Understanding the spatial patterns of land-use and land-cover(LULC)and their driving forces in transnational areas is important for the sustainable development of these regions.However,the spatial patterns of LULC and...Understanding the spatial patterns of land-use and land-cover(LULC)and their driving forces in transnational areas is important for the sustainable development of these regions.However,the spatial patterns of LULC and their driving forces across multiple scales are poorly understood in transnational areas.In this study,we analyzed the spatial patterns of LULC and driving forces in the transnational area of Tumen River(TATR)in 2016 across two scales:the entire region and the sub-regions of China,the Democratic People’s Republic of Korea(DPRK),and Russia.Results showed that the LULC was dominated by broadleaf forest and dry farmland in the TATR in 2016,which accounted for 66.86%and 13.60%of the entire region,respectively.Meanwhile,the LULC in the three sub-regions exhibited noticeable differences.In the Chinese and the DPRK’s sub-regions,the area of broadleaf forest was greater than those for the other LULC types,while the Russian sub-region was dominated by broadleaf forest and grassland.The spatial patterns of LULC were mainly influenced by topography,climate,soil properties,and human activities.In addition,the driving forces of the spatial patterns of LULC in the TATR had an obvious scaling effect.Therefore,we suggest that effective policies and regulations with cooperation among China,the DPRK,and Russia are needed to plan the spatial patterns of LULC and improve the sustainable development of the TATR.展开更多
The availability of better economic possibilities and well-connected transportation networks has attracted people to migrate to peri-urban and rural neighbourhoods,changing the landscape of regions outside the city an...The availability of better economic possibilities and well-connected transportation networks has attracted people to migrate to peri-urban and rural neighbourhoods,changing the landscape of regions outside the city and fostering the growth of physical infrastructure.Using multi-temporal satellite images,the dynamics of Land Use/Land Cover(LULC)changes,the impact of urban growth on LULC changes,and regional environmental implications were investigated in the peri-urban and rural neighbourhoods of Durgapur Municipal Corporation in India.The study used different case studies to highlight the study area’s heterogeneity,as the phenomenon of change is not consistent.Landsat TM and OLI-TIRS satellite images in 1991,2001,2011,and 2021 were used to analyse the changes in LULC types.We used the relative deviation(RD),annual change intensity(ACI),uniform intensity(UI)to show the dynamicity of LULC types(agriculture land;built-up land;fallow land;vegetated land;mining area;and water bodies)during 1991-2021.This study also applied the Decision-Making Trial and Evaluation Laboratory(DEMATEL)to measure environmental sensitivity zones and find out the causes of LULC changes.According to LULC statistics,agriculture land,built-up land,and mining area increased by 51.7,95.46,and 24.79 km^(2),respectively,from 1991 to 2021.The results also suggested that built-up land and mining area had the greatest land surface temperature(LST),whereas water bodies and vegetated land showed the lowest LST.Moreover,this study looked at the relationships among LST,spectral indices(Normalized Differenced Built-up Index(NDBI),Normalized Difference Vegetation Index(NDVI),and Normalized Difference Water Index(NDWI)),and environmental sensitivity.The results showed that all of the spectral indices have the strongest association with LST,indicating that built-up land had a far stronger influence on the LST.The spectral indices indicated that the decreasing trends of vegetated land and water bodies were 4.26 and 0.43 km^(2)/a,respectively,during 1991-2021.In summary,this study can help the policy-makers to predict the increasing rate of temperature and the causes for the temperature increase with the rapid expansion of built-up land,thus making effective peri-urban planning decisions.展开更多
The purpose of this study was to classify current forest cover types,and to investigate stand development patterns for natural forests in six areas in northern Baekdudaegan,South Korea.Twenty-eight independent forest ...The purpose of this study was to classify current forest cover types,and to investigate stand development patterns for natural forests in six areas in northern Baekdudaegan,South Korea.Twenty-eight independent forest communities were aggregated into eight forest cover types by species composition in the overstory of each forest community.The forest cover types were of mixed mesophytic,‘‘others’ ’ deciduous,Quercus mongolica dominant,Q.mongolica pure,Pinus densiflora–Q.mongolica,P.densiflora,Betula ermanii,and Q.mongolica–P.koraiensis.The ecological information was organized by importance value and species diversity for each forest type.Based on the correlation between species diversity index and the abundance of Q.mongolica plus P.densiflora for corresponding forest cover types,we compared the developmental process and approximate successional pathway between each cover type.The P.densiflora forest cover type changes into the P.densiflora–Q.mongolica cover type,followed by the Q.mongolica dominant cover type through continuous invasion of the oak trees.Furthermore,the Q.mongolica pure cover type would spread toward the Q.mongolica dominant cover type with a mixture of various deciduous tree species.The Q.mongolica dominant cover type progresses through the other deciduous cover types to the mixed mesophytic cover type with diversified composition and structure.On the mid to lower slopes,with loamy soils and good moisture conditions,various deciduous forest types should progress,by ecological succession,toward the mixed mesophytic cover type without any further disturbance.展开更多
With the objectives to acquire the fundamental dat a of the territorial resource, understand the impacts of human activit ies on the land use and cover patterns and evaluate the potential of the future exploitation, a...With the objectives to acquire the fundamental dat a of the territorial resource, understand the impacts of human activit ies on the land use and cover patterns and evaluate the potential of the future exploitation, an intensive land cover classification with an accuracy of 93% has been completed for North Ningxia by remote sen sing technique based on the adoption of a combination method composed o f texture training, maximum likelihood classification and post-processing such as re-allocation and aggregation. This classification result was incorporated with the contemporaneous socio-economic and meteorological d ata for cross-sectional regression modelling to reveal the spatial dete rminants of the land cover patterns and understand the human-environmen tal relationships. A tentative evaluation on the potential of soil exp loitation in the near future was carried out in combination with our land use and cover change detection results aiming at supplying some useful references for the central and local governments in their sustainable l and use planning.展开更多
