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  • Research Articles
    FAN Zemeng, LI Saibo, FANG Haiyan
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    Land cover change has presented clear spatial differences in the New Eurasian Continental Bridge Economic Corridor (NECBEC) region in the 21st century. A spatiotemporal dynamic probability model and a driving force analysis model of land cover change were developed to analyze explicitly the dynamics and driving forces of land cover change in the NECBEC region. The results show that the areas of grassland, cropland and built-up land increased by 114.57 million ha, 8.41 million ha and 3.96 million ha, and the areas of woodland, other land, and water bodies and wetlands decreased by 74.09 million ha, 6.26 million ha, and 46.59 million ha in the NECBEC region between 2001 and 2017, respectively. Woodland and other land were mainly transformed to grassland, and grassland was mainly transformed to woodland and cropland. Built-up land had the largest annual rate of increase and 50% of this originated from cropland. Moreover, since the Belt and Road Initiative (BRI) commenced in 2013, there has been a greater change in the dynamics of land cover change, and the gaps in the socio-economic development level have gradually decreased. The index of socio-economic development was the highest in western Europe, and the lowest in northern Central Asia. The impacts of socio-economic development on cropland and built-up land were greater than those for other land cover types. In general, in the context of rapid socio-economic development, the rate of land cover change in the NECBEC has clearly shown an accelerating trend since 2001, especially after the launch of the BRI in 2013.

  • Research Articles
    WU Xue, PAUDEL Basanta, ZHANG Yili, LIU Linshan, WANG Zhaofeng, XIE Fangdi, GAO Jungang, SUN Xiaomin
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    The study of mountain vertical natural belts is an important component in the study of regional differentiation. These areas are especially sensitive to climate change and have indicative function, which is the core of three-dimensional zonality research. Thus, based on high precision land cover and digital elevation model (DEM) data, and supported by MATLAB and ArcGIS analyses, this paper aimed to study the present situation and changes of the land cover vertical belts between 1990 and 2015 on the northern and southern slopes of the Koshi River Basin (KRB). Results showed that the vertical belts on both slopes were markedly different from one another. The vertical belts on the southern slope were mainly dominated by cropland, forest, bare land, and glacier and snow cover. In contrast, grassland, bare land, sparse vegetation, glacier and snow cover dominated the northern slope. Study found that the main vertical belts across the KRB within this region have not changed substantially over the past 25 years. In contrast, on the southern slope, the upper limits of cropland and bare land have moved to higher elevation, while the lower limits of forest and glacier and snow cover have moved to higher elevation. The upper limit of alpine grassland on the northern slope retreated and moved to higher elevation, while the lower limits of glacier and snow cover and vegetation moved northward to higher elevations. Changes in the vertical belt were influenced by climate change and human activities over time. Cropland was mainly controlled by human activities and climate warming, and the reduced precipitation also led to the abandonment of cropland, at least to a certain extent. Changes in grassland and forest ecosystems were predominantly influenced by both human activities and climate change. At the same time, glacier and snow cover far away from human activities was also mainly influenced by climate warming.

  • Research Articles
    CHEN Tongde, JIAO Juying, CHEN Yixian, LIN Hong, WANG Haolin, BAI Leichao
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    In Lhasa River Basin (LRB), land suitable for settlement or living is experiencing a shortage of resources. Alluvial fans have the potential to alleviate this problem. However, basic information, such as the distribution and land use types of alluvial fans, is rarely studied. In this study, Google Earth, ArcGIS and visual interpretation were used to obtain the outlines, areas, quantities and distribution of alluvial fans. Meanwhile, to show the utilisation potential of alluvial fans, we analysed the land use, their distance from the roads, places (town and village) and rivers. The results showed 826 alluvial fans exist in LRB, with a total area of 1166.03 km². The number of alluvial fans with areas between 0.1 and 1 km2 is 517, accounting for 62.59% of the total number of alluvial fans. Grassland is the dominant land use type, accounting for 68.70% of the total area of alluvial fans. The cropland area accounted for 2.16% of alluvial fans and accounted for 18.98% of the total cropland area in LRB. Exactly 93.70%, 53.63% and 61.86% of the total number of alluvial fans were located within 5 km from the tertiary road, village, and river, respectively. To sum up, our survey results showed that alluvial fans are important land resources in LRB and may have huge utilisation potential.

