Table of Content

    31 January 2018, Volume 73 Issue 1 Previous Issue    Next Issue
    Climate Change
    Simulated CO2 emissions from 2016-2060 with comparison to INDCs for EU, US, China and India
    GE Quansheng,LIU Yang,WANG Fang,ZHENG Jingyun
    2018, 73 (1):  3-12.  doi: 10.11821/dlxb201801001
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    Examining the CO2 emissions by country in the future whether the mitigation plans are implemented or not, as well as their comparison with INDCs, is important to promote the ambition and cooperation on global long-term goal of climate change. A dynamic model of CO2 emissions from fuel combustion is established based on statistical analysis between economy and energy development using the latest data from the World Bank and International Energy Agency. Extending and planning scenarios are designed according to whether there exist additional and explicit efforts to mitigate climate change. Then annual CO2 emissions during 2016-2060 for the European Union, the United States, China and India are simulated and compared with INDCs respectively, from which three main conclusions are derived. (1) In planning scenario China will achieve its INDCs. For detail, the CO2 emissions per unit of GDP in China will be 63.6% lower than the level of 2005 and the share of non-fossil fuels in primary energy consumption will increase to 24.7%. Besides, China will reach the emission peak 11277±643 Mt CO2 in 2030, which is 10 years earlier and almost 3000 Mt CO2 lower than the peak of extending scenario. (2) In planning scenario, the CO2 emissions of EU and US will significantly decrease and the growth rate of India will slow down, which makes EU and India achieve their INDCs likely but US still has a gap around 300 Mt CO2. (3) INDCs are ambitious for all countries, especially for China and US. However, making further efforts on global warming mitigation to control the temperature rise below 2 ℃ or even 1.5 ℃, which requires the developed countries to play an important role on policy, technique and finance, including promoting carbon capture and storage technique, achieving negative growth of CO2 emissions, and providing support for developing countries.

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    Spatiotemporal variability of temperature in northern and southern Qinling Mountains and its influence on climatic boundary
    LI Shuangshuang,LU Jiayu,YAN Junping,LIU Xianfeng,KONG Feng,WANG Juan
    2018, 73 (1):  13-24.  doi: 10.11821/dlxb201801002
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    A study on temperature variations in the northern and southern Qinling Mountains is performed using temperature series at 70 meteorological stations for the period 1970-2015. Temporal trends, spatial characteristics, 0 ℃ isotherm displacement and the number of days with active accumulated temperature above 10 ℃ are evaluated, using extreme-point symmetric mode decomposition (ESMD), spatial analysis and other climate diagnosis methods. The significance of climatic boundary line of the Qinling Mountains is explored in the context of global warming. Four new insights have been achieved: (1) The changing trends of temperature in the northern and southern Qinling Mountains over the past 46 years are synchronous, with the warming process shown as a 'non-smooth, nonlinear, and ladder-shaped' pattern. The evolution process can be divided into three periods: the low stationary fluctuation period in 1960-1993, followed by a rapid increase period in 1994-2002, and finally a warming stagnation period in 2003-2015. (2) The ESMD decomposition indicates that the changing trends of temperature over the northern and southern Qinling Mountains are dominated by interannual fluctuation, and have no obvious linear trend. (3) The spatial variation of temperature in the Qinling Mountains is characterized by 'synchronous warming, and differential north-south change'. In the north, the spatial variation of temperature is relatively consistent, while in the south low temperature centers are observed at Xixiang-Ankang basin and Shangdan basin. (4) The Qinling Mountains, as a climatic boundary line, still play a major/obvious role; however, there exists difference in the response of temperature variations to global warming over the north and south of the Qinling Mountains. The northern boundary of north subtropical zone extends upward along the southern Qinling Mountains; while warming zone extends by the form of enclave in the northern Qinling Mountains due to rapid urbanization and mountain blocking.