Understanding the trajectories and driving mechanisms behind land use/land cover(LULC)changes is essential for effective watershed planning and management.This study quantified the net change,exchange,total change,and...Understanding the trajectories and driving mechanisms behind land use/land cover(LULC)changes is essential for effective watershed planning and management.This study quantified the net change,exchange,total change,and transfer rate of LULC in the Jinghe River Basin(JRB),China using LULC data from 2000 to 2020.Through trajectory analysis,knowledge maps,chord diagrams,and standard deviation ellipse method,we examined the spatiotemporal characteristics of LULC changes.We further established an index system encompassing natural factors(digital elevation model(DEM),slope,aspect,and curvature),socio-economic factors(gross domestic product(GDP)and population),and accessibility factors(distance from railways,distance from highways,distance from water,and distance from residents)to investigate the driving mechanisms of LULC changes using factor detector and interaction detector in the geographical detector(Geodetector).The key findings indicate that from 2000 to 2020,the JRB experienced significant LULC changes,particularly for farmland,forest,and grassland.During the study period,LULC change trajectories were categorized into stable,early-stage,late-stage,repeated,and continuous change types.Besides the stable change type,the late-stage change type predominated the LULC change trajectories,comprising 83.31% of the total change area.The period 2010-2020 witnessed more active LULC changes compared to the period 2000-2010.The LULC changes exhibited a discrete spatial expansion trend during 2000-2020,predominantly extending from southeast to northwest of the JRB.Influential driving factors on LULC changes included slope,GDP,and distance from highways.The interaction detection results imply either bilinear or nonlinear enhancement for any two driving factors impacting the LULC changes from 2000 to 2020.This comprehensive understanding of the spatiotemporal characteristics and driving mechanisms of LULC changes offers valuable insights for the planning and sustainable management of LULC in the JRB.展开更多
Rapid urbanization creates complexity,results in dynamic changes in land and environment,and influences the land surface temperature(LST)in fast-developing cities.In this study,we examined the impact of land use/land ...Rapid urbanization creates complexity,results in dynamic changes in land and environment,and influences the land surface temperature(LST)in fast-developing cities.In this study,we examined the impact of land use/land cover(LULC)changes on LST and determined the intensity of urban heat island(UHI)in New Town Kolkata(a smart city),eastern India,from 1991 to 2021 at 10-a intervals using various series of Landsat multi-spectral and thermal bands.This study used the maximum likelihood algorithm for image classification and other methods like the correlation analysis and hotspot analysis(Getis–Ord Gi^(*) method)to examine the impact of LULC changes on urban thermal environment.This study noticed that the area percentage of built-up land increased rapidly from 21.91%to 45.63%during 1991–2021,with a maximum positive change in built-up land and a maximum negative change in sparse vegetation.The mean temperature significantly increased during the study period(1991–2021),from 16.31℃to 22.48℃in winter,29.18℃to 34.61℃in summer,and 19.18℃to 27.11℃in autumn.The result showed that impervious surfaces contribute to higher LST,whereas vegetation helps decrease it.Poor ecological status has been found in built-up land,and excellent ecological status has been found in vegetation and water body.The hot spot and cold spot areas shifted their locations every decade due to random LULC changes.Even after New Town Kolkata became a smart city,high LST has been observed.Overall,this study indicated that urbanization and changes in LULC patterns can influence the urban thermal environment,and appropriate planning is needed to reduce LST.This study can help policy-makers create sustainable smart cities.展开更多
Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact ...Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact on the change of ecosystem.The primary goal of this study is to determine the impacts of LULC changes on ecosystem service values(ESVs)in the upper Gilgel Abbay watershed,Ethiopia.Changes in LULC types were studied using three Landsat images representing 1986,2003,and 2021.The Landsat images were classified using a supervised image classification technique in Earth Resources Data Analysis System(ERDAS)Imagine 2014.We classified ESs in this study into four categories(including provisioning,regulating,supporting,and cultural services)based on global ES classification scheme.The adjusted ESV coefficient benefit approach was employed to measure the impacts of LULC changes on ESVs.Five LULC types were identified in this study,including cultivated land,forest,shrubland,grassland,and water body.The result revealed that the area of cultivated land accounted for 64.50%,71.50%,and 61.50%of the total area in 1986,2003,and 2021,respectively.The percentage of the total area covered by forest was 9.50%,5.90%,and 14.80%in 1986,2003,and 2021,respectively.Result revealed that the total ESV decreased from 7.42×10^(7) to 6.44×10^(7) USD between 1986 and 2003.This is due to the expansion of cultivated land at the expense of forest and shrubland.However,the total ESV increased from 6.44×10^(7) to 7.76×10^(7) USD during 2003-2021,because of the increment of forest and shrubland.The expansion of cultivated land and the reductions of forest and shrubland reduced most individual ESs during 1986-2003.Nevertheless,the increase in forest and shrubland at the expense of cultivated land enhanced many ESs during 2003-2021.Therefore,the findings suggest that appropriate land use practices should be scaled-up to sustainably maintain ESs.展开更多
The Kulpawn River Basin(KRB)plays a critical role in supporting rural livelihoods through agriculture,water supply,and biodiversity conservation.However,between 1995 and 2023,significant land use and land cover(LULC)c...The Kulpawn River Basin(KRB)plays a critical role in supporting rural livelihoods through agriculture,water supply,and biodiversity conservation.However,between 1995 and 2023,significant land use and land cover(LULC)changes have been observed,affecting ecosystem services(ESs).This study evaluated the ecosystem service values(ESVs)associated with LULC changes.The random forest algorithm was applied to extract LULC information from Landsat images for 1995,2005,2015,and 2023.The benefit transfer method was employed to estimate the ESVs over the study period.Questionnaires were also used to assess the views of respondents on the drivers of the ES changes in the basin.The results showed that agricultural lands expanded by 14.14%,built-up areas by 15.17%,and light savannah forest by 8.73%,while dense savannah forest and water bodies declined by 25.71%and 20.00%,respectively.The total estimated ESV was 410.09×10^(8),362.92×10^(8),335.30×10^(8),and 319.28×10^(8) USD/(hm^(2)·a)in 1995,2005,2015,and 2023,respectively,indicating that the total ESV declined from 410.09×10^(8) USD/(hm^(2)·a)in 1995 to 319.28×10^(8) USD/(hm^(2)·a)in 2023.The study concludes that the reduction in ESVs is due to the LULC changes resulting from agricultural activities,expansion of built-up areas,population sprawl,and artisanal mining activities.Hence,there is an urgent need to develop programs and strategies to mitigate and curtail the degradation of LULC and ESVs in the basin.These findings reveal a growing ecological vulnerability,threatening water security and rural livelihoods.The study offers valuable insights to guide sustainable land use planning and ecosystem conservation strategies.展开更多
