financed by the National Basic Research Program of China(973 Program,2010CB951504)the National Natural Science Foundation of China(41201089 and 41271112)
文摘Rice is one of the most important grain crops in Northeast China （NEC） and its cultivation is sensitive to climate change. This study aimed to explore the spatio-temporal changes in the NEC rice planting area over the period of 1980-2010 and to analyze their relationship to climate change. To do so, the CLUE-S （conversion of land use and its effects at small region extent） model was ifrst updated and used to simulate dynamic changes in the rice planting area in NEC to understand spatio-temporal change trends during three periods： 1980-1990, 1990-2000 and 2000-2010. The changing results in individual periods were then linked to climatic variables to investigate the climatic drivers of these changes. Results showed that the NEC rice planting area expanded quickly and increased by nearly 4.5 times during 1980-2010. The concentration of newly planted rice areas in NEC constantly moved northward and the changes were strongly dependent on latitude. This conifrmed that climate change, increases in temperature in particular, greatly inlfuenced the shift in the rice planting area. The shift in the north limit of the NEC rice planting area generally followed a 1＆#176;C isoline migration pattern, but with an obvious time-lag effect. These ifndings can help policy makers and crop producers take proper adaptation measures even when exposed to the global warming situation in NEC.
基金National Basic Task Project, No.2006FY110200Strategic pilot programs of the Chinese Academy of Sciences,No.XDA05060700Ministry of Environmental Protection Special Funds for Scientific Research on Public Causes, No.200909050
文摘The source regions of the Yangtze and Yellow rivers are important water conservation areas of China. In recent years, ecological deterioration trend of the source regions caused by global climate change and unreasonable resource development increased gradually. In this paper, the spatial distribution and dynamic change of vegetation cover in the source regions of the Yangtze and Yellow rivers are analyzed in recent 10 years based on 1-km resolution multi-temporal SPOTVGT-DN data from 1998 to 2007. Meanwhile, the cor- relation relationships between air temperature, precipitation, shallow ground temperature and NDVI, which is 3x3 pixel at the center of Wudaoliang, Tuotuohe, Qumalai, Maduo, and Dari meteorological stations were analyzed. The results show that the NDVI values in these two source regions are increasing in recent 10 years. Spatial distribution of NDVI which was consistent with hydrothermal condition decreased from southeast to northwest of the source regions. NDVI with a value over 0.54 was mainly distributed in the southeastern source region of the Yellow River, and most NDVI values in the northwestern source region of the Yangtze River were less than 0.22. Spatial changing trend of NDVI has great difference and most parts in the source regions of the Yangtze and Yellow rivers witnessed indistinct change. The regions with marked increasing trend were mainly distributed on the south side of the Tongtian River, some part of Keqianqu, Tongtian, Chumaer, and Tuotuo rivers in the source region of the Yangtze River and Xingsuhai, and southern Dari county in the source region of the Yellow River. The regions with very marked increasing tendency were mainly distributed on the south side of Tongtian Rriver and sporadically distributed in hinterland of the source re- gion of the Yangtze River. The north side of Tangula Range in the source region of the Yangtze River and Dari and Maduo counties in the source region of the Yellow River were areas in which NDVI changed with marked decreasing tendency. The NDVI change was positively correlated with average temperature, precipitation and shallow ground temperature. Shallow ground temperature had the greatest effect on NDVI change, and the second greatest factor influencing NDVI was average temperature. The correlation between NDVI and shallow ground temperature in the source regions of the Yangtze and Yellow rivers increased significantly with the depth of soil layer.
