Table of Content

    20 November 2018, Volume 33 Issue 11 Previous Issue    Next Issue
    Resource Utilization and Management
    Coupling Analysis of Rural Residential Land and Rural Population in China during 2007-2015
    LIU Ji-lai, LIU Yan-sui, LI Yu-rui, HU Yin-gen
    2018, 33 (11):  1861-1871.  doi: 10.31497/zrzyxb.20171068
    Abstract ( )   HTML ( )   PDF (8456KB) ( )   Save
    The spatial and temporal coupling relationship between rural residential land and population is the theoretical base for optimizing rural land resources. This paper aims to analyze the sequential variation characteristics, spatial heterogeneity rules and coupling relationship types of Chinese rural land resource and population. Demographic data and land survey data are analyzed with elastic coefficient model. The main research results include: 1) During 2007-2015, rural residential land linearly increased at an average annual rate of 1.94%, and totally increased 257.27×104 hm2. 2) Per capita residential land area of rural population and agriculture population increased at an average annual rate of 4.61% and 1.98%, respectively, and the gap between them was widen at an average annual rate of 16.2%. 3) The coupling relationship between rural residential land and rural population was type G (land area increase, population decrease and the former grows less rapidly than the latter) unbalanced development at national scale, and was type G or type H (land area increase, population decrease and the former grows faster than the latter) unbalanced development in all provinces. The coupling relationship between rural residential land and agriculture population was type H unbalanced development at national scale, and was unbalanced in 93.55% provinces. The research results indicated that the coupling relationship between rural residential land and rural population was unbalanced development in China during 2007-2015. This research could provide scientific supports for optimizing rural land resources and promoting coordinated development of rural man-land relationship.
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    Reclamation Decision for Temporary Construction Land of Coal Mines Based on Niche-fitness and Triangle Model
    DU Jian-ping, SHAO Jing-an, ZHOU Chun-rong, SUN Jing
    2018, 33 (11):  1872-1885.  doi: 10.31497/zrzyxb.20171063
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    The ecological reclamation and utilization of temporary construction land of coal mines is an important way of responding to the strategy of ecological civilization construction, practicing the idea of “ecological land improvement +” and optimizing the layout of the land. Based on the temporary construction land of 14 coal mines in Qijiang District of Chongqing City, an index system of suitability evaluation consisting of eight factors such as nature, location and population were constructed, which includes more than 20 evaluation factors such as slope, distance from road and soil pollution degree. By adopting the comprehensive weight method (AHP + TOPSIS), the niche-fitness model and the triangle model are introduced into the decision analysis of ecological reclamation and utilization of temporary construction land of coal mine. The results show that: 1) The average value of ecological index of each evaluation unit is more than 0.5, and the overall condition of the study area is good and is basically suitable for different kinds of reclamation. However, the niche-fitness coefficient of some plots is low, which indicated engineering or biological measures are needed to improve and renovate the situation. 2) In the unidirectional reclamation and utilization analysis, the appropriateness of agricultural reclamation showed “inverted pyramid” distribution that grade Ⅰ (optimum) has the largest area, accounting for 44.94% of the land; the appropriateness of construction land and ecological land showed a shape of olive that the grade Ⅱ (suitability) has the largest area, accounting for 76.54% and 58.02%, respectively. In the analysis of comprehensive reclamation and utilization, agricultural land showed the most in number and area of evaluation units in each reclamation and utilization direction, followed by ecological land and construction land. The three kinds of land accounted for 46.29%, 30.17% and 23.54% of the total area respectively. 3) The main factors influencing the direction of land reclamation are soil texture, public reclamation intention and proportion of cultivated land, and the main factors influencing the reclamation and utilization of construction land are the degree of geological disaster susceptibility, public intention and the development potential of non-agricultural industry. The main factors of reclamation and utilization of ecological land are forest land ratio, forest area per capita and soil organic contents. The study can provide the method and reference for decision in reclamation of temporary construction land of coal mines.