Optimizing the spatial pattern of carbon sequestration service is essential for advancing regional low-carbon development,accelerating the achievement of the"dual carbon"goals,and promoting the high-quality ...Optimizing the spatial pattern of carbon sequestration service is essential for advancing regional low-carbon development,accelerating the achievement of the"dual carbon"goals,and promoting the high-quality development of ecological environment.The carbon sequestration capacity within the mountain-desert-oasis system(MDOS),a unique landscape pattern,exhibits significant gradient characteristics,and its carbon sink potential can be substantially improved through multi-scale spatial optimization.This study employed the Integrated Valuation of Ecosystem Services and Tradeoff(InVEST)model to estimate carbon storage and sequestration(CSS)in the Gansu section of Heihe River Basin,China,a representative MDOS,based on land use/land cover(LULC)data from 1990 to 2020.The Patch-level Land Use Simulation(PLUS)model was coupled to simulate LULC and estimate carrying CSS under natural development(ND),ecological protection(EP),water constraint(WC),and economic development(ED)scenarios for 2035.Furthermore,the study constructed and optimized the CSS pattern on the basis of economic and ecological benefits,exploring the guiding significance of different scenarios for pattern optimization.The results showed that CSS spatial distribution is closely correlated with LULC pattern,and CSS is expected to improve in the future.CSS showed an overall increase across subsystems during 1990–2020,but varied across LULC types.CSS of construction land in all subsystems exhibited an increasing trend,while CSS of unused land showed a decreasing trend,with specific changes of 1.68×103 and 3.43×105 t,respectively.Regional CSS dynamics were mainly driven by conversions among unused land,cultivated land,and grassland.The CSS pattern of MDOS was divided into carbon sink functional region(CSFR),low carbon conservation region(LCCR),low carbon economic region(LCER),and economic development region(EDR).Water resources coordination served as the basis of pattern optimization,while the four dimensions—ecological carbon sink,low-carbon maintenance,agricultural carbon reduction and sink enhancement,and urban carbon emission reduction—framed the optimization framework.ND,EP,WC,and ED scenarios provided guidance as the basic reference,optimal benefit,"dual carbon"baseline,and upper development limit,respectively.Additionally,the detailed CSS sub-partitions of MDOS covered most potential scenarios of such ecosystems,demonstrating the applicability of these sub-partitions.These findings provide valuable references for enhancing CSS and hold important significance for low-carbon territorial spatial planning in the MDOS.展开更多
Combining the integrated technology of ecological quantity analytical method with GIS technology, based on the Landsat TM images and SPOT images in 1995 and 2009, this paper made a quantitative analysis of the changin...Combining the integrated technology of ecological quantity analytical method with GIS technology, based on the Landsat TM images and SPOT images in 1995 and 2009, this paper made a quantitative analysis of the changing process of land use/cover. The results showed that land use/cover in study area had undergone obviously changes from 1995 to 2009. The artificial landscapes which were mainly tropical crops plantation increased dramatically, natural forest and rubber forest was substantially reduced. The major patterns of land use change in the study area were the conversions of the natural forest and rubber forest to tropical crops plantation and cultivated land, cultivated land converted to tropical crops plantation and residential area. The analysis of landscape index showed that the role of landscape structure more diverse and uniform with the diversity of landscape fragmentation increases, the dominance of natural forest and rubber forest on the overall control of landscape reduced under the influence of human activities in the study area. The driving force analysis showed that economic development, agriculture industrial structure, policy and technology factors were the dominant factors of land use/change in the study area in the short term.展开更多
Remote sensing is one of the tool which is very important for the production of Land use and land cover maps through a process called image classification. For the image classification process to be successfully, seve...Remote sensing is one of the tool which is very important for the production of Land use and land cover maps through a process called image classification. For the image classification process to be successfully, several factors should be considered including availability of quality Landsat imagery and secondary data, a precise classification process and user’s experiences and expertise of the procedures. The objective of this research was to classify and map land-use/land-cover of the study area using remote sensing and Geospatial Information System (GIS) techniques. This research includes two sections (1) Landuse/Landcover (LULC) classification and (2) accuracy assessment. In this study supervised classification was performed using Non Parametric Rule. The major LULC classified were agriculture (65.0%), water body (4.0%), and built up areas (18.3%), mixed forest (5.2%), shrubs (7.0%), and Barren/bare land (0.5%). The study had an overall classification accuracy of 81.7% and kappa coefficient (K) of 0.722. The kappa coefficient is rated as substantial and hence the classified image found to be fit for further research. This study present essential source of information whereby planners and decision makers can use to sustainably plan the environment.展开更多
The 13 provinces （autonomous regions and municipalities） in northern China are located in latitude 31°-54°N and longitude 73°-136°E including Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Jili...The 13 provinces （autonomous regions and municipalities） in northern China are located in latitude 31°-54°N and longitude 73°-136°E including Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Jilin, Liaoning, Heilongjiang, Shaanxi, Gansu, Ningxia, Qinghai, and Xinjiang, where environments are fragile. In recent years, the eco-environmental problems such as vegetation destruction, desertification and soil erosion etc. become serious because of climate change and unreasonable human activities. In this paper, landscape pattern and its evolution in northern China from 1989 to 2003 was investigated by the combined use of RS and GIS based on the basic theory and method of landscape ecology. Land use/cover maps of the study area in 1989, 1999 and 2003 were produced by using 1 km monthly NOAA Advanced Very High Resolution Radiometer （AVHRR） and SPOTNGT Normalized Difference Vegetation Index （NDVI） dataset from national climate bureau of China which were geo-registered to Lambert azimuthal equal-area map projection and were used in the paper. Landscape evolution in the area over the study period was investigated by two methods： （a） the changes of various landscape metrics were analyzed using the landscape structure analysis program FRAGSTATS; （b） the transition matrix of landscape patch types was calculated with the help of the RS and GIS software. The results showed that from 1989 to 2003, the landscape within the study area had undertaken a complicated evolution in landscape structure and composition. The diversity index and evenness index increased during the period, which means that the landscape pattern tended to be diversified and even. The fragmentation index of grassland, forestland and water areas also increased significantly. This showed that the distribution and structure of forestland, grassland and water areas had been changed greatly during the period, especially grassland which became more and more fragmentized, and its fragmentation index increased from 19.23% to 88.72%. The transitions of the landscape types were mainly shown by the changes among forestland, grassland and farmland, and grassland changing into unable land. Over the study period, grassland and water areas had decreased remarkably, accounting for 15% and 37% from 1989 to 1999 and 24.79% and 49.25% from 1999 to 2003 respectively. The grassland and water resources play an important role in the eco-environment and economic development of the region. So, they must be protected carefully. According to the analysis, we can conclude that the eco-environment in the study area is obviously degenerated due to unreasonable human activities and climate changes and some measures should be taken to combat the environmental degradation.展开更多