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    Characteristics of dry-wet abrupt alternation events in the middle and lower reaches of the Yangtze River Basin and their relationship with ENSO
    SHAN Lijie,ZHANG Liping,ZHANG Yanjun,SHE Dunxian,XIA Jun
    2018, 73 (1):  25-40.  doi: 10.11821/dlxb201801003
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    Based on the daily precipitation data from 75 rainfall gauging stations covering 1960-2015 in the middle and lower reaches of the Yangtze River Basin, we analyzed the temporal and spatial distribution characteristics of dry-wet abrupt alternation (DWAA) events during the summer (from May to August) and its relationship with ENSO by defining the daily scale dry-wet abrupt alternation index (DWAAI) based on the modification of original index. The results showed that: (1) Modified DWAAI, which was defined by taking into account the differences of dry-wet degree between the earlier and later periods as well as how slowly or quickly the process changes from dry to wet in the abrupt alteration period, could be used to identify DWAA events accurately and effectively. (2) On the whole, areas where DWAA events occurred had expanded gradually since 1960. Meanwhile, the frequencies and intensities of such events had gradually increased over time. DWAA events mainly occurred in May-June, and the Hanjiang River watershed sub-basin, the middle reaches of the Yangtze River, the northern Dongting Lake watershed sub-basin and the northwestern Poyang Lake watershed sub-basin were high-incidence areas of such events. (3) There were some relationships between DWAA events and phenomena of continuously low SST in Nino3.4 region before such events occurred. Specifically, La Ni?a early-warning reacted to the occurrence of DWAA events. About 41.04% of such events occurred during decline stages of La Ni?a or within the first 8 months after La Ni?a ended. In terms of intensity, there were significant negative correlations between DWAAI at all the stations and SST anomalies in Nino 3.4 region within 6 months before DWAA events occurred, especially in the Poyang Lake watershed sub-basin and the middle reaches of the Yangtze River. The conclusions indicated that these methods and results were meaningful for the fighting against drought and flood in the Yangtze River Basin.

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    Phenology of forest vegetation and its response to climate change in the Funiu Mountains
    ZHANG Xiaodong,ZHU Wenbo,ZHANG Jingjing,ZHU Lianqi,ZHAO Fang,CUI Yaoping
    2018, 73 (1):  41-53.  doi: 10.11821/dlxb201801004
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    The study on vegetation phenology is of great importance to understand the relationship between vegetation and climate. In areas where the vegetation is sensitive to climate change, a phenological study is helpful to reveal the response mechanism of vegetation to climate change. Based on Moderate Resolution Imaging Spectro radiometer (MODIS) Enhanced Vegetation Index (EVI) time-series images from 2000 to 2015, we utilized Savitzky-Golay (S-G) filter and dynamic threshold method to extract the phenological parameters of forest vegetation in the Funiu Mountains. Combining temperature and precipitation data, we used Mann-Kendall (M-K) trend test, Theil-Sen estimator, ANUSPLIN interpolation, and correlation analysis methods to analyze phenological changes of vegetation in response to climate factors (temperature/precipitation) in the Funiu Mountains. The results showed that: (1) The start and end of growing season ranged mainly from 105 d to 120 d and from 285 d to 315 d, respectively. The length of the growth season ranged mainly from 165 d to 195 d. There is an evident correlation between forest phenology and altitude. With increasing altitude, the start, end and length of the growing season presented a significantly delayed, advanced and shortened trend, respectively. (2) In terms of the interannual variations, both the start and end of the growing season mainly displayed a delayed trend in 76.57% and 83.81% of the total area, and the length of the growing season exhibited a lengthened trend of 61.21%. The start of forest growing season is mainly affected by the decrease of spring temperature in the region. (3) A significant correlation was found between the start of growing season and mean temperature in March. The negative correlation coefficient indicated that a delayed start of the growing season was primarily due to the temperature decrease in March. The end of growing season was mainly influenced by September precipitation, and their correlation was positive, that is, the increased precipitation in September can delay the end of the growing season. In addition, the length of the growing season was influenced by temperature and precipitation during the whole growing season, for most parts of the region, the mean temperature and precipitation in August were obviously correlated with the length of forest growing season.