基金supported by the Special Fund of Industrial (Agriculture) Research for Public Welfare of China(200903001)the Special Fund of Industrial (Marine) Research for Public Welfare of China (201105020-3 and 201105020-4)+2 种基金the Science and Technology Support Program of Jiangsu Province, China (BE2010313)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-359)the National Natural Science Foundation of China (41171181)
文摘The aim of this paper was to research the spatio-temporal changes in total soluble salt content （TS） in a typical arid region of South Xinjiang, China, where the climate is arid and soil salinization happens easily. The total soluble salt content was interpreted by measurements made in the horizontal mode with EM38 and EM31. The electromagnetic induction （EM） surveys were made three times with the apparent soil electrical conductivity （ECa） measurements taken at 3 873 locations in Nov. 2008, 4 807 locations in Apr. 2009 and 6 324 locations in Nov. 2009, respectively. For interpreting the ECa measurements into total soluble salt content, calibtion sites were needed for EM survey of each time, e.g., 66 sites were selected in Nov. 2008 to measure ECa, and soils-core samples were taken by different depth layers of 0-10, 10-20 and 20-40 cm at the same time. On every time duplicate samples were taken at five sites to allevaite the local-scale variability, and soil temperatures in different layers through the profiles were also measured. Factors including TS, pH, water content, bulk density were analyzed by lab experiments. ECa calibration equations were obtained by linear regression analysis, which indicated that soil salinity was one primary concern to ECa with a determination coefficient of 0.792 in 0-10 cm layer, 0.711 in 10-20 cm layer and 0.544 in 20-40 cm layer, respectively. The maps of spatial distribution were predicted by Kriging interpolation, which showed that the high soil salinity was located near the drainage canal, which validated the trend effect caused by the irrigation canal and the drainage canal. And by comparing the soil salinity in different layers, the soluble salt accumulated to the top soil surface only in the area where the soil salinization was serious, and in the other areas, the soil salinity trended to increase from the top soil surface to 40 cm depth. Temporal changes showed that the soil salinity in November was higher than that in April, and the soil salinization trended to aggravate, especially in the top soil layer of 0-10 cm.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korean government(MSIT)(NRF-2020R1A2C2005790,NRF2023R1A2C1007510,RS-2023-00269830,RS-2024-00438542)。
文摘Primary cilia function as critical sensory organelles that mediate multiple signaling pathways,including the Hedgehog(Hh)pathway,which is essential for organ patterning and morphogenesis.Disruptions in Hh signaling have been implicated in supernumerary tooth formation and molar fusion in mutant mice.Cilk1,a highly conserved serine/threonine-protein kinase localized within primary cilia,plays a critical role in ciliary transport.Loss of Cilk1 results in severe ciliopathy phenotypes,including polydactyly,edema,and cleft palate.However,the role of Cilk1 in tooth development remains unexplored.In this study,we investigated the role of Cilk1 in tooth development.Cilk1 was found to be expressed in both the epithelial and mesenchymal compartments of developing molars.Cilk1 deficiency resulted in altered ciliary dynamics,characterized by reduced frequency and increased length,accompanied by downregulation of Hh target genes,such as Ptch1 and Sostdc1,leading to the formation of diastemal supernumerary teeth.Furthermore,in Cilk1^(-/-);PCS1–MRCS1^(△/△)mice,which exhibit a compounded suppression of Hh signaling,we uncovered a novel phenomenon:diastemal supernumerary teeth can be larger than first molars.Based on these findings,we propose a progressive model linking Hh signaling levels to sequential changes in tooth patterning:initially inducing diastemal supernumerary teeth,then enlarging them,and ultimately leading to molar fusion.This study reveals a previously unrecognized role of Cilk1 in controlling tooth morphology via Hh signaling and highlights how Hh signaling levels shape tooth patterning in a gradient-dependent manner.
