Spatial-temporal differentiation and influencing factors of rural settlements in mountainous areas: an example of Liangshan Yi Autonomous Prefecture, Southwestern China

Rural settlement is the basic spatial unit for compact communities in rural area. Scientific exploration of spatial-temporal differentiation and its influencing factors is the premise of spatial layout rationalization. Based on land use data of Liangshan Yi Autonomous Prefecture(hereinafter referred to as Liangshan Prefecture) in Sichuan Province, China from 1980 to 2020, compactness index, fractal dimension, imbalance index, location entropy and the optimal parameters-based geographical detector(OPGD) model are used to analyze the spatial-temporal evolution of the morphological characteristics of rural settlements, and to explore the influence of natural geographical factors, socioeconomic factors, and policy factors on the spatial differentiation of rural settlements. The results show that:(1) From 1980 to 2020, the rural settlements area in Liangshan Prefecture increased by 15.96 km^(2). In space, the rural settlements are generally distributed in a local aggregation, dense in the middle and sparse around the periphery. In 2015, the spatial density and expansion index of rural settlements reached the peak.(2) From 1980 to 2020, the compactness index decreased from 0.7636 to 0.7496, the fractal dimension increased from 1.0283 to 1.0314, and the fragmentation index decreased from 0.1183 to 0.1047. The spatial morphological structure of rural settlements tended to be loose, the shape contour tended to be complex, the degree of fragmentation decreased, and the spatial distribution was significantly imbalanced.(3) The results of OPGD detection in 2015 show that the influence of each factor is slope(0.2371) > traffic accessibility(0.2098) > population(0.1403) > regional GDP(0.1325) > elevation(0.0987) > poverty alleviation(0). The results of OPGD detection in 2020 show that the influence of each factor is slope(0.2339) > traffic accessibility(0.2198) > population(0.1432) > regional GDP(0.1219) > poverty alleviation(0.0992) > elevation(0.093). Natural geographical factors(slope and elevation) are the basic factors affecting the spatial distribution of rural settlements, and rural settlements are widely distributed in the river valley plain and the second half mountain area. Socioeconomic factors(traffic accessibility, population, and regional GDP) have a greater impact on the spatial distribution of rural settlements, which is an important factor affecting the spatial distribution of rural settlements. Policy factors such as poverty alleviation relocation have an indispensable impact on the spatial distribution of rural settlements. The research results can provide decisionmaking basis for the spatial arrangement of rural settlements in Liangshan Prefecture, and optimize the implementation of rural revitalization policies.

Exploring the coupling relationship of industrial agglomeration and low-carbon economy considering spatiotemporal differentiation:An empirical study in China’s construction machinery industry

Although China’s construction machinery thrives to meet the needs of construction,a number of challenges still remain to be overcome,such as lack of thorough knowledge of regional disparities and several limitations in terms of carbon emissions and economic development.Meanwhile,a low-carbon economy was proposed and implemented in China.This research aims to investigate the differences in industrial agglomeration of construction machineries and further explore the relationship between industrial agglomeration and low-carbon economy.On this basis,spatiotemporal analysis was performed to evaluate the levels of industrial agglomeration in different regions based on the situations of China’s construction machinery industry.Furthermore,this study explored the interaction between industrial agglomeration and low-carbon economy utilizing the coupling coordination analysis method.Results showed that the coupling coordination of the two subsystems was extremely unbalanced in 2006,and it maintained an increasing trend,reaching a relatively high level in 2018.Finally,suggestions,such as establishing a policy guarantee system and implementing variable policies in different regions,were proposed to provide guidelines for the government decision-making and promote the sustainable development of China’s construction machinery industry.

