Land use and cover change(LUCC)is the most direct manifestation of the interaction between anthropological activities and the natural environment on Earth's surface,with significant impacts on the environment and ...Land use and cover change(LUCC)is the most direct manifestation of the interaction between anthropological activities and the natural environment on Earth's surface,with significant impacts on the environment and social economy.Rapid economic development and climate change have resulted in significant changes in land use and cover.The Shiyang River Basin,located in the eastern part of the Hexi Corridor in China,has undergone significant climate change and LUCC over the past few decades.In this study,we used the random forest classification to obtain the land use and cover datasets of the Shiyang River Basin in 1991,1995,2000,2005,2010,2015,and 2020 based on Landsat images.We validated the land use and cover data in 2015 from the random forest classification results(this study),the high-resolution dataset of annual global land cover from 2000 to 2015(AGLC-2000-2015),the global 30 m land cover classification with a fine classification system(GLC_FCS30),and the first Landsat-derived annual China Land Cover Dataset(CLCD)against ground-truth classification results to evaluate the accuracy of the classification results in this study.Furthermore,we explored and compared the spatiotemporal patterns of LUCC in the upper,middle,and lower reaches of the Shiyang River Basin over the past 30 years,and employed the random forest importance ranking method to analyze the influencing factors of LUCC based on natural(evapotranspiration,precipitation,temperature,and surface soil moisture)and anthropogenic(nighttime light,gross domestic product(GDP),and population)factors.The results indicated that the random forest classification results for land use and cover in the Shiyang River Basin in 2015 outperformed the AGLC-2000-2015,GLC_FCS30,and CLCD datasets in both overall and partial validations.Moreover,the classification results in this study exhibited a high level of agreement with the ground truth features.From 1991 to 2020,the area of bare land exhibited a decreasing trend,with changes primarily occurring in the middle and lower reaches of the basin.The area of grassland initially decreased and then increased,with changes occurring mainly in the upper and middle reaches of the basin.In contrast,the area of cropland initially increased and then decreased,with changes occurring in the middle and lower reaches.The LUCC was influenced by both natural and anthropogenic factors.Climatic factors and population contributed significantly to LUCC,and the importance values of evapotranspiration,precipitation,temperature,and population were 22.12%,32.41%,21.89%,and 19.65%,respectively.Moreover,policy interventions also played an important role.Land use and cover in the Shiyang River Basin exhibited fluctuating changes over the past 30 years,with the ecological environment improving in the last 10 years.This suggests that governance efforts in the study area have had some effects,and the government can continue to move in this direction in the future.The findings can provide crucial insights for related research and regional sustainable development in the Shiyang River Basin and other similar arid and semi-arid areas.展开更多
Internal migration is highly valued due to its increasingly acknowledged potential for social and economic development. However, despite its significant contribution to the development of towns and cities, it has led ...Internal migration is highly valued due to its increasingly acknowledged potential for social and economic development. However, despite its significant contribution to the development of towns and cities, it has led to the deterioration of many ecosystems globally. Lake Bosomtwe, a natural Lake in Ghana and one of the six major meteoritic lakes in the world is affected by land cover changes caused by the rising effects of migration, population expansion, and urbanization, owing to the development of tourist facilities on the lakeshore. This study investigated land cover change trajectories using a post-classification comparison approach and identified the factors influencing alteration in the Lake Bosomtwe Basin. Using Landsat imagery, an integrated approach of remote sensing, geographical information systems (GIS), and statistical analysis was successfully employed to analyze the land cover change of the basin. The findings show that over the 17 years, the basin’s forest cover decreased significantly by 16.02%, indicating that population expansion significantly affects changes in land cover. Ultimately, this study will raise the awareness of stakeholders, decision-makers, policy-makers, government, and non-governmental agencies to evaluate land use development patterns, optimize land use structures, and provide a reference for the formulation of sustainable development policies to promote the sustainable development of the ecological environment.展开更多
Based on the NOAA AVHRR-NDVI monthly data from 1981 to 2001, the spatial distribution and dynamic change of land cover along the Qinghai-Tibet Highway and Railway were studied. The results of the analytical data indic...Based on the NOAA AVHRR-NDVI monthly data from 1981 to 2001, the spatial distribution and dynamic change of land cover along the Qinghai-Tibet Highway and Railway were studied. The results of the analytical data indicate that the NDVI values in July, August and September are rather high during a year, and a linear trend by calculating NDVI of each pixel computed based on the average values of NDVI in July, August and September were obtained. The results are as follows: 1) Land cover of the study area by NDVI displays high at two sides of the area and low in the center, and agriculture area 〉 alpine meadow 〉 alpine grassland 〉 desert grassland. 2) In the study area, the amount ofpixels with high increase, slight increase, no change, slight decrease and high decrease account for 0.29%, 14.86%, 67.61%, 16.7% and 0.57% of the whole area, respectively. The increase of land cover pixels is mainly in the agriculture and alpine meadow and the decrease pixels mainly in the alpine grassland, desert grassland and hungriness. Grassland and hungriness contribute to the decrease mostly and artificial land and meadow contribute to the increase mostly. 3) In the area where human beings live, the changing trend is obvious, such as the valleys of Lhasa River and Huangshui River and area along the Yellow River; in the high altitude area with fewer people living, the changing trend is relatively low, like the area of Hoh Xil. 4) Human being's behaviors are a key factor followed by the climate changes affecting land cover.展开更多
A series of 17-yr equilibrium simulations using the NCAR COM3 (T42resolution) were performed to investigate the regional scale impacts of land cover change andincreasing CO_2 over China. Simulations with natural and c...A series of 17-yr equilibrium simulations using the NCAR COM3 (T42resolution) were performed to investigate the regional scale impacts of land cover change andincreasing CO_2 over China. Simulations with natural and current land cover at CO_2 levels of 280,355, 430, and 505 ppmv were conducted. Results show statistically significant changes in majorclimate fields (e.g. temperature and surface wind speed) on a 15-yr average following land coverchange. We also found increases in the maximum temperature and in the diurnal temperature range dueto land cover change. Increases in CO_2 affect both the maximum and minimum temperature so thatchanges in the diurnal range are small. Both land cover change and CO_2 change also impact thefrequency distribution of precipitation with increasing CO_2 tending to lead to more intenseprecipitation and land cover change leading to less intense precipitation―indeed, the impact ofland cover change typically had the opposite effect versus the impacts of CO_2. Our results providesupport for the inclusion of future land cover change scenarios in long-term transitory climatemodelling experiments of the 21st Century. Our results also support the inclusion of land surfacemodels that can represent future land cover changes resulting from an ecological response to naturalclimate variability or increasing CO_2. Overall, we show that land cover change can have asignificant impact on the regional scale climate of China, and that regionally, this impact is of asimilar magnitude to increases in CO_2 of up to about 430 ppmv. This means that that the impact ofland cover change must be accounted for in detection and attribution studies over China.展开更多