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    Resource Ecology
    Dynamics of Urban Food Metabolism with Water-Carbon Footprint Respond: A Case Study of Beijing
    XIONG Xin, ZHANG Li-xiao, ZHANG Peng-peng, HAO Yan, CHANG Yuan, WANG Can
    2018, 33 (11):  1886-1896.  doi: 10.31497/zrzyxb.20171137
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    Food metabolism is one of the basic processes of urban metabolism. Continuously growing urban population drives sharply increasing food demand with related impacts. Aimed at providing adequate information about dynamic process of urban food metabolism and related environmental footprint to identify measures for future diet optimization and impact reduction, this study systematically analyzed the dynamic characteristics of urban food metabolism on metabolic flux, structure and efficiency during 1978-2015 based on a case study of Beijing. Life cycle assessment (LCA) approach was used to calculate water-carbon footprint caused by food consumption, and an eco-efficiency index E was constructed to evaluate the efficiency of food metabolism in Beijing. At last, this study explored several effective ways to optimize urban food metabolism. The results indicated that: 1) In 2015, the urban food metabolic flux was 881.4×104 t in Beijing, which increased 3.3 times compared with the one in 1978, while water footprint and carbon footprint increased 6.1 times and 4.4 times respectively. 2) The structure of both metabolic flux and environmental footprint presented the evolution characteristics of shifting from staple food as main food to non-staple food as main food and from plant-derived food dominated diet to diet with equal importance of plant-derived food and animal-derived food. 3) The over-consumption diets, especially high proportion of meat consumption, not only affected the health status of urban inhabitants in Beijing, but also pushed tempestuously per capita environmental footprint of urban inhabitants into a high level, resulting in the eco-efficiency’s decreasing from 1.27 to 0.32. 4) Alleviating the environmental footprint impacts of urban food metabolism should be based on the following aspects: optimizing the industrial supply chain; sparkplugging healthy diet habits and sustainable consumption patterns.
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    Landscape Pattern Changes in Alpine Wetland of Bayanbulak Swan Lake during 1996-2015
    XU Xiao-long, WANG Xin-jun, ZHU Xin-ping, JIA Hong-tao, HAN Dong-liang
    2018, 33 (11):  1897-1911.  doi: 10.31497/zrzyxb.20171041
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    The changes in landscape pattern of alpine wetland ecosystem, one of the special ecosystems in arid areas, attracted global attentions. The objective of this study was to analyze the landscape pattern changes and the relationship between the changes and climate factors in the alpine wetland of Bayanbulak Swan Lake during 1996-2015. Five remote sensing images, including three TM images in 1996, 2006 and 2010, one ETM image in 2000 and one OLI image in 2015 were used. Results showed that: 1) The area of the wetland decreased by 5.62% during 1996-2015 with a loss rate of 1.91 km2/a. The changes of the wetland area can be divided into two periods by 2010. The changes were very small before 2010 and the percentage of wetland area in Bayanbulak Swan Lake ranged from 77.24% to 78.26%. After 2010, the wetland area continued decreasing at a low speed and the area decreased by 5.28%. 2) At the landscape level, the landscape fragmentation and the spatial heterogeneity increased during 1996-2015. At the same time, the shape of patches tended to be complex. At the class level, the fragmentation of wetland patches increased and the shape of patches tended to be complex. 3) Average daily maximum air temperature had much greater effect on the landscape pattern changes in Bayanbulak Swan Lake wetland than average annual precipitation. The area of the wetland tended to be stable with the increase of the daily maximum temperature and the changes of fragmentation degree were not obvious when the daily maximum temperature was below 18.7 ℃. In contrast, the area of wetland decreased and the fragmentation increased with the increase of the daily maximum temperature when the daily maximum temperature was over 18.7 ℃. These results indicated that the wetland in Bayanbulak Swan Lake degraded and the environment of the wetland became worse during 1996-2015.