Spatiotemporal differentiation of changes in wheat phenology in China under climate change from 1981 to 2010

Phenology is a reliable biological indicator for reflecting climate change. An examination of changes in crop phenology and the mechanisms driving them is critical for guiding regional agricultural activities in attempts to adapt to climate change. Due to a lack of records based on continuous long-term observation, studies on changes in multiple consecutive phenological stages throughout a whole growing season on a national scale are rarely found, especially with regard to the spatiotemporal differentiation of phenological changes. Using a long-term dataset(1981-2010) of wheat phenology collected from 48 agro-meteorological stations in China, we qualified the spatiotemporal changes of 10 phenological stages as well as the length of wheat growth phases. Results showed that climate and wheat phenology changed significantly during the growing seasons from 1981 to 2010. On average, on a national scale, dates of sowing(0.19 d a-1), emergence(0.06 d a-1), trefoil(0.05 d a-1), and milk ripe(0.06 d a-1) showed a delaying trend, whereas dates of tillering(-0.02 d a-1), jointing(-0.15 d a-1),booting(-0.21 d a-1), heading(-0.17 d a-1), anthesis(-0.19 d a-1), and maturity(-0.10 d a-1) showed an advancing trend.Furthermore, the vegetative growth phase and growing season were shortened by 0.23 and 0.29 d a-1, respectively, whereas the reproductive growth phase was lengthened by 0.06 d a-1. Trends in dates of phenological stages or length of growing phases varied across wheat-planting regions. Moreover, spatiotemporal differentiation of sensitivity in growing season length(GSL) to variations in climatic factors during the growing season between spring and winter wheat were remarkable. The GSL of spring(winter) wheat decreased(increased) with an increase in average temperature during the growing season. In all wheat-planting regions, the GSL increased with the increasing of total precipitation and sunshine duration during the growing season. In particular, the sensitivity of GSL to precipitation for spring wheat was weaker than for winter wheat, while the sensitivity of GSL to sunshine duration for spring wheat was stronger than for winter wheat. Recognition of the spatiotemporal differentiation of phenological changes and their response to various climatic factors will provide scientific support for decision-making in agricultural production.

Spatiotemporal differentiation and development process of tidal creek network morphological characteristics in the Yellow River Delta

Tidal creeks are the main channels of land-sea ecosystem interactions,and their high dynamics are an important factor affecting the hydrological connectivity of tidal flats.Taking the Yellow River Delta as the research area,we selected remote sensing images obtained during five periods from 1998 to 2018 as the data sources.Based on the spatial analysis function in GIS,the typical morphological characteristics of tidal creeks,such as the level,length,density,curvature,bifurcation ratio,and overmarsh path length(OPL),were extracted to characterize the degree of development of the tidal creeks in the Yellow River Delta wetlands.The spatio-temporal evolution of the tidal creeks was studied,and the development process and the characteristics of the tidal creeks during the different stages of development were investigated.The results revealed that(1)The number,density,and bifurcation ratio of tidal creeks exhibit an increasing trend,but the growth of the trend is slowing.The number of tidal creeks increased by 44.9%from the initial stage of the Yellow River diversion to the late stage of the wetland restoration,but it only increased by 26.2%from the late stage of the wetland restoration to the slow expansion of the Spartina alterniflora.(2)The curvature of the tidal creeks on the landward side is greater than that on the seaward side.(3)The development degree of tidal creek has spatial heterogenetiy,which is AreaⅢ>AreaⅡ>AreaⅠ.(4)The drainage efficiency is significantly correlated with the tidal creak density and bifurcation ratio.Based on the analysis of the various morphological parameters and the drainage efficiency,it was found that after the rapid change in the tidal creek system in the early stage,the tidal creeks entered a state of slow change,and the development state of the tidal creeks tends to be in dynamic balance.The results of this study are expected to provide scientific support for the sustainable development and utilization of coastal tidal flats.