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    Impacts of climatic factors and El Niño/La Niña events on the changes of terrestrial ecosystem NPP in China
    CUI Linli,SHI Jun,XIAO Fengjin
    2018, 73 (1):  54-66.  doi: 10.11821/dlxb201801005
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    Net primary productivity (NPP) is one of the most important indicators of terrestrial ecosystem carbon cycle, and is also the material basis for the survival and development of human society. Therefore it plays an important role in the global environment change and the development and utilization of natural resources. Based on the simulated NPP data from GLOPEM-CEVSA model, air temperature, precipitation and sunshine hours data from 2043 weather stations as well as El Ni?o/La Ni?a events from 1982 to 2011, the spatial and temporal distributions and dynamic changes of NPP in terrestrial ecosystem were analyzed, and the relationships between NPP and climatic factors and ENSO events in China were examined using the GIS spatial analysis and mathematical statistics methods. Results indicated that vegetation NPP increased at a rate of 5.66 gCm-2 per decade in China during 1982-2011, especially in the 1980s it increased significantly at a linear rate of 50.0 gCm-2 per decade. Spatially, vegetation NPP increased in western China and the northern and eastern parts of Northeast China, whereas it decreased in the central part of Northeast China, North China Plain, the mid-eastern part of Inner Mongolia, the Yangtze River Delta and the Pearl River Delta in the past 30 years. In the Yangtze-Huaihe river basins, the decrease of vegetation NPP and the reduction of sunshine hours had good corresponding relationships, and in northern China and northern Xinjiang, the increase (decrease) of NPP was relied more on the increase (decrease) of precipitation. In Northeast China, the increase of NPP was associated with the increases in sunshine hours and temperature. For China as a whole, in El Ni?o years, regions with the increase of vegetation NPP were slightly larger than those of NPP decrease, but in La Ni?a years regions with the increase of vegetation NPP was basically equal to those of NPP decrease, and sunshine hours was the main climate factor which leads to the differences of vegetation NPP between El Ni?o years and La Ni?a years. More attentions should be paid to the impacts of radiation, extreme climatic events and anthropogenic air pollution on vegetation NPP in different regions of China in future.

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    Nonparametric integrated agro-meteorological drought monitoring in China: New monitoring technique and applicability
    LI Qin,ZHANG Qiang,HUANG Qingzhong,SHI Peijun
    2018, 73 (1):  67-80.  doi: 10.11821/dlxb201801006
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    Drought is one of the most catastrophic natural hazards which have severe impacts on human society and yet it is the least understood hazard. Monitoring drought in a reliable way plays a critical role in the early warning as well as the mitigation of drought hazard. Generally, the integrated agro-meteorological drought monitoring is one of the most popular drought monitoring methods and it is the key step to mitigate droughts effectively. However, the originally developed integrated drought monitoring index included nothing about evapotranspiration, and it does perform not well in reflecting impacts of evapotranspiration on occurrence of droughts. In this case, this study attempted to propose an improved version of the multivariate standardized drought index (MSDI) using standardized precipitation evapotranspiration index (SPEI) and standardized soil moisture index (SSI), i.e. modified multivariate standardized drought index (MMSDI). Based on the statistical records of drought-affected crop area in 7 geographical zones across China, this study tests the applicability of MMSDI in drought monitoring across China in 3-month and 6-month time scales, with comparison to the meteorological drought monitored by SPEI, agricultural drought monitored by SSI and integrated agro-meteorological drought monitored by MSDI. The result indicates that MMSDI can monitor meteorological drought and agricultural drought simultaneously. Furthermore, MMSDI has greater superiority than SPEI, SSI and MSDI in the veracity of drought monitoring. Besides, MMSDI can monitor droughts in bad conditions where meteorological drought and agricultural drought monitoring technique cannot be applied. Moreover, MSDI tends to overestimate the drought intensity and the size of drought-affected regions across China. In sum, MMSDI proposed in this study can be used to monitor and detect drought conditions in a more accurate way from perspectives of meteorological drought and agricultural drought. Meanwhile, drought conditions monitored by MMSDI are very close to in-situ observations and to the real-world observations of droughts in terms of drought-affected regions and related losses. In this sense, this study provides a theoretical foundation for large-scale drought monitoring across China, and provides practical regional case studies for related research in other regions of the world.

