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REGIONAL ASSESSMENT OF SOIL NITROGEN MINERALIZATION IN DIVERSE Cropland OF A REPRESENTATIVE INTENSIVE AGRICULTURAL AREA

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Frontiers of Agricultural Science and Engineering 2023年第4期10卷 530-540页

作者： Peng XU Minghua ZHOU Bo ZHU Klaus BUTTERBACH-BAHL Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and EnvironmentChineseAcademyof SciencesChengdu610041China Institute for Meteorology and Climate Research Atmospheric Environmental Research(IMK-IFU)Karlsruhe Institute of Technology(KIT)Garmisch-Partenkirchen 82467Germany

Soil nitrogen mineralization(Nmin)is a key process that converts organic N into mineral N that controls soil N availability to plants.However,regional assessments of soil Nmin in Cropland and its affecting factors are lacking,especially in relation to variation in elevation.In this study,a 4-week incubation experiment was implemented to measure net soil Nmin rate,gross nitrification(Nit)rate and corresponding soil abiotic properties in five field soils(A-C,maize;D,flue-cured tobacco;and E,vegetables;with elevation decreasing from A to E)from different altitudes in a typical intensive agricultural area in Dali City,Yunnan Province,China.The results showed that soil Nmin rate ranged from 0.10 to 0.17 mg·kg^(-1)·d^(-1)N,with the highest value observed in field E,followed by fields D,C,B,and A,which indicated that soil Nmin and Nit rates varied between fields,decreasing with elevation.The soil Nit rate ranged from 434.2 to 827.1μg·kg^(-1)·h^(-1)N,with the highest value determined in field D,followed by those in fields E,C,B,and A.The rates of soil Nmin and Nit were positively correlated with several key soil parameters,including total soil N,dissolved organic carbon and dissolved inorganic N across all fields,which indicated that soil variables regulated soil Nmin and Nit in Cropland fields.In addition,a strong positive relationship was observed between soil Nmin and Nit.These findings provide a greater understanding of the response of soil Nmin among Cropland fields related to spatial variation.It is suggested that the soil Nmin from Cropland should be considered in the evaluation of the N transformations at the regional scale.

关键词： Cropland gross nitrification rate regulatory factors soil nitrogen mineralization spatial variation

Exploring the rules of Cropland elevation uplift in China

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Journal of Mountain Science 2023年第7期20卷 1824-1841页

作者： YUAN Jin-tao CHEN Wan-xu ZENG Jie YE Xin-yue Hubei Key Laboratory of Regional Ecology and Environmental Change School of Geography and Information EngineeringChina Universityof GeosciencesWuhan430074China Department of Landscape Architecture and Urban Planning Texas A&M UniversityCollege StationTX 77840USA

Cropland elevation uplift(CLEU) has recently become a new challenge for agricultural modernization,food security,and sustainable Cropland use in China.Uncovering the rules of CLEU is of great theoretical and practical significance for China’s sustainable agricultural development and rural revitalization strategy.However,existing studies lack in-depth disclosure of multi-scale CLEU evolution rules,making it difficult to support the formulation of specific Cropland protection policies.We analyzed the spatio-temporal evolution and multiscale CLEU in China from 1980 to 2020 using the Lorenz curve,gravity center model,hotspot analysis,and Cropland elevation spectrum.The results indicated that the center of gravity of Cropland moved to the northeast from 1980 to 2000 and then shifted to the northwest.The spatial distribution of Cropland became increasingly imbalanced from 1980 to 2000.The change hotspots clustered in the northwest and the northeast,whereas cold-spots were mainly in southeastern China.The average elevation of Cropland increased by 17.38 m,and the elevation uplift rule in different regions differed evidently across scales.From 1980 to 2000,all provinces except Xinjiang,Inner Mongolia,Gansu,and Yunnan exhibited CLEU,with Qinghai,Tibet,Beijing,and Guangdong showing the most noticeable uplifting.The CLEU can alleviate the shortage of Cropland to some extent.However,without a planning constraint,the CLEU will lead to the increase of ecological risk and food security risk.