  • Research Articles
    SUN Zhongxiang, BAI Huiqing, YE Huichun, ZHUO Zhiqing, HUANG Wenjiang
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    Soil organic carbon density (SOCD) and soil organic carbon sequestration potential (SOCP) play an important role in carbon cycle and mitigation of greenhouse gas emissions. However, the majority of studies focused on a two-dimensional scale, especially lacking of field measured data. We employed the interpolation method with gradient plane nodal function (GPNF) and Shepard (SPD) across a range of parameters to simulate SOCD with a 40 cm soil layer depth in a dryland farming region (DFR) of China. The SOCP was estimated using a carbon saturation model. Results demonstrated the GPNF method was proved to be more effective in simulating the spatial distribution of SOCD at the vertical magnification multiple and search point values of 3.0×106 and 25, respectively. The soil organic carbon storage (SOCS) of 40 cm and 20 cm soil layers were estimated as 22.28×1011 kg and 13.12×1011 kg simulated by GPNF method in DFR. The SOCP was estimated as 0.95×1011 kg considered as a carbon sink at the 20-40 cm soil layer. Furthermore, the SOCP was estimated as -2.49×1011 kg considered as a carbon source at the 0-20 cm soil layer. This research has important values for the scientific use of soil resources and the mitigation of greenhouse gas emissions.

  • Research Articles
    CAI Xingran, LI Zhongqin, ZHANG Hui, XU Chunhai
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    The glacier is a crucial freshwater resource in arid and semiarid regions, and the vulnerability of the glacier change is intimately linked to regional ecological services and socio-economic sustainability. Taking the Tianshan Mountains region in China as an example, a basic framework for studying the vulnerability of glacier change was constructed so as to address factors such as physical geography, population status, socio-economic level, agricultural development, and social services. The framework was based on key dimensions, that is, exposure, sensitivity, and adaptability, and this constituted a targeted evaluation index system. We examined the spatial structure and spatial autocorrelation of the glacier change vulnerability using ArcGIS and GeoDa software. The influence and interaction of natural, social, economic, population and other factors on glacier change adaptability was examined using the GeoDetector model. The results suggested the following: (1) The vulnerability level decreased from the western region to the eastern region with significant differences between the two regions. The eastern region had the lowest vulnerability, followed by the central region, and then western region which had the highest vulnerability. (2) Significant positive and negative correlations were found between exposure, sensitivity, and adaptability, indicating that the areas with high exposure and high sensitivity to glacier change tended to have a low adaptive capacity, which led to high vulnerability, and vice versa. (3) The spatial heterogeneity regarding the ability to cope with glacier change reflected the combined effects of the natural, social, economic, and demographic factors. Among them, factors such as the production value of secondary and tertiary industries, the urban population, urban fixed-asset investment, and the number of employees played major roles regarding the spatial heterogeneity of glacier change.