The recent progresses on the reconstruction of historical land cover and the studies on regional climatic effects to temperature, precipitation, and the East Asian Monsoon across China were reviewed. Findings show tha...The recent progresses on the reconstruction of historical land cover and the studies on regional climatic effects to temperature, precipitation, and the East Asian Monsoon across China were reviewed. Findings show that the land cover in China has been significantly modified by human activities over the last several thousands years, mainly through cropland expansion and forest clearance. The cropland over traditional Chinese agricultural areas increased from 5.32×10^5 km^2 in the mid-17th century to 8.27×10^5 km^2 in the mid-20th century, while the forest area over the Chinese mainland had been reduced by 1.66×10^6 km^2 during the last 300 years. These changes of land cover have been detected as an important driving force of climate change by simulations of climatic effects based on various climate models (including RegCM3, RegCM2-NCC, RIEMS version1, MM5 version 2, and AGCM+SSiB) with reconstructed historical land cover data or by contrasting current land cover to potential natural vegetation. The human-induced land cover changes over China have led to the enhancement of the East Asian winter monsoon, as well as cooling in winter and warming in summer approximately since 1700. However, the simulation results on annual mean temperature, precipitation, and the East Asian summer monsoon varied from model to model, which cannot be simply attributed to certain forcing so far, but undoubtedly, using different land cover datasets in various simulations played a key role. Thus, developing different regional scales with high time resolution more accurate gridded historical land cover datasets on is needed in the future.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
Qinghai Lake is the largest saline lake in China.The change in the lake volume is an indicator of the variation in water resources and their response to climate change on the Qinghai-Tibetan Plateau(QTP)in China.The p...Qinghai Lake is the largest saline lake in China.The change in the lake volume is an indicator of the variation in water resources and their response to climate change on the Qinghai-Tibetan Plateau(QTP)in China.The present study quantitatively evaluated the effects of climate change and land use/cover change(LUCC)on the lake volume of the Qinghai Lake in China from 1958 to 2018,which is crucial for water resources management in the Qinghai Lake Basin.To explore the effects of climate change and LUCC on the Qinghai Lake volume,we analyzed the lake level observation data and multi-period land use/land cover(LULC)data by using an improved lake volume estimation method and Integrated Valuation of Ecosystem Services and Trade-offs(InVEST)model.Our results showed that the lake level decreased at the rate of 0.08 m/a from 1958 to 2004 and increased at the rate of 0.16 m/a from 2004 to 2018.The lake volume decreased by 105.40×10^(8) m^(3) from 1958 to 2004,with the rate of 2.24×10^(8) m^(3)/a,whereas it increased by 74.02×10^(8) m^(3) from 2004 to 2018,with the rate of 4.66×10^(8) m^(3)/a.Further,the climate of the Qinghai Lake Basin changed from warm-dry to warm-humid.From 1958 to 2018,the increase in precipitation and the decrease in evaporation controlled the change of the lake volume,which were the main climatic factors affecting the lake volume change.From 1977 to 2018,the measured water yield showed an"increase-decrease-increase"fluctuation in the Qinghai Lake Basin.The effects of climate change and LUCC on the measured water yield were obviously different.From 1977 to 2018,the contribution rate of LUCC was -0.76% and that of climate change was 100.76%;the corresponding rates were 8.57% and 91.43% from 1977 to 2004,respectively,and -4.25% and 104.25% from 2004 to 2018,respectively.Quantitative analysis of the effects and contribution rates of climate change and LUCC on the Qinghai Lake volume revealed the scientific significance of climate change and LUCC,as well as their individual and combined effects in the Qinghai Lake Basin and on the QTP.This study can contribute to the water resources management and regional sustainable development of the Qinghai Lake Basin.展开更多
Land change is a cause and consequence of global environmental change.Land use and land cover have changed considerably due to increasing human activities and climate change,which has become the core issue of major in...Land change is a cause and consequence of global environmental change.Land use and land cover have changed considerably due to increasing human activities and climate change,which has become the core issue of major international research projects.This study interprets land use and land cover status and the changes within the Koshi River Basin(KRB)using Landsat remote sensing(RS)image data,and employs logistic regression model to analyze the influence of natural and socioeconomic driving forces on major land cover changes.The results showed that the areas of built-up land,bare land and forest in KRB increased from 1990 to 2015,including the largest increases in forest and the highest growth rate in construction land.Areas of glacier,grassland,sparse vegetation,shrub land,cropland,and wetland all decreased over the study period.From the perspective of driving analysis,the role of human activities in land use and land cover change is significant than climate factors.Cropland expansion is the reclamation of cropland by farmers,mainly from early deforestation.However,labor force separation,geological disasters and drought are the main factors of cropland shrinkage.The increase of forest area in India and Nepal was attributed to the government’s forest protection policies,such as Nepal’s community forestry has achieved remarkable results.The expansion and contraction of grassland were both dominated by climatic factors.The probability of grassland expansion increases with temperature and precipitation,while the probability of grassland contraction decreases with temperature and precipitation.展开更多
In recent years, the streamflow of the Laohahe Basin in China showed a dramatic decrease during the rainy season as a result of climate change and/or human activities. The objective of this work was to document signif...In recent years, the streamflow of the Laohahe Basin in China showed a dramatic decrease during the rainy season as a result of climate change and/or human activities. The objective of this work was to document significant streamflow changes caused by land use and land cover (LULC) changes and to quantify the impacts of the observed changes in Laohahe Basin. in the study area, the observed streamflow has been influenced by LULC changes, dams, and irrigation from rivers, industry, livestock and human consumption. Most importantly, the growth of population and gross domestic product (GDP) accompanied by the growth in industrial and agricultural activities, which led to LULC changes with increased residential land and cropland and decreased grassland since 2000s. Statistical methods and Variable Infiltration Capacity (VIC) hydrological model were used to estimate the effects of climate change and LULC changes on streamflow and evaportranspiration lET). First, the streamflow data of the study area were divided into three sub-periods according to the Pettitt test. The hydrological process was then simulated by VIC model from 1964 to 2009. Furthermore, we compared the simulated results based on land use scenarios in 1989, 1999 and 2007, respectively for exploring the effect of LULC changes on the spatio-temporal distribution of streamflow and ET in the Laohahe Basin. The results suggest that, accompanied with climate change, the LULC changes and human water consumption appeared to be the most likely factors contributing to the sig- nificant reduction in streamflow in the Laohahe Basin by 64% from1999 to 2009.展开更多
Land use/land cover(LULC) is an important part of exploring the interaction between natural environment and human activities and achieving regional sustainable development. Based on the data of LULC types(cropland, fo...Land use/land cover(LULC) is an important part of exploring the interaction between natural environment and human activities and achieving regional sustainable development. Based on the data of LULC types(cropland, forest land, grassland, built-up land, and unused land) from 1990 to 2015, we analysed the intensity and driving factors of land use/cover change(LUCC) in the Yarlung Zangbo River,Nyang Qu River, and Lhasa River(YNL) region, Qinghai-Tibet Plateau of China, using intensity analysis method, cross-linking table method, and spatial econometric model. The results showed that LUCC in the YNL region was nonstationary from 1990 to 2015, showing a change pattern with "fast-slow-fast" and "U-shaped". Built-up land showed a steady increase pattern, while cropland showed a steady decrease pattern. The gain of built-up land mainly came from the loss of cropland. The transition pattern of LUCC in the YNL region was relatively single and stable during 1990–2015. The transition pattern from cropland and forest land to built-up land was a systematic change process of tendency and the transition pattern from grassland and unused land to cropland was a systematic change process of avoidance. The transition process of LUCC was the result of the combined effect of natural environment and social economic development in the YNL region. This study reveals the impact of ecological environment problems caused by human activities on the land resource system and provides scientific support for the study of ecological environment change and sustainable development of the Qinghai-Tibet Plateau.展开更多
