International food trade has become a key driving force of agricultural land-use changes in trading countries, which has influenced food production and the global environment. Researchers have studied agricultural lan...International food trade has become a key driving force of agricultural land-use changes in trading countries, which has influenced food production and the global environment. Researchers have studied agricultural land-use changes and related environmental issues across multi-trading countries together, but most studies rely on statistic data without spatial attributes. However, agricultural land-use changes are spatially heterogeneous. Uncovering spatial attributes can reveal more critical information that is of scientific significance and has policy implications for enhancing food security and protecting the environment. Based on an integrated framework of telecoupling （socioeconomic and environmental interactions over distances）, we studied spatial attributes of soybean land changes within and among trading countries at the same time. Three distant countries -- Brazil, China, and the United States -- constitute an excellent example of telecoupled systems through the process of soybean trade. Our results presented the spatial distribution of soybean land changes-- highlighting the hotspots of soybean gain and soybean loss, and indicated these changes were spatially clustered, different across multi-spatial scales, and varied among the trading countries. Assisted by the results, global challenges like food security and biodiversity loss within and among trading countries can be targeted and managed efficiently. Our work provides simul- taneously spatial information for understanding agricultural land-use changes caused by international food trade globally, highlights the needs of coordination among trading countries, and promotes global sustainability.展开更多
<span style="font-family:Verdana;">Land-use change has been</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">...<span style="font-family:Verdana;">Land-use change has been</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">a factor that alters the hydrologic response of the watersheds leading to influencing on sediment yield changes. This study is mainly focusing on the assessment of the impacts of the land-use changes on sediment load and lake depth reduction on Lake Ziway, Ethiopia using an integrated approach of Remote Sensing (RS), GIS and SWAT model. ERDAS IMAGINE 14 model was used to generate land-use maps from Landsat TM, ETM+, and Ls8 acquired, in 1988, 2002 and 2015 as representative for the periods of (1988</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">1998), (1998</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">2008) and (2008</span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""><span style="font-family:Verdana;">2018), respectively. The maximum likelihood algorithm of supervised classification applied to classify the </span><span style="font-family:Verdana;">basin land-use into seven land-use classes. The SWAT hydrological model</span><span style="font-family:Verdana;"> with ArcGIS interface setup for the basin to evaluate the flow and sediment load with calibration and validation performance of the model range R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> (0.71 </span></span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> 0.89) and NSE (0.57 </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> 0.87). As a result, the total average annual sediment yield from the sub-basins estimated as 3.59</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">t/ha/yr, 4.36</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">t/ha/yr, and 4.89</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">t/ha/yr for three consecutive decadal periods 1988</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">1998, 1998</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">2008, and</span><span style="font-family:Verdana;"> 2008</span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""><span style="font-family:Verdana;">2018 respectively. The increasing trend of sediment yield in the Lake Ziway watershed through one period to another justified as due to land-use. Similarly, the net sediment volume deposited in the lake also showed incremental </span><span style="font-family:Verdana;">trained with the land-use changes as 1.5</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">mcm/yr, 1.81 mcm/yr, and 2.033</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">mcm/yr for the period of 1988-1998, 1999-2008, and 2009-2018, respectively. The depth and water holding capacity of the lake reduced by 4.3</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">m and 25.76</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">mcm, respectively, from the depth and capacity recorded on the 2006 bathy</span><span style="font-family:Verdana;">metric survey, which was the effect of deposited sediment over the last 12</span><span style="font-family:Verdana;"> years.</span></span>展开更多
Land-use/land-cover changes （LUCCs） have links to both human and nature inter- actions. China＇s Land-Use/cover Datasets （CLUDs） were updated regularly at 5-year inter- vals from the late 1980s to 2010, with stand...Land-use/land-cover changes （LUCCs） have links to both human and nature inter- actions. China＇s Land-Use/cover Datasets （CLUDs） were updated regularly at 5-year inter- vals from the late 1980s to 2010, with standard procedures based on Landsat TM／ETM＋ im- ages. A land-use dynamic regionalization method was proposed to analyze major land-use conversions. The spatiotemporal characteristics, differences, and causes of land-use changes at a national scale were then examined. The main findings are summarized as fol- lows. Land-use changes （LUCs） across China indicated a significant variation in spatial and temporal characteristics in the last 20 years （1990-2010）. The area of cropland change de- creased in the south and increased in the north, but the total area remained almost un- changed. The reclaimed cropland was shifted from the northeast to the northwest. The built-up lands expanded rapidly, were mainly distributed in the east, and gradually spread out to central and western China. Woodland decreased first, and then increased, but desert area was the opposite. Grassland continued decreasing. Different spatial patterns of LUC in China were found between the late 20th century and the early 21st century. The original 13 LUC zones were replaced by 15 units with changes of boundaries in some zones. The main spatial characteristics of these changes included （1） an accelerated expansion of built-up land in the Huang-Huai-Hai region, the southeastern coastal areas, the midstream area of the Yangtze River, and the Sichuan Basin; （2） shifted land reclamation in the north from northeast China and eastern Inner Mongolia to the oasis agricultural areas in northwest China; （3） continuous transformation from rain-fed farmlands in northeast China to paddy fields; and （4） effective- ness of the ＂Grain for Green＂ project in the southern agricultural-pastoral ecotones of Inner Mongolia, the Loess Plateau, and southwestern mountainous areas. In the last two decades, although climate change in the north affected the change in cropland, policy regulation and economic driving forces were still the primary causes of LUC across China. During the first decade of the 21st century, the anthropogenic factors that drove variations in land-use pat- terns have shifted the emphasis from one-way land development to both development and conservation. The ＂dynamic regionalization method＂ was used to analyze changes in the spatial patterns of zoning boundaries, the internal characteristics of zones, and the growth and decrease of units. The results revealed ＂the pattern of the change process,＂ namely the process of LUC and regional differences in characteristics at different stages. The growth and decrease of zones during this dynamic LUC zoning, variations in unit boundaries, and the characteristics of change intensities between the former and latter decades were examined. The patterns of alternative transformation between the ＂pattern＂ and ＂process＂ of land use and the causes for changes in different types and different regions of land use were explored.展开更多
The consequence of land-use change from forest to agriculture and other uses has become one of the world’s greatest concerns.The soil,one of the most important components of forests and containing all the required pl...The consequence of land-use change from forest to agriculture and other uses has become one of the world’s greatest concerns.The soil,one of the most important components of forests and containing all the required plant nutrients as soluble ions,is highly impacted by these changes.Because vast areas of the Zagros forests in western Iran have changed in use during the last few decades,the present study investigated the effects of landuse changes of forest area to agriculture,orchard,and agroforestry on soil chemical and physical properties.Soil was sampled at four land-use areas:less-disturbed forest areas(control)and agricultural,orchard,and agroforestry areas.Among each of the two forest-use areas(agroforestry and orchard),we selected five trees with similar-sized crowns and sampled under each tree crown at 0-15 and>15-30 cm depths.Five soil samples also were taken in agriculture area at each depth.The findings indicated that during land-use changes,soil sand particles decreased,and clay and silt particles of soil increased,resulting in a fine soil texture.Moreover,the amount of nitrogen(N),phosphorus(P),organic carbon(OC),and electrical conductivity(EC)of soil decreased at both depths due to the decrease in organic matter.Soil pH and magnesium(Mg)level rose during land-use change at both depths except at agricultural sites.Soil potassium(K)content decreased during agricultural use due to the elimination of tree cover.The level of K decreased only at the depth of 0-15 cm because of K dependency on parent materials.Generally,most soil nutrients were affected by plant removal in the conversion.Forest and agricultural soil are distinguishable by their properties,while land-uses such as agroforestry-orchard separated from the others.Soil nutrients were severely affected by the decrease and elimination of tree cover,plowing,and continuous harvesting,resulting in a decline in soil quality and fertility.展开更多