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    Resource Evaluation
    Study on the Influence of Land Use Change on the Thermal Environment in Beijing-Tianjin-Hebei Urban Agglomeration
    YANG Hao, WANG Zi-yi, WANG Jing, MENG Na
    2018, 33 (11):  1912-1925.  doi: 10.31497/zrzyxb.20180163
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    This paper quantified the impact of land use change on thermal environment of Beijing, Tianjin and Hebei based on Landsat TM/ETM remote sensing data and WRF simulation and mathematical statistics method, and four schemes of experiments with different land use data were designed so as to find the spatial interactive impact of land use change . The results showed that: Firstly, during 2000-2015, urban construction land increased by 2 840 km2, mainly transferred from farmland and wetland which accounted for 94.37% and 4.93% of the increase of construction land, respectively. Secondly, Langfang, Tianjin and Tangshan are three cities most affected by land use change in Beijing, while Langfang was mostly affected by land use change in Tianjin. However, the temperature of other cities was less affected by land use change that the impact of land use change process in these cities is much smaller than in Beijing. Thirdly, from the perspective of seasons, the temperature in Beijing and Tianjin was most sensitive to land use change in autumn, followed by summer and spring, and basically had no response in winter through 2000-2015. Fourthly, land use change in areas other than Beijing increased the annual average temperature of Beijing by 0.07 ℃, but had obvious cooling effect in summer. As for Tianjin, land use change in other areas had little effect on temperature. Temperature rising area in autumn and winter formed a contiguous space of Beijing-Tianjin (Baodi District, Wuqing District, Jixian County). In view of this, we should construct urban ventilation corridors, promote the use of cleaner energy sources and upgrade the construction of urban green space system to optimize the thermal environment in the urban agglomeration of Beijing-Tianjin-Hebei. At the end of the paper, countermeasures and suggestions for building urban ventilation corridors, promoting the use of clean energy, improving energy efficiency, and scientifically planning urban green space system were put forward.
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    Disaster Risk Assessment of Continuous Rain during Harvest Period of Winter Wheat in China
    LI Ya-nan, QIN Yao-chen, XIE Zhi-xiang, NING Xiao-ju, ZHANG Li-jun
    2018, 33 (11):  1926-1939.  doi: 10.31497/zrzyxb.20171263
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    Continuous rain is an extreme weather event relevant to climate change that has caused difficulties in the harvesting, drying, storage, and transportation of winter wheat. These issues generally degrade wheat quality, resulting in high yield but poor crop income. Based on daily precipitation observation data from 839 national meteorological stations in China and crop phenology data from 778 Chinese agrometeorological stations, the frequency, longest duration and maximum total precipitation during the harvesting period of winter wheat were extracted and calculated for 265 stations in winter wheat region of China. By constructing a “disaster stress-exposure-adaptation” risk evaluation system and using an entropy weight grey correlation model, we evaluated the continuous rain disaster risk for winter wheat in 166 cities in China. On this basis, areas with high risk of continuous rain disaster were partitioned for risk prevention according to different dominant risk factors. Results showed that: 1) Spatially, disaster stress decreased significantly from south of the Qinling-Huaihe to north in a banded pattern. Both exposure level and adaptation level of disaster showed the pattern interlaced with high and low levels. The high exposure areas were mainly concentrated in western part of North China, the western Huang-Huai region and the southeastern part of Southwest China. The high adaptability areas were concentrated in municipalities, provincial capitals and their neighboring cities. 2) The disaster risk level for continuous rain on winter wheat was determined on the basis of three factors: disaster stress, exposure and adaptability. The regions with the highest and higher risk levels were mainly concentrated in the western Huang-Huai region, the western Yangtze-Huaihe region, the southeastern part of Southwest China and Southwest China, while the lowest and low risk levels were mainly concentrated in municipalities, provincial capitals and their surrounding cities. The number of cities above the medium level of risk accounted for 73% of all cities, directly threatening the harvest of 22.262 3 million hectares of winter wheat. 3) Disaster stress and disaster adaptation factors were each divided into two grades, high and low, according to natural breaks method, and the two factors were combined to partition the prevention areas of winter wheat. Areas of high stress and high adaptability were named stress-dominated areas, areas of low stress and low adaptability were named adaptation-dominated areas, areas of high stress and low adaptability were named stress-adaptation-dominated areas, and areas of low stress and high adaptability were named exposure areas. The hotspots of disaster risk were mainly stress-adaptation-dominated areas and adaptation-dominated areas. Strengthening disaster monitoring and early warning and improving regional adaptability can serve as effective ways for reducing the risk of continuous rain disaster.
