Table of Content

    02 August 2017, Volume 32 Issue 7 Previous Issue    Next Issue
    Resource Ecology
    Evaluation of Ecological and Environmental Cost of Rare Earth Resource Exploitation in China from 2001 to 2013
    MA Guo-xia, ZHU Wen-quan, WANG Xiao-jun, ZHOU Xia-fei, YU Fang
    2017, 32 (7):  1087-1099.  doi: 10.11849/zrzyxb.20160660
    Abstract ( )   HTML ( )   PDF (2440KB) ( )   Save
    Scientific evaluation of ecological and environmental cost of rare earth (RE) resources exploitation is very important for designing the strategy of the sustainable utilization of rare earth resources and reforming the pricing policy of the rare earth market in China. The paper aims to quantitatively assess the ecological and environmental cost of RE resources exploitation in three major production bases in China from 2001 to 2013. To achieve this goal, the paper constructed an accounting framework of ecological damage loss and environmental pollution loss during the process of RE resources mining and smelting with the consideration of the characteristic that “light rare earth in north and heavy rare earth in south” in China. The qualitative data used were remote sensing images, pollution sources census, dynamically update data of pollution sources census and environment statistics. The results showed as follows: 1) The total ecological and environmental cost for RE resources development was 76.17 billion yuan from 2001 to 2013, of which 72.18 billion yuan was the ecological damage loss caused by mining, 3.99 billion yuan was the environmental pollution cost caused by smelting. 2) In the three main production bases of RE resources, ecological and environmental cost of Baotou ore was mainly for environmental pollution caused by RE smelting, and the environmental pollution control cost is 2.55 billion yuan, accounting for 74.3% of the total cost in Baotou. The ecological and environmental cost of bastnaesite and ionic rare earth ore was mainly caused by ecological damage loss, which was 5.43 billion yuan and 65.86 billion yuan, respectively, accounting for 89.5% and 98.8% of their respective ecological and environmental cost. 3) As for per unit of rare earth oxides (REO), the ecological and environmental cost of ionic rare earth ore was high, which was 9.6 times of the cost of bastnaesite, and 41.4 times of the cost in Baotou. 4) Ecological and environmental cost of RE exploitation in China is more than 45% of its price. Considering the ecological and environmental cost and scarcity cost of RE resource under the current market prices, China’s rare earth industry profit is negative.
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    Evaluating Natural Resource Assets and Gross Ecosystem Products Using Ecological Accounting System:A Case Study in Yunnan Province
    BAI Yang, LI Hui, WANG Xiao-yuan, Juha M. ALATALO, JIANG Bo, WANG Min, LIU Wen-jun
    2017, 32 (7):  1100-1112.  doi: 10.11849/zrzyxb.20160755
    Abstract ( )   HTML ( )   PDF (1254KB) ( )   Save
    As one of the important ecological assets, ecosystems provide human with ecological products and services, which is the foundation of human survival and social-economic sustainable development. Gross ecosystem product (GEP) is the value of products and services provided by ecosystems, which is an important part of ecological asset. Taking Yunnan Province as a case study, we used an accounting system to analyze the connotation and relevance of ecological assets and GEP in 2010. The evaluation results showed that the condition of ecological asset was overall good in 2010. Forest, shrub and grassland were mainly of good quality level; farmland was mainly of poor quality, while biodiversity had excellent quality level. Total worth of GEP was 2 986.95 billion yuan in 2010, in which, direct products contributed 413.27 billion yuan, and indirect services value amounted to 2 573.68 billion yuan. The results showed that the ecological asset accounting system works well in reflecting the contribution of ecological asset to local social and economic development, and can be used to assess the ecological asset conditions. Thus, the ecological asset accounting system can be used in ecosystem management and governmental performance appraisal.
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    The Impact of Urbanization on the Composition and Structure of Urban Forest
    YAO Xin, ZHAO Min
    2017, 32 (7):  1113-1124.  doi: 10.11849/zrzyxb.20160721
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    Ecosystems adjacent to and in cities are experiencing increasing disturbance from urbanizations and alteration of vegetation, soils, and biogeochemical cycles. Indeed the structure, function and subsequent ecosystem services of urban forests are highly influenced by land use change and human activities. And the fast urbanization process affected the composition and structure of urban ecosystem. The major data sources included in this study are remote sensing images and field inventory data of urban forests. Also, GIS tools and statistical analysis methods were used in this study. The study tried to explore the impacts of urbanization process on urban forest by taking Shanghai “urban-to-suburban” transect as an example. Based on remote sensing images, geographic information system (ArcGIS 9.3), landscape pattern analysis (Fragstates 3.3) and statistics (SPSS 17) were used to calculate six commonly used indicators, including physical variables and landscape metrics. Principal components analysis and multiple linear regression were used to assess the urbanization level of Shanghai. The results showed that: 1) The species richness (S), Simpson diversity (D), Shannon-Wiener diversity (H) of tree species in urban area were higher than those in suburban area, and there were significant differences (P < 0.05). While the species evenness of trees in urban area and suburban area were 0.448 ± 0.043 and 0.394 ± 0.038, with no significant difference. 2) The number of trees per unit area (hectare) in urban area was in the urban area, less than 472 ± 57 in the suburban area. It showed significant difference between them (P <0.05). 3) There were differences in the tree size potential in urban and suburban areas. The suburban area had more trees with high size potential, while the urban area had more large evergreens trees per hectare. 4) DBH (diameter at breast height) distribution presented an inverse “J-curve” in both urban and suburban areas. The study might be useful in scientific managing urban forest ecosystem function and provide a baseline for improving urban forest function.