North China is the most important food basket of China, where the majority of wheat and corn are produced. Most crops grown in North China are irrigated, thus water security is food security. Since the 1980s, drying h...North China is the most important food basket of China, where the majority of wheat and corn are produced. Most crops grown in North China are irrigated, thus water security is food security. Since the 1980s, drying has been frequently observed, as shown by a reduction in precipitation, cutoff in riverflow, and shrinkage of lakes. This increase in drying cannot be explained by climate change alone. We propose that intensive land-use in this area in recent decades has had a significant impact. The objectives of the study are to develop a quantitative model of the concurrent processes of climate change and land-use in North China, and to estimate the relative contributions of each on the observed drying. We integrated relevant socioeconomic data, land-use data, and climate data in the model, and carried out a detailed multi-temporal （decade, year, day） analysis. Results showed that land-use has greatly changed since 1999. This change is mainly associated with an extremely important 1999 national policy of ＂returning farmland and grazing land to forest and grassland＂. We found an interesting interaction between climate change and land use policy on riverflow, runoff, and evapotranspiration. During 1970s and 1980s, climate change explained more than 80%, while the land-use change explained only 10% of the riverflow change. The relative contributions were 45 and 45% in the 1980s-1990s and 35 and 55% in the 1990s-2000s respectively for climate change and land-use change. Since the 1990s land-use change has also contributed more to runoff change than climate change. The opposite trend was found for changes in evapotranspiration. Water availability for agriculture in northern China is simultaneously stressed by extensive changes in land-use and rapid climate change. Adaptation of ecological principles, such as the ＂returning farmland/grazing land to forest and grassland＂ policy, and other adjustments of economic developmental strategies can be effective tools to mitigate the water shortage problem in northern China and promote sustainable agricultural and food development.展开更多
We analyzed the characteristics and trends of land-use change in and near the coastal zone of the Yangtze River Delta(YRD) during five periods(1995, 2000 2005, 2010, and 2015) using remotely sensed Landsat imagery. Us...We analyzed the characteristics and trends of land-use change in and near the coastal zone of the Yangtze River Delta(YRD) during five periods(1995, 2000 2005, 2010, and 2015) using remotely sensed Landsat imagery. Using automatic supervised classification combined with visual interpretation, we obtained land-use information for five study areas(Nantong, Shanghai, Jiaxing, Ningbo, and Zhoushan). Significant land-use changes have occurred in this area between 1995 and 2015, characterized in particular by large reductions in cultivated land and rapid increases in urbanized land. In addition, land reclamation was very active in this period as an effective supplement to the increased demand for land development: since 1995, 1622 km^2 of land was reclaimed from near-coastal regions in the study area. This increase in urbanization was jointly driven by population, economic, transportation, and policy factors. Urban areas expanded from the center outward in concentric rings, with infrastructure guiding the radial expansion of development along transportation corridors, thus forming a network of connections. Due to the influence of national land regulation policies, the expansion rate of development in the YRD gradually diminished after 2010. This indicates that the area's resource and environmental carrying capacity has reached a saturation stage in which urbanization has transitioned from broad and incremental expansion to the intensive use of land resources.展开更多
This paper describes a GIS-based sp atial analysis method that combines qualitative analysis and quantita-tive analysis to characterize land-use patterns and predict the trend of future land-use changes in Haizhu Di s...This paper describes a GIS-based sp atial analysis method that combines qualitative analysis and quantita-tive analysis to characterize land-use patterns and predict the trend of future land-use changes in Haizhu Di strict of Guangzhou City,China.Spatial tech nique is introduced to manage land-u se data and derive information of lan d-use changes.Through the case study for t he selected area,it is demonstrated that the method and technique introd uced in the paper can be effectively utilized fo r the analysis of urban land-use chan ges.Based upon this analysis,the paper also pro-vides discussions and recommendati on on urban land-use planning,urban planning and land management.Both l and-use maps of Haizhu District of Guangzhou in 1995and 1997and the remote sensin g images of 1999are utilized in the cu r-rent research.It is convenient to ge t various statistic data and to combi ne attribute data with spatial data s o as to analyze land-use changes in a geographic con text,which is especially suitable f or the need of urban construction dep artment,ur-ban management department and urban planning department.展开更多
Amid the euphoria of Reducing Emissions from Deforestation and Forest Degradation (REDD) and REDD+ discussions, the expectations of large financial gains raise the interest of all. A country, however, will only enjoy ...Amid the euphoria of Reducing Emissions from Deforestation and Forest Degradation (REDD) and REDD+ discussions, the expectations of large financial gains raise the interest of all. A country, however, will only enjoy REDD benefits if the cost of REDD is lower than the benefit. The opportunity cost analysis is an effective tool for assessing the feasibility of REDD+ since the largest portion of costs associated with REDD+ and can help to identify fair compensation for those who change their land use. The opportunity cost analysis has been exercised in Tanjung Jabung Barat (Tanjabar) district-Indonesia to examine the economic-feasibility of carbon emission reduction under different type carbon price scenarios. This study reveals a sharp decline of land-use systems with high carbon-stock and low profitability is obvious. On mineral soil, low carbon-stock and high profitability (mostly oil palm) has increased rapidly, especially in the period 2000-2009. It has become the dominant land-use system. The low-to-medium carbon stock and medium profitability land-use category increased from 1990 to 2005 but declined from 2005 to 2009. The low carbon-stock and low profitability category was constant and the proportion of the area was below 15%. The ex-ante analysis in predicting the potential for future emissions reduction in Tanjabar through REDD+ approaches shows that the cumulative emission of Tanjabar in 2020 is estimated at 61.91 Mg CO2-eq/Ha.Year, while the reduced emission by excluding all land use conversion below $5 threshold is estimated at 51.71 Mg CO2-eq/Ha.Year. This means that there is a potential for 16% emission reduction using $5/ton CO2-eq incentive. Another important finding in this study is that if the price of carbon increases by double to $10, the amount of reduced emission does not change much. This can use as a basis for determining the right amount of incentive for trade-off between economic profitability and climate change mitigation effort in Tanjabar using REDD+ scheme both at seller and buyer perspectives.展开更多
Water resources are a crucial factor that determines the health of ecosystems and socio-economic development;however,they are under threat due to climate change and human activities.The quantitative assessment of wate...Water resources are a crucial factor that determines the health of ecosystems and socio-economic development;however,they are under threat due to climate change and human activities.The quantitative assessment of water resources using the concept of blue water and green water can improve regional water resources management.In this study,spatiotemporal distributions of blue water and green water were simulated and analyzed under scenarios of climate change and land-use changes using the Soil and Water Assessment Tool(SWAT)in Ningxia Hui Autonomous Region,Northwest China,between 2009 and 2014.Green water,a leading component of water resources,accounted for more than 69.00%of the total water resources in Ningxia.Blue water and green water showed a single peak trend on the monthly and annual scales during the study period.On the spatial scale,the southern region of Ningxia showed higher blue water and green water resources than the northern region.The spatiotemporal distribution features of blue water,green water,and green water flow had strong correlations with precipitation.Furthermore,the simulation identified the climate change in Ningxia to be more influential on blue water and green water than land-use changes.This study provides a specific scientific foundation to manage water resources in Ningxia when encountered with climate change together with human activities.展开更多