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    Diagnostic Analysis of the Waterlogging Influence Factors in Beijing City: A Case Study of Shangqingqiao Catchment
    LI Rui, PAN Xing-yao, DI Su-chuang, YANG Mo-yuan, SU Yao
    2018, 33 (11):  1940-1952.  doi: 10.31497/zrzyxb.20171070
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    Due to the high frequency of heavy rainstorm events, waterlogging disaster is considered widely in urban area. However, the key factors of inundation for quantitative study is one of the most difficult issues and research cores of urban hydrology. In this study, we constructed a watershed flood model for Shangqingqiao Catchment of Qinghe River Basin, which is very representative urban waterlogging region. The flood model is built upon detailed data of urban water cycle such as rainstorm drainage pipe networks, river networks, topography, land use composition and surface construction. The model is validated with maximum waterlogging depth, area and occurrence time measured in rainstorm events which happened on July 21, 2012 and July 20, 2016. We applied the validated model in simulation of rainfalls with different reappearing periods, such as 1-year storm, 3-year storm, 5-year storm and 10-year storm. The results show that the rainstorm drainage pipe networks in Shangqingqiao Catchment can only undertake rainfall less than the flood volume of 1-year rainfall, and there would be inundation risk in heavier rainfall. Based on the constructed flood model, we singled four typical factors which in descending order of insensibility are regional low terrain, drainage capability of pipe networks, impervious area ratio of land surface, and backwater effect from river flood. Besides, scenario simulation on flood model shows that modifying these four typical factors can maximize depth, area, quantity and time of waterlogging. We also simulated the flood model in scenarios with different improvement measures, such as building pump stations, developing low impact development measures and reasonably regulating dams. The results show that all improvement measures can release the waterlogging caused by the four typical factors effectively. With comprehensively analyzing current situation and waterlogging influence factors of Shangqingqiao Catchment in Qinghe River Basin, we gave some measurements to release the inundation risk in Shangqingqiao Catchment, such as setting up pump stations and reservoirs to release waterlogging caused by regional low terrain, perfecting the drainage pipe network system progressively to improve drainage ability, developing low impact development measures to decrease impervious area ratio of land surface, reasonably regulating dams to avoid backwater effect from river flood. The results could provide a technical support for flood control and drainage projects in urban area.