关键词： Cropland Elevation uplift rules Multi-scale Elevation spectrum China

Floristic composition and management of Cropland agroforest in southwestern Bangladesh

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Journal of Forestry Research 2014年第3期25卷 597-604页

作者： Md. Hasanuzzaman Mahmood Hossain Mustafa Saroar Forestry and Wood Technology Discipline Khulna University Urban and Rural Planning Discipline Khulna University

Cropland agroforest is an important production system in the southwest region of Bangladesh. This study focused on the floristic composition and management of existing Cropland agroforests. A total of 313 Cropland agroforests were surveyed and 83%respondents practiced pure agroforestry while the remaining 17% practiced agroforestry with fisheries. A total of 18 forest trees and 2 shrubs were recorded from 11 families and 59 species of agricultural crops were from 28 families. A higher proportion （79%） of Cropland agroforests were occupied small land areas （0.12-0.80 ha）. About 63% of respondents planted trees for fruit production and 47%for timber production, and 35%of respondents engaged in commercial production （35%）. Swietenia macrophylla was the most prevalent species （relative prevalence 20.83） followed by Man-gifera indica （relative prevalence 15.57） and Cocos nucifera （relative prevalence 7.08）. Shorter spacing was used for timber and fuel wood species and wider spacing for fruit trees. A wide range of rotation periods, from 5 to 25 years, was observed for both cases. The use of chemical fertilizer was highest followed by cow dung and compost in Cropland agroforests. Overall management practices of Cropland agroforest in southwest Bangladesh were determined by the end product and local demand.

关键词： agroforestry Bangladesh Cropland fruit production timber production

Assessing quality of volunteer crowdsourcing contributions:lessons from the Cropland Capture game

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International Journal of Digital Earth 2016年第4期9卷 410-426页

作者： Carl F.Salk Tobias Sturn Linda See Steffen Fritz Christoph Perger Ecosystems Services and Management Program International Institute for Applied Systems AnalysisLaxenburgAustria Southern Swedish Forest Research Center Swedish University of Agricultural SciencesAlnarpSweden

Volunteered geographic information(VGI)is the assembly of spatial information based on public input.While VGI has proliferated in recent years,assessing the quality of volunteer-contributed data has proven challenging,leading some to question the efficiency of such programs.In this paper,we compare several quality metrics for individual volunteers’contributions.The data were the product of the‘Cropland Capture’game,in which several thousand volunteers assessed 165,000 images for the presence of Cropland over the course of 6 months.We compared agreement between volunteer ratings and an image’s majority classification with volunteer self-agreement on repeated images and expert evaluations.We also examined the impact of experience and learning on performance.Volunteer self-agreement was nearly always higher than agreement with majority classifications,and much greater than agreement with expert validations although these metrics were all positively correlated.Volunteer quality showed a broad trend toward improvement with experience,but the highest accuracies were achieved by a handful of moderately active contributors,not the most active volunteers.Our results emphasize the importance of a universal set of expert-validated tasks as a gold standard for evaluating VGI quality.

关键词： crowdsourcing volunteered geographic information Cropland data quality image classification Geo-Wiki

Untangling the increasing elevation of Cropland in China from 1980 to 2020

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Geography and Sustainability 2023年第4期4卷 281-293页

作者： Wanxu Chen Liyan Yang Jie Zeng Jintao Yuan Tianci Gu Zhiling Liu Department of Geography School of Geography and Information EngineeringChina University of GeosciencesWuhan 430078China School of Public Administration China University of GeosciencesWuhan 430074China

The redistribution of Cropland to areas of higher elevation in China has long affected agricultural development and could seriously threaten national food security.However,there is currently little research reported on this phenomenon,which may limit the improvement of Cropland protection policies.To fill this gap,we analyzed the spatiotemporal characteristics and driving mechanisms of increased Cropland elevation in China during the period 1980-2020.The average Cropland elevation in China increased by 17.38 m from 1980 to 2020.The gravity center of the Cropland area and average Cropland elevation in China moved to the northwest by 81.00 km and 51.47 km,respectively.The amount of newly added Cropland in eastern China was less than that in occupied regions;however,the average elevation of newly added Cropland was greater than that of occupied Cropland,though the opposite phenomenon was observed in western China.Slope,temperature,land-use intensity,population,economic density,and distance to main roads were the main factors affecting the redistribution of Cropland to areas of higher elevation.The effects of these major driving factors exhibited significant spatial and temporal variations in China.This study has important implications for improving existing Cropland protection policies and developing more effective Cropland management systems in China.