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    Surface Process and Ecological Environment
    Development of debris flows in Guanba River and its effect on sediment deposition in Qionghai Lake of Sichuan
    WEI Xueli,CHEN Ningsheng
    2018, 73 (1):  81-91.  doi: 10.11821/dlxb201801007
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    Since the late-Cenozoic, the strong uplift of Tibetan Plateau not only formed a large number of tectonic fractures on the southeast edge, but also generated many tectonic rift lakes due to structural stretching and compression. However, in recent years, some of the lakes started to shrink and depicted a reduction in lake depth, which has eventually exerted great influence on local ecological environment and socio-economic development. In this paper the Qionghai Lake, located on the southeast edge of the Tibetan Plateau, is selected as the study area. Based on exploring the debris flow characteristics of Guanba river in the north of Qionghai Lake, the effect of sediment deposition deriving from debris flows on Qionghai Lake is analyzed. The research shows that: (1) The scale and frequency of debris flow occurrence is higher in the Guanba River, and the primary material sources are landslide and non-point source erosion with a movable volume of 428.03×104 m3. (2) The frequent occurrence of floods and debris flows are the primary cause of sediment accumulation in the Qionghai Lake, and the debris flows are controlled by the coupling effect of frequent earthquakes and heavy rainfall. It is predicted that debris flows will still occur frequently, and sedimentation disasters will become more severe in the future. (3) Since 1950, the average deposition rate was about 17.09 mm/a. In terms of current deposition rate, it is inferred that the longevity of the Qionghai Lake will be only about 600 years. (4) The comprehensive governance model with management of administrative law is proposed in the Guanba River. The results can not only provide reference bases for planning management and disaster prevention in Qionghai Lake basin, but also contribute to reveal the reason of lake shrinkage on the southeast edge of Tibetan Plateau.

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    Dynamic changes of habitats in China's typical nature reserves on spatial and temporal scales
    ZHU Ping,HUANG Lin,XIAO Tong,WANG Junbang
    2018, 73 (1):  92-103.  doi: 10.11821/dlxb201801008
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    Establishment of protected areas is one of the most important approaches for biodiversity conservation. Until 2015, China had established 2740 sites for nature reserves with a total area of 1.47 million km2, which covering 14.8% of Chinese land surface. Based on remote sensing inversion, model simulation and spatial analysis methods, this study analyzed spatial and temporal variations of habitat from vegetation coverage, net primary production (NPP) and their driving forces in different types and climate zones on the typical nature reserves of China, in the first 15 years of the 21st Century. Results showed that from 2000 to 2015, the vegetation coverage of national nature reserves increased from 36.3% to 37.1%, with all types of nature reserves improved to some extent. The forest ecological nature reserves observed annual growth of 0.1%, grassland meadow type 0.8%, inland wetlands classes 0.2%, desert ecological class 0.1%, wild animal 0.1% and wild plants 0.1%. The NPP of grassland meadow, inland wetlands, desert ecology, wild animal nature reserve had a growth of 2.0 g·m-2, 1.2 g·m-2, 0.3 g·m-2 and 0.4 g·m-2 respectively. However, the NPP of forest ecological and wild plants nature reserves reduced by a rate of 3.5 g·m-2 and 2.5 g·m-2 respectively. In the 15 years, national nature reserves had a weak change from human disturbance, in addition to nature reserves which located in the Qinghai-Tibet Plateau and the south subtropical humid area with a slightly fall, others are increased, especially in the north subtropical and temperate humid zone, the human disturbance increased significantly from 4.7% to 5.4%.