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    Temporal and Spatial Variation of Winter Precipitation over Dongting Lake Basin and Its Relationship with Global Sea Surface Temperature
    SHANG Cheng-peng, ZHANG Xin-ping, SUN Jia, LI Yi-long
    2018, 33 (11):  1953-1965.  doi: 10.31497/zrzyxb.20171100
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    Based on the monthly precipitation data of 96 meteorological stations from 1961 to 2015 in the Dongting Lake Basin and monthly mean sea surface temperature (SST) dataset from Met Office Hadley Centre, the temporal and spatial variation and periodic properties of winter precipitation were analyzed with the methods of empirical orthogonal function (EOF), Morlet wavelet and partial correlation analysis. We also discussed the key areas and key periods which influence winter precipitation over Dongting Lake Basin. The result of EOF method showed that there were three leading modes of winter precipitation at inter-annual temporal scales: the mode being consistent over the whole area, the mode of opposite relationship between south Dongting Lake Basin and north Dongting Lake Basin, the mode of opposite relationship between central Dongting Lake Basin and south/north Dongting Lake Basin. Each mode has long periods of 12 a, 16 a, 7 a and short period of 3 a, respectively. With respect to the relationship between winter precipitation over Dongting Lake Basin and global SST, winter precipitation had a good relationship with El Niño-Southern Oscillation and South China Sea SST. On the average, when ENSO is in warm phase or South China Sea SST is higher than normal years, winter precipitation over Dongting Lake Basin is likely to be more. Reversely, winter precipitation over Dongting Lake Basin is likely to be less when ENSO is in cold phase or South China Sea SST is lower than normal years. However, there were distinct differences between the areas and key periods affected by ENSO and South China Sea SST. ENSO mainly affects south Dongting Lake Basin, and it has the best correlation with winter precipitation over Dongting Lake Basin in preceding October. South China Sea mainly affects east Dongting Lake Basin, and South China Sea SST has the best correlation with winter precipitation over Dongting Lake Basin at next Feburary.

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    Projection of the Impacts of Global Warming of 1.5 ℃ and 2.0 ℃ on Runoff in the Upper-Middle Reaches of Huaihe River Basin
    WANG Sheng, XU Hong-mei, LIU Lü-liu, WANG Yong, SONG A-wei
    2018, 33 (11):  1966-1978.  doi: 10.31497/zrzyxb.20171050
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    The climate change in the upper-middle reaches of Huaihe River Basin was projected in scenarios of 1.5 ℃ and 2.0 ℃ global warming using five General Circulation Models (GCMs) of the Coupled Model Intercomparison Project Phase 5 (CMIP5) and three Representative Concentration Pathways (RCPs). Then the hydrological responses to climate change were simulated using hydrological model SWAT (Soil Water Assessment Tool), and the uncertainties of the results were estimated and compared quantitatively. This study draws following conclusions: 1) The simulation results of SWAT model are in agreement with discharge observations very well in both calibration period and validation period, so it is feasible to apply SWAT model in estimating the impacts of climate change. 2) The annual average temperature in the upper-middle reaches of Huaihe River Basin will rise by 1.1 ℃ and 1.7 ℃ compared to the baseline (1986-2005). The annual precipitation will increase by 4% and 7% in scenarios of 1.5 ℃ and 2.0 ℃ global warming respectively. The ensemble mean (MME) annual runoff simulated based on SWAT will increase by 5% and 8% in scenarios of 1.5 ℃ and 2.0 ℃ global warming respectively. 3) The projected monthly runoff distribution will not change, and runoff will be concentrated in midsummer and early autumn (from June to September). Global warming will increase monthly high runoff dramatically, especially 2.0 ℃ global warming. As a result, the risk of flooding would increase obviously in the future, especially by 2.0 ℃ global warming. 4) There are big uncertainties in projected precipitation and runoff, and the uncertainty comes mainly from GCMs structure, especially in the scenario of 2.0 ℃ global warming.
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    Effect of Variation in Water Source Area on Stable Isotopes in Precipitation in the Middle Reach of the Yellow River Basin
    GUO Zheng-sheng, ZHENG Guo-zhang, ZHAO Pei, XIAO Jie
    2018, 33 (11):  1979-1991.  doi: 10.31497/zrzyxb.20171125
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    Using the precipitation isotope data observed at nine stations in the middle reach of the Yellow River Basin, the spatial and temporal distribution characteristics and environmental effect of isotope in precipitation are analyzed, the trajectories of air mass transport in this area are simulated, and the changes of the water source area and the influence of conveying process on stable isotopes in precipitation in summer half year are studied by using OLR technology. The result shows: the content of δ18O precipitation has obvious seasonal variation that it is lower in spring and summer and higher in autumn and winter; the content of δ18O in precipitation increases from southeast to northwest; the meteoric water line shows obvious transitional features, and the precipitation effect is relatively significant; the water vapor source is transported mainly through the two channels: the northwest and southeast. The water vapor from east and the thermal and dynamic properties of the Tibetan Plateau have a great influence on the sources of water vapor in the basin. The change of water vapor source region and water vapor content field in the upper and middle troposphere have good relationship with the characteristics of stable isotope. In August and September, ITCZ formed in the western Pacific makes the southeast monsoon the main water vapor channel in summer in the middle reach of the Yellow River Basin.