Land use and land cover(LULC) changes and their impact on the mountain environment were studied in six catchments(～10 km^2 each) in the Polish Western Carpathians from the mid-19^(th) century to the early 21^(st) cen...Land use and land cover(LULC) changes and their impact on the mountain environment were studied in six catchments(～10 km^2 each) in the Polish Western Carpathians from the mid-19^(th) century to the early 21^(st) century. The analysis of cadastral and orthophoto maps indicates that during the investigated period, the forest area increased, quantified by an annual change index(Annch), between +0.12% to +0.27%, with a decrease of arable land index to –0.45% and –2.28% in the analysed catchments. LULC changes were accompanied by a continuous increase in settlement developments(residential and farming houses) by 50%-140% as well as significant changes related to their spatial distribution. Abandonment of arable land and forest succession have resulted in the geomorphological transformation of hillslopes, which predominantly includes a decrease in used road density, their transformation to road cuts and gorges. Overpopulation and the domination agriculture in the past caused the expansion of unpaved roads density and then the fragmentation of hillslopes, as well as the development of agricultural terraces.展开更多
Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China. Understanding the composition, distribution, and transport processes of...Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China. Understanding the composition, distribution, and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion. In this study, based on laboratory rainfall simulation experiments, we analyzed rainfall-induced erosion processes on sand-covered loess slopes （SS） with different sand cover patterns （including length and thickness） and uncovered loess slopes （LS） to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion. The grain-size curves of eroded sediments were fitted using the Weibull function. Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS. The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed. The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS. Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes. The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage. Sand cover on loess slopes aggravates loess erosion, not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess, compared with the loess slopes without sand cover. The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount. Furthermore, given the same sand cover pattern, a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion. This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.展开更多
Landscape ecology and landscape pattern analysis are important components of national-scale programs to identify trends in land cover change because: 1) Statistics on changes in land cover prop...Landscape ecology and landscape pattern analysis are important components of national-scale programs to identify trends in land cover change because: 1) Statistics on changes in land cover proportions are not spatial. A change matrix derived from GIS provides useful information, but it does not show the spatial form of change in the landscape. Landscape pattern metrics reveal spatial pattern. 2) A growing body of literature has shown that a change in landscape pattern might indicate important changes in ecological functions: forest connectivity and species movements, number and size of farm patches, effects on water quality. Spatial pattern is important in structuring ecological communities and in maintaining existence of competitors. Spatial pattern may be determined by disturbance and may in turn, determine how disturbances propagate through the system. 3) Sometimes landscape pattern may not significantly change, even though land cover proportions do change. Or, vice-versa, sometimes landscape pattern can significantly change, even though land cover proportions don't significantly change. 4) Landscape pattern is an inherent and important part of describing landscapes: based on the literature, one of the most important descriptive characteristics of a landscape is its texture. The objectives of this paper are to: 1) Explain the importance of the role of landscape ecology and landscape pattern analysis in land cover change studies; 2) Review the literature that specifically incorporates landscape ecology into land cover change studies; and 3) List the theoretical and technical issues involved and suggest solutions for them.展开更多
Vegetation or land cover maps have been made directly or indirectly available for the entire territory of China. The certainties and uncertainties of land cover statistics were analyzed by comparing three data sources...Vegetation or land cover maps have been made directly or indirectly available for the entire territory of China. The certainties and uncertainties of land cover statistics were analyzed by comparing three data sources: China's Vegetation Map, IGPB DISCover, and University of Maryland Product. Great similarities in the statistics of 7 aggregated land cover types were found among the three data sources, particularly between the two global land cover maps. The per pixel agreement between any 2 of 3 maps was between 38.0%—51.4%; the per pixel agreement among all three maps was only 27.1%. Certainties were found in regions where vegetation types are typical and human land use practice is relatively homogenous; the uncertainties occurred to either vegetation transition zones or regions where land cover types and land use practice are relatively diversified. Systematic and multidisciplinary efforts are necessary to promote accurate mapping of nationwide land cover types in China. Intensive efforts should be made in regions where uncertainties of land cover information are found.展开更多
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 ...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.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41771094,41871185,41801184)。
文摘Understanding the spatial patterns of land-use and land-cover(LULC)and their driving forces in transnational areas is important for the sustainable development of these regions.However,the spatial patterns of LULC and their driving forces across multiple scales are poorly understood in transnational areas.In this study,we analyzed the spatial patterns of LULC and driving forces in the transnational area of Tumen River(TATR)in 2016 across two scales:the entire region and the sub-regions of China,the Democratic People’s Republic of Korea(DPRK),and Russia.Results showed that the LULC was dominated by broadleaf forest and dry farmland in the TATR in 2016,which accounted for 66.86%and 13.60%of the entire region,respectively.Meanwhile,the LULC in the three sub-regions exhibited noticeable differences.In the Chinese and the DPRK’s sub-regions,the area of broadleaf forest was greater than those for the other LULC types,while the Russian sub-region was dominated by broadleaf forest and grassland.The spatial patterns of LULC were mainly influenced by topography,climate,soil properties,and human activities.In addition,the driving forces of the spatial patterns of LULC in the TATR had an obvious scaling effect.Therefore,we suggest that effective policies and regulations with cooperation among China,the DPRK,and Russia are needed to plan the spatial patterns of LULC and improve the sustainable development of the TATR.