The Middle Route of the South-to-North Water Diversion Project(MR-SNWDP)in China,with construction beginning in 2003,diverts water from Danjiangkou Reservoir to North China for residential,agriculture and industrial u...The Middle Route of the South-to-North Water Diversion Project(MR-SNWDP)in China,with construction beginning in 2003,diverts water from Danjiangkou Reservoir to North China for residential,agriculture and industrial use.The water source area of the MR-SNWDP is the region that is most sensitive to and most affected by the construction of this water diversion project.In this study,we used Landsat Thematic Mapper(TM)and HJ-1 A/B images from 2000 to 2015 by an object-based approach with a hierarchical classification method for mapping land cover in the water source area.The changes in land cover were illuminated by transfer matrixes,single dynamic degree,slope zones and fractional vegetation cover(FVC).The results indicated that the area of cropland decreased by 31%and was replaced mainly by shrub over the past 15 years,whereas forest and settlements showed continuous increases of 29.2% and 77.7%,respectively.The changes in cropland were obvious in all slope zones and decreased most remarkably(–43.8%)in the slope zone above 25°.Compared to the FVC of forest and shrub,significant improvement was exhibited in the FVC of grassland,with a growth rate of 16.6%.We concluded that local policies,including economic development,water conservation and immigration resulting from the construction of the MR-SNWDP,were the main drivers of land cover changes;notably,they stimulated the substantial and rapid expansion of settlements,doubled the wetlands and drove the transformation from cropland to settlements in immigration areas.展开更多
This study investigated forest cover change and the driving forces behind it in Fagita Lekoma District of Ethiopia that resulted in increased forest cover,which might be uncommon outside this case study area.The LULC ...This study investigated forest cover change and the driving forces behind it in Fagita Lekoma District of Ethiopia that resulted in increased forest cover,which might be uncommon outside this case study area.The LULC change analysis was made from 2003 to 2017 based on Landsat images.Socioeconomic analysis was carried out to identify the major driving forces that resulted in LULC change.A questionnaire survey,focused group discussion,key informant interviews and field observation were employed to analyze the link between LULC change and the driving forces.The 15-year period(2003–2017)image analysis revealed that the coverage of forest lands,built-up areas and grassland has increased by 256%,100%and 96%,respectively,at the expense of cultivated lands and wetlands.The increased forest cover is due to the woodlots expansion of Acacia decurrens Willd,which are designed for sustainable livelihoods and a land revitalization strategy in the study area.Rapid population growth,an increasing demand for charcoal and subsequent market opportunities,preferred qualities of A.decurrens or black wattle to halt land degradation as well as to improve land productivity,have been identified as the major driving forces of forest cover change.Chi squared analysis revealed that:a comparative cash income from the sale of A.decurrens;a dependency on natural forests;the distance from the district administrative center;the size of the active labor force,and the area of land owned have significantly affected the cover change.The major forest cover change is due to the expansion of A.decurrens plantations that have socioeconomic and environmental implications to improve rural livelihoods and revitalize the land.Thus,the positive experiences identified in this study should be scaled-up and applied in other similar settings.展开更多
This paper deals with land use and land cover change in China in the last 500 years. It aims at sensitizing related fields in giving due consideration on integration of environmental change and social economic develo...This paper deals with land use and land cover change in China in the last 500 years. It aims at sensitizing related fields in giving due consideration on integration of environmental change and social economic development process and at proposing a framework for discussion towards further study. Based on historical review,several important changes were summarized as: natural vegetation were replaced by secondary or cultivated Plants, land cover changes differ from time to time and from place to place:and cropping pattern change is a sensitive indicator of land cover change in China. In the history of Cnina, many factors contributed to land use and land cover change either in positive or negative Ways. Four major driving forces were concluded, namely, climatic change, social transformation and turbulence, technology improvement, and international trade competition. In the last Part of tne Paper, a proposal on 'land use/land cover cnange' is framed, so as to calling comments on improving tne study and collaborations from varied authorities and researcn institutions.展开更多
Understanding the effects of land use/cover change(LUCC) on regional climate is critical for achieving land use system sustainability and global climate change mitigation. However, the quantitative analysis of the con...Understanding the effects of land use/cover change(LUCC) on regional climate is critical for achieving land use system sustainability and global climate change mitigation. However, the quantitative analysis of the contribution of LUCC to the changes of climatic factors, such as precipitation & temperature(P&T), is lacking. In this study, we combined statistical methods and the gravity center model simulation to quantify the effects of long-term LUCC on P&T in the Songnen Plain(SNP) of Northeast China from 1980–2018. The results showed the spatiotemporal variability of LUCC. For example, paddy field had the largest increase(15 166.43 km2) in the SNP, followed by dry land, while wetland had the largest decrease(19 977.13 km;) due to the excessive agricultural utilization and development. Annual average precipitation decreased at a rate of –9.89 mm per decade, and the warming trends were statistically significant with an increasing rate of 0.256°C per decade in this region since 1980. The model simulation revealed that paddy field, forestland, and wetland had positive effects on precipitation, which caused their gravity centers to migrate towards the same direction accompanied by the center of precipitation gravity, while different responses were seen for building land, dry land and unused land. These results indicated that forestland had the largest influence on the increase of precipitation compared with the other land use types.The responses in promoting the temperature increase differed significantly, being the highest in building land, and the lowest in forestland. In general, the analysis of regional-scale LUCC showed a significant reduction of wetland, and the increases in building land and cropland contributed to a continuous drying and rapid warming in the SNP.展开更多
Land surface temperature(LST) is the skin temperature of the earth surface. LST depends on the amount of sunlight received by any geographical area. Apart from sun light, LST is also affected by the land cover, which ...Land surface temperature(LST) is the skin temperature of the earth surface. LST depends on the amount of sunlight received by any geographical area. Apart from sun light, LST is also affected by the land cover, which leads to change in land surface temperature. Impact of land cover change(LCC) on LST has been assessed using Landsat TM5, Landsat 8 TIRS/OLI and Digital Elevation Model(ASTER) for Spiti Valley, Himachal Pradesh, India. In the present study, Spiti valley was divided into three altitudinal zones to check the pattern of changing land cover along different altitudes and LST was calculated for all the four land cover categories extracted from remote sensing data for the years of 1990 and 2015. Matrix table was used as a technique to evaluate the land cover change between two different years. Matrix table shows that as a whole, about 2,151,647 ha(30%) area of Spiti valley experienced change in land cover in the last 25 years. The result also shows vegetation and water bodies increased by 107,560.2 ha(605.87%) and 45 ha(0.98%), respectively. Snow cover and barren land decreased by 19,016.5 ha(23.92%) and 88,589(14.14%), during the study period. A significant increase has been noticed in vegetation amongst all land cover types. Minimum, maximum and mean LST for three altitudinal zones have been calculated. The mean LST recorded was 11℃ in 1990 but it rose by 2℃ and reached to 13℃ in 2015. Changes in LST were obtained for each land cover categories. The mean temperature of different land cover types was calculated by averaging value of all pixels of a given land cover types. The mean LST of vegetation, barren land, snow cover and water body increased by 6℃, 9℃, 1℃, and 7℃, respectively. Further, relationships between LST, Normalized Difference Snow Index(NDSI), and Normalised Difference Vegetation Index(NDVI) were established using Linear Regression.展开更多