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    Water Resources Security Status Alteration and Its Attribution Analysis in the Three Outlets of Southern Jingjiang River after the Operation of the Three Gorges Reservoir
    WANG Yan-jia, LI Jing-bao
    2018, 33 (11):  1992-2005.  doi: 10.31497/zrzyxb.20171151
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    Based on the concept of driving-force-pressure-state-impact-response (DPSIR) model, an evaluation index system for water resources safety in the three outlets of southern Jingjiang River was established, and a fuzzy comprehensive evaluation based on entropy weight is carried out on water security status in this region during 2000-2015. Based on the factor analysis method, the changes of water security status in the region was analyzed. The results showed that: during the period 2000-2015, the overall water resources security in the three outlets was dominated by the Grade Ⅲ, accounting for 45.83%, which was still in the middle level. Water resources security showed a significant spatial and temporal variations. 1) From the perspective of time, water security status in Huarong County increased from Grade Ⅱ in 2000 to Grade Ⅴ in 2015, and the degree of membership to high levels became higher and to low levels became lower in general; water security status in Anxiang were Grade Ⅳ-Ⅴ during 2000-2002 and dropped to Grade Ⅲ after the operation of the Three Gorges Reservoir, but the change of membership degree to each level was small, and the growth of membership degree to high levels was slow. During this period, water security status in Nanxian County fluctuated most intensely. It dropped from Grade Ⅲ to Grade Ⅱ during 2000-2002 and slowly rose to Grade Ⅲ again after 2003. However, after 2010, its state of water resources safety fell from Grade Ⅱ to Grade Ⅰ and remained at Grade Ⅰ for three consecutive years during 2011-2013. After the operation of the Three Gorges Reservoir, the water resources security degree in Nanxian County fluctuated greatly and mainly moved from high level to low level. 2) From the perspective of space, before the operation of the Three Gorges Reservoir, water security status in the three outlets ranked from high to low was Anxiang, Nanxian and Huarong. In the initial operation period, the order was Anxiang, Huarong and Nanxian. In the trial operation period, it was Huarong, Anxiang and Nanxian. 3) Human economic activity and water supply capacity were the main contributing factors that affected the water resources security in the three outlets, whose variance contribution rates were 26.758% and 25.587%, respectively. The climate and population factors were the secondary factors, whose variance contribution rates were 16.240% and 15.469%, respectively.