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    Impact of rapid urbanization on river system in a river network plain
    WU Lei,XU Youpeng,XU Yu,YUAN Jia,XIANG Jie,XU Xing,XU Yong
    2018, 73 (1):  104-114.  doi: 10.11821/dlxb201801009
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    To reveal the impact of rapid urbanization on river system in a river network plain, characteristic indexes of river system, such as grid river density, development coefficient of tributary and fractal dimension, were used to evaluate the temporal and spatial changes of river system in Suzhou City from 1980s to 2010s, based on topographic map in 1:50000 scale and remote sensing image in 30m scale. The results were as following: The length of river system was decreased by 10.55%. From view of each order river, the length of 1st order river was increased by 3.24%, while that of 2nd order river and 3rd order river was decreased by 18.87% and 11.76%, respectively. The grid river density of river system was mainly decreased across most area of this region, and the change trend between main river and tributary was opposite in space, i.e., the grid river density of main river was mostly increased, while that of tributary was mostly decreased. The development coefficient of tributary and fractal dimension of river system respectively changed from 3.36 to 2.78 and 1.70 to 1.63, which indicated that the structure and morphology of river system became simplified. The attenuation of river system became remarkable when the land urbanization rate was greater than 40%. The response to land urbanization for each order river was different. Overall, 1st order river experienced a slight increase, to enhance the capability of flood control and drainage. When the land urbanization rate was less than 40%, some 2nd order rivers were occupied by farmland, and many 3rd order rivers were dug to improve the capacity of drainage and irrigation. When the land urbanization rate was greater than 40%, a lot of tributaries were buried and converted to construction land. And the lower the order river, the more severe the attenuation was.

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    Interconnected river system network scheme of urban lake group based on water environment improvement
    YANG Wei,ZHANG Liping,LI Zongli,ZHANG Yanjun,XIAO Yi,XIA Jun
    2018, 73 (1):  115-128.  doi: 10.11821/dlxb201801010
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    The Interconnected River System Network (IRSN), which plays a significant role in water resource allocation, water ecological restoration and water quality improvement, has become a key part of the urban lake management. The optimization of IRSN scheme and the evaluation of IRSN effects have a direct influence on the improvement of hydrodynamics and water quality. However, no comprehensive evaluation system has been built up to evaluate the hydrodynamics and water quality of the connected lakes. In this paper, a two-dimensional mathematical hydrodynamics and water quality model was built, and indexes including NH3-N, TN and TP were chosen as the water quality indexes to simulate the flow field and water quality of the Tangxun Lake group under different IRSN schemes. In addition, a comprehensive evaluation system based on evaluation indexes from the aspects of water hydrodynamics, water quality and socioeconomics was established to evaluate the IRSN effects of the Tangxun Lake group. The results showed that the fluidity of lakes improved greatly after the water diversion. The IRSN project can improve water quality of the lakes in a short time, while the improvement rate decreased gradually as the water diversion time increased. The comparison of these five schemes mentioned in this paper indicated that the fifth scheme (concurrent diversion from Donghu Lake and Liangzi Lake) can achieve the most obvious improvement in both hydrodynamics and water quality and generate the most economic benefits.

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    The change of the Gaobao lakes and its driving forces (1717-2011)
    YANG Xiao,HAN Zhaoqing
    2018, 73 (1):  129-137.  doi: 10.11821/dlxb201801011
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    The Gaobao lakes refer to a group of lakes to the west bank of the Grand Canal in the central part of Jiangsu Province. They used to be one of the important passages for the Huaihe River draining into the Yangtze River. Under the influence of the changing relationship between the Yellow River and the Huaihe River and land reclamation activities, the shape of the Gaobao lakes has changed dramatically in recent 300 years. This article analyzes three digitized earliest surveyed maps of the Gaobao lakes, discusses related historical literature and investigates some borehole data. In doing so, this article discovers that the evolution of the Gaobao lakes can be divided into three stages. The first stage is from the Kangxi reign to the Qianlong reign (1662-1795), when the Gaobao lakes in recent 300 years reached the top in area - 1606 km2 on the first surveyed map of China complied in 1717. The second stage is after the Qianlong reign, when sandbars began to develop in the Gaobao lakes as the sediments from the Hongze Lake gradually deposited to its northwest. The third stage is after 1851 when the Sanhe River which originated from the southeast part of the Hongze Lake became a main passage for the Huaihe River to empty into the Yangtze River. The Sanhe River brought a large amount of sediments into the Gaobao lakes and formed the Sanhe delta. With the expansion of the Sanhe delta, the Gaobao lakes have been quickly shrinking, from 1606 km2 in 1717 to 1494 km2 in 1868, 1072 km2 in 1916 and 887 km2 in 2011. This article argues that the sediments deposited from the Hongze Lake is a main reason for the shrinkage of the Gaobao lakes. Human reclamation activities expedited the process of sedimentation and changes of the Gaobao lakes.