关键词： Cropland Elevation Geodetector Geographically weighted regression Spatial analysis China

Changes of Population, Built-up Land, and Cropland Exposure to Natural Hazards in China from 1995 to 2015

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International Journal of Disaster Risk Science 2019年第4期10卷 557-572页

作者： Yimin Chen Wei Xie Xiaocong Xu School of Geography and Planning Sun Yat-sen UniversityGuangzhou 510275China Guangdong Key Laboratory for Urbanization and Geosimulation Sun Yat-sen UniversityGuangzhou 510275China

By using the latest China population grid and land-use data,we assess the changing exposure of China’s population and land uses to the hazards of storm surges,droughts,earthquakes,floods,and landslides from 1995 to2015.We found that the single-hazard areas and the multihazard areas covered 43%and 26%of China’s territory,respectively.Population grew faster in the hazard-prone areas than in the non-hazard areas.Built-up area expanded more rapidly in the areas prone to earthquakes and landslides.Cropland changed rapidly in many hazard-prone areas.The hazard-prone areas affected by floods featured the highest Cropland loss rates,while the areas prone to earthquakes and landslides featured the highest Cropland growth rates.We detected areas with significant exposure changes by using hot spot analysis.It was found that population and built-up land in the Pearl River Basin were increasingly exposed to storm surges,floods,and landslides.The Haihe River Basin and Huaihe River Basin also showed a consistent increase of population and built-up land exposure to droughts and earthquakes.These findings can provide a foundation for the design and implementation of protection and adaptation strategies to improve the resilience of Chinese society to natural hazards.

关键词： China Exposure to natural hazards Population change Built-up land Cropland

基于地貌分区的1990-2015年中国耕地时空特征变化分析（英文）

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Journal of Geographical Sciences 2019年第2期29卷 180-196页

作者：高晓雨程维明王楠刘樯漪马廷陈印军周成虎 State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources Research CAS University of Chinese Academy of Sciences Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Institute of Agricultural Resources and Regional Planning of CAAS

Landforms are an important factor determining the spatial pattern of Cropland through allocation of surface water and heat. Therefore, it is of great importance to study the change in Cropland distribution from the perspective of geomorphologic divisions. Based on China's multi-year land cover data(1990, 1995, 2000, 2005, 2010 and 2015) and geomorphologic regionalization data, we analyzed the change in Cropland area and its distribution pattern in six geomorphologic regions of China over the period of 1990-2015 with the aid of GIS techniques. Our results showed that the total Cropland area increased from 177.1 to 178.5 million ha with an average increase rate of 0.03%. Cropland area decreased in southern China and increased in northern China. Region I(Eastern hilly plains) had the highest Cropland increase rate, while the Cropland dynamic degree of Region IV(Northwestern middle and high mountains, basins and plateaus) was significantly higher than that of other regions. The barycenter of China's Cropland shifted from northern China to the northwest over the 25-year period. Regions IV and I were the two regions with the greatest increase of Cropland. Region II(Southeastern low and middle mountains) and Region V(Southwestern middle and low mountains, plateaus and basins) were the main decreasing Cropland regions. The area of Cropland remained almost unchanged in Region III(Northern China and Inner Mongolia eastern-central mountains and plateaus) and Region VI(Tibetan Plateau). The loss of Cropland occurred mostly in Regions I and II as a result of growing industrialization and urbanization, while the increase of Cropland occurred mainly in Region IV because of reclamation of grassland and other wasteland. These analyzing results would provide fundamental information for further studies of urban planning, ecosystem management, and natural resourcesconservation in China.