Landsat ETM/TM data and an artificial neural network (ANN) were applied to analyse the expansion of the city of Xi'an and land use/cover change of its surrounding area between 2000 and 2003. Supervised classificati...Landsat ETM/TM data and an artificial neural network (ANN) were applied to analyse the expansion of the city of Xi'an and land use/cover change of its surrounding area between 2000 and 2003. Supervised classification and normalized difference barren index (NDBI) were used respectively to retrieve its urban boundary. Results showed that the urban area increased by an annual rate of 12.3%, with area expansion from 253.37 km^2 in 2000 to 358.60 km^2 in 2003. Large areas of farmland in the north and southwest were converted into urban construction land. The land use/cover changes of Xi'an were mainly caused by fast development of urban economy, population immigration from countryside, great development of infrastructure such as transportation, and huge demands for urban market. In addition, affected by the government policy of “returning farmland to woodland”, some farmland was converted into economic woodland, such as Chinese goosebeerv garden, vineyard etc.展开更多
Using Landsat remote sensing images, we analyzed changes in each land use type and transitions among different land use types during land use and land cover change (LUCC) in Ningwu County, located in the eastern Loe...Using Landsat remote sensing images, we analyzed changes in each land use type and transitions among different land use types during land use and land cover change (LUCC) in Ningwu County, located in the eastern Loess Plateau of China, from 1990 to 2010. We found that grassland, woodland, and farmland were the main land use types in the study area, and the area of each type changed slightly from 1990 to 2010, whereas the area of water, construction land, and unused land increased greatly. For the whole area, the net change and total change were insignificant due to weak human activity intensity in most of the study area, and the LUCC was dominated by quasi-balanced two-way transitions from 1990 to 2010. The insignificant overall amount of LUCC appears to have resulted from offsetting of rapid increases in population, economic growth, and the im- plementation of a program to return farmland to woodland and grassland in 2000. This program converted more farmland into woodland and grassland from 2000 to 2010 than from 1990 to 2000, but reclamation of woodland and grassland for use as farmland continued from 2000 to 2010, and is a cause for concern to the local government.展开更多
Studies on carbon emissions associated with land use and cover change(LUCC)are key to understanding the impact of human activities on regional sustainability.In this study,we analyzed the temporal and spatial changes ...Studies on carbon emissions associated with land use and cover change(LUCC)are key to understanding the impact of human activities on regional sustainability.In this study,we analyzed the temporal and spatial changes in carbon emissions associated with LUCC for production,living,and ecological spaces in Zhengzhou City of China.Landsat remote sensing images were used to classify the land use and land cover(LULC)types in Zhengzhou City in 1988,2001,2009,and 2015.Carbon emissions associated with LUCC were evaluated using a spatial gradient model and the niche mechanism.It was found that during 1988-2015,carbon emissions associated with LUCC in Zhengzhou City increased by 17.1×10^(6) t,while the carbon sink resulted from cultivated land,forests,water bodies,and unused land decreased significantly.Most of the increase in carbon emissions associated with LUCC occurred in the center of the city.The peak carbon emissions were located in the northeastern,southeastern,northwestern,and southwestern regions of Zhengzhou City,and carbon emissions varied considerably in the different spatial gradient rings over time.Among the three spaces,carbon emissions associated with LUCC were mainly affected by the living space.The population size and population urbanization rate were negatively correlated with the ecological space and positively correlated with the production and living spaces.Our results highlight that Zhengzhou City should take the new urbanization path of urban transformation development and ecological civilization construction to ensure the realization of the promised carbon emission reduction targets.展开更多
Land use/cover changes(LUCCs)significantly affect ecosystem services(ESs)and their corresponding monetary value.ESs can be evaluated to analyze the ecological and environmental changes caused by LUCCs.This research ai...Land use/cover changes(LUCCs)significantly affect ecosystem services(ESs)and their corresponding monetary value.ESs can be evaluated to analyze the ecological and environmental changes caused by LUCCs.This research aims to estimate variations in the ecosystem services value(ESV)due to LUCCs in Lahore of Pakistan,and to offer information and recommendations to policy-makers concerned with the economic improvement of metropolis areas.We first investigated the historical LUCCs from 1990 to 2019,and then simulated the future land use/cover in 2030 and 2050 based on the CA-Markov model under three scenarios,including business-as-usual(BAU),rapid economic growth(REG),and coordinated environmental sustainability(CES).Subsequently,we evaluated the ESV from 1990 to 2050 and evaluated the historical and potential future ESV changes induced by LUCCs during 1990–2019 and 2019–2050,respectively.The results showed that,land use/cover exhibited an increase in built-up land and decreases in vegetation,water body,and unused land both in the past and future.The net ESV decreased from 58.26 million USD in 1990 to 50.31 million USD in 2019.In 2050,the decrease in ESV is most rapid under the REG scenario(decrease ESV of 7.13 million USD and decrease percentage of 14.18%),followed by the BAU(decrease ESV of 5.61 million USD and decrease percentage of 11.15%)and CES(decrease ESV of 5.18 million USD and decrease percentage of 10.30%)scenarios.For each ecosystem service type,the ESV of waste treatment decreased by 18.37%from 1990 to 2019,followed by soil formation and conservation(17.52%),biodiversity and maintenance(13.23%),climate regulation(11.80%),food production(11.69%),hydrological regulation(11.11%),and aesthetic value(3.07%).These outcomes indicate that continuous land use/cover planning should focus on regenerating aquatic areas and vegetation restoration.展开更多
We evaluated the use of spatial sampling and satellite images to identify deforested areas in Wonju, South Korea. The changes in land cover were identified using a grid of sample points overlaid onto medium and high-r...We evaluated the use of spatial sampling and satellite images to identify deforested areas in Wonju, South Korea. The changes in land cover were identified using a grid of sample points overlaid onto medium and high-resolution remote sensing (RS) satellite images. Deforestation identified in this way (hereafter, RSD) was compared to administrative data on deforestation. We also compared high-resolution satellite images (HR-RSD) and actual deforestation based on categories which were Intergovernmental Panel on Climate Change data. RSD generated by medium-resolution satellite images overesti- mated the amount of deforested area by 1.5-2.4 times the actual deforested area, whereas RSD generated by HR- RSD underestimated the amount of deforested area by 0.4-0.9 times the actual area. The highest degree of matching (90 %) was found in HR-RSD with a grid interval of 500 m and the accuracy of HR-RSD was the highest, at 67 %. The results also revealed that the largest cause of deforestation was the establishment of settlements followed by conversion to cropland and grassland. We conclude that for the identification of deforestation using satellite images, HR-RSD with a grid interval of 500 m is most suitable.展开更多
基金supported by the Central Government to Guide Local Technological Development(23ZYQH0298)the Science and Technology Project of Gansu Province(20JR10RA656,22JR5RA416)the Science and Technology Project of Wuwei City(WW2202YFS006).