Anthropogenic activities and natural processes are continuously altering the mountainous environment through deforestation, forest degradation and other land-use changes. It is highly important to assess, monitor and ...Anthropogenic activities and natural processes are continuously altering the mountainous environment through deforestation, forest degradation and other land-use changes. It is highly important to assess, monitor and forecast forest cover and other land-use changes for the protection and conservation of mountainous environment. The present study deals with the assessment of forest cover and other land-use changes in the mountain ranges of Dir Kohistan in northern Pakistan, using high resolution multi-temporal SPOT-5 satellite images. The SPOT-5 satellite images of years 2004, 2007, 2010 and 2013 were acquired and classified into land-cover units. In addition, forest cover and land-use change detection map was developed using the classified maps of 2004 and 2013. The classified maps were verified through random field samples and Google Earth imagery(Quick birds and SPOT-5). The results showed that during the period 2004 to 2013 the area of forest land decreased by 6.4%, however, area of range land and agriculture land have increased by 22.1% and 2.9%, respectively. Similarly, barren land increased by 1.1%, whereas, area of snow cover/glacier is significantly decreased by 21.3%. The findings from the study will be useful for forestry and landscape planning and can be utilized by the local, provincial and national forest departments; and REDD+ policy makers in Pakistan.展开更多
As more and more farmland is converted to forestry, the need for effective decision support regarding the use of land in the fragile ecological environment of the Loess Plateau hilly-gully area. The Luoyugou watershed...As more and more farmland is converted to forestry, the need for effective decision support regarding the use of land in the fragile ecological environment of the Loess Plateau hilly-gully area. The Luoyugou watershed was chosen as the study area to calculate the single dynamic degree, integrated dynamic degree, and change indexes of land use, as well as the land-use type transition matrix. This was done by interpreting the TM and SPOT images of the Luoyugou watershed in 1986, 1995, and2004 and making statistical analysis. The results of ou statistical analysis show that the conversion of slope farm land to terrace and forest land plays a dominant role in land-use changes in the Luoyugou watershed from 1986 to2004. The land-use changes are mainly driven by popula tion growth, socio-economic development, consume spending, and investment in forest ecology.展开更多
Comprehensive study on land-use change of spatial pattern and temporal process is the key component in land use/land cover changes (LUCC) study nowadays. According to the theories and methods of Geo-information Tupu (...Comprehensive study on land-use change of spatial pattern and temporal process is the key component in land use/land cover changes (LUCC) study nowadays. According to the theories and methods of Geo-information Tupu (Carto-methodology in Geo-information, CMGI) for geospatial and temporal analysis and integration models of spatial pattern and temporal processes in GIS, the paper puts forward Tupu methodology of land-use change and names the basic synthetic unit of spatial-temporal information Tupu unit. Tupu unit is the synthetic unit for geospatial-temporal analysis, which is synthesized by “space·attribute·process”features and composed of relatively homogeneous geographic unit and temporal unit. Based on the spatial features of 4 stages of land-use change in 1956, 1984, 1991, and 1996, a series of Tupu on land-use change in the Yellow River Delta (YRD) are created and studied in the paper, which includes 3 temporal units of spatial-temporal Tupu, process Tupu of land-use changes during the last 40 years, and reconstructions of a series of “arisen”Tupu, “arisen”process Tupu and pattern Tupu on land-use changes in the last 40 years by remapping tables of a reclassifying system. There are 3 methods of Tupu analysis on land-use change that are used to disclose change processes of land-use spatial conversion in YRD, such as spatial query and statistics, order of Tupu units by area and land-use conversion matrixes. In order to reveal the spatial pattern of land-use change processes, we analyze spatial-temporal changes of each Tupu above in various temporal units and spatial difference of pattern Tupu in the last 40 years by dynamic Tupu units. Tupu analysis on regional land-use is a promising trial on the comprehensive research of “spatial pattern of dynamic process”and “temporal process of spatial pattern”in LUCC research. The geo-information Tupu methodology would be a powerful and efficient tool on integrated studies of spatial pattern and temporal process in geoscience.展开更多
By using the improved regional climate model （BCC_ RegCM1.0）, a series of modeling experiments are undertaken to investigate the impacts of historical land-use changes （LUCs） on the regional climate in China. Simu...By using the improved regional climate model （BCC_ RegCM1.0）, a series of modeling experiments are undertaken to investigate the impacts of historical land-use changes （LUCs） on the regional climate in China. Simulations are conducted for 2 years using estimated land-use for 1700, 1800, 1900, 1950, and 1990. The conversion of land cover in these periods was extensive over China, where large areas were altered from forests to either grass or crops, or from grasslands to crops. Results show that, since 1700, historical LUCs have significant effects on regional climate change, with rainfall increasing in the middle and lower reaches of the Yangtze River Basin, Northwest China, and Northeast China, but decreasing by different degrees in other regions. The air temperature shows significant warming over large areas in recent hundred years, especially from 1950 to 1990, which is consistent with the warming caused by increasing greenhouse gases. On the other hand, historical LUCs have obvious effects on mean circulation, with the East Asian winter and summer monsoonal flows becoming more intensive, which is mainly attributed to the amplified temperature difference between ocean and land due to vegetation impacts of LUCs on regional climate change. change. Thus, it would be given more attention to the展开更多
River runoff is affected by many factors, including long-term effects such as climate change that alter rainfall-runoff relationships, and short-term effects related to human intervention(e.g., dam construction, land-...River runoff is affected by many factors, including long-term effects such as climate change that alter rainfall-runoff relationships, and short-term effects related to human intervention(e.g., dam construction, land-use and land-cover change(LUCC)). Discharge from the Yellow River system has been modified in numerous ways over the past century, not only as a result of increased demands for water from agriculture and industry, but also due to hydrological disturbance from LUCC, climate change and the construction of dams. The combined effect of these disturbances may have led to water shortages. Considering that there has been little change in long-term precipitation, dramatic decreases in water discharge may be attributed mainly to human activities, such as water usage, water transportation and dam construction. LUCC may also affect water availability, but the relative contribution of LUCC to changing discharge is unclear. In this study, the impact of LUCC on natural discharge(not including anthropogenic usage) is quantified using an attribution approach based on satellite land cover and discharge data. A retention parameter is used to relate LUCC to changes in discharge. We find that LUCC is the primary factor, and more dominant than climate change, in driving the reduction in discharge during 1956–2012, especially from the mid-1980 s to the end-1990 s. The ratio of each land class to total basin area changed significantly over the study period. Forestland and cropland increased by about 0.58% and 1.41%, respectively, and unused land decreased by 1.16%. Together, these variations resulted in changes in the retention parameter, and runoff generation showed a significant decrease after the mid-1980 s. Our findings highlight the importance of LUCC to runoff generation at the basin scale, and improve our understanding of the influence of LUCC on basin-scale hydrology.展开更多
Soil harbors remarkably stabilize bacterial communities at the phylum level. However, no two soils have exactly the same structure of bacterial phyla. The structure of microbial community is strongly influenced by the...Soil harbors remarkably stabilize bacterial communities at the phylum level. However, no two soils have exactly the same structure of bacterial phyla. The structure of microbial community is strongly influenced by the type of land-use through changes in soil attributes. Using high-throughput pyrosequencing and quantitative polymerase chain reaction techniques, soil microbial community structures were investigated along a land-use gradient of 100- and 27-year farmlands, a 33-year Pinus forest, a 28-year poplar forest, and a 21-year shrubland, as well as a native desert from which all cultivated systems were converted. The results revealed that the dominant phylotypes in the native soil comprised primarily of Alphaproteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes, accounting for 〉 71.4% of the total bacterial 16S rRNA sequence reads. Changes in land-use led to a significant decrease in these dominant phylotypes down to 33.4%. In contrast, the phylotypes with low abundance, such as Acidobaeteria, Chloroflexi, Nitrospira, and Gammaproteobaeteria, increased sharply from 4.5%-5.9% in the native soil to 20.9% 30.2% of the total 16S rRNA gene sequences in the cultivated soils except for the soil from the shrubland. These contrasting changes in the major taxa appear to be correlated with the changes in soil attributes. For instance, bacterial and archaeal amoA genes were found to be 960- and 3 800-fold more abundant in the soil from the 100-year farmland than the native soil. The changes in numerically less dominant nitrifying phylotypes are consistent with soil inorganic nitrogen dynamics. Quantification of the 16S rRNA genes demonstrated that bacteria and archaea were about two to three orders of magnitude more abundant in the cultivated soil than in the native soil. Hence, land-use type affects the soil bacterial community structure, which has profound consequences on ecosystem function.展开更多
Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO_2) buildup is greatly affected by human activities.To evaluate the influence of land-use changes on SOC stock...Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO_2) buildup is greatly affected by human activities.To evaluate the influence of land-use changes on SOC stocks in paddy soils,a new algorithm was developed by integrating MODIS (moderate resolution imaging spectral-radiometer) and TM/ETM data for timely monitoring the land-use change in Wujiang County.Thereafter,the land-use class-maps derived from MODIS and TM/ETM analyses were further used to estima...展开更多
Remote-sensing data for protected areas in northern Togo, obtained in three different years （2007, 2000, and 1987）, were used to assess and map changes in land cover and land use for this drought prone zone. The nor...Remote-sensing data for protected areas in northern Togo, obtained in three different years （2007, 2000, and 1987）, were used to assess and map changes in land cover and land use for this drought prone zone. The normalized difference vegetation index （NDVI） was applied to the images to map changes in vegetation. An unsupervised classification, followed by classes recoding, filtering, identifications, area computing and post-classification process were applied to the composite of the three years of NDVI images. Maximum likelihood classification was applied to the 2007 image （ETM＋2007） using a supervised classification process. Seven vegetation classes were defined from training data sets. The seven classes included the following biomes： riparian forest, dry forest, flooded vegetation, wooded savanna, fallows, parkland, and water. For these classes, the overall accuracy and the overall kappa statistic for the classi- fied map were 72.5% and 0.67, respectively. Data analyses indicated a great change in land resources; especially between 1987 and 2000 proba- bly due to the impact of democratization process social, economic, and political disorder from 1990. Wide-scale loss of vegetation occurred during this period. However, areas of vegetation clearing and regrowth were more visible between 2000 and 2007. The main source of confusion in the contingency matrix was due to heterogeneity within certain classes. It could also be due to spectral homogeneity among the classes. This research provides a baseline for future ecological landscape research and for the next management program in the area.展开更多
To solve the problems caused by irrational land-use, studying the functions of land-use, its changing characteristics, and the relationship between each land-use function will be beneficial for achieving sustainable l...To solve the problems caused by irrational land-use, studying the functions of land-use, its changing characteristics, and the relationship between each land-use function will be beneficial for achieving sustainable land development. In this research, we constructed an evaluation framework of multiple land-use functions(LUFs) based on sustainable land-use theory. Specifically,, we classified the multiple LUFs into three types: agricultural production function(APF), living function(LVF), and ecological service function(ESF).We then spatialized the economic and social data, and implemented the InVEST(Integrated Valuation of Ecosystem Services and Tradeoffs) model and RUSLE(Revised Universal Soil Loss Equation) model to evaluate each sub-LUF(crop production, aquatic production, woodlands production, livestock production, living space, life quality, water supply, soil conservation, climate regulation, biological conservation) in central China in 2000 and again in 2015. Moreover, by analyzing the changes to LUFs and the relationships between each LUF change, we were able to discern patterns of LUF change in central China. The results show that: (1)42.12% of total territory in the study area increased their APF from 2000 to 2015, while 43.41% of the lands increased their ESF yet only 8.98% of the lands increased their LVF;(2) in Hubei and Hunan, there was more land with an increase of APF than in Anhui or Jiangxi. The APF in Jiangxi exhibited the greatest decline over time period, the LVF increased more in the provincial capital cities than in other regions, and the ESF expanded more in Jiangxi than in the other provinces;and (3) the changes in APF were significantly and positively correlated with changes in LVF. Additionally, changes in ESF were negatively but non-significantly correlated with changes in APF and LVF.展开更多
The relationship between landslides,land use,and sediment connectivity is not only a critical interdisciplinary topic,but also remains a challenging issue in assessing dynamic landslide susceptibility within reservoir...The relationship between landslides,land use,and sediment connectivity is not only a critical interdisciplinary topic,but also remains a challenging issue in assessing dynamic landslide susceptibility within reservoir areas.To explore the interactions among landslide,land use changes,and sediment dynamic,this study took Zigui Basin,the head area of the Three Gorges Reservoir,as the study area to examine this triadic relationship by single-factor detection and interactive detection.Here,we utilized Dynamic Attitude(DA)analysis to quantify land use changes and applied the Index of Connectivity(IC)to assess sediment connectivity evolution from 2018 to 2023.A multi-temporal analysis using the Landslide Susceptibility Index(LSI)was conducted to evaluate the degree of transformation in the three objects and the influence of these changes on the landslide susceptibility.According to the spatial analyst and statistics tools in ArcGIS,the results reveal that most of the landslides distributed in areas with high land use dynamic attitude,such as cultivated land transfers to forestland or garden plot,and the garden plot continuously increased across the study period with largest variation of 5%and an increment of 1.9%.Furthermore,linkage between land use and sediment transport can be effectively quantified by IC,and the resulting map indicated that garden plot increased,and catchment channel characteristics had a greater influence on the IC value than differences in vegetation cover.A comprehensive evaluation of the differences among the susceptibility maps reveals that the very high susceptibility classes are predominantly influenced by enhanced connectivity,whereas land use change has a greater effect on medium-low susceptibility region than that of sediment evolution.That is,both changes of land use and connectivity have positively correlated with landslide activity,but they exhibit differential influences on landslides susceptibility.展开更多
Climate and land-use changes are predicted to impact biodiversity,threatening ecosystem services and functions.However,their combined effects on the functional diversity of mammals at the regional scale remain unclear...Climate and land-use changes are predicted to impact biodiversity,threatening ecosystem services and functions.However,their combined effects on the functional diversity of mammals at the regional scale remain unclear,especially at the beta level.Here,we use projected climate and land-use changes in China to investigate their potential effects on the alpha and beta functional diversities of terrestrial mammals under low-and high-emission scenarios.In the current projection,we showed strong positive spatial correlations between functional richness and species richness.Functional evenness(FEve),functional specialization(FSpe),and functional originality(FOri)decreased with species richness,and functional divergence(FDiv)increased first and then plateaued.Functional beta diversity was dominated by its nestedness component,in contrast to the taxonomic facet.Potential changes in species richness are more strongly influenced by land-use change under the low-emission scenario,while under the high-emission scenario,they are more strongly influenced by climate change.Changes in functional richness(FRic)were inconsistent with those in species richness,with a magnitude of decreases greater than predicted from species richness.Moreover,mammal assemblages showed potential functional differentiation(FD)across the country,and the trends exceeded those towards taxonomic differentiation(TD).Our findings help us understand the processes underlying biodiversity responses to global changes on multiple facets and provide new insight for conservation plans.展开更多
基金financial support from the National Science FoundationMichigan State UniversityMichigan AgBio Research,United States
文摘International food trade has become a key driving force of agricultural land-use changes in trading countries, which has influenced food production and the global environment. Researchers have studied agricultural land-use changes and related environmental issues across multi-trading countries together, but most studies rely on statistic data without spatial attributes. However, agricultural land-use changes are spatially heterogeneous. Uncovering spatial attributes can reveal more critical information that is of scientific significance and has policy implications for enhancing food security and protecting the environment. Based on an integrated framework of telecoupling （socioeconomic and environmental interactions over distances）, we studied spatial attributes of soybean land changes within and among trading countries at the same time. Three distant countries -- Brazil, China, and the United States -- constitute an excellent example of telecoupled systems through the process of soybean trade. Our results presented the spatial distribution of soybean land changes-- highlighting the hotspots of soybean gain and soybean loss, and indicated these changes were spatially clustered, different across multi-spatial scales, and varied among the trading countries. Assisted by the results, global challenges like food security and biodiversity loss within and among trading countries can be targeted and managed efficiently. Our work provides simul- taneously spatial information for understanding agricultural land-use changes caused by international food trade globally, highlights the needs of coordination among trading countries, and promotes global sustainability.