文摘The availability of better economic possibilities and well-connected transportation networks has attracted people to migrate to peri-urban and rural neighbourhoods,changing the landscape of regions outside the city and fostering the growth of physical infrastructure.Using multi-temporal satellite images,the dynamics of Land Use/Land Cover(LULC)changes,the impact of urban growth on LULC changes,and regional environmental implications were investigated in the peri-urban and rural neighbourhoods of Durgapur Municipal Corporation in India.The study used different case studies to highlight the study area’s heterogeneity,as the phenomenon of change is not consistent.Landsat TM and OLI-TIRS satellite images in 1991,2001,2011,and 2021 were used to analyse the changes in LULC types.We used the relative deviation(RD),annual change intensity(ACI),uniform intensity(UI)to show the dynamicity of LULC types(agriculture land;built-up land;fallow land;vegetated land;mining area;and water bodies)during 1991-2021.This study also applied the Decision-Making Trial and Evaluation Laboratory(DEMATEL)to measure environmental sensitivity zones and find out the causes of LULC changes.According to LULC statistics,agriculture land,built-up land,and mining area increased by 51.7,95.46,and 24.79 km^(2),respectively,from 1991 to 2021.The results also suggested that built-up land and mining area had the greatest land surface temperature(LST),whereas water bodies and vegetated land showed the lowest LST.Moreover,this study looked at the relationships among LST,spectral indices(Normalized Differenced Built-up Index(NDBI),Normalized Difference Vegetation Index(NDVI),and Normalized Difference Water Index(NDWI)),and environmental sensitivity.The results showed that all of the spectral indices have the strongest association with LST,indicating that built-up land had a far stronger influence on the LST.The spectral indices indicated that the decreasing trends of vegetated land and water bodies were 4.26 and 0.43 km^(2)/a,respectively,during 1991-2021.In summary,this study can help the policy-makers to predict the increasing rate of temperature and the causes for the temperature increase with the rapid expansion of built-up land,thus making effective peri-urban planning decisions.
基金support of ‘Forest Science&Technology Projects(Project No.S211012L030110)’ provided by Korea Forest Service
文摘The purpose of this study was to classify current forest cover types,and to investigate stand development patterns for natural forests in six areas in northern Baekdudaegan,South Korea.Twenty-eight independent forest communities were aggregated into eight forest cover types by species composition in the overstory of each forest community.The forest cover types were of mixed mesophytic,‘‘others’ ’ deciduous,Quercus mongolica dominant,Q.mongolica pure,Pinus densiflora–Q.mongolica,P.densiflora,Betula ermanii,and Q.mongolica–P.koraiensis.The ecological information was organized by importance value and species diversity for each forest type.Based on the correlation between species diversity index and the abundance of Q.mongolica plus P.densiflora for corresponding forest cover types,we compared the developmental process and approximate successional pathway between each cover type.The P.densiflora forest cover type changes into the P.densiflora–Q.mongolica cover type,followed by the Q.mongolica dominant cover type through continuous invasion of the oak trees.Furthermore,the Q.mongolica pure cover type would spread toward the Q.mongolica dominant cover type with a mixture of various deciduous tree species.The Q.mongolica dominant cover type progresses through the other deciduous cover types to the mixed mesophytic cover type with diversified composition and structure.On the mid to lower slopes,with loamy soils and good moisture conditions,various deciduous forest types should progress,by ecological succession,toward the mixed mesophytic cover type without any further disturbance.
基金The Sino-Belgian co-operation project on Northwest China funded by the Federal Office for the Scientific, Technical and Cultural Affairs (OSTC) of the Belgium Government, No.BL/10/C15
文摘With the objectives to acquire the fundamental dat a of the territorial resource, understand the impacts of human activit ies on the land use and cover patterns and evaluate the potential of the future exploitation, an intensive land cover classification with an accuracy of 93% has been completed for North Ningxia by remote sen sing technique based on the adoption of a combination method composed o f texture training, maximum likelihood classification and post-processing such as re-allocation and aggregation. This classification result was incorporated with the contemporaneous socio-economic and meteorological d ata for cross-sectional regression modelling to reveal the spatial dete rminants of the land cover patterns and understand the human-environmen tal relationships. A tentative evaluation on the potential of soil exp loitation in the near future was carried out in combination with our land use and cover change detection results aiming at supplying some useful references for the central and local governments in their sustainable l and use planning.