关键词： spatio-temporal distribution transformation of Cropland geomorphologic regions China

Dry Cropland changes in China's Three Gorges Reservoir Region during the period 1990 to 2015

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Journal of Mountain Science 2020年第3期17卷 516-527页

作者： WANG Ming-feng TIAN Feng-xia HE Xiu-bin Raheel ANJUM BAO Yu-hai Adrian LCOLLINS Key Laboratory of Mountain Surface Process and Ecological Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China Department of Tourism and Geography Tongren UniversityTongrenGuizhou Province554300China Abdul Wali Khan University MardanPakistan Sustainable Agriculture Sciences Department Rothamsted ResearchNorth WykeOkehamptonDevon EX202SBUK

Monitoring and analyzing changes in the extent of cultivated land may inform strategic decisions on issues of environmental and food security.The dry Cropland area of 12000 km^2in the Three Gorges Reservoir Region(TGRR)of China is essential for feeding the local population of^20 million,but is highly prone to soil erosion,leading to the delivery of excessive amounts of sediment and associated pollutants to the Three Gorges Reservoir(TGR),and causing serious eco-environmental consequences.Against this background,this paper used Landsat images and a digital elevation model to analyze the altitudinal distribution of,and dynamic changes in,the area of dry Cropland during the period 1990 to 2015.The results suggest that dry Cropland was mainly distributed in the elevation range of 200-600 m.The dry Cropland area decreased from 12525.37 km^2to 11796.27 km^2during the 25-year study period,including a particularly significant decrease in the rate of decrease from 6.93 km^2/yr to 43.99 km^2/yr after 2000.The largest decline in the dry Cropland area occurred in the elevation range of 600-900 m.The transformations between dry Cropland and forest revealed the impact of the TGR operation on the extent of dry Cropland.A total of 528.79 km^2of dry Cropland with slopes>25°were converted to forest after 2000,whereas a total of 642 km^2of forest was converted to dry Cropland during the study period,and these conversions mainly occurred between the elevation of 200–900 m.These spatiotemporal changes in the dry Cropland area are likely to raise new issues concerning food security in the TGRR.

关键词： Dry Cropland Altitude Reservoir operation Three Gorges Reservoir Region Landuse change Soil erosion

中国东北松嫩平原1990–2015年的农田环境变化特征分析（英文）

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Journal of Geographical Sciences 2019年第5期29卷 658-674页

作者：张远臧淑英孙丽阎炳和杨天鹏闫文佳 MEADOWS E Michael WANG Cuizhen QI Jiaguo Key Laboratory of Geographic Information Science(Ministry of Education) School of Geographic SciencesEast China Normal University Institute of Eco-Chongming East China Normal University Key Laboratory of Remote Sensing Monitoring of Geographic Environment College of Heilongjiang ProvinceHarbin Normal University Department of Environmental&Geographical Science University of Cape Town Department of Geography University of South Carolina Center for Global Change and Earth Observations and Department of Geography Michigan State University

Quantitative characterization of environmental characteristics of Cropland(ECC)plays an important role in maintaining sustainable development of agricultural systems and ensuring regional food security. In this study, the changes in ECC over the Songnen Plain, a major grain crops production region in Northeast China, were investigated for the period 1990–2015. The results revealed significant changes in climate conditions, soil physical properties and Cropland use patterns with socioeconomic activities. Trends in climate parameters showed increasing temperature(+0.49°C/decade, p Croplands, although some do exhibited slight improvement. The changing amplitude for each of the four above parameters ranged within –0.052 to 0.029 kg C/kg, –0.38 to 0.30,–0.60 to 0.39 g/cm^3, –3.29 to 2.34, respectively. Crop production significantly increased(44.0 million tons) with increasing sown area of Croplands(～2.5 million ha) and fertilizer application(～2.5 million tons). The study reveals the dynamics of ECC in the Songnen Plain with intensive cultivation from 1990 to 2015. Population growth, economic development, and policy reform are shown to strongly influence the spatiotemporal changes in Cropland characteristics.The study potentially provides valuable scientific information to support sustainable agroecosystem management in the context of global climate change and national socioeconomic development.

关键词： Songnen Plain environmental characteristics of Cropland climate change soil properties grain yield