2001-2020年中国地表温度时空分异及归因分析

The variation of land surface temperature(LST)has a vital impact on the energy balance of the land surface process and the ecosystem stability.Based on MDO11C3,we mainly used regression analysis,GIS spatial analysis,correlation analysis,and center-of-gravity model,to analyze the LST variation and its spatiotemporal differentiation in China from 2001 to 2020.Furthermore,we employed the Geodetector to identify the dominant factors contributing to LST variation in 38 eco-geographic zones of China and investigate the underlying causes of its pattern.The results indicate the following:(1)From 2001 to 2020,the LST climate average in China is 9.6℃,with a general pattern of higher temperatures in the southeast and northwest regions,lower temperatures in the northeast and Qinghai-Tibet Plateau,and higher temperatures in plains compared to lower temperatures in mountainous areas.Generally,LST has a significant negative correlation with elevation,with a correlation coefficient of–0.66.China’s First Ladder has the most pronounced negative correlation,with a correlation coefficient of–0.76 and the lapse rate of LST is 0.57℃/100 m.(2)The change rate of LST in China during the study is 0.21℃/10 a,and the warming area accounts for 78%,demonstrating the overall spatial pattern a“multi-core warming and axial cooling”.(3)LST’s variation exhibits prominent seasonal characteristics in the whole country.The spatial distribution of average value in winter and summer differs significantly from other seasons and shows more noticeable fluctuations.The centroid trajectory of the seasonal warming/cooling area is close to a loop shape and displays corresponding seasonal reverse movement.Cooling areas exhibit more substantial centroid movement,indicating greater regional variation and seasonal variability.(4)China’s LST variation is driven by both natural influences and human activities,of which natural factors contribute more,with sunshine duration and altitude being key factors.The boundary trend between the two dominant type areas is highly consistent with the“Heihe-Tengchong Line”.The eastern region is mostly dominated by human activity in conjunction with terrain factors,while the western region is predominantly influenced by natural factors,which enhance/weaken the change range of LST through mutual coupling with climate,terrain,vegetation,and other factors.This study offers valuable scientific references for addressing climate change,analyzing surface environmental patterns,and protecting the ecological environment.

Urban land development intensity:New evidence behind economic transition in the Yangtze River Delta,China

Over the past 20 years,China has experienced multiple economic transitions characterized by marketization,globalization,decentralization,and urbanization;as a result,urban land development intensity(ULDI)has become a significant issue for sustainable development.As China’s largest globalized urban area,the rapid socio-economic development of the Yangtze River Delta has created a huge demand for urban land.We apply a theoretical framework for a four-dimensional analysis tool to understand the dynamic evolution of the ULDI in the context of economic transition.It reveals that marketization,globalization,decentralization,and urbanization affect the ULDI in the economic transition of Yangtze River Delta.Marketization,especially the continuous improvement of land marketization,optimizes the spatial allocation of land resources and encourages urban land users to improve ULDI.Globalization promotes the rapid growth of economy and population through an increase in foreign direct investment.In the process of decentralization,local governments rely on developing a mode of land finance,resulting in a disordered urban space and low ULDI.Population growth and agglomeration during urbanization stimulates residents’consumption capacity and promotes economic growth,thus creating a greater demand for urban land.However,a low level of development and utilization restricts the improvement of development intensity.Economic development can improve the level of land-intensive use by promoting the adjustment,optimization,and upgrade of urban industrial structures.

Visual simulation of regional development differen- tiation in Beijing-Tianjin-Hebei Metropolitan Region

Regional development differentiation is a complicated spatial and temporal dynamic process. Recent developments in spatial statistics and Geographic Information Systems （GIS） have led to an increasing interest in quantitative analysis and visualization of the process. However, so far, few direct qonnections have been made between the newly developed methods and classic spatial development theories, which would be very helpful for the inter- pretation and understanding of regional spatiotemporal differentiation. Using basic concepts and academic principles of polarized growth theory and gradient transfer theory, this paper quantifies the concept of regional development space. It then proposes a method based on GIS to visually simulate and analyze regional development spatiotemporal differentiation through a case study of the Beijing-Tianjin-Hebei Metropolitan Region （BTHMR）, China. The main research results are as follows. 1） The proposed method, built on classic theories and well-developed GIS technology, presents a good picture of regional development spatiotem- poral differentiation. 2） The levels of regional development, in terms of per capita GDP across BTHMR, diminished significantly with increased distances away from city propers （which can be seen as the regional growth poles）, leading to the appearance of development valley zones between different cities. The development valley zones between each city coincided with their boundary areas, which indicates that administrative boundaries have some impact on regional development, if the regional division is based on administrative boundaries. 3） From 1993 to 2007, the development level in the whole BTHMR improved significantly, of which polarized growth was dominant, especially for Beijing and Tianjin. However, as the two economic development engines in BTHMR, the pull effects of both Beijing and Tianjin on their peripheral areas were comparatively weak, except for those on Tangshan. 4） The structure and pattern of gradient transfer and balanced development in the BTHMR had not been completely developed yet, and the sustained polarized development of the regional economy in BTHMR was still going to be the main trend in the next 5-10 years.