基金Agricultural Outstanding Talents Research Foundation of Ministry of Agriculture(MOA)Key Laboratory of Agri–Informatics Foundation of MOA No.2015001+1 种基金Natural Science Foundation of Hubei Province No.2016CFB558The Fundamental Research Funds for the Central Universities,No.CCNU15A05058
文摘Land use and its dynamics have attracted considerable scientific attention for their significant ecological and socioeconomic implications.Many studies have investigated the past changes in land use,but efforts exploring the potential changes in land use and implications under future scenarios are still lacking.Here we simulate the future land use changes and their impacts on ecosystem services in Northeast China(NEC) over the period of 2000–2050 using the CLUE–S(Conversion of Land Use and its Effects at Small regional extent) model under the scenarios of ecological security(ESS),food security(FSS) and comprehensive development(CDS).The model was validated against remote sensing data in 2005.Overall,the accuracy of the CLUE–S model was evaluated at 82.5%.Obtained results show that future cropland changes mainly occur in the Songnen Plain and the Liaohe Plain,forest and grassland changes are concentrated in the southern Lesser Khingan Mountains and the western Changbai Mountains,while the Sanjiang Plain will witness major changes of the wetlands.Our results also show that even though CDS is defined based on the goals of the regional development plan,the ecological service value(ESV) under CDS is RMB 2656.18 billion in 2050.The ESV of CDS is lower compared with the other scenarios.Thus,CDS is not an optimum scenario for eco-environmental protection,especially for the wetlands,which should be given higher priority for future development.The issue of coordination is also critical in future development.The results can help to assist structural adjustments for agriculture and to guide policy interventions in NEC.
基金funded by the Ministry-level Scientific and Technological Key Programs of Ministry of Natural Resources and Environment of Viet Nam "Application of thermal infrared remote sensing and GIS for mapping underground coal fires in Quang Ninh coal basin" (Grant No. TNMT.2017.08.06)
文摘Underground coal fires are one of the most common and serious geohazards in most coal producing countries in the world. Monitoring their spatio-temporal changes plays an important role in controlling and preventing the effects of coal fires, and their environmental impact. In this study, the spatio-temporal changes of underground coal fires in Khanh Hoa coal field(North-East of Viet Nam) were analyzed using Landsat time-series data during the 2008-2016 period. Based on land surface temperatures retrieved from Landsat thermal data, underground coal fires related to thermal anomalies were identified using the MEDIAN+1.5×IQR(IQR: Interquartile range) threshold technique. The locations of underground coal fires were validated using a coal fire map produced by the field survey data and cross-validated using the daytime ASTER thermal infrared imagery. Based on the fires extracted from seven Landsat thermal imageries, the spatiotemporal changes of underground coal fire areas were analyzed. The results showed that the thermalanomalous zones have been correlated with known coal fires. Cross-validation of coal fires using ASTER TIR data showed a high consistency of 79.3%. The largest coal fire area of 184.6 hectares was detected in 2010, followed by 2014(181.1 hectares) and 2016(178.5 hectares). The smaller coal fire areas were extracted with areas of 133.6 and 152.5 hectares in 2011 and 2009 respectively. Underground coal fires were mainly detected in the northern and southern part, and tend to spread to north-west of the coal field.
基金Projects 40401038 supported by National Natural Science Foundation of China, and 05KJB420133 by Natural Science Foundation for Colleges and Universities in Jiangsu Province
文摘Based on the satellite remote sensing TM/ETM images of Xuzhou city, basic data about land use of the city from 1994 to 2000 are obtained with the neural network classification module of PCI software, and the dynamic con- version matrix of land use is thus calculated. The areas of construction land and water body have increased by 1833.93 hm2 and 804.87 hm2, respectively. On the contrary, the area of cropland has decreased by 3207.24 hm2. The area of cropland converted into construction land makes up 26.84%, and that converted into water body amounts for 8.17% of the total area of cropland in 1994. The variation index of land use degree and the dynamic degree index of land use computed are 1.38 and 57.81%, respectively, which demonstrate that land use in Xuzhou is in a development period and the changes are drastic. The frequency index and importance index of the form in which cropland converted into con- struction land are 29.91% and 68.93% respectively. The results indicate that the change is not only widespread in space but a major form of spatial change of land use in the area.