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    The river development of the Qingyijiang River in the northern piedmont of Mt. Huangshan
    HU Chunsheng,LIU Shaochen,HU Chenqi,CAO Le,ZHOU Yingqiu
    2018, 73 (1):  138-151.  doi: 10.11821/dlxb201801012
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    The Qingyijiang River, which is located in the northern piedmont of Mt. Huangshan, is the longest branch of the lower Yangtze River. Based on the field survey, a well-preserved sequence of one diluvial platform (P) and three river terraces (i.e., T3, T2 and T1) was found, and a corresponding sequence of four gravel beds was also presented, according to two natural sections of Xikou cross section and Chengbei cross section in the Jingxian Basin. In addition to the gravel fabric analysis method, the Electron Spin Resonance dating and palaeomagnetic dating were used to discuss the age, process and cause of river development of the Qingyijiang River. This study concludes that: (1) the results of the gravel fabric analysis show that the T3 terrace is the oldest terrace of the Qingyijiang River, and the T3 gravel bed is the oldest gravel bed of the same river; (2) the dating results show that the formation timing of the Qingyijiang River can be traced back to the period from ~1300 ka BP to ~900 ka BP, and the oldest timing of the river is ~1300 ka BP, whereas the most recent timing is ~900 ka BP; (3) the Qingyijiang River originated from one of the braided rivers on the diluvial fan before 1377 ka BP, and successively experienced three stages of the diluvial fan and braided rivers, the incision by the braided river and the Qingyijiang River formation, that is, the so-called development model of the Qingyijiang River from one braided river on the diluvial fan; and (4) the development of the Qingyijiang River may be a combined result of precipitation increase and tectonic uplift. This study provides a reference for the studies of the small and medium river development in eastern China.

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    Characteristic of tradeoffs between timber production and carbon storage for plantation under harvesting impact: A case study of Huitong National Research Station of Forest Ecosystem
    ZHU Jianjia,DAI Erfu,ZHENG Du,WANG Xiaoli
    2018, 73 (1):  152-163.  doi: 10.11821/dlxb201801013
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    The tradeoffs and optimizations of ecosystem services are the key research fields of ecology and geography. As the most important and complex ecosystem in terrestrial ecosystems, forest ecosystem plays a very important part in the biogeochemical cycle which include terrestrial carbon cycle and water cycle, and also provides numerous ecosystem services that are crucial to human wellbeing. China has the largest plantation area worldwide. Under the background of global warming, there are more and more concerns on timber production and carbon storage of plantations, nevertheless, they have a relationship of restricting each other. Thus, it is necessary to maximize the overall benefit of timber production and carbon storage for forest ecological development in China. We selected the Huitong National Research Station of Forest Ecosystem as our study area, and used permanent sample plot data of plantations and InVEST model to evaluate timber production and carbon storage quantitatively. Then, we constructed a conceptual framework of forest ecosystem service tradeoffs under different management regimes. Lastly, tradeoffs countermeasures for optimizing overall benefits of ecosystem services were put forward. The results showed that: (1) When timber production increased with harvesting intensity over the entire 100 year planning horizon, carbon storage decreased. There were tradeoffs between timber production and carbon storage according to the significant negative relationship. (2) When the overall benefits of timber production and carbon storage increased with harvesting intensity, the value of tradeoffs decreased. T1 and T2 scenarios, with harvesting intensity of 10%-20% every 10 years, were the optimum management regime for timber production and carbon storage to gain more benefits and less tradeoffs. (3) The current harvesting intensity in Huitong County was slightly higher than the optimum harvesting intensity. On practical dimension, these findings suggested that obvious objectives are needed to formulate the corresponding countermeasures of tradeoffs, in order to realize the improvement of ecosystem services and the optimization of ecosystem structures.

