Explicitly identifying the ecotone distribution and scenario change is of important significance to understand the response of ecosystem to climatic change. In this paper, a spatial identification method was developed to analyze the ecotone distribution in terms of the improved Holdridge life zone (iHLZ) model. Based on the climatic observation data of 782 weather stations of China in the T0 (1981-2010) period, and the climatic scenario data of IPCC CMIP5 RCP2.6, RCP4.5 and RCP8.5 in T1 (2011-2040), T2 (2041-2070) and T3 (2071-2100), the ecotones distribution and scenarios in China were simulated in the four periods. Moreover, a spatial shift trend model of mean center was introduced to quantitatively calculate the shift direction and distance of each ecotone type during the periods from T0 to T3. The simulated results show that there are 41 ecotone types in China, accounting for 18% of the total land area of China. The ecotones of cold temperate grassland / humid forest and warm temperate arid forest (564238.5 km²), cold temperate humid forest and warm temperate arid / humid forest (566549.75 km²), and northern humid / humid forest and cold temperate humid forest (525750.25 km²) are the main ecotone types, accounting for 35% of the total area of ecotones in China. Between T0 and T3, the area in the ecotone of cold temperate desert shrub and warm temperate desert shrub / thorn steppe will increase at a rate of 4% per decade, which is up by 3604.2, 10063.1 and 17242 km² per decade under the RCP2.6, RCP4.5 and RCP8.5 scenarios, respectively. The cold ecotones will transform to the warm humid ecotones in the future. The average shift distance of mean center in the ecotone of north wet forest and cold temperate desert shrub / thorn grassland will be generally larger than that of other ecotones, whose mean center will move to the northeast, and the shift distance will be more than 150 km between T0 and T3. In addition, with a gradual increase of temperature and precipitation, the ecotones in northern China will show a shifting northward trend, while the ecotones in southern China will decrease gradually, and their mean center move to the high-altitude areas. The effects of climate change on ecotones will show an increasing trend in China, especially in the Qinghai-Tibet Plateau.

Quantitative evaluation and comprehensive measurement of resource and environmental carrying capacity are the technical keys in the research of resource and environmental carrying capacity from classification to synthesis. From a system perspective, this paper proposes a three-dimensional tetrahedron model with physical meaning to comprehensively evaluate resource and environmental carrying capacity, which is conducted on the structure of "human settlement environment suitability classification - resource and environmental carrying capacity restrictive classification - socioeconomic development adaptability classification - resource and environmental carrying capacity warning classification". Its results have clear policy guidance significance for the establishment of the dynamic-monitoring and early-warning mechanism for regional resource and environmental carrying capacity. Based on the above methods, this research, taking Tibet Autonomous Region as an example and using 1-km gridded data, quantitatively assessed regional resource and environmental carrying capacity at county level. The results show that there were about 3/4 areas in good condition of resources and environmental carrying status (surplus or balanced state), with more than 4/5 of population; the human settlement environment in Tibet was mainly characterized by unsuitability and critical suitability, while the socioeconomic development level there generally lagged behind. Within this context, we suggest that human settlement environment suitability and socioeconomic development level have greatly restricted the performance and improvement of resource and environmental carrying capacity in Tibet.

Environmental governance plays a pivotal role in promoting the high-quality development of environment, and the implementation of source control and zoning management is the foundation of the refined governance of environmental space. This paper aims to put forward the theoretical and technical methods of regional environmental function management and control zoning, and carry out an empirical study on Shengzhou city, Zhejiang province. First, a spatial structure model of the environmental pollution sources (EPSs) for human activities, which is composed of control units (CUs) and hierarchical control areas (HCAs), has been formed and identified. Then, the solid waste, air pollutants and water pollutants are selected as the main pollutants, and the single evaluation and weighted sum have been measured for each CU. Finally, according to the spatial classification of the CUs and the integrated eigenvalues, key countermeasures and supporting projects of each HCA are proposed. The main results are as follows: (1) Shengzhou city has a total of 18 CUs, which can be divided into 6 HCAs. HACs of levels Ⅴ and Ⅳ are the areas where pollutants are discharged intensively, with integrated eigenvalues of 11 and 10 respectively. The CUs, including refuse landfill, sewage-treatment plant, high-pollution industrial zone, livestock and poultry farm, mining area, and basic industrial zone, have hugh impact on water and atmosphere, and have great hazards. It is necessary to promote the resource utilization of industrial and mining production space in the key area of environmental governance. (2) The emissions of pollutants in the HACs of levels Ⅲ and Ⅱ are medium or even less. The CUs of level-Ⅲ HAC cover urban settlements, rural settlements and transportation land, with integrated eigenvalues of 6 and 7. It is important to improve the collection and treatment technology of solid waste and sewage in all living space. In addition, HAC of level-Ⅱ includes two CUs, which are cultivated land and garden plot, with integrated eigenvalues of 4. It has a small amount of agricultural solid waste and sewage discharge, therefore, it is urgent to solve the problems of non-point source pollution and eutrophication. (3) HACs of level-Ⅰ is composed of forest land, garden land, water area, bare land and other ecological space, with more emphasis on ecological protection function. Large scale industrialization and urbanization are prohibited in the area. HAC of level 〇 highly overlaps ecological redline, which requires complete prohibition of human activities and the elimination of external environmental impact.

