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Uphill or downhill?Cropland use change and its drivers from the perspective of slope spectrum

Journal of Mountain Science 2024年第2期21卷 484-499页

作者： PAN Sipei LIANG Jiale CHEN Wanxu PENG Yelin College of Land Management Nanjing Agricultural UniversityNanjing 210095China National&Local Joint Engineering Research Center for Rural Land Resources Use and Consolidation Nanjing 210095China Jiangsu Provincial Key Laboratory of Geographic Information Technology School of Geography and Ocean ScienceNanjing UniversityNanjing 210023China Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region Ministry of Natural ResourcesChangsha 410118China Yunnan Key Laboratory of Plateau Geographic Processes and Environmental Changes Faculty of GeographyYunnan Normal UniversityKunming 650500China Hubei Key Laboratory of Regional Ecology and Environmental Change School of Geography and Information EngineeringChina University of GeosciencesWuhan 430074China

The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food *** spectrum analysis of topographic and geomorphic features is considered as a digital terrain analysis method which reflects the macro-topographic features by using micro-topographic ***,pieces of studies have extended the concept of slope spectrum in the field of geoscience to construction land to explore its expansion law,while research on the slope trend of cropland from that perspective remains *** address the gap,in virtue of spatial analysis and geographically weighted regression(GWR)model,the cropland use change in the Yangtze River Basin(YRB)from 2000 to 2020 was analyzed and the driving factors were explored from the perspective of slope *** showed that the slope spectrum curves of cropland area-frequency in the YRB showed a first upward then a downward *** change curve of the slope spectrum of cropland in each province(municipality)exhibited various distribution *** analysis of morphological parameters of cropland slope spectrum revealed that the further down the YRB,the stronger the flattening characteristics,the more obvious the *** province experienced the greatest downhill cropland climbing(CLC)was Shannxi,while province experienced the highest uphill CLC was *** most common cropland use change type in the YRB was horizontal expansion *** factors affecting average cropland climbing index(ACCI)were quite stable in different periods,while population density(POP)changed from negative to positive during the study *** research is of practical significance for the rational utilization of cropland at the watershed scale.

关键词： Cropland climbing Land use change slope spectrum Driving factors Geographically weighted regression Yangtze River Basin

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slope spectrum critical area and its spatial variation in the Loess Plateau of China

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Journal of Geographical Sciences 2015年第12期25卷 1452-1466页

作者： TANG Guoan SONG Xiaodong LI Fayuan ZHANG Yong XION-GLiyang Key Laboratory of Virtual Geographic Environment (Nanjing Normal University) Ministry of Education Nanjing 210023 China State Key Laboratory Cultivation Base of Geographical Environment Evolution (Jiangsu Province) Nanjing 210023 China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Ap- plication Nanjing 210023 China State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science CAS Nanjing 210008 China Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites National Satellite Meteorological Center China Meteorological Administration Beijing 100081 China

slope spectrum has been proved to be a significant methodology in revealing geomorphological features in the study of Chinese loess terrain. The determination of critical areas in deriving slope spectra is an indispensable task. Along with the increase in the size of the study area, the derived spectra are becoming more and more alike, such that their dif- ferences can be ignored in favor of a standard. Subsequently, the test size is defined as the slope spectrum Critical Area （SSCA）. SSCA is not only the foundation of the slope spectrum calculation but also, to some extent, a reflection of geomorphological development of loess relief. High resolution DEMs are important in extracting the slope spectrum. A set of 48 DEMs with different landform areas of the Loess Plateau in northern Shaanxi province was selected for the experiment. The spatial distribution of SSCA is investigated with a geo-statistical analysis method, resulting in values ranging from 6.18 km^2 to 35.1 km^2. Primary experimental results show that the spatial distribution of SSCA is correlated with the spatial distribution of the soil erosion intensity, to a certain extent reflecting the terrain complexity. The critical area of the slope spectrum presents a spatial variation trend of weak-strong-weak from north to south. Four terrain parameters, gully density, slope skewness, terrain driving force （Td） and slope of slope （SOS）, were chosen as indicators. There exists a good exponential function relationship between SSCA and gully density, terrain driving force （Td） and SOS and a loga- rithmic function relationship between SSCA and slope skewness. slope skewness increases, and gully density, terrain driving force and SOS decrease with increasing SSCA. SSCA can be utilized as a discriminating factor to identify loess landforms, in that spatial distributions of SSCA and the evolution of loess landforms are correlative. Following the evolution of a loess landform from tableland to gully-hilly region, this