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    Scenarios simulation of vascular plant species abundance distribution on Qinghai-Tibet Plateau
    FAN Zemeng,HUANG Yan,YUE Tianxiang
    2018, 73 (1):  164-176.  doi: 10.11821/dlxb201801014
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    For quantitatively explaining the relationship between the vascular plant abundance and habitat factors in the Qinghai-Tibet Plateau, a spatial simulation method has been developed to simulate the distribution of vascular plant species abundance. In this paper, seven datasets covering 37 national nature reserves were used to screen the best correlation equation between the vascular plant abundance and habitat factors in the plateau. These datasets include imformation on the vascular plant type, land cover, mean annual biotemperature, average total annual precipitation, topographic relief, patch connectivity and ecological diversity index. The results show that the multiple correlation coefficient between vascular plant abundance and various of habitat factors is 0.94, the mean error validated with the vascular plant species data of 37 national nature reserves is 2.21 types/km2, and the distribution of vascular plant species abundance gradually decreases from southeast to northwest, and reduces with increasing altitude except for the desert area of Qaidam Basin on the Qinghai-Tibet Plateau. Furthermore, the changes of vascular plant species abundance in the plateau during the periods from 1981 to 2010 (T0), from 2011-2040 (T2), from 2041to 2070 (T3) and from 2071 to 2100 (T4) were simulated by combining the land cover change in China and the climatic scenarios of CMIP5 RCP2.6, RCP4.5 and RCP8.5. The results from T0 to T4 show that the vascular plant species abundance in the plateau would decrease in the future, the vascular plant species abundance had the biggest change ranges under RCP8.5 scenario and the smallest change ranges under RCP2.6 scenario. In short, dynamic change and interaction of habitat factors directly affect the spatial distribution of vascular plant species abundance on the Qinghai-Tibet Plateau.

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    The spatial-temporal characteristics and influencing factors of air pollution in Beijing-Tianjin-Hebei urban agglomeration
    LIU Haimeng,FANG Chuanglin,Huang Jiejun,ZHU Xiangdong,ZHOU Yi,WANG Zhenbo,ZHANG Qiang
    2018, 73 (1):  177-191.  doi: 10.11821/dlxb201801015
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    Air pollution is now the most serious environmental problem in China, especially for Beijing-Tianjin-Hebei (Jing-Jin-Ji) urban agglomeration. Under the background of Jing-Jin-Ji integrated development, it is of great importance to study the spatio-temporal distribution and its influencing factors. This paper firstly analyzed the spatio-temporal characteristics of PM2.5 concentration in 202 counties of Jing-Jin-Ji urban agglomeration using spatial analysis and visualization. Then we quantified the effect degree of different natural and human factors and the spatial spillover effect of these factors using Spatial Durbin Model (SDM). The results are as follows: (1) The PM2.5 concentration was on the rise as a whole from 2000-2014, and it was high in autumn and winter, while low in spring and summer. Seen from spatial distribution, the PM2.5 concentration was high in the southeast, while low in the northwest of the study area, and the concentration in urban built-up area was 10-20 μg/m3 higher than that of its surrounding suburban and rural areas. (2) The counties, whose PM2.5 concentration was below 35 μg/m3, only accounted for 13.9% in 2014. There were significant spatial agglomeration and diffusivity of PM2.5, and the mean distance interacting among the cities was 200 km. The PM2.5 of a city increased by more than 0.5% for every 1% increase in the average PM2.5 of neighboring cities. (3) Socio-economic factors have positive impact on PM2.5, and most of natural factors have negative impact. (4) Among the influencing factors, contributions to local atmospheric pollution with direct effect are: mean wind speed > annual mean temperature > population density > relief amplitude > the secondary industry share of GDP > energy consumption > vegetation coverage; however, per capita GDP, annual precipitation, and relative humidity have no significant effect on local pollution. (5) Contributions to neighborhood atmospheric pollution with spatial spillover effect are: vegetation coverage > relief amplitude > population density. The findings suggest that we should adopt the adaptation strategies for natural factors and control strategies for human factors. A coordinated and strengthened cooperation between local governments should be established for air pollution control, and environmental planning and legislation should be strengthened in a new round of urban agglomeration planning in China.

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