文摘<span style="font-family:Verdana;">Land-use change has been</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">a factor that alters the hydrologic response of the watersheds leading to influencing on sediment yield changes. This study is mainly focusing on the assessment of the impacts of the land-use changes on sediment load and lake depth reduction on Lake Ziway, Ethiopia using an integrated approach of Remote Sensing (RS), GIS and SWAT model. ERDAS IMAGINE 14 model was used to generate land-use maps from Landsat TM, ETM+, and Ls8 acquired, in 1988, 2002 and 2015 as representative for the periods of (1988</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">1998), (1998</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">2008) and (2008</span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""><span style="font-family:Verdana;">2018), respectively. The maximum likelihood algorithm of supervised classification applied to classify the </span><span style="font-family:Verdana;">basin land-use into seven land-use classes. The SWAT hydrological model</span><span style="font-family:Verdana;"> with ArcGIS interface setup for the basin to evaluate the flow and sediment load with calibration and validation performance of the model range R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> (0.71 </span></span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> 0.89) and NSE (0.57 </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> 0.87). As a result, the total average annual sediment yield from the sub-basins estimated as 3.59</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">t/ha/yr, 4.36</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">t/ha/yr, and 4.89</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">t/ha/yr for three consecutive decadal periods 1988</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">1998, 1998</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">2008, and</span><span style="font-family:Verdana;"> 2008</span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""><span style="font-family:Verdana;">2018 respectively. The increasing trend of sediment yield in the Lake Ziway watershed through one period to another justified as due to land-use. Similarly, the net sediment volume deposited in the lake also showed incremental </span><span style="font-family:Verdana;">trained with the land-use changes as 1.5</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">mcm/yr, 1.81 mcm/yr, and 2.033</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">mcm/yr for the period of 1988-1998, 1999-2008, and 2009-2018, respectively. The depth and water holding capacity of the lake reduced by 4.3</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">m and 25.76</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">mcm, respectively, from the depth and capacity recorded on the 2006 bathy</span><span style="font-family:Verdana;">metric survey, which was the effect of deposited sediment over the last 12</span><span style="font-family:Verdana;"> years.</span></span>
基金National Basic Research Program of China,No.2010CB950900No.2014CB954302+1 种基金National Key Technol-ogy R&D Program,No.2013BAC03B00The Key Research Program of the Chinese Academy of Sciences,No.KSZD-EW-Z-021-02
文摘Land-use/land-cover changes （LUCCs） have links to both human and nature inter- actions. China＇s Land-Use/cover Datasets （CLUDs） were updated regularly at 5-year inter- vals from the late 1980s to 2010, with standard procedures based on Landsat TM／ETM＋ im- ages. A land-use dynamic regionalization method was proposed to analyze major land-use conversions. The spatiotemporal characteristics, differences, and causes of land-use changes at a national scale were then examined. The main findings are summarized as fol- lows. Land-use changes （LUCs） across China indicated a significant variation in spatial and temporal characteristics in the last 20 years （1990-2010）. The area of cropland change de- creased in the south and increased in the north, but the total area remained almost un- changed. The reclaimed cropland was shifted from the northeast to the northwest. The built-up lands expanded rapidly, were mainly distributed in the east, and gradually spread out to central and western China. Woodland decreased first, and then increased, but desert area was the opposite. Grassland continued decreasing. Different spatial patterns of LUC in China were found between the late 20th century and the early 21st century. The original 13 LUC zones were replaced by 15 units with changes of boundaries in some zones. The main spatial characteristics of these changes included （1） an accelerated expansion of built-up land in the Huang-Huai-Hai region, the southeastern coastal areas, the midstream area of the Yangtze River, and the Sichuan Basin; （2） shifted land reclamation in the north from northeast China and eastern Inner Mongolia to the oasis agricultural areas in northwest China; （3） continuous transformation from rain-fed farmlands in northeast China to paddy fields; and （4） effective- ness of the ＂Grain for Green＂ project in the southern agricultural-pastoral ecotones of Inner Mongolia, the Loess Plateau, and southwestern mountainous areas. In the last two decades, although climate change in the north affected the change in cropland, policy regulation and economic driving forces were still the primary causes of LUC across China. During the first decade of the 21st century, the anthropogenic factors that drove variations in land-use pat- terns have shifted the emphasis from one-way land development to both development and conservation. The ＂dynamic regionalization method＂ was used to analyze changes in the spatial patterns of zoning boundaries, the internal characteristics of zones, and the growth and decrease of units. The results revealed ＂the pattern of the change process,＂ namely the process of LUC and regional differences in characteristics at different stages. The growth and decrease of zones during this dynamic LUC zoning, variations in unit boundaries, and the characteristics of change intensities between the former and latter decades were examined. The patterns of alternative transformation between the ＂pattern＂ and ＂process＂ of land use and the causes for changes in different types and different regions of land use were explored.
文摘The consequence of land-use change from forest to agriculture and other uses has become one of the world’s greatest concerns.The soil,one of the most important components of forests and containing all the required plant nutrients as soluble ions,is highly impacted by these changes.Because vast areas of the Zagros forests in western Iran have changed in use during the last few decades,the present study investigated the effects of landuse changes of forest area to agriculture,orchard,and agroforestry on soil chemical and physical properties.Soil was sampled at four land-use areas:less-disturbed forest areas(control)and agricultural,orchard,and agroforestry areas.Among each of the two forest-use areas(agroforestry and orchard),we selected five trees with similar-sized crowns and sampled under each tree crown at 0-15 and>15-30 cm depths.Five soil samples also were taken in agriculture area at each depth.The findings indicated that during land-use changes,soil sand particles decreased,and clay and silt particles of soil increased,resulting in a fine soil texture.Moreover,the amount of nitrogen(N),phosphorus(P),organic carbon(OC),and electrical conductivity(EC)of soil decreased at both depths due to the decrease in organic matter.Soil pH and magnesium(Mg)level rose during land-use change at both depths except at agricultural sites.Soil potassium(K)content decreased during agricultural use due to the elimination of tree cover.The level of K decreased only at the depth of 0-15 cm because of K dependency on parent materials.Generally,most soil nutrients were affected by plant removal in the conversion.Forest and agricultural soil are distinguishable by their properties,while land-uses such as agroforestry-orchard separated from the others.Soil nutrients were severely affected by the decrease and elimination of tree cover,plowing,and continuous harvesting,resulting in a decline in soil quality and fertility.