关键词： digital elevation model slope spectrum critical area spatial variation independent geomorphological unit Loess Plateau

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slope spectrum variation in a simulated loess watershed

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Frontiers of Earth Science 2016年第2期10卷 328-339页

作者： Fayuan LI Guoan TANG Chun WANG Lingzhou CUI Rui ZHU State Key Laboratory Cultivation Base of Geographical Environment Evolution (Jiangsu Province) Nanjing 210023 China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing 210023 China Land Information Engineering Department Chuzhou University Chuzhou 239000 China College of Life and Environment Science Wenzhou University Wenzhou 325035 China Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic University Hong Kong China

A simulated loess watershed, where the loess material and relief properly represent the true loess surface, is adopted to investigate the variation in slope spectrum with loess watershed evolution. The evolution of the simulated loess watershed was driven by the exogenetic force of artificial rainfall. For a period of three months, twenty artificial rainfall events with different intensities and durations were carried out. In the process, nine DEM data sets, each with 10mm grid resolution, were established by the method of close-range photogrammetry. The slope spectra were then extracted from these DEMs. Subsequent series of carefully designed quantitative analyses indicated a strong relationship between the slope spectrum and the evolution of the simulated loess watershed. Quantitative indices of the slope spectrum varied regularly following the evolution of the simulated loess watershed. Mean slope, slope spectrum information entropy （H）, terrain driving force （Td）, Mean patch area （AREA_MN）, Contagion Index （CONTAG）, and Patch Cohesion Index （COHESION） kept increasing following the evolution of the simulated watershed, while skewness （S）, Perimeter-Area Fractal Dimension （PAFRAC）, and Interspersion and Juxtaposition Index （IJl） represented an opposite trend. All the indices changed actively in the early and active development periods, but slowly in the stable development periods. These experimental results indicate that the time series of slope spectra was able to effectively depict the slope distribution of the simulated loess watershed, thus presenting a potential method for model- ing loess landforms.

关键词： slope spectrum evolution simulatedwatershed loess landform

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slope-climbing of cropland and its effects in China

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Journal of Mountain Science 2024年第8期21卷 2754-2769页

作者： CHEN Wanxu XIE Youping YUAN Jintao ZENG Jie YANG Liyan GU Tianci LEI Fan Hubei Key Laboratory of Regional Ecology and Environmental Change School of Geography and Information EngineeringChina University of GeosciencesWuhan 430074China Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region Ministry of Natural ResourcesChangsha 410118China Yunnan Key Laboratory of Plateau Geographic Processes and Environmental Changes Faculty of GeographyYunnan Normal UniversityKunming 650500China

In recent decades,the spatio-temporal patterns of China’s croplands have been reshaped by disturbances from anthropogenic activities,with complex changes in the topographic characteristics of ***-climbing of croplands(SCCL)is an important issue that threatens sustainable agricultural *** providing land with prominent location advantages,SCCL weakens the water and fertilizer retention capacity for cropland,intensifies various geological disasters,and adversely affects the ecological environment and food yield of these *** is crucial to determine the spatio-temporal variation features and effects of SCCL in China to formulate more accurate cropland protection policies and to maintain food security;however,the current lack of relevant studies is detrimental for capturing trends in cropland resources and sustainable cropland *** this study,we constructed a multi-scale slope spectrum for cropland and total terrain to explore the spatial differences and trends of SCCL from a three-dimensional *** evaluated the natural and socioeconomic effects of SCCL in China from multiple *** indicate that the proportion of cropland with slopes below 2°,5°,and 6°in China decreased by 0.43%,0.47%,and 0.50%from 1980 to 2020,*** became apparent during 1980-1990 and 2010-2020,especially over the recent *** cropland climbing index(CCI)and upper limited slope change(ULSC)to measure the spatio-temporal pattern of SCCL were 0.99%and 1.17°,respectively,during *** the agricultural regional scale,the SCCL was also concentrated in 1980-1990 and 2010-2020,and it is more pronounced in the southern *** proportion of provinces and prefecture-level cities with high-intensity SCCL during 1980-2020 were 87.10%and 49.73%,*** was comparatively more pronounced and broader from 2010 to *** this period,17.84%of prefecture-level cities had no SCCL,and the average CCI for all prefecture-level citi

关键词： Croplands slope spectrum slope-climbing Three-dimensional perspective Multi-scale China

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