基金partly funded by the National Key Research and Development Program of China(NK2023190801)the National Foreign Experts Program of China(G2023041024L)the Key Scientific Research Program of Shaanxi Provincial Education Department,China(21JT028)。
文摘Understanding the trajectories and driving mechanisms behind land use/land cover(LULC)changes is essential for effective watershed planning and management.This study quantified the net change,exchange,total change,and transfer rate of LULC in the Jinghe River Basin(JRB),China using LULC data from 2000 to 2020.Through trajectory analysis,knowledge maps,chord diagrams,and standard deviation ellipse method,we examined the spatiotemporal characteristics of LULC changes.We further established an index system encompassing natural factors(digital elevation model(DEM),slope,aspect,and curvature),socio-economic factors(gross domestic product(GDP)and population),and accessibility factors(distance from railways,distance from highways,distance from water,and distance from residents)to investigate the driving mechanisms of LULC changes using factor detector and interaction detector in the geographical detector(Geodetector).The key findings indicate that from 2000 to 2020,the JRB experienced significant LULC changes,particularly for farmland,forest,and grassland.During the study period,LULC change trajectories were categorized into stable,early-stage,late-stage,repeated,and continuous change types.Besides the stable change type,the late-stage change type predominated the LULC change trajectories,comprising 83.31% of the total change area.The period 2010-2020 witnessed more active LULC changes compared to the period 2000-2010.The LULC changes exhibited a discrete spatial expansion trend during 2000-2020,predominantly extending from southeast to northwest of the JRB.Influential driving factors on LULC changes included slope,GDP,and distance from highways.The interaction detection results imply either bilinear or nonlinear enhancement for any two driving factors impacting the LULC changes from 2000 to 2020.This comprehensive understanding of the spatiotemporal characteristics and driving mechanisms of LULC changes offers valuable insights for the planning and sustainable management of LULC in the JRB.
基金the University Grants Commission,New Delhi,India,for providing financial support in the form of the Junior Research Fellowship。
文摘Rapid urbanization creates complexity,results in dynamic changes in land and environment,and influences the land surface temperature(LST)in fast-developing cities.In this study,we examined the impact of land use/land cover(LULC)changes on LST and determined the intensity of urban heat island(UHI)in New Town Kolkata(a smart city),eastern India,from 1991 to 2021 at 10-a intervals using various series of Landsat multi-spectral and thermal bands.This study used the maximum likelihood algorithm for image classification and other methods like the correlation analysis and hotspot analysis(Getis–Ord Gi^(*) method)to examine the impact of LULC changes on urban thermal environment.This study noticed that the area percentage of built-up land increased rapidly from 21.91%to 45.63%during 1991–2021,with a maximum positive change in built-up land and a maximum negative change in sparse vegetation.The mean temperature significantly increased during the study period(1991–2021),from 16.31℃to 22.48℃in winter,29.18℃to 34.61℃in summer,and 19.18℃to 27.11℃in autumn.The result showed that impervious surfaces contribute to higher LST,whereas vegetation helps decrease it.Poor ecological status has been found in built-up land,and excellent ecological status has been found in vegetation and water body.The hot spot and cold spot areas shifted their locations every decade due to random LULC changes.Even after New Town Kolkata became a smart city,high LST has been observed.Overall,this study indicated that urbanization and changes in LULC patterns can influence the urban thermal environment,and appropriate planning is needed to reduce LST.This study can help policy-makers create sustainable smart cities.
文摘Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact on the change of ecosystem.The primary goal of this study is to determine the impacts of LULC changes on ecosystem service values(ESVs)in the upper Gilgel Abbay watershed,Ethiopia.Changes in LULC types were studied using three Landsat images representing 1986,2003,and 2021.The Landsat images were classified using a supervised image classification technique in Earth Resources Data Analysis System(ERDAS)Imagine 2014.We classified ESs in this study into four categories(including provisioning,regulating,supporting,and cultural services)based on global ES classification scheme.The adjusted ESV coefficient benefit approach was employed to measure the impacts of LULC changes on ESVs.Five LULC types were identified in this study,including cultivated land,forest,shrubland,grassland,and water body.The result revealed that the area of cultivated land accounted for 64.50%,71.50%,and 61.50%of the total area in 1986,2003,and 2021,respectively.The percentage of the total area covered by forest was 9.50%,5.90%,and 14.80%in 1986,2003,and 2021,respectively.Result revealed that the total ESV decreased from 7.42×10^(7) to 6.44×10^(7) USD between 1986 and 2003.This is due to the expansion of cultivated land at the expense of forest and shrubland.However,the total ESV increased from 6.44×10^(7) to 7.76×10^(7) USD during 2003-2021,because of the increment of forest and shrubland.The expansion of cultivated land and the reductions of forest and shrubland reduced most individual ESs during 1986-2003.Nevertheless,the increase in forest and shrubland at the expense of cultivated land enhanced many ESs during 2003-2021.Therefore,the findings suggest that appropriate land use practices should be scaled-up to sustainably maintain ESs.