  • Research Articles
    LIU Zhilin, DING Yinping, JIAO Yuanmei
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    Following climate change, changes in precipitation patterns and food security are major challenges faced by humans. However, research on how these changes in precipitation pattern impacts food supply is limited. This study aims to elucidate this impact and response mechanisms using precipitation data of a climate change-sensitive confluence zone of the southwest and southeast monsoons in Yunnan Province from 1988 to 2018. The results revealed that the precipitation pattern could be divided into three periods: abundant precipitation (Stage I, from 1988 to 2004), decreased precipitation (Stage II, from 2005 to 2015), and drought recovery (Stage III, from 2016 to 2018). Following the transition from Stage I to Stage II and from Stage II to Stage III, the area of precipitation changed significantly, accounting for 15.07%, 13.87%, and 16.53% of Yunnan’s total area, for Stages I, II, and III, respectively. At the provincial level, a significant positive correlation was observed between precipitation and food production (r = 0.535, P < 0.01), and the correlation coefficient between precipitation and grain yield was higher than that between precipitation and meat and milk production. Based on a precipitation-grain yield transect and breakpoint detection method, key precipitation thresholds affecting grain yield were estimated as 700 and 1500 mm, respectively; when precipitation was < 700, 700-1500, and ≥1500 mm, the correlation coefficients between precipitation and grain yield were 0.448 (P < 0.01), 0.370 (P < 0.01), and -0.229 (P > 0.05), respectively. Based on the precipitation thresholds, Yunnan Province can be divided into precipitation surplus, precipitation equilibrium, and precipitation deficit regions, corresponding countermeasures to stabilize grain yield were proposed for each of these regions. The threshold effect of precipitation on grain yield is controlled by molecular-level water-crop mechanisms, in which reactive oxygen species, a by-product of plant aerobic metabolism, plays a key regulatory role.

  • Research Articles
    YANG Ren, PAN Yuxin
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    An indicator system is constructed and applied for comprehensive measurement of rural vulnerability in China’s counties. Through the selection of five representative transects we explore regional differences in, and driving forces of, China’s rural vulnerability. The results show that (1) The rural vulnerability of counties in China is generally within the threshold range of low to medium, and exhibits obvious spatial differences. Along the “Bole-Taipei Line”, there is a spatial pattern of north-south differentiation. Villages in the northeast part of the counties have low vulnerability, while those in the southwest are relatively vulnerable (2) External environmental phenomena are the leading factors that induce rural vulnerability. Specifically, the rural ecological subsystem composed of ecological exposure, ecological sensitivity, and ecological adaptation is the principal determinant of rural vulnerability. The rural economic subsystem composed of economic exposure, economic sensitivity, and economic adaptation is also a core determinant of rural vulnerability. The social subsystem composed of social exposure, social sensitivity, and social adaptation is also an important determinant of rural vulnerability. (3) According to the principle of adapting measures to local conditions, different regions should seek to reduce regional embeddedness and path dependence. We should strengthen the prediction and monitoring of sources of disturbance in rural areas, and scientifically control the sensitivity of the system itself. Then the adaptive capacity of the rural system can be improved pursuant of promoting sustainable development.

  • Research Articles
    Leandro Ismael de Azevedo LACERDA, José Augusto Ribeiro da SILVEIRA, Celso Augusto Guimarães SANTOS, Richarde Marques da SILVA, Alexandro Medeiros SILVA, Thiago Victor Medeiros do NASCIMENTO, Edson Leite RIBEIRO, Paulo Vitor Nascimento de FREITAS
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    Urban forests play an important role in the thermal comfort and overall life of local populations in large- and medium-sized cities. This study analyzes urban forest loss and maps land use and land cover (LULC) changes between 1991 and 2018 by evaluating the use of urban planning instruments for the mitigation of urban forest loss in João Pessoa, Brazil. For this purpose, satellite-derived LULC images from 1991, 2006, 2010 and 2018 and data on urban forest loss areas obtained using the Google Earth Engine were used. In addition, this paper also discusses the instruments used for integrated urban planning, which are (a) the legal sector, responsibility and nature; (b) the urban expansion process; and (c) the elements of urban infrastructure. The results show a clear shift in land use in the study area. The major changes in LULC classes occurred in urban areas and herbaceous vegetation, while the greatest loss was in arboreal/shrub vegetation. Thus, an increase in the pressure to occupy zones intended for environmental preservation could be estimated. Our results showed similar accuracies with other studies and more spatial details. The characteristics of the patterns, traces, and hotspots of urban expansion and forest cover loss were explored. We highlighted the potential use of this proposed framework to be applied and validated in other parts of the world to help better understand and quantify various aspects of urban-related problems such as urban forest loss mapping using instruments for integrated urban planning and low-cost approaches.