基金the financial support from the National Natural Science Foundation of China (91025008 and 30972421)
文摘North China is the most important food basket of China, where the majority of wheat and corn are produced. Most crops grown in North China are irrigated, thus water security is food security. Since the 1980s, drying has been frequently observed, as shown by a reduction in precipitation, cutoff in riverflow, and shrinkage of lakes. This increase in drying cannot be explained by climate change alone. We propose that intensive land-use in this area in recent decades has had a significant impact. The objectives of the study are to develop a quantitative model of the concurrent processes of climate change and land-use in North China, and to estimate the relative contributions of each on the observed drying. We integrated relevant socioeconomic data, land-use data, and climate data in the model, and carried out a detailed multi-temporal （decade, year, day） analysis. Results showed that land-use has greatly changed since 1999. This change is mainly associated with an extremely important 1999 national policy of ＂returning farmland and grazing land to forest and grassland＂. We found an interesting interaction between climate change and land use policy on riverflow, runoff, and evapotranspiration. During 1970s and 1980s, climate change explained more than 80%, while the land-use change explained only 10% of the riverflow change. The relative contributions were 45 and 45% in the 1980s-1990s and 35 and 55% in the 1990s-2000s respectively for climate change and land-use change. Since the 1990s land-use change has also contributed more to runoff change than climate change. The opposite trend was found for changes in evapotranspiration. Water availability for agriculture in northern China is simultaneously stressed by extensive changes in land-use and rapid climate change. Adaptation of ecological principles, such as the ＂returning farmland/grazing land to forest and grassland＂ policy, and other adjustments of economic developmental strategies can be effective tools to mitigate the water shortage problem in northern China and promote sustainable agricultural and food development.
基金supported by China-ASEAN maritime cooperation fund: Comparative Study of Holocene Sedimentary Evolution of the Yangtze River Delta and the Red River Deltathe Natural Science Foundation of Shandong Province, China (No. ZR2014DQ020)+1 种基金China Geological Survey Project (No. DD20160145)the National Natural Science Foundation of China (Nos. 41706074 and 41506107)
文摘We analyzed the characteristics and trends of land-use change in and near the coastal zone of the Yangtze River Delta(YRD) during five periods(1995, 2000 2005, 2010, and 2015) using remotely sensed Landsat imagery. Using automatic supervised classification combined with visual interpretation, we obtained land-use information for five study areas(Nantong, Shanghai, Jiaxing, Ningbo, and Zhoushan). Significant land-use changes have occurred in this area between 1995 and 2015, characterized in particular by large reductions in cultivated land and rapid increases in urbanized land. In addition, land reclamation was very active in this period as an effective supplement to the increased demand for land development: since 1995, 1622 km^2 of land was reclaimed from near-coastal regions in the study area. This increase in urbanization was jointly driven by population, economic, transportation, and policy factors. Urban areas expanded from the center outward in concentric rings, with infrastructure guiding the radial expansion of development along transportation corridors, thus forming a network of connections. Due to the influence of national land regulation policies, the expansion rate of development in the YRD gradually diminished after 2010. This indicates that the area's resource and environmental carrying capacity has reached a saturation stage in which urbanization has transitioned from broad and incremental expansion to the intensive use of land resources.
基金Under the auspices of National Laboratory for Information Engineering in SurveyingMapping and Remote Sensing(No.A003002002023).
文摘This paper describes a GIS-based sp atial analysis method that combines qualitative analysis and quantita-tive analysis to characterize land-use patterns and predict the trend of future land-use changes in Haizhu Di strict of Guangzhou City,China.Spatial tech nique is introduced to manage land-u se data and derive information of lan d-use changes.Through the case study for t he selected area,it is demonstrated that the method and technique introd uced in the paper can be effectively utilized fo r the analysis of urban land-use chan ges.Based upon this analysis,the paper also pro-vides discussions and recommendati on on urban land-use planning,urban planning and land management.Both l and-use maps of Haizhu District of Guangzhou in 1995and 1997and the remote sensin g images of 1999are utilized in the cu r-rent research.It is convenient to ge t various statistic data and to combi ne attribute data with spatial data s o as to analyze land-use changes in a geographic con text,which is especially suitable f or the need of urban construction dep artment,ur-ban management department and urban planning department.
文摘Amid the euphoria of Reducing Emissions from Deforestation and Forest Degradation (REDD) and REDD+ discussions, the expectations of large financial gains raise the interest of all. A country, however, will only enjoy REDD benefits if the cost of REDD is lower than the benefit. The opportunity cost analysis is an effective tool for assessing the feasibility of REDD+ since the largest portion of costs associated with REDD+ and can help to identify fair compensation for those who change their land use. The opportunity cost analysis has been exercised in Tanjung Jabung Barat (Tanjabar) district-Indonesia to examine the economic-feasibility of carbon emission reduction under different type carbon price scenarios. This study reveals a sharp decline of land-use systems with high carbon-stock and low profitability is obvious. On mineral soil, low carbon-stock and high profitability (mostly oil palm) has increased rapidly, especially in the period 2000-2009. It has become the dominant land-use system. The low-to-medium carbon stock and medium profitability land-use category increased from 1990 to 2005 but declined from 2005 to 2009. The low carbon-stock and low profitability category was constant and the proportion of the area was below 15%. The ex-ante analysis in predicting the potential for future emissions reduction in Tanjabar through REDD+ approaches shows that the cumulative emission of Tanjabar in 2020 is estimated at 61.91 Mg CO2-eq/Ha.Year, while the reduced emission by excluding all land use conversion below $5 threshold is estimated at 51.71 Mg CO2-eq/Ha.Year. This means that there is a potential for 16% emission reduction using $5/ton CO2-eq incentive. Another important finding in this study is that if the price of carbon increases by double to $10, the amount of reduced emission does not change much. This can use as a basis for determining the right amount of incentive for trade-off between economic profitability and climate change mitigation effort in Tanjabar using REDD+ scheme both at seller and buyer perspectives.
基金This study was funded by the Science and Technology Innovation Funds of Gansu Agricultural University for Special Funds for Discipline Construction,China(GAU-XKJS-2018-203)the Supporting Funds for Youth Mentor of Gansu Agricultural University,China(GAU-QDFC-2018-17)+1 种基金the Innovation Fund of Colleges and Universities in Gansu Province,China(2021A-061)the Natural Science Foundation of Gansu province(20JR10RA543).
文摘Water resources are a crucial factor that determines the health of ecosystems and socio-economic development;however,they are under threat due to climate change and human activities.The quantitative assessment of water resources using the concept of blue water and green water can improve regional water resources management.In this study,spatiotemporal distributions of blue water and green water were simulated and analyzed under scenarios of climate change and land-use changes using the Soil and Water Assessment Tool(SWAT)in Ningxia Hui Autonomous Region,Northwest China,between 2009 and 2014.Green water,a leading component of water resources,accounted for more than 69.00%of the total water resources in Ningxia.Blue water and green water showed a single peak trend on the monthly and annual scales during the study period.On the spatial scale,the southern region of Ningxia showed higher blue water and green water resources than the northern region.The spatiotemporal distribution features of blue water,green water,and green water flow had strong correlations with precipitation.Furthermore,the simulation identified the climate change in Ningxia to be more influential on blue water and green water than land-use changes.This study provides a specific scientific foundation to manage water resources in Ningxia when encountered with climate change together with human activities.
基金akistan Space and Upper Atmospheric Research Commission(SUPARCO),for the provision of SPOT satellite imagesnational center of excellence in Geology(NCEG)+1 种基金University of Peshawar and Department of ForestryShaheed Benazir Bhutto University,Sheringal
文摘Anthropogenic activities and natural processes are continuously altering the mountainous environment through deforestation, forest degradation and other land-use changes. It is highly important to assess, monitor and forecast forest cover and other land-use changes for the protection and conservation of mountainous environment. The present study deals with the assessment of forest cover and other land-use changes in the mountain ranges of Dir Kohistan in northern Pakistan, using high resolution multi-temporal SPOT-5 satellite images. The SPOT-5 satellite images of years 2004, 2007, 2010 and 2013 were acquired and classified into land-cover units. In addition, forest cover and land-use change detection map was developed using the classified maps of 2004 and 2013. The classified maps were verified through random field samples and Google Earth imagery(Quick birds and SPOT-5). The results showed that during the period 2004 to 2013 the area of forest land decreased by 6.4%, however, area of range land and agriculture land have increased by 22.1% and 2.9%, respectively. Similarly, barren land increased by 1.1%, whereas, area of snow cover/glacier is significantly decreased by 21.3%. The findings from the study will be useful for forestry and landscape planning and can be utilized by the local, provincial and national forest departments; and REDD+ policy makers in Pakistan.