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    Carbon Effect Accounting and Analysis of Land Consolidation in Hubei Province
    ZHANG Li-guo, WANG Zhan-qi, LI Bing-qing
    2018, 33 (11):  2006-2019.  doi: 10.31497/zrzyxb.20171141
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    An analytical framework is established to analyze the carbon effects of land consolidation projects, which includes short-term effects (SE) and long-term effects (LE). The SE includes engineering construction effects (ECE) and land use conversion effects (LUCE). The LE contains farmland ecosystem effects (FEE) and agricultural activities effects (AAE). Carbon emission coefficient method and ecosystem type method were used to account carbon emission for consolidation projects. After calculating the carbon emission, the time needed to achieve carbon balance after implementation was accounted. The comparative analysis is used to analyze the carbon effects of each project which belongs to different topography regions and engineering regions. We selected fourteen consolidation projects in Hubei Province as research cases. Five of them locate in plain area, four in hilly area, and five in mountains area. Among 14 projects, eight belong to the plain engineering model area (Ⅱ2), and six belong to the river (gully) valley basin engineering model area (Ⅲ1). During the implementation, all the projects showed carbon emission effect. The average amount of carbon emissions of projects located in plain, hilly, mountain areas, Ⅱ2 region and Ⅲ1 region was 8 541.47, 14 266.45, 12 591.86, 11 415.09 and 11 901.97 t, respectively. The average carbon emission per unit area was 6.29, 12.37, 15.80, 9.06 and 14.58 t/hm2, respectively. The average carbon emission per unit investment was 2.76, 3.77, 4.92, 3.31 and 4.50 t/million yuan, respectively. As to LUCE, the projects in plain area mainly showed carbon absorption effects, with an average value of 184.13 t per project. The projects in mountainous area showed carbon emission effects with an average value of 5 398.49 t per project, depending on the conversions of land use types such as forest land or grassland with high carbon reserves converting into other types of land. After consolidation, the area, quality and biological yield of cultivated land increased in different degrees. The average added value of carbon sequestration of FEE in plain area is 1 554.43 t/a, in hilly area is 1 125.40 t/a and in mountain area is 1 241.65 t/a. After land consolidation, irrigation and drainage facilities of each project area generally increased, thus leading to a larger increase of paddy field irrigation. Therefore, the carbon emission increased. The carbon emission of AAE increased in varying degrees (from 8.11 t/a to 463.76 t/a) after consolidation. It took different time for projects to balance SE caused by remediation activities. For these projects, the average time needed to achieve carbon balance after consolidation in plain area was 5.24 a, in hilly area was 10.87 a and in mountainous area was 19.68 a. At the end of this paper, some suggestions on how to form a low-carbon consolidation model were put forward.
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    Distribution of Plant Litter on the Slope and Its Effect of Litter Incorporated in the Soil on Soil Properties in Typical Vegetation Community in Loess Hilly Region
    WANG Zhong-yu, WANG Bing, LIU Guo-bin, LIU Jia-xin, LI Zhao-song
    2018, 33 (11):  2020-2031.  doi: 10.31497/zrzyxb.20171199
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    The plant litter incorporate in soil generally has great effect on soil properties. During the process of vegetation restoration in the hilly region of the Loess Plateau, the distribution of plant litter would be changed and hence affect the soil property. Four typical vegetation communities, Robinia pseudoacacia plantation, Caragana intermedia plantation, Artemisia gmelinii community and Bothriochloa ischaemum community were selected to study the distribution of litter on the slope (ranged from 40 to 80 m) and to discuss the effects of plant litter incorporated in soil on soil properties. The results showed that: 1) The volume (range from 143.89 to 833.04 g/m2), coverage (range from 36% to 63%) and thickness (range from 0.77 to 2.03 cm) of aboveground litter in Robinia pseudoacacia plantation were the highest, followed by those in Caragana intermedia plantation, Artemisia gmelinii community and Bothriochloa ischaemum community. For the biomass of incorporated litter (ranged from 178.80 to 657.21 g/m2) and the litter incorporation depth (ranged from 1.33 to 2.29 cm), the maximum values were found in Robinia pseudoacacia plantation, then followed by those in Artemisia gmelinii community, Caragana intermedia plantation and Bothriochloa ischaemum community. The amount of litter incorporated in soil accounts for the highest proportion of the total volume of litter (ranged from 45.91% to 74.02%). The vegetation communities with the ratio of the amount of litter incorporated in soil to total litter volume in descending order were Artemisia gmelinii plantation, Caragana intermedia plantation, Bothriochloa ischaemum community, and Robinia pseudoacacia community. 2) The aboveground litter volume and the amount of litter incorporated in soil on lower slopes were 1.05-2.48 times and 1.04-1.41 times higher than those on higher slope. While for the middle slope, the aboveground litter volume and the amount of litter incorporated in soil varied greatly and no significant relationship was found between middle slope and upper slope or lower slope due to the influence of runoff scouring and the process of sediment detachment, transport and deposition. The aboveground litter volume increased exponentially with the increase of litter coverage (P<0.01). The amount of litter incorporated in soil increased with the aboveground litter volume, and the relationship between them is a logarithm function (P<0.01). 3) With the increasing of litter incorporated in soil, soil properties of bulk density, cohesive force and WAS-GMD decreased linearly (P<0.01). The soil organic carbon and total nitrogen content increased linearly with the increase of litter incorporated in soil in grasslands (Artemisia gmelinii community and Bothriochloa ischaemum community), while no significant relationship was found between Robinia pseudoacacia plantation and Caragana intermedia plantation. This study would provide theoretical basis for assessing ecological effect of vegetation restoration and improving soil erosion model on the Loess Plateau.