Assessing the effectiveness of nature reserves for mitigating anthropogenic pressures is essential for effective nature protection. The current research at national scale in China only compares anthropogenic pressures inside nature reserves to that outside, but fails to solve the problem of sample selection deviation, which will lead to bias in assessment results. In order to solve this problem, we adopted propensity score matching method to improve the accuracy of the results in the evaluation of nature reserves. The multi-source data were firstly integrated to build Anthropogenic Pressure Index in 2013, 2015, and 2017, then the propensity score matching method was applied to match the random points inside and outside the nature reserves, to make sure that the observed variables of the two comparison groups were as similar as possible. Finally, we used relative effectiveness indicator and panel model to assess the effectiveness of 680 nature reserves in China for mitigating anthropogenic pressures from 2013 to 2017 at different levels. The results show that: (1) From 2013 to 2017, 86.72% of China's nature reserves experienced a positive trend of anthropogenic pressures, which accounted for 43.80% of the total area. (2) Some 69.85% of nature reserves performed well in mitigating anthropogenic pressures. Except for marine coasts, wild plants, and wild animals, the types of nature reserves were under sound protection, and the higher the level of nature reserves, the better the protection effectiveness. (3) From 2013 to 2017, anthropogenic pressures were mitigated by 22.90% by the construction of China's nature reserves, and there were regional differences regarding the degree of mitigation. The results can provide a more scientific reference for future monitoring, assessment and management of nature reserves in China.

This paper attempts to explore the feature and efficiency of the ventilation channel in the main built-up area of Guangzhou, one of the four first-tier cities in China. Building groups were simplified and then the centerlines of open areas were sketched out, and finally proceeded to the identification of the ventilation channels. Data of hourly wind direction and velocity of the year 2016 were used. Indicators based on GIS for measuring the physical and thermal properties of ventilation channels were proposed, which facilitate the analysis of the characteristics of the ventilation channels and the evaluation of their efficiency. The results show that: (1) There are 2451 potential ventilation channel centerlines at a 40-m resolution, when composed, 142 meet the standard of ventilation channel. The total ventilation area reached 96.49 km², accounting for 21.59% of the study area. (2) Centering around the Pearl River New Town, the potential ventilation network in the study area presents dense-sparse-dense concentric characteristics, and inclines slightly to the northeast direction. The ventilation area of the old town is relatively limited. The width-height ratio of ventilation channel in the Pearl River New Town is 6.54 while in wetland area it reaches the highest to 74.43, illustrating that width-height ratio among different districts varies greatly. Green lands and waters cover more than 90% of the ventilation area of the peripheral region outside the main urban area. (3) According to the similarity in spatial distribution of direction efficiency, there exist three patterns: spring, summer and autumn/winter. In line with the seasonal variation rule of efficiency, three categories of ventilation channel are classified: perennial paths, seasonal paths, and communication paths. The result of seasonal ventilation efficiency assessment shows that autumn outperforms winter which outperforms spring which outperforms summer (autumn > winter > spring > summer). (4) Regarding retardation degree, the contribution of overpassing bridge is two times and ever higher than that of street trees. The maximum retardation in the study area is 4.70 m³/m² and most of the high retardation values concentrated west of the study area, especially around Sanyuanli where high-density overpassing bridges exist.

Soil security plays an important role in the sustainable agriculture. With the rapid economic development, the soil quality faces great human-related threats from the contamination, and it is essential to conduct the investigation of heavy metals in soils of the areas with intensive human activities. Source apportionment and spatial prediction are the key issues of the investigation of soil heavy metals pollution, which could provide scientific references for the regional soil pollution management and remediation. For this purpose, a total of 1067 samples were collected in surface soils of Yantai coastal zone, eastern China; and As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, and Zn concentrations were analyzed. Positive matrix factorization (PMF) was applied to estimate source apportionment of heavy metals. Multivariate independent simulation combining Independent Component Analysis (ICA) and Sequential Gaussian Simulation (SGS) were proposed to predict the spatial distributions of heavy metals, and local and spatial uncertainty analysis was used to identify the polluted areas. As, Co, Cr, Mn, and Ni originated from natural sources, with their spatial distributions consistent with parent materials. Cd, Cu, Hg, Pb, and Zn exhibited significant accumulation in soils, but the mean contents of these five heavy metals did not exceed the risk screening values for soil contamination of agricultural land. Industrial and traffic emissions contributed 58.3%, 40.3%, and 35.8% of Cd, Pb, and Zn concentrations, respectively; and these three heavy metals presented high values in gold and copper tailings as well as the urban district of Yantai. Cu mainly came from the application of bordeaux mixture and organic fertilizer, with its high-value hotspots associated with orchard soils. Hg originated from the atmosphere deposition originated from coal combustion and gold smelting by the mixed mercury method, and its high-value hotspots were related to the surrounding of gold mine as well as urban areas of Longkou and Penglai. The potential contaminated areas of Cu, Hg, and Cd accounted for 37.5%, 14.3%, and 8.6% of the total study area, respectively.