基金supported by the National Basic Research Program of China(No.2012CB955903)
文摘A socio-economic data set on China＇s historical flood losses for the period 1984--2012 was compiled to analyze the exposed population, economy, and crop area as well as the vulnerabilities of the population and economy to floods. The results revealed that the exposed population was approximately 126 persons km-2 per year when taking China as a whole; in terms of the economy, potential losses due to floods were estimated to be approximately 1.49 million C/W4 km 2 and the crop area exposed to floods covered 153 million hm2 per year. China＇s total exposure to floods significantly increased over the analysis period. The areas that showed the higher exposure were mainly located along the east coast. The population＇s vulnerability to floods showed a significantly increasing trend, however, the economic vulnerability showed a decreasing trend. The populations and economies that were most vulnerable to floods were in Hunan, Anhui, Chongqing, Jiangxi, and Hubei provinces. The municipalities of Shanghai, Beijing, and Tianjin showed the lowest vulnerabilities to floods.
基金supported by the National Key Research and Development Program of China(2019YFA0606603)the National Natural Science Foundation of China(No.41971234)the Project of Graduate Student Innovative and Practical Research in Jiangsu Province(KYCX20-0028)。
文摘Forests play a central role in the global carbon cycle.China's forests have a high carbon sequestration potential owing to their wide distribution,young age and relatively low carbon density.Forest biomass is an essential variable for assessing carbon sequestration capacity,thus determining the spatio-temporal changes of forest biomass is critical to the national carbon budget and to contribute to sustainable forest management.Based on Chinese forest inventory data(1999–2013),this study explored spatial patterns of forest biomass at a grid resolution of 1 km by applying a downscaling method and further analyzed spatiotemporal changes of biomass at different spatial scales.The main findings are:(1)the regression relationship between forest biomass and the associated infuencing factors at a provincial scale can be applied to estimate biomass at a pixel scale by employing a downscaling method;(2)forest biomass had a distinct spatial pattern with the greatest biomass occurring in the major mountain ranges;(3)forest biomass changes had a notable spatial distribution pattern;increase(i.e.,carbon sinks)occurred in east and southeast China,decreases(i.e.,carbon sources)were observed in the northeast to southwest,with the largest biomass losses in the Hengduan Mountains,Southern Hainan and Northern Da Hinggan Mountains;and,(4)forest vegetation functioned as a carbon sink during 1999–2013 with a net increase in biomass of 3.71 Pg.
文摘By constructing evaluation indicator system of sustainable land use of Tibet from three aspects of ecological environment, economic development, resources and social advancement, this article studies the following contents respectively in two dimensions of time and space： the changes of sustainable land use of Tibet in recent 20 years and spatial characteristics of sustainable land use of Tibet in 2002. The following conclusions can be drawn from evaluation results .① With regard to com- prehensive evaluation value of sustainable land use, the trend of Tibet sustainable land use evaluation values from 1983 to 2002 are very close to the comprehensive evaluation values of ecological environment, which is up trend; ② sustainable utilization degree of land use in eastern region of Tibet is much higher than that of western region. ③ the sustainable land use evaluation value of Nyingtri County is the highest, and the counties with relatively higher land sustainable use values include Lhasa, Lhoka, Chamdo. While Nakchu, Ngari, Shigatse counties have the relatively lower evaluation values; ④ By analyzing each evaluation indicator＇s weight on sustainable land use, it can be concluded that the key limiting factors of sustainable Tibet land resource utilization are land desertification, grassland degradation and low economic level.