基金supported by the National Basic Research Program of China (2007CB407207)National Natural Science Foundation of China (30800888)
文摘As more and more farmland is converted to forestry, the need for effective decision support regarding the use of land in the fragile ecological environment of the Loess Plateau hilly-gully area. The Luoyugou watershed was chosen as the study area to calculate the single dynamic degree, integrated dynamic degree, and change indexes of land use, as well as the land-use type transition matrix. This was done by interpreting the TM and SPOT images of the Luoyugou watershed in 1986, 1995, and2004 and making statistical analysis. The results of ou statistical analysis show that the conversion of slope farm land to terrace and forest land plays a dominant role in land-use changes in the Luoyugou watershed from 1986 to2004. The land-use changes are mainly driven by popula tion growth, socio-economic development, consume spending, and investment in forest ecology.
基金supported by the National Natural Science Foundation of China(40371093)the Special Funds for Major State Basic Research Project(G20000779,2002CB412408)+2 种基金Opening Fund projects of State Key Laboratory of Remote Sensing Science in the Institute of Remote Sensing Applications(SK040006)Opening Fund projects of State Key Laboratory of Estuarine and Coastal Research of East China Normal University,China Postdoctoral Science Foundationthe Project from'863'Marine Monitor of Hi-Tech Research and Development Program of China(2001AA633010).
文摘Comprehensive study on land-use change of spatial pattern and temporal process is the key component in land use/land cover changes (LUCC) study nowadays. According to the theories and methods of Geo-information Tupu (Carto-methodology in Geo-information, CMGI) for geospatial and temporal analysis and integration models of spatial pattern and temporal processes in GIS, the paper puts forward Tupu methodology of land-use change and names the basic synthetic unit of spatial-temporal information Tupu unit. Tupu unit is the synthetic unit for geospatial-temporal analysis, which is synthesized by “space·attribute·process”features and composed of relatively homogeneous geographic unit and temporal unit. Based on the spatial features of 4 stages of land-use change in 1956, 1984, 1991, and 1996, a series of Tupu on land-use change in the Yellow River Delta (YRD) are created and studied in the paper, which includes 3 temporal units of spatial-temporal Tupu, process Tupu of land-use changes during the last 40 years, and reconstructions of a series of “arisen”Tupu, “arisen”process Tupu and pattern Tupu on land-use changes in the last 40 years by remapping tables of a reclassifying system. There are 3 methods of Tupu analysis on land-use change that are used to disclose change processes of land-use spatial conversion in YRD, such as spatial query and statistics, order of Tupu units by area and land-use conversion matrixes. In order to reveal the spatial pattern of land-use change processes, we analyze spatial-temporal changes of each Tupu above in various temporal units and spatial difference of pattern Tupu in the last 40 years by dynamic Tupu units. Tupu analysis on regional land-use is a promising trial on the comprehensive research of “spatial pattern of dynamic process”and “temporal process of spatial pattern”in LUCC research. The geo-information Tupu methodology would be a powerful and efficient tool on integrated studies of spatial pattern and temporal process in geoscience.
基金Supported by the State Key Development program for Basic Research (2006 CB 400503)Climate Change Special Fund of China Meteorological Administration "The Effect on Farming-Pastoral Ecotones in North China of Climate Change and Its Policy-Reply in the next 30 years" (CCSF 2007-8)China Meteorological Administration Model Develop Project "Assessment and Improvement of the BCC_RegCM1.0".
文摘By using the improved regional climate model （BCC_ RegCM1.0）, a series of modeling experiments are undertaken to investigate the impacts of historical land-use changes （LUCs） on the regional climate in China. Simulations are conducted for 2 years using estimated land-use for 1700, 1800, 1900, 1950, and 1990. The conversion of land cover in these periods was extensive over China, where large areas were altered from forests to either grass or crops, or from grasslands to crops. Results show that, since 1700, historical LUCs have significant effects on regional climate change, with rainfall increasing in the middle and lower reaches of the Yangtze River Basin, Northwest China, and Northeast China, but decreasing by different degrees in other regions. The air temperature shows significant warming over large areas in recent hundred years, especially from 1950 to 1990, which is consistent with the warming caused by increasing greenhouse gases. On the other hand, historical LUCs have obvious effects on mean circulation, with the East Asian winter and summer monsoonal flows becoming more intensive, which is mainly attributed to the amplified temperature difference between ocean and land due to vegetation impacts of LUCs on regional climate change. change. Thus, it would be given more attention to the
基金Under the auspices of Key Program of Chinese Academy of Sciences(No.KJZD-EW-TZ-G10)National Key Research and Development Program of China(No.2016YFA0602704)Breeding Project of Institute of Geographic Sciences and Natural Resources Research,CAS(No.TSYJS04)
文摘River runoff is affected by many factors, including long-term effects such as climate change that alter rainfall-runoff relationships, and short-term effects related to human intervention(e.g., dam construction, land-use and land-cover change(LUCC)). Discharge from the Yellow River system has been modified in numerous ways over the past century, not only as a result of increased demands for water from agriculture and industry, but also due to hydrological disturbance from LUCC, climate change and the construction of dams. The combined effect of these disturbances may have led to water shortages. Considering that there has been little change in long-term precipitation, dramatic decreases in water discharge may be attributed mainly to human activities, such as water usage, water transportation and dam construction. LUCC may also affect water availability, but the relative contribution of LUCC to changing discharge is unclear. In this study, the impact of LUCC on natural discharge(not including anthropogenic usage) is quantified using an attribution approach based on satellite land cover and discharge data. A retention parameter is used to relate LUCC to changes in discharge. We find that LUCC is the primary factor, and more dominant than climate change, in driving the reduction in discharge during 1956–2012, especially from the mid-1980 s to the end-1990 s. The ratio of each land class to total basin area changed significantly over the study period. Forestland and cropland increased by about 0.58% and 1.41%, respectively, and unused land decreased by 1.16%. Together, these variations resulted in changes in the retention parameter, and runoff generation showed a significant decrease after the mid-1980 s. Our findings highlight the importance of LUCC to runoff generation at the basin scale, and improve our understanding of the influence of LUCC on basin-scale hydrology.