Based on the scientific connotation of green development, a comprehensive evaluation index system for green development in the Yellow River Basin was constructed, and various measurement methods such as entropy method, spatial autocorrelation analysis, and geographical detector model were used to study the spatio-temporal differentiation characteristics and the influencing factors of the green development in the eco-economic corridor of the Yellow River Basin. The results are obtained as follows: (1) The green development in the Yellow River Basin mainly originates from the external driving effects of large-scale expansion and the growth of total volume. Focusing only on pursuing the speed and scale of development but ignoring the connotative improvement of quality and efficiency will inevitably lead to the insufficiency of internal driving effects and unsustainability. (2) The number of areas with lower level of green development in the study area decreased continuously while that with a higher-level of green development rose slightly during the limited study period. However, the proportion of the numbers of areas with the lower level and medium-low level of green development remained above 65% for a long time, indicating that the level of green development needs further improvement. (3) From 2005 to 2017, the 61 prefecture-level cities in the Yellow River Basin generally showed relatively obvious spatial dependencies, and the green development level displayed a relatively obvious characteristic of spatial club convergence. The phenomenon of polarization in the study area was obvious. (4) The economic development level, science and technology level and government regulation are still the leading factors influencing the green development, and the explanatory power of interactions between factors for the green development far exceeds that of a single factor. This reflects the driving factors for green development in the Yellow River Basin are complex.

In order to investigate the pollution characteristics and human health risk of polycyclic aromatic hydrocarbons (PAHs) in heavy polluted weather in the typical urban and rural areas of the Fenwei Plain, PM_2.5 samples were collected from Xi'an and Longxian in the winter of 2018-2019. The mass concentrations of 15 PAHs characterized by carcinogenicity, mutagenicity and teratogenicity in the samples were determined using gas chromatograph-mass spectrometer (GC-MS). The source of PAHs was analyzed by the diagnostic ratio and principal component method and the possible relation between PAHs mass concentrations and meteorological parameters was elaborated. In addition, human health risk caused by PAHs in PM_2.5 was assessed through the equivalent carcinogenic concentration of benzo(a)pyrene (BaP) and incremental lifetime cancer risk (ILCR). The results showed that the average mass concentrations of PAHs in PM_2.5 in heavy polluted weather in Xi'an and Longxian were 243.78 μg/m³ and 609.39 μg/m³, respectively, and 4-6 rings of PAHs had the highest proportion of the total. Moreover, PAHs concentrations had a significant negative correlation with atmospheric temperature, atmospheric pressure and wind speed, but irrelevant with relative humidity. Combustion source and automobile exhaust emissions were the main factors contributing to the high concentration of PAHs in Xi'an, while coal and biomass burning were the main factors contributing most to PAHs of Longxian. Health risk assessment results revealed that the carcinogenic risk caused by breathing during heavy polluted weather was higher in Longxian than that in Xi'an and the cancer risk for females was higher than that for males, and the cancer risk for adults was higher than that for children. In addition, the ILCR value of adults in both urban and rural areas exceeded the risk threshold recommended by EPA and had potential carcinogenic risks, while there was no obvious carcinogenic risk for children.

Developing large-scale farm management through farmland transfer is an important trend of agricultural land use change in China. The farmland rents regarding large parcels have profound impacts on the establishment of large farms and their sustainable development, however, there is still a lack of systematic monitoring and research on the rent of large consolidated land at the national level. Based on more than 20000 farmland parcels collected from the most influential land transfer information releasing platform (www.tuliu.com) in China, this paper reveals the overall picture and regional differences of farmland transfer price, and employs the quantile regression method to identify the impacts of parcel attributes on farmland rent differentiation and their heterogeneity. The results show that the average and median of scale-farmland rent are 11339.10 yuan per hectare and 9511.95 yuan per hectare, respectively. The farmland rents were further divided into four levels, namely, ≤ 7500 yuan per hectare, 7500~15000 yuan per hectare, 15000~22500 yuan per hectare and > 22500 yuan per hectare. According to this classification, the proportions of parcels in different rent ranges are 38.93%, 37.97%, 14.52% and 8.59%, respectively. Regarding regional difference, the farmland rents in the Yunnan-Guizhou Plateau and Huang-Huai-Hai Plain are relatively high, 32% and 23% higher than the national average respectively, while the rent in the arid and semiarid regions of northern China was relatively low, which was about half of the national average. Quantile regression results show that land quality, land suitability for large-scale farming operation, land location and land property attributes exert significant impacts on farmland rent. In particular, for lower-rent parcels, the marginal effects of irrigation availability, land flatness and road quality are stronger. However, expressway proximity has a stronger value-added effect on these higher-rent parcels. To reduce the farmland cost of agricultural production in China, the governments at all levels should continue to reduce transaction costs, set up market-based land rent mechanisms, strengthen the construction of farmland infrastructure, and establish a price monitoring system for large-scale land circulation.