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    Spatial Distribution of Organic Carbon in Topsoil of the Loess Tableland in Shaanxi Province during 1985-2015
    ZHANG Meng-meng, LIU Meng-yun, CHANG Qing-rui, LIU Huan, ZHANG Jie
    2018, 33 (11):  2032-2045.  doi: 10.31497/zrzyxb.20171085
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    The long-term dynamic of soil organic carbon in the mesoscale range is critical to the concentration of atmospheric greenhouse gases and the ecological effects of the local environment. Taking twelve soil types and seven types of land use in the Loess Tableland in Shaanxi Province as the research object, this paper studied the spatial distribution characteristics of soil organic carbon density (0-20 cm) in the past three decades. The relationships between soil temperature, topographic factor, soil type, land use type and soil organic carbon density and storage are discussed. The results show: 1) In the past three decades, the soil organic carbon density and storage in the Loess Tableland have increased, and the increase rates were bigger and bigger. The increments of soil organic carbon density and storage were 0.14 kg/m2 and 2.04×106 t during 1985-2000, and the increments were 0.80 kg/m2 and 10.10×106 t during 2000-2015. 2) From 1985 to 2015, with the increases of temperature and precipitation, the soil organic carbon density showed an increasing trend. With the increases of elevation and slope, the organic carbon density increased first and then decreased, reaching the maximum in the ranges of 679-779 m and 10°-20°. 3) The organic carbon density and storages in most soil types increased with time, among which the soil organic carbon density of the black loam increased the most (1.59 kg/m2) and the storage capacity of the yellow soil increased the most (5.64×106 t). The organic carbon density and storage in different land use types increased with time. The organic carbon density in forest grassland is obvious higher than that in cultivated land. 4) Surface soil organic carbon density is significantly correlated with temperature, soil type and land use type with P <0.001, and significantly correlate with precipitation with P <0.05. Regardless of which factor is the controlling factor, both soil type and land use type are significantly related to the organic carbon density of the topsoil (P <0.001), indicating that these two factors are the dominant factors affecting the organic carbon density.
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    Research Progress on the Relationship between Productivity and Biodiversity
    ZHAO Feng-xia, XU Ming
    2018, 33 (11):  2046-2056.  doi: 10.31497/zrzyxb.20171129
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    Productivity and biodiversity are two fundamental properties of ecosystems. However, there has been a long-running debate over their interrelationship and the mechanisms behind their relationship for decades. In this paper, the control experiments, meta-analysis and multi-site observation studies over the past decades for testing relationships between productivity and biodiversity and the mechanisms of their relationships are reviewed. It is found that the forms of productivity-biodiversity relationships mainly are: unimodal relationship, positive relationship, negative relationship, no relationship and U-shaped relationship. Besides, there is no general consensus about underlying mechanisms of their relationships. Meanwhile, both the relationships and the underlying mechanisms are strongly dependent on scales. These results illustrate that the productivity-biodiversity relationships are not a simple or direct causal relationship, but are driven by interconnected and multivariate ecological processes. Therefore, we should give up a fixation on bivariate patterns and adopt the approach of multivariate drivers to the problem of the biodiversity pattern in order to further strengthen our understanding of complex ecosystem processes and provide more meaningful guidance for conservation management.
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