基金Supported by the National Natural Science Foundation of China (No.91025021)the Knowledge Innovation Programs of the Chinese Academy of Sciences (Nos.KSCX2-EW-G-16-02 and KSCX2-YW-G-074-02)the E-Science Program of the Chinese Academy of Sciences (No.INFO-115-D01-Z006)
文摘Soil harbors remarkably stabilize bacterial communities at the phylum level. However, no two soils have exactly the same structure of bacterial phyla. The structure of microbial community is strongly influenced by the type of land-use through changes in soil attributes. Using high-throughput pyrosequencing and quantitative polymerase chain reaction techniques, soil microbial community structures were investigated along a land-use gradient of 100- and 27-year farmlands, a 33-year Pinus forest, a 28-year poplar forest, and a 21-year shrubland, as well as a native desert from which all cultivated systems were converted. The results revealed that the dominant phylotypes in the native soil comprised primarily of Alphaproteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes, accounting for 〉 71.4% of the total bacterial 16S rRNA sequence reads. Changes in land-use led to a significant decrease in these dominant phylotypes down to 33.4%. In contrast, the phylotypes with low abundance, such as Acidobaeteria, Chloroflexi, Nitrospira, and Gammaproteobaeteria, increased sharply from 4.5%-5.9% in the native soil to 20.9% 30.2% of the total 16S rRNA gene sequences in the cultivated soils except for the soil from the shrubland. These contrasting changes in the major taxa appear to be correlated with the changes in soil attributes. For instance, bacterial and archaeal amoA genes were found to be 960- and 3 800-fold more abundant in the soil from the 100-year farmland than the native soil. The changes in numerically less dominant nitrifying phylotypes are consistent with soil inorganic nitrogen dynamics. Quantification of the 16S rRNA genes demonstrated that bacteria and archaea were about two to three orders of magnitude more abundant in the cultivated soil than in the native soil. Hence, land-use type affects the soil bacterial community structure, which has profound consequences on ecosystem function.
文摘Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO_2) buildup is greatly affected by human activities.To evaluate the influence of land-use changes on SOC stocks in paddy soils,a new algorithm was developed by integrating MODIS (moderate resolution imaging spectral-radiometer) and TM/ETM data for timely monitoring the land-use change in Wujiang County.Thereafter,the land-use class-maps derived from MODIS and TM/ETM analyses were further used to estima...
基金supported by the Chinese Ministry of Sciences and Technology--the host of China-Africa Science and Technology Partnership Program(CASTEP)the National Special Research Program for Forestry Welfare of China(201104009)
文摘Remote-sensing data for protected areas in northern Togo, obtained in three different years （2007, 2000, and 1987）, were used to assess and map changes in land cover and land use for this drought prone zone. The normalized difference vegetation index （NDVI） was applied to the images to map changes in vegetation. An unsupervised classification, followed by classes recoding, filtering, identifications, area computing and post-classification process were applied to the composite of the three years of NDVI images. Maximum likelihood classification was applied to the 2007 image （ETM＋2007） using a supervised classification process. Seven vegetation classes were defined from training data sets. The seven classes included the following biomes： riparian forest, dry forest, flooded vegetation, wooded savanna, fallows, parkland, and water. For these classes, the overall accuracy and the overall kappa statistic for the classi- fied map were 72.5% and 0.67, respectively. Data analyses indicated a great change in land resources; especially between 1987 and 2000 proba- bly due to the impact of democratization process social, economic, and political disorder from 1990. Wide-scale loss of vegetation occurred during this period. However, areas of vegetation clearing and regrowth were more visible between 2000 and 2007. The main source of confusion in the contingency matrix was due to heterogeneity within certain classes. It could also be due to spectral homogeneity among the classes. This research provides a baseline for future ecological landscape research and for the next management program in the area.
基金Under the auspices of National Natural Science Foundation of China(No.41271534)China Scholarship Council(No.201906770044)。
文摘To solve the problems caused by irrational land-use, studying the functions of land-use, its changing characteristics, and the relationship between each land-use function will be beneficial for achieving sustainable land development. In this research, we constructed an evaluation framework of multiple land-use functions(LUFs) based on sustainable land-use theory. Specifically,, we classified the multiple LUFs into three types: agricultural production function(APF), living function(LVF), and ecological service function(ESF).We then spatialized the economic and social data, and implemented the InVEST(Integrated Valuation of Ecosystem Services and Tradeoffs) model and RUSLE(Revised Universal Soil Loss Equation) model to evaluate each sub-LUF(crop production, aquatic production, woodlands production, livestock production, living space, life quality, water supply, soil conservation, climate regulation, biological conservation) in central China in 2000 and again in 2015. Moreover, by analyzing the changes to LUFs and the relationships between each LUF change, we were able to discern patterns of LUF change in central China. The results show that: (1)42.12% of total territory in the study area increased their APF from 2000 to 2015, while 43.41% of the lands increased their ESF yet only 8.98% of the lands increased their LVF;(2) in Hubei and Hunan, there was more land with an increase of APF than in Anhui or Jiangxi. The APF in Jiangxi exhibited the greatest decline over time period, the LVF increased more in the provincial capital cities than in other regions, and the ESF expanded more in Jiangxi than in the other provinces;and (3) the changes in APF were significantly and positively correlated with changes in LVF. Additionally, changes in ESF were negatively but non-significantly correlated with changes in APF and LVF.
基金supported by the National Key R&D Program of China(Grant No.2024YFC3012702)National Natural Science Foundation of China(Grant No.42371014)+2 种基金Hubei Provincial Engineering Research Center of Slope Habitat Construction Technique Using Cement-based Materials Open Research Program(Grant No.2022SNJ11)National Natural Science Foundation of China(Grant No.42201094)Hubei Key Laboratory of Disaster Prevention and Mitigation(China Three Gorges University)Open Research Program(Grant No.2022KJZ12)。
文摘The relationship between landslides,land use,and sediment connectivity is not only a critical interdisciplinary topic,but also remains a challenging issue in assessing dynamic landslide susceptibility within reservoir areas.To explore the interactions among landslide,land use changes,and sediment dynamic,this study took Zigui Basin,the head area of the Three Gorges Reservoir,as the study area to examine this triadic relationship by single-factor detection and interactive detection.Here,we utilized Dynamic Attitude(DA)analysis to quantify land use changes and applied the Index of Connectivity(IC)to assess sediment connectivity evolution from 2018 to 2023.A multi-temporal analysis using the Landslide Susceptibility Index(LSI)was conducted to evaluate the degree of transformation in the three objects and the influence of these changes on the landslide susceptibility.According to the spatial analyst and statistics tools in ArcGIS,the results reveal that most of the landslides distributed in areas with high land use dynamic attitude,such as cultivated land transfers to forestland or garden plot,and the garden plot continuously increased across the study period with largest variation of 5%and an increment of 1.9%.Furthermore,linkage between land use and sediment transport can be effectively quantified by IC,and the resulting map indicated that garden plot increased,and catchment channel characteristics had a greater influence on the IC value than differences in vegetation cover.A comprehensive evaluation of the differences among the susceptibility maps reveals that the very high susceptibility classes are predominantly influenced by enhanced connectivity,whereas land use change has a greater effect on medium-low susceptibility region than that of sediment evolution.That is,both changes of land use and connectivity have positively correlated with landslide activity,but they exhibit differential influences on landslides susceptibility.
基金supported by the National Natural Science Foundation of China(32225033,32071496)Ministry of Science and Technology of China(2022YFF1301500)。
文摘Climate and land-use changes are predicted to impact biodiversity,threatening ecosystem services and functions.However,their combined effects on the functional diversity of mammals at the regional scale remain unclear,especially at the beta level.Here,we use projected climate and land-use changes in China to investigate their potential effects on the alpha and beta functional diversities of terrestrial mammals under low-and high-emission scenarios.In the current projection,we showed strong positive spatial correlations between functional richness and species richness.Functional evenness(FEve),functional specialization(FSpe),and functional originality(FOri)decreased with species richness,and functional divergence(FDiv)increased first and then plateaued.Functional beta diversity was dominated by its nestedness component,in contrast to the taxonomic facet.Potential changes in species richness are more strongly influenced by land-use change under the low-emission scenario,while under the high-emission scenario,they are more strongly influenced by climate change.Changes in functional richness(FRic)were inconsistent with those in species richness,with a magnitude of decreases greater than predicted from species richness.Moreover,mammal assemblages showed potential functional differentiation(FD)across the country,and the trends exceeded those towards taxonomic differentiation(TD).Our findings help us understand the processes underlying biodiversity responses to global changes on multiple facets and provide new insight for conservation plans.