文摘Land use and cover change(LUCC)is the most direct manifestation of the interaction between anthropological activities and the natural environment on Earth's surface,with significant impacts on the environment and social economy.Rapid economic development and climate change have resulted in significant changes in land use and cover.The Shiyang River Basin,located in the eastern part of the Hexi Corridor in China,has undergone significant climate change and LUCC over the past few decades.In this study,we used the random forest classification to obtain the land use and cover datasets of the Shiyang River Basin in 1991,1995,2000,2005,2010,2015,and 2020 based on Landsat images.We validated the land use and cover data in 2015 from the random forest classification results(this study),the high-resolution dataset of annual global land cover from 2000 to 2015(AGLC-2000-2015),the global 30 m land cover classification with a fine classification system(GLC_FCS30),and the first Landsat-derived annual China Land Cover Dataset(CLCD)against ground-truth classification results to evaluate the accuracy of the classification results in this study.Furthermore,we explored and compared the spatiotemporal patterns of LUCC in the upper,middle,and lower reaches of the Shiyang River Basin over the past 30 years,and employed the random forest importance ranking method to analyze the influencing factors of LUCC based on natural(evapotranspiration,precipitation,temperature,and surface soil moisture)and anthropogenic(nighttime light,gross domestic product(GDP),and population)factors.The results indicated that the random forest classification results for land use and cover in the Shiyang River Basin in 2015 outperformed the AGLC-2000-2015,GLC_FCS30,and CLCD datasets in both overall and partial validations.Moreover,the classification results in this study exhibited a high level of agreement with the ground truth features.From 1991 to 2020,the area of bare land exhibited a decreasing trend,with changes primarily occurring in the middle and lower reaches of the basin.The area of grassland initially decreased and then increased,with changes occurring mainly in the upper and middle reaches of the basin.In contrast,the area of cropland initially increased and then decreased,with changes occurring in the middle and lower reaches.The LUCC was influenced by both natural and anthropogenic factors.Climatic factors and population contributed significantly to LUCC,and the importance values of evapotranspiration,precipitation,temperature,and population were 22.12%,32.41%,21.89%,and 19.65%,respectively.Moreover,policy interventions also played an important role.Land use and cover in the Shiyang River Basin exhibited fluctuating changes over the past 30 years,with the ecological environment improving in the last 10 years.This suggests that governance efforts in the study area have had some effects,and the government can continue to move in this direction in the future.The findings can provide crucial insights for related research and regional sustainable development in the Shiyang River Basin and other similar arid and semi-arid areas.
文摘Internal migration is highly valued due to its increasingly acknowledged potential for social and economic development. However, despite its significant contribution to the development of towns and cities, it has led to the deterioration of many ecosystems globally. Lake Bosomtwe, a natural Lake in Ghana and one of the six major meteoritic lakes in the world is affected by land cover changes caused by the rising effects of migration, population expansion, and urbanization, owing to the development of tourist facilities on the lakeshore. This study investigated land cover change trajectories using a post-classification comparison approach and identified the factors influencing alteration in the Lake Bosomtwe Basin. Using Landsat imagery, an integrated approach of remote sensing, geographical information systems (GIS), and statistical analysis was successfully employed to analyze the land cover change of the basin. The findings show that over the 17 years, the basin’s forest cover decreased significantly by 16.02%, indicating that population expansion significantly affects changes in land cover. Ultimately, this study will raise the awareness of stakeholders, decision-makers, policy-makers, government, and non-governmental agencies to evaluate land use development patterns, optimize land use structures, and provide a reference for the formulation of sustainable development policies to promote the sustainable development of the ecological environment.
基金National Natural Science Foundation of China No.90202012+1 种基金 National Basic Research Program of China, No.2005CB422006 No. 2002CB412507
文摘Based on the NOAA AVHRR-NDVI monthly data from 1981 to 2001, the spatial distribution and dynamic change of land cover along the Qinghai-Tibet Highway and Railway were studied. The results of the analytical data indicate that the NDVI values in July, August and September are rather high during a year, and a linear trend by calculating NDVI of each pixel computed based on the average values of NDVI in July, August and September were obtained. The results are as follows: 1) Land cover of the study area by NDVI displays high at two sides of the area and low in the center, and agriculture area 〉 alpine meadow 〉 alpine grassland 〉 desert grassland. 2) In the study area, the amount ofpixels with high increase, slight increase, no change, slight decrease and high decrease account for 0.29%, 14.86%, 67.61%, 16.7% and 0.57% of the whole area, respectively. The increase of land cover pixels is mainly in the agriculture and alpine meadow and the decrease pixels mainly in the alpine grassland, desert grassland and hungriness. Grassland and hungriness contribute to the decrease mostly and artificial land and meadow contribute to the increase mostly. 3) In the area where human beings live, the changing trend is obvious, such as the valleys of Lhasa River and Huangshui River and area along the Yellow River; in the high altitude area with fewer people living, the changing trend is relatively low, like the area of Hoh Xil. 4) Human being's behaviors are a key factor followed by the climate changes affecting land cover.
文摘A series of 17-yr equilibrium simulations using the NCAR COM3 (T42resolution) were performed to investigate the regional scale impacts of land cover change andincreasing CO_2 over China. Simulations with natural and current land cover at CO_2 levels of 280,355, 430, and 505 ppmv were conducted. Results show statistically significant changes in majorclimate fields (e.g. temperature and surface wind speed) on a 15-yr average following land coverchange. We also found increases in the maximum temperature and in the diurnal temperature range dueto land cover change. Increases in CO_2 affect both the maximum and minimum temperature so thatchanges in the diurnal range are small. Both land cover change and CO_2 change also impact thefrequency distribution of precipitation with increasing CO_2 tending to lead to more intenseprecipitation and land cover change leading to less intense precipitation―indeed, the impact ofland cover change typically had the opposite effect versus the impacts of CO_2. Our results providesupport for the inclusion of future land cover change scenarios in long-term transitory climatemodelling experiments of the 21st Century. Our results also support the inclusion of land surfacemodels that can represent future land cover changes resulting from an ecological response to naturalclimate variability or increasing CO_2. Overall, we show that land cover change can have asignificant impact on the regional scale climate of China, and that regionally, this impact is of asimilar magnitude to increases in CO_2 of up to about 430 ppmv. This means that that the impact ofland cover change must be accounted for in detection and attribution studies over China.