基金Under the auspices of National Key Research and Development Program of China(No.2017YFA0603002)National Natural Science Foundation of China(No.31800358,31700369)+1 种基金Jiangsu Agricultural Science and Technology Innovation Fund(No.CX(19)3099)the Foundation of Jiangsu Vocational College of Agriculture and Forestry(No.2019kj014)。
文摘Detailed information on the spatio-temporal changes of cropland soil organic carbon(SOC) can significantly contribute to the improvement of soil fertility and mitigate climate change. Nonetheless, information and knowledge on the national scale spatio-temporal changes and the corresponding uncertainties of SOC in Chinese upland soils remain limited. The CENTURY model was used to estimate the SOC storages and their changes in Chinese uplands from 1980 to 2010. With the Monte Carlo method, the uncertainties of CENTURY-modelled SOC dynamics associated with the spatial heterogeneous model inputs were quantified. Results revealed that the SOC storage in Chinese uplands increased from 3.03(1.59 to 4.78) Pg C in 1980 to 3.40(2.39 to 4.62) Pg C in 2010. Increment of SOC storage during this period was 370 Tg C, with an uncertainty interval of –440 to 1110 Tg C. The regional disparities of SOC changes reached a significant level, with considerable SOC accumulation in the Huang-Huai-Hai Plain of China and SOC loss in the northeastern China. The SOC lost from Meadow soils, Black soils and Chernozems was most severe, whilst SOC accumulation in Fluvo-aquic soils, Cinnamon soils and Purplish soils was most significant. In modelling large-scale SOC dynamics, the initial soil properties were major sources of uncertainty. Hence, more detailed information concerning the soil properties must be collected. The SOC stock of Chinese uplands in 2010 was still relatively low, manifesting that recommended agricultural management practices in conjunction with effectively economic and policy incentives to farmers for soil fertility improvement were indispensable for future carbon sequestration in these regions.
基金This paper was supported by the National Natural Sci-ence Foundation of China (Grant No. 40371001) and the Youth Foundation of Beijing Normal University
文摘An improved Carnegie Ames Stanford Approach model （CASA model） was used to estimate the net primary productivity （NPP） of the Northeast China Transect （NECT） every month from 1982 to 2000. The spatial-temporal distribution of NPP along NECT and its response to climatic change were also analyzed. Results showed that the change tendency of NPP spatial distribution in NECT is quite similar to that of precipitation and their spatial correlation coefficient is up to 0.84 （P 〈 0.01）. The inter-annual variation of NPP in NECT is mainly affected by the change of the aestival NPP every year, which accounts for 67.6% of the inter-annual increase in NPP and their spatial correlation coefficient is 0.95 （P 〈 0.01）. The NPP in NECT is mainly cumulated between May and September, which accounts for 89.8% of the annual NPP. The NPP in summer （June to August） accounts for 65.9% of the annual NPP and is the lowest in winter. Recent climate changes have enhanced plant growth in NECT. The mean NPP increased 14.3% from 1980s to 1990s. The inter-annual linear trend of NPP is 4.6 gC·m^-2·a^-1, and the relative trend is 1.17%, which owns mainly to the increasing temperature.
文摘By using GIS, RS and landscape ecology, LandsatTM (1993 and 2009) and ETM (2001) remote sensing images of Licheng District of Ji’nan City, Shandong Province were interpreted, and dynamic changes of landscape pattern in the district were analyzed at the levels of class and landscape. The results showed that during the 16 years the landscape pattern in the district had changed significantly. (a) From the perspective of patch category, areas of arable land, woodland and grassland decreased unceasingly, and arable land accounted for the largest reduction from 488.15 km 2 in 1993 down to 324.37 km 2 in 2009, witnessing a reduction rate of 33.56%. But the patch quantity and fragmentation increased, patch connectivity reduced. Spatial pattern of construction land expanded and its area witnessed a significant increase of 147.05%. Patch cohesion index increased and connectivity grew better. (b) From the perspective of overall landscape, patch quantity, contagion and perimeter-area fractal dimension decreased, patch shape became simple, the Shannon’s diversity index, Shannon’s evenness index and splitting index increased, landscape heterogeneity rose. With the rapid social and economic development, landscape pattern will be more and more influenced by human behaviors
文摘Based on analyzing the changes of land use in Wuzhong District, Suzhou City from 2005 to 2008, temporal and spatial changes of land use from 2008 to 2020 were analyzed by using the model CLUE-S and, from the perspective of landscape ecology, future landscape pattern changes of land use in Wuzhong District were also quantitatively discussed by utilizing landscape indices. The results indicated that there was a large variation range of land use in Wuzhong District from 2005 to 2008 and massive farmland and woodland were transformed into construction land and gardens. Guided by the policy of saving intensive land and protecting farmland, future variation range of land use will get smaller obviously. The fragmentation degree for farmland, woodland and water area will get decreased but will get increased relatively for construction land. In general, all landscapes tend to a balanced development.