基金financial assistance from the European Union(Contract number:AFS2023/444-387)。
文摘The Kulpawn River Basin(KRB)plays a critical role in supporting rural livelihoods through agriculture,water supply,and biodiversity conservation.However,between 1995 and 2023,significant land use and land cover(LULC)changes have been observed,affecting ecosystem services(ESs).This study evaluated the ecosystem service values(ESVs)associated with LULC changes.The random forest algorithm was applied to extract LULC information from Landsat images for 1995,2005,2015,and 2023.The benefit transfer method was employed to estimate the ESVs over the study period.Questionnaires were also used to assess the views of respondents on the drivers of the ES changes in the basin.The results showed that agricultural lands expanded by 14.14%,built-up areas by 15.17%,and light savannah forest by 8.73%,while dense savannah forest and water bodies declined by 25.71%and 20.00%,respectively.The total estimated ESV was 410.09×10^(8),362.92×10^(8),335.30×10^(8),and 319.28×10^(8) USD/(hm^(2)·a)in 1995,2005,2015,and 2023,respectively,indicating that the total ESV declined from 410.09×10^(8) USD/(hm^(2)·a)in 1995 to 319.28×10^(8) USD/(hm^(2)·a)in 2023.The study concludes that the reduction in ESVs is due to the LULC changes resulting from agricultural activities,expansion of built-up areas,population sprawl,and artisanal mining activities.Hence,there is an urgent need to develop programs and strategies to mitigate and curtail the degradation of LULC and ESVs in the basin.These findings reveal a growing ecological vulnerability,threatening water security and rural livelihoods.The study offers valuable insights to guide sustainable land use planning and ecosystem conservation strategies.
基金funded by the Gansu Provincial Department of Education's University Teacher Innovation Fund Project(2025A-001)the Gansu Provincial Philosophy and Social Science Planning Project(2024YB088).
文摘Optimizing the spatial pattern of carbon sequestration service is essential for advancing regional low-carbon development,accelerating the achievement of the"dual carbon"goals,and promoting the high-quality development of ecological environment.The carbon sequestration capacity within the mountain-desert-oasis system(MDOS),a unique landscape pattern,exhibits significant gradient characteristics,and its carbon sink potential can be substantially improved through multi-scale spatial optimization.This study employed the Integrated Valuation of Ecosystem Services and Tradeoff(InVEST)model to estimate carbon storage and sequestration(CSS)in the Gansu section of Heihe River Basin,China,a representative MDOS,based on land use/land cover(LULC)data from 1990 to 2020.The Patch-level Land Use Simulation(PLUS)model was coupled to simulate LULC and estimate carrying CSS under natural development(ND),ecological protection(EP),water constraint(WC),and economic development(ED)scenarios for 2035.Furthermore,the study constructed and optimized the CSS pattern on the basis of economic and ecological benefits,exploring the guiding significance of different scenarios for pattern optimization.The results showed that CSS spatial distribution is closely correlated with LULC pattern,and CSS is expected to improve in the future.CSS showed an overall increase across subsystems during 1990–2020,but varied across LULC types.CSS of construction land in all subsystems exhibited an increasing trend,while CSS of unused land showed a decreasing trend,with specific changes of 1.68×103 and 3.43×105 t,respectively.Regional CSS dynamics were mainly driven by conversions among unused land,cultivated land,and grassland.The CSS pattern of MDOS was divided into carbon sink functional region(CSFR),low carbon conservation region(LCCR),low carbon economic region(LCER),and economic development region(EDR).Water resources coordination served as the basis of pattern optimization,while the four dimensions—ecological carbon sink,low-carbon maintenance,agricultural carbon reduction and sink enhancement,and urban carbon emission reduction—framed the optimization framework.ND,EP,WC,and ED scenarios provided guidance as the basic reference,optimal benefit,"dual carbon"baseline,and upper development limit,respectively.Additionally,the detailed CSS sub-partitions of MDOS covered most potential scenarios of such ecosystems,demonstrating the applicability of these sub-partitions.These findings provide valuable references for enhancing CSS and hold important significance for low-carbon territorial spatial planning in the MDOS.
基金Supported by National Natural Science Foundation (40963001,40661013,40061003)~~
文摘Combining the integrated technology of ecological quantity analytical method with GIS technology, based on the Landsat TM images and SPOT images in 1995 and 2009, this paper made a quantitative analysis of the changing process of land use/cover. The results showed that land use/cover in study area had undergone obviously changes from 1995 to 2009. The artificial landscapes which were mainly tropical crops plantation increased dramatically, natural forest and rubber forest was substantially reduced. The major patterns of land use change in the study area were the conversions of the natural forest and rubber forest to tropical crops plantation and cultivated land, cultivated land converted to tropical crops plantation and residential area. The analysis of landscape index showed that the role of landscape structure more diverse and uniform with the diversity of landscape fragmentation increases, the dominance of natural forest and rubber forest on the overall control of landscape reduced under the influence of human activities in the study area. The driving force analysis showed that economic development, agriculture industrial structure, policy and technology factors were the dominant factors of land use/change in the study area in the short term.
文摘Remote sensing is one of the tool which is very important for the production of Land use and land cover maps through a process called image classification. For the image classification process to be successfully, several factors should be considered including availability of quality Landsat imagery and secondary data, a precise classification process and user’s experiences and expertise of the procedures. The objective of this research was to classify and map land-use/land-cover of the study area using remote sensing and Geospatial Information System (GIS) techniques. This research includes two sections (1) Landuse/Landcover (LULC) classification and (2) accuracy assessment. In this study supervised classification was performed using Non Parametric Rule. The major LULC classified were agriculture (65.0%), water body (4.0%), and built up areas (18.3%), mixed forest (5.2%), shrubs (7.0%), and Barren/bare land (0.5%). The study had an overall classification accuracy of 81.7% and kappa coefficient (K) of 0.722. The kappa coefficient is rated as substantial and hence the classified image found to be fit for further research. This study present essential source of information whereby planners and decision makers can use to sustainably plan the environment.