基金supported by the National Natural Science Foundation of China(GrantsNos40771017,40625002)the Chinese Academy of Sciences(Grant NoKZCX2–YW–315)
文摘The recent progresses on the reconstruction of historical land cover and the studies on regional climatic effects to temperature, precipitation, and the East Asian Monsoon across China were reviewed. Findings show that the land cover in China has been significantly modified by human activities over the last several thousands years, mainly through cropland expansion and forest clearance. The cropland over traditional Chinese agricultural areas increased from 5.32×10^5 km^2 in the mid-17th century to 8.27×10^5 km^2 in the mid-20th century, while the forest area over the Chinese mainland had been reduced by 1.66×10^6 km^2 during the last 300 years. These changes of land cover have been detected as an important driving force of climate change by simulations of climatic effects based on various climate models (including RegCM3, RegCM2-NCC, RIEMS version1, MM5 version 2, and AGCM+SSiB) with reconstructed historical land cover data or by contrasting current land cover to potential natural vegetation. The human-induced land cover changes over China have led to the enhancement of the East Asian winter monsoon, as well as cooling in winter and warming in summer approximately since 1700. However, the simulation results on annual mean temperature, precipitation, and the East Asian summer monsoon varied from model to model, which cannot be simply attributed to certain forcing so far, but undoubtedly, using different land cover datasets in various simulations played a key role. Thus, developing different regional scales with high time resolution more accurate gridded historical land cover datasets on is needed in the future.
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.
基金funded by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20100101)the National Key Research and Development Program of China(2019YFC0507404)the Gansu Province Science Foundation for Youth,China(20JR5RA543).
文摘Qinghai Lake is the largest saline lake in China.The change in the lake volume is an indicator of the variation in water resources and their response to climate change on the Qinghai-Tibetan Plateau(QTP)in China.The present study quantitatively evaluated the effects of climate change and land use/cover change(LUCC)on the lake volume of the Qinghai Lake in China from 1958 to 2018,which is crucial for water resources management in the Qinghai Lake Basin.To explore the effects of climate change and LUCC on the Qinghai Lake volume,we analyzed the lake level observation data and multi-period land use/land cover(LULC)data by using an improved lake volume estimation method and Integrated Valuation of Ecosystem Services and Trade-offs(InVEST)model.Our results showed that the lake level decreased at the rate of 0.08 m/a from 1958 to 2004 and increased at the rate of 0.16 m/a from 2004 to 2018.The lake volume decreased by 105.40×10^(8) m^(3) from 1958 to 2004,with the rate of 2.24×10^(8) m^(3)/a,whereas it increased by 74.02×10^(8) m^(3) from 2004 to 2018,with the rate of 4.66×10^(8) m^(3)/a.Further,the climate of the Qinghai Lake Basin changed from warm-dry to warm-humid.From 1958 to 2018,the increase in precipitation and the decrease in evaporation controlled the change of the lake volume,which were the main climatic factors affecting the lake volume change.From 1977 to 2018,the measured water yield showed an"increase-decrease-increase"fluctuation in the Qinghai Lake Basin.The effects of climate change and LUCC on the measured water yield were obviously different.From 1977 to 2018,the contribution rate of LUCC was -0.76% and that of climate change was 100.76%;the corresponding rates were 8.57% and 91.43% from 1977 to 2004,respectively,and -4.25% and 104.25% from 2004 to 2018,respectively.Quantitative analysis of the effects and contribution rates of climate change and LUCC on the Qinghai Lake volume revealed the scientific significance of climate change and LUCC,as well as their individual and combined effects in the Qinghai Lake Basin and on the QTP.This study can contribute to the water resources management and regional sustainable development of the Qinghai Lake Basin.
基金financially supported by the National Natural Science Foundation of China(Grant No.41761144081)Second Tibetan Plateau Scientific Expedition and Research(Grant No.2019QZKK0603)Strategic Priority Research Program of the ChineseAcademyofSciences(GrantNo.XDA20040201)。
文摘Land change is a cause and consequence of global environmental change.Land use and land cover have changed considerably due to increasing human activities and climate change,which has become the core issue of major international research projects.This study interprets land use and land cover status and the changes within the Koshi River Basin(KRB)using Landsat remote sensing(RS)image data,and employs logistic regression model to analyze the influence of natural and socioeconomic driving forces on major land cover changes.The results showed that the areas of built-up land,bare land and forest in KRB increased from 1990 to 2015,including the largest increases in forest and the highest growth rate in construction land.Areas of glacier,grassland,sparse vegetation,shrub land,cropland,and wetland all decreased over the study period.From the perspective of driving analysis,the role of human activities in land use and land cover change is significant than climate factors.Cropland expansion is the reclamation of cropland by farmers,mainly from early deforestation.However,labor force separation,geological disasters and drought are the main factors of cropland shrinkage.The increase of forest area in India and Nepal was attributed to the government’s forest protection policies,such as Nepal’s community forestry has achieved remarkable results.The expansion and contraction of grassland were both dominated by climatic factors.The probability of grassland expansion increases with temperature and precipitation,while the probability of grassland contraction decreases with temperature and precipitation.
基金financed by the National Natural Science Foundation of China (41201031)the Special Basic Research Fund for Methodology in Hydrology of Ministry of Sciences and Technology, China (2011IM011000)+2 种基金the Innovative Research Team Project of Basic Research Funds for National University at State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering (2009585412)the 111 Project of Ministry of Education and State Administration of Foreign Experts Affairs, China (B08048)the National Key Technology R&D Program by Ministry of Sciences and Technology, China (2013BAC10B02)
文摘In recent years, the streamflow of the Laohahe Basin in China showed a dramatic decrease during the rainy season as a result of climate change and/or human activities. The objective of this work was to document significant streamflow changes caused by land use and land cover (LULC) changes and to quantify the impacts of the observed changes in Laohahe Basin. in the study area, the observed streamflow has been influenced by LULC changes, dams, and irrigation from rivers, industry, livestock and human consumption. Most importantly, the growth of population and gross domestic product (GDP) accompanied by the growth in industrial and agricultural activities, which led to LULC changes with increased residential land and cropland and decreased grassland since 2000s. Statistical methods and Variable Infiltration Capacity (VIC) hydrological model were used to estimate the effects of climate change and LULC changes on streamflow and evaportranspiration lET). First, the streamflow data of the study area were divided into three sub-periods according to the Pettitt test. The hydrological process was then simulated by VIC model from 1964 to 2009. Furthermore, we compared the simulated results based on land use scenarios in 1989, 1999 and 2007, respectively for exploring the effect of LULC changes on the spatio-temporal distribution of streamflow and ET in the Laohahe Basin. The results suggest that, accompanied with climate change, the LULC changes and human water consumption appeared to be the most likely factors contributing to the sig- nificant reduction in streamflow in the Laohahe Basin by 64% from1999 to 2009.
基金jointly supported by the Second Tibetan Plateau Scientific Expedition and Research of China(2019QZKK0603)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20040200)Reconstruction of Historical Cultivated Land and Human Activities around the North Slope of Everest Area of China(42061023)。
文摘Land use/land cover(LULC) is an important part of exploring the interaction between natural environment and human activities and achieving regional sustainable development. Based on the data of LULC types(cropland, forest land, grassland, built-up land, and unused land) from 1990 to 2015, we analysed the intensity and driving factors of land use/cover change(LUCC) in the Yarlung Zangbo River,Nyang Qu River, and Lhasa River(YNL) region, Qinghai-Tibet Plateau of China, using intensity analysis method, cross-linking table method, and spatial econometric model. The results showed that LUCC in the YNL region was nonstationary from 1990 to 2015, showing a change pattern with "fast-slow-fast" and "U-shaped". Built-up land showed a steady increase pattern, while cropland showed a steady decrease pattern. The gain of built-up land mainly came from the loss of cropland. The transition pattern of LUCC in the YNL region was relatively single and stable during 1990–2015. The transition pattern from cropland and forest land to built-up land was a systematic change process of tendency and the transition pattern from grassland and unused land to cropland was a systematic change process of avoidance. The transition process of LUCC was the result of the combined effect of natural environment and social economic development in the YNL region. This study reveals the impact of ecological environment problems caused by human activities on the land resource system and provides scientific support for the study of ecological environment change and sustainable development of the Qinghai-Tibet Plateau.