基金National Basic Research Program of China,No.2010CB950900No.2014CB954302+1 种基金National Key Technol-ogy R&D Program,No.2013BAC03B00The Key Research Program of the Chinese Academy of Sciences,No.KSZD-EW-Z-021-02
文摘Land-use/land-cover changes （LUCCs） have links to both human and nature inter- actions. China＇s Land-Use/cover Datasets （CLUDs） were updated regularly at 5-year inter- vals from the late 1980s to 2010, with standard procedures based on Landsat TM／ETM＋ im- ages. A land-use dynamic regionalization method was proposed to analyze major land-use conversions. The spatiotemporal characteristics, differences, and causes of land-use changes at a national scale were then examined. The main findings are summarized as fol- lows. Land-use changes （LUCs） across China indicated a significant variation in spatial and temporal characteristics in the last 20 years （1990-2010）. The area of cropland change de- creased in the south and increased in the north, but the total area remained almost un- changed. The reclaimed cropland was shifted from the northeast to the northwest. The built-up lands expanded rapidly, were mainly distributed in the east, and gradually spread out to central and western China. Woodland decreased first, and then increased, but desert area was the opposite. Grassland continued decreasing. Different spatial patterns of LUC in China were found between the late 20th century and the early 21st century. The original 13 LUC zones were replaced by 15 units with changes of boundaries in some zones. The main spatial characteristics of these changes included （1） an accelerated expansion of built-up land in the Huang-Huai-Hai region, the southeastern coastal areas, the midstream area of the Yangtze River, and the Sichuan Basin; （2） shifted land reclamation in the north from northeast China and eastern Inner Mongolia to the oasis agricultural areas in northwest China; （3） continuous transformation from rain-fed farmlands in northeast China to paddy fields; and （4） effective- ness of the ＂Grain for Green＂ project in the southern agricultural-pastoral ecotones of Inner Mongolia, the Loess Plateau, and southwestern mountainous areas. In the last two decades, although climate change in the north affected the change in cropland, policy regulation and economic driving forces were still the primary causes of LUC across China. During the first decade of the 21st century, the anthropogenic factors that drove variations in land-use pat- terns have shifted the emphasis from one-way land development to both development and conservation. The ＂dynamic regionalization method＂ was used to analyze changes in the spatial patterns of zoning boundaries, the internal characteristics of zones, and the growth and decrease of units. The results revealed ＂the pattern of the change process,＂ namely the process of LUC and regional differences in characteristics at different stages. The growth and decrease of zones during this dynamic LUC zoning, variations in unit boundaries, and the characteristics of change intensities between the former and latter decades were examined. The patterns of alternative transformation between the ＂pattern＂ and ＂process＂ of land use and the causes for changes in different types and different regions of land use were explored.
基金supported by International Science & Technology Cooperation Program of China (2010DFA92720)the Scientific Innovation Research Project for Graduate Students of XinjiangSoil Science Key Discipline Project of Xinjiang Uygur Autonomous Region
文摘Drought, which is one of the most frequently occurring severe hazards with long time scales and cov- ering wide geographical areas, is a natural phenomenon resulting in significant economic losses in agriculture and industry. Drought is caused by an imbalance between the inputs of and the demand for water which is insufficient to meet the demands of human activities and the eco-environment. As a major arid and semi-arid area and an important agricultural region in Northwest China, North Xinjiang （NX） shows great vulnerability to drought. In this paper, the characteristics of inter-annual and seasonal drought were analyzed in terms of drought occurrence and drought coverage, by using the composite index of meteorological drought and the data of daily precipitation, air temperature, wind speed, relative humidity and sunshine duration from 38 meteorological stations during the period 1961-2012. Trend analysis, wavelet analysis and empirical orthogonal function were also applied to investigate change trend, period and regional characteristics, respectively. In NX, annual and seasonal drought occurrence and drought coverage all showed a decreasing trend that was most significant in winter （with rates of-0.26 month/10a and -15.46%, respectively）, and drought occurrence in spring and summer were more frequent than that in autumn and winter. Spatially, drought was severe in eastern regions but mild in western regions of NX. Annual and seasonal drought occurrence at 38 meteorological stations displayed decreasing trends and were most significant in ＂Shi- hezi-Urumqi-Changji＂, which can help to alleviate severe drought hazards for local agricultural production and improve human livelihood. NX can be approximately classified into three sub-regions （severe drought region, moder- ate drought region and mild drought region）, which were calculated from annual drought frequencies. The cross wavelet transform suggested that SOl （Southern Oscillation Index）, AOI （Arctic Oscillation Index）, AAOI （Antarctic Oscillation Index）, PAOI （Pacific/North American Oscillation Index） and NAOI （North Atlantic Oscillation Index） have significant correlation with the variation of drought occurrence in NX. To prevent and mitigate the occurrence of drought disasters in NX, agricultural and government managers should pay more attention to those drought events that occur in spring and summer.