基金Science & Technology Research Project of Chongqing Municipal Education Commission, No.KJ070811Doctor Startup Fund of Chongqing Normal University, No. 06XLB004National Basic Research Program of China, No.G2000018604
文摘The 13 provinces （autonomous regions and municipalities） in northern China are located in latitude 31°-54°N and longitude 73°-136°E including Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Jilin, Liaoning, Heilongjiang, Shaanxi, Gansu, Ningxia, Qinghai, and Xinjiang, where environments are fragile. In recent years, the eco-environmental problems such as vegetation destruction, desertification and soil erosion etc. become serious because of climate change and unreasonable human activities. In this paper, landscape pattern and its evolution in northern China from 1989 to 2003 was investigated by the combined use of RS and GIS based on the basic theory and method of landscape ecology. Land use/cover maps of the study area in 1989, 1999 and 2003 were produced by using 1 km monthly NOAA Advanced Very High Resolution Radiometer （AVHRR） and SPOTNGT Normalized Difference Vegetation Index （NDVI） dataset from national climate bureau of China which were geo-registered to Lambert azimuthal equal-area map projection and were used in the paper. Landscape evolution in the area over the study period was investigated by two methods： （a） the changes of various landscape metrics were analyzed using the landscape structure analysis program FRAGSTATS; （b） the transition matrix of landscape patch types was calculated with the help of the RS and GIS software. The results showed that from 1989 to 2003, the landscape within the study area had undertaken a complicated evolution in landscape structure and composition. The diversity index and evenness index increased during the period, which means that the landscape pattern tended to be diversified and even. The fragmentation index of grassland, forestland and water areas also increased significantly. This showed that the distribution and structure of forestland, grassland and water areas had been changed greatly during the period, especially grassland which became more and more fragmentized, and its fragmentation index increased from 19.23% to 88.72%. The transitions of the landscape types were mainly shown by the changes among forestland, grassland and farmland, and grassland changing into unable land. Over the study period, grassland and water areas had decreased remarkably, accounting for 15% and 37% from 1989 to 1999 and 24.79% and 49.25% from 1999 to 2003 respectively. The grassland and water resources play an important role in the eco-environment and economic development of the region. So, they must be protected carefully. According to the analysis, we can conclude that the eco-environment in the study area is obviously degenerated due to unreasonable human activities and climate changes and some measures should be taken to combat the environmental degradation.
文摘Land use and land cover(LULC) changes and their impact on the mountain environment were studied in six catchments(～10 km^2 each) in the Polish Western Carpathians from the mid-19^(th) century to the early 21^(st) century. The analysis of cadastral and orthophoto maps indicates that during the investigated period, the forest area increased, quantified by an annual change index(Annch), between +0.12% to +0.27%, with a decrease of arable land index to –0.45% and –2.28% in the analysed catchments. LULC changes were accompanied by a continuous increase in settlement developments(residential and farming houses) by 50%-140% as well as significant changes related to their spatial distribution. Abandonment of arable land and forest succession have resulted in the geomorphological transformation of hillslopes, which predominantly includes a decrease in used road density, their transformation to road cuts and gorges. Overpopulation and the domination agriculture in the past caused the expansion of unpaved roads density and then the fragmentation of hillslopes, as well as the development of agricultural terraces.
基金supported by the National Key Research and Development Program of China (2016YFC0402404, 2016YFC0402407)the National Natural Science Foundation of China (L1624052, 41330858, 41471226, and 51509203)the Dr.Innovation Fund of Xi’an University of Technology (310-252071505)
文摘Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China. Understanding the composition, distribution, and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion. In this study, based on laboratory rainfall simulation experiments, we analyzed rainfall-induced erosion processes on sand-covered loess slopes （SS） with different sand cover patterns （including length and thickness） and uncovered loess slopes （LS） to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion. The grain-size curves of eroded sediments were fitted using the Weibull function. Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS. The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed. The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS. Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes. The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage. Sand cover on loess slopes aggravates loess erosion, not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess, compared with the loess slopes without sand cover. The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount. Furthermore, given the same sand cover pattern, a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion. This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.
基金USGS Geographic Research and Applications Programthe U.S. Environmental Protection Agency Landscape Ecology Program in Las Vegas (Interagency Agreement DW14938108-01-0)and the NASA Land Cover/Land Use Change Program
文摘Landscape ecology and landscape pattern analysis are important components of national-scale programs to identify trends in land cover change because: 1) Statistics on changes in land cover proportions are not spatial. A change matrix derived from GIS provides useful information, but it does not show the spatial form of change in the landscape. Landscape pattern metrics reveal spatial pattern. 2) A growing body of literature has shown that a change in landscape pattern might indicate important changes in ecological functions: forest connectivity and species movements, number and size of farm patches, effects on water quality. Spatial pattern is important in structuring ecological communities and in maintaining existence of competitors. Spatial pattern may be determined by disturbance and may in turn, determine how disturbances propagate through the system. 3) Sometimes landscape pattern may not significantly change, even though land cover proportions do change. Or, vice-versa, sometimes landscape pattern can significantly change, even though land cover proportions don't significantly change. 4) Landscape pattern is an inherent and important part of describing landscapes: based on the literature, one of the most important descriptive characteristics of a landscape is its texture. The objectives of this paper are to: 1) Explain the importance of the role of landscape ecology and landscape pattern analysis in land cover change studies; 2) Review the literature that specifically incorporates landscape ecology into land cover change studies; and 3) List the theoretical and technical issues involved and suggest solutions for them.
文摘Vegetation or land cover maps have been made directly or indirectly available for the entire territory of China. The certainties and uncertainties of land cover statistics were analyzed by comparing three data sources: China's Vegetation Map, IGPB DISCover, and University of Maryland Product. Great similarities in the statistics of 7 aggregated land cover types were found among the three data sources, particularly between the two global land cover maps. The per pixel agreement between any 2 of 3 maps was between 38.0%—51.4%; the per pixel agreement among all three maps was only 27.1%. Certainties were found in regions where vegetation types are typical and human land use practice is relatively homogenous; the uncertainties occurred to either vegetation transition zones or regions where land cover types and land use practice are relatively diversified. Systematic and multidisciplinary efforts are necessary to promote accurate mapping of nationwide land cover types in China. Intensive efforts should be made in regions where uncertainties of land cover information are found.
基金National Key Basic Research Program of China(973 Program),No.2010CB950902
文摘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.