基金Under the auspices of the National Key Research and Development Program of China(No.2016YFC0500201-01)National Natural Science Foundation of China(No.41671365,41771464)the Annual Project of the Office of the South-to-North Water Diversion Project(No.2018-21)
文摘The Middle Route of the South-to-North Water Diversion Project(MR-SNWDP)in China,with construction beginning in 2003,diverts water from Danjiangkou Reservoir to North China for residential,agriculture and industrial use.The water source area of the MR-SNWDP is the region that is most sensitive to and most affected by the construction of this water diversion project.In this study,we used Landsat Thematic Mapper(TM)and HJ-1 A/B images from 2000 to 2015 by an object-based approach with a hierarchical classification method for mapping land cover in the water source area.The changes in land cover were illuminated by transfer matrixes,single dynamic degree,slope zones and fractional vegetation cover(FVC).The results indicated that the area of cropland decreased by 31%and was replaced mainly by shrub over the past 15 years,whereas forest and settlements showed continuous increases of 29.2% and 77.7%,respectively.The changes in cropland were obvious in all slope zones and decreased most remarkably(–43.8%)in the slope zone above 25°.Compared to the FVC of forest and shrub,significant improvement was exhibited in the FVC of grassland,with a growth rate of 16.6%.We concluded that local policies,including economic development,water conservation and immigration resulting from the construction of the MR-SNWDP,were the main drivers of land cover changes;notably,they stimulated the substantial and rapid expansion of settlements,doubled the wetlands and drove the transformation from cropland to settlements in immigration areas.
基金The work was supported by the Shanghai Science and Technology Innovation Fund for Soft Science(17692102400)the Shanghai Pujiang Program(17PJC098).
文摘This study investigated forest cover change and the driving forces behind it in Fagita Lekoma District of Ethiopia that resulted in increased forest cover,which might be uncommon outside this case study area.The LULC change analysis was made from 2003 to 2017 based on Landsat images.Socioeconomic analysis was carried out to identify the major driving forces that resulted in LULC change.A questionnaire survey,focused group discussion,key informant interviews and field observation were employed to analyze the link between LULC change and the driving forces.The 15-year period(2003–2017)image analysis revealed that the coverage of forest lands,built-up areas and grassland has increased by 256%,100%and 96%,respectively,at the expense of cultivated lands and wetlands.The increased forest cover is due to the woodlots expansion of Acacia decurrens Willd,which are designed for sustainable livelihoods and a land revitalization strategy in the study area.Rapid population growth,an increasing demand for charcoal and subsequent market opportunities,preferred qualities of A.decurrens or black wattle to halt land degradation as well as to improve land productivity,have been identified as the major driving forces of forest cover change.Chi squared analysis revealed that:a comparative cash income from the sale of A.decurrens;a dependency on natural forests;the distance from the district administrative center;the size of the active labor force,and the area of land owned have significantly affected the cover change.The major forest cover change is due to the expansion of A.decurrens plantations that have socioeconomic and environmental implications to improve rural livelihoods and revitalize the land.Thus,the positive experiences identified in this study should be scaled-up and applied in other similar settings.
文摘This paper deals with land use and land cover change in China in the last 500 years. It aims at sensitizing related fields in giving due consideration on integration of environmental change and social economic development process and at proposing a framework for discussion towards further study. Based on historical review,several important changes were summarized as: natural vegetation were replaced by secondary or cultivated Plants, land cover changes differ from time to time and from place to place:and cropping pattern change is a sensitive indicator of land cover change in China. In the history of Cnina, many factors contributed to land use and land cover change either in positive or negative Ways. Four major driving forces were concluded, namely, climatic change, social transformation and turbulence, technology improvement, and international trade competition. In the last Part of tne Paper, a proposal on 'land use/land cover cnange' is framed, so as to calling comments on improving tne study and collaborations from varied authorities and researcn institutions.
基金supported by the National Natural Science Foundation of China(41671520)the Harbin Youth Reserve Talent Program,China(2016RAQXJ058)。
文摘Understanding the effects of land use/cover change(LUCC) on regional climate is critical for achieving land use system sustainability and global climate change mitigation. However, the quantitative analysis of the contribution of LUCC to the changes of climatic factors, such as precipitation & temperature(P&T), is lacking. In this study, we combined statistical methods and the gravity center model simulation to quantify the effects of long-term LUCC on P&T in the Songnen Plain(SNP) of Northeast China from 1980–2018. The results showed the spatiotemporal variability of LUCC. For example, paddy field had the largest increase(15 166.43 km2) in the SNP, followed by dry land, while wetland had the largest decrease(19 977.13 km;) due to the excessive agricultural utilization and development. Annual average precipitation decreased at a rate of –9.89 mm per decade, and the warming trends were statistically significant with an increasing rate of 0.256°C per decade in this region since 1980. The model simulation revealed that paddy field, forestland, and wetland had positive effects on precipitation, which caused their gravity centers to migrate towards the same direction accompanied by the center of precipitation gravity, while different responses were seen for building land, dry land and unused land. These results indicated that forestland had the largest influence on the increase of precipitation compared with the other land use types.The responses in promoting the temperature increase differed significantly, being the highest in building land, and the lowest in forestland. In general, the analysis of regional-scale LUCC showed a significant reduction of wetland, and the increases in building land and cropland contributed to a continuous drying and rapid warming in the SNP.
文摘Land surface temperature(LST) is the skin temperature of the earth surface. LST depends on the amount of sunlight received by any geographical area. Apart from sun light, LST is also affected by the land cover, which leads to change in land surface temperature. Impact of land cover change(LCC) on LST has been assessed using Landsat TM5, Landsat 8 TIRS/OLI and Digital Elevation Model(ASTER) for Spiti Valley, Himachal Pradesh, India. In the present study, Spiti valley was divided into three altitudinal zones to check the pattern of changing land cover along different altitudes and LST was calculated for all the four land cover categories extracted from remote sensing data for the years of 1990 and 2015. Matrix table was used as a technique to evaluate the land cover change between two different years. Matrix table shows that as a whole, about 2,151,647 ha(30%) area of Spiti valley experienced change in land cover in the last 25 years. The result also shows vegetation and water bodies increased by 107,560.2 ha(605.87%) and 45 ha(0.98%), respectively. Snow cover and barren land decreased by 19,016.5 ha(23.92%) and 88,589(14.14%), during the study period. A significant increase has been noticed in vegetation amongst all land cover types. Minimum, maximum and mean LST for three altitudinal zones have been calculated. The mean LST recorded was 11℃ in 1990 but it rose by 2℃ and reached to 13℃ in 2015. Changes in LST were obtained for each land cover categories. The mean temperature of different land cover types was calculated by averaging value of all pixels of a given land cover types. The mean LST of vegetation, barren land, snow cover and water body increased by 6℃, 9℃, 1℃, and 7℃, respectively. Further, relationships between LST, Normalized Difference Snow Index(NDSI), and Normalised Difference Vegetation Index(NDVI) were established using Linear Regression.