基金Human Geography provincialkeystonesubjectofHenan University
文摘Agricultural landscape along the riparian zones is designated as important landscape components for partly controlling water quality, biodiversity, as well as for their aesthetic role in landscapes. Therefore, the change of agricultural landscape along the riparian zones is at the top of the agenda for many policy makers and landscape planners. As a basis for conservation management, sufficient information about landscape structure should be provided. In the present study, we reconstructed the former landscape structure and elucidated the changes in landscape patterns during a period of about 15 years. Two sets of maps were used： a landsat-5 TM image （1987） and landsat-7 ETM image （2002）. The frequency index, landscape diversity index and landscape fragmentation index were calculated for analyses. The results showed that： （1） the areas of the irrigated land, river, forest and beach landscape classes presented a decreasing trend while the areas of landscape classes of pool, paddy fields, dry land and construction land increased. （2） Disturbed by human activity, landscape diversity index increased but landscape fragmentation index decreased. In short, Human activities have had important influences on agricultural landscape of the riparian zones along the Yellow River in Henan Province.
基金National Natural Science Foundation of China,No.41871120Priority Research Program of Chinese Academy of Sciences,No.XDA20010102。
文摘Border area is not only an important gateway for inland opening-up,but also an important part of completing the building of a moderately prosperous society and optimizing national urban spatial pattern in China.Due to the location,natural resources endowment,and traffic accessibility,the urbanization speed is relatively slow in border areas.Therefore,it is a special area that needs to pay close attention to,especially under the background of the Belt and Road Initiative and China's regional coordinated development program.Based on the county-level data from 2000 to 2015,this paper tries to analyze the spatio-temporal pattern of urbanization in 134 border counties,and applies geographical detector method to study the driving forces of urbanization in border areas.Conclusions are as follows:(1)From 2000 to 2015,urbanization rate in border areas has been lower than the national average,and the gap has been widening.Some border counties in southern Xinjiang,Tibet,northeast of Inner Mongolia,and Yunnan,are even facing the problem of population loss.(2)In the same period,urbanization rate in the northwestern and southwestern border is low,while their urbanization rate grows relatively faster comparing with other border counties;urbanization rate in Tibet border is the lowest and grows relatively slowly;urbanization rate in the northeastern and northern border is slightly higher,but it grows slowly or even stagnates.(3)Transportation and industry are the important driving forces of urbanization in border areas,while the driving forces of market is relatively weak.And there are obvious mutual reinforcements among the driving forces,while the effort and explanatory power of resource force increases obviously after interaction.(4)Urbanization rate in the northwestern and southwestern border areas grows relatively fast,with industrial force and transportation force,market force and administrative force as the main driving forces respectively.Tibet border area has the lowest urbanization rate and growth rate,as the driving force of urbanization with strong contribution has not yet formed in Tibet.In the northeastern and northern border areas,the contribution of transportation force to urbanization is greater than other forces,and its interaction with market and industry has obvious effects.