基金European Commission Project,No.ICA4-CT-2002-10004Knowledge Innovation ProjectofChinese Academ y ofSciences,No.KZCX3-SW -146
文摘Landsat ETM/TM data and an artificial neural network (ANN) were applied to analyse the expansion of the city of Xi'an and land use/cover change of its surrounding area between 2000 and 2003. Supervised classification and normalized difference barren index (NDBI) were used respectively to retrieve its urban boundary. Results showed that the urban area increased by an annual rate of 12.3%, with area expansion from 253.37 km^2 in 2000 to 358.60 km^2 in 2003. Large areas of farmland in the north and southwest were converted into urban construction land. The land use/cover changes of Xi'an were mainly caused by fast development of urban economy, population immigration from countryside, great development of infrastructure such as transportation, and huge demands for urban market. In addition, affected by the government policy of “returning farmland to woodland”, some farmland was converted into economic woodland, such as Chinese goosebeerv garden, vineyard etc.
基金supported by the Open Fund Project of the Key Laboratory of Desert and Desertification, Chinese Academy of Sciences (No. KLDD-2014-001)the Important Specialized Science and Technology Item of Shanxi Province, China (No. 20121101011)the Natural Science Foundation of China (Nos. 41271513, 41271030)
文摘Using Landsat remote sensing images, we analyzed changes in each land use type and transitions among different land use types during land use and land cover change (LUCC) in Ningwu County, located in the eastern Loess Plateau of China, from 1990 to 2010. We found that grassland, woodland, and farmland were the main land use types in the study area, and the area of each type changed slightly from 1990 to 2010, whereas the area of water, construction land, and unused land increased greatly. For the whole area, the net change and total change were insignificant due to weak human activity intensity in most of the study area, and the LUCC was dominated by quasi-balanced two-way transitions from 1990 to 2010. The insignificant overall amount of LUCC appears to have resulted from offsetting of rapid increases in population, economic growth, and the im- plementation of a program to return farmland to woodland and grassland in 2000. This program converted more farmland into woodland and grassland from 2000 to 2010 than from 1990 to 2000, but reclamation of woodland and grassland for use as farmland continued from 2000 to 2010, and is a cause for concern to the local government.
基金supported by the National Natural Science Foundation of China(41601175,41801362)the Young Backbone Teachers Foundation from Henan Province,China(2018GGJS019,2020GGJS114)+2 种基金the Program for Innovative Research Talent in University of Henan Province,China(20HASTIT017)the 2021 Project of Henan Soft Science Funds,China(212400410250)the 2020 Philosophy and Social Science Planning Project of Henan Province,China(2020BJJ020).
文摘Studies on carbon emissions associated with land use and cover change(LUCC)are key to understanding the impact of human activities on regional sustainability.In this study,we analyzed the temporal and spatial changes in carbon emissions associated with LUCC for production,living,and ecological spaces in Zhengzhou City of China.Landsat remote sensing images were used to classify the land use and land cover(LULC)types in Zhengzhou City in 1988,2001,2009,and 2015.Carbon emissions associated with LUCC were evaluated using a spatial gradient model and the niche mechanism.It was found that during 1988-2015,carbon emissions associated with LUCC in Zhengzhou City increased by 17.1×10^(6) t,while the carbon sink resulted from cultivated land,forests,water bodies,and unused land decreased significantly.Most of the increase in carbon emissions associated with LUCC occurred in the center of the city.The peak carbon emissions were located in the northeastern,southeastern,northwestern,and southwestern regions of Zhengzhou City,and carbon emissions varied considerably in the different spatial gradient rings over time.Among the three spaces,carbon emissions associated with LUCC were mainly affected by the living space.The population size and population urbanization rate were negatively correlated with the ecological space and positively correlated with the production and living spaces.Our results highlight that Zhengzhou City should take the new urbanization path of urban transformation development and ecological civilization construction to ensure the realization of the promised carbon emission reduction targets.
基金supported by the National Natural Science Foundation of China(41971130).
文摘Land use/cover changes(LUCCs)significantly affect ecosystem services(ESs)and their corresponding monetary value.ESs can be evaluated to analyze the ecological and environmental changes caused by LUCCs.This research aims to estimate variations in the ecosystem services value(ESV)due to LUCCs in Lahore of Pakistan,and to offer information and recommendations to policy-makers concerned with the economic improvement of metropolis areas.We first investigated the historical LUCCs from 1990 to 2019,and then simulated the future land use/cover in 2030 and 2050 based on the CA-Markov model under three scenarios,including business-as-usual(BAU),rapid economic growth(REG),and coordinated environmental sustainability(CES).Subsequently,we evaluated the ESV from 1990 to 2050 and evaluated the historical and potential future ESV changes induced by LUCCs during 1990–2019 and 2019–2050,respectively.The results showed that,land use/cover exhibited an increase in built-up land and decreases in vegetation,water body,and unused land both in the past and future.The net ESV decreased from 58.26 million USD in 1990 to 50.31 million USD in 2019.In 2050,the decrease in ESV is most rapid under the REG scenario(decrease ESV of 7.13 million USD and decrease percentage of 14.18%),followed by the BAU(decrease ESV of 5.61 million USD and decrease percentage of 11.15%)and CES(decrease ESV of 5.18 million USD and decrease percentage of 10.30%)scenarios.For each ecosystem service type,the ESV of waste treatment decreased by 18.37%from 1990 to 2019,followed by soil formation and conservation(17.52%),biodiversity and maintenance(13.23%),climate regulation(11.80%),food production(11.69%),hydrological regulation(11.11%),and aesthetic value(3.07%).These outcomes indicate that continuous land use/cover planning should focus on regenerating aquatic areas and vegetation restoration.
文摘We evaluated the use of spatial sampling and satellite images to identify deforested areas in Wonju, South Korea. The changes in land cover were identified using a grid of sample points overlaid onto medium and high-resolution remote sensing (RS) satellite images. Deforestation identified in this way (hereafter, RSD) was compared to administrative data on deforestation. We also compared high-resolution satellite images (HR-RSD) and actual deforestation based on categories which were Intergovernmental Panel on Climate Change data. RSD generated by medium-resolution satellite images overesti- mated the amount of deforested area by 1.5-2.4 times the actual deforested area, whereas RSD generated by HR- RSD underestimated the amount of deforested area by 0.4-0.9 times the actual area. The highest degree of matching (90 %) was found in HR-RSD with a grid interval of 500 m and the accuracy of HR-RSD was the highest, at 67 %. The results also revealed that the largest cause of deforestation was the establishment of settlements followed by conversion to cropland and grassland. We conclude that for the identification of deforestation using satellite images, HR-RSD with a grid interval of 500 m is most suitable.