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    Effects of Human Activities on Net Primary Productivityin the Xilingol Grassland
    ZHANG Jun, REN Hong-rui
    2017, 32 (7):  1125-1133.  doi: 10.11849/zrzyxb.20160736
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    Net primary productivity is a key index of production capacity of grassland ecosystem, and is also an important indicator of carbon fixation of ecosystem. With MODIS MOD17A3 net primary productivity (NPP) data and meteorological data, we analyzed the effects of human activities on NPP in the Xilingol grassland from 2001 to 2010. NPPA (actual NPP) was influenced by both climate change and human activities. NPPA was mainly in the range of 41.32-362.27 g C·m-2·a-1 with average value of 150.78 g C·m-2·a-1, and showed horizontal zonal feature gradually decreasing from east to west. NPPA in the meadow steppe was the highest, followed by that in typical steppe, while NPPA in the desert steppe was the lowest. NPPH (NPP affected by human activities) was mainly in the range of -185.07- 153.92 g C·m-2·a-1 with average value of -34.80 g C·m-2·a-1 in the Xilingol grassland. Human activities had negative effects on 93.4% of the study area, and had positive effects on only 6.6% of the area. However, the impact of human activities on NPP is changing from negative effect to positive effect in most of the area. There is a boundary between the southern and the northern Xilingol grassland. The negative effect is strengthening in the southern area, while the positive effect is strengthening in the northern area. The study provided references for the management and sustainable utilization of grassland resources in the Xilingol.
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    Resource Evaluation
    Analysis of Correlation between the Characteristics of Farmers and Their Perceived Risk of Environmental Disasters in Desertification Area—From the Perspective of Environmental Justice
    WEI Hui-lan, WANG Guang-yao
    2017, 32 (7):  1134-1144.  doi: 10.11849/zrzyxb.20160674
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    On the basis of a survey of farmers in desertification areas of Gansu Province, this thesis, employing Logit model, discusses the relations between the features of farmers in soil desertification areas and their perception of the environmental disasters risk from the perspective of environmental equity. Individually, the gender and marriage status have inconspicuous connections with the perception of risks of environmental disasters, while the educational level of farmers and the perception of risks of environmental disasters significantly demonstrate a positive correlation. In terms of economic features, the risk perception of environmental disasters of farmers is mainly reflected in the loss of land management income; the relations between the farmers’ perception of the environmental disasters risks and their annual household income present an inverted U-shaped trend. From the perspective of ecological features, the environmental governance strikingly lowers the perceivable environmental disasters risks. Through analysis, it is assumed that the unequal risks of environmental disasters posed on farmers is to some extent the reflection of the inequality they suffer in the social-economic realm, which is manifest in that: 1) from the perspective of individual characteristics, farmers aged 40-60 years and those more educated are more perceptive of environmental inequality; 2) from the perspective of economic characteristics, environmental inequality is mainly reflected by the impact of the risk of environmental disaster on land management income, and is associated with the income disparities among different groups that farmers with annual household income around 100 000 yuan are more sensitive to environmental inequality; 3) from the perspective of ecological characteristics, effective ecological governance is favorable for promoting environmental equality; however, farmers’ attitude towards environmental protection is not subject to ecological changes.
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    Remote Sensing Monitoring of Summer Drought at Monthly-scale Considering Vegetation, Temperature and Precipitation in Sichuan Province
    LU Xiao-ning, ZHANG Jing-yi, WANG Ling-ling, MENG Cheng-zhen, ZENG De-yu
    2017, 32 (7):  1145-1157.  doi: 10.11849/zrzyxb.20160655
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    Considering the comprehensive role of precipitation (TRM), vegetation (VCI) and surface thermal state (TCI) in the occurrence and development of droughts, a drought monitoring model is constructed at monthly scale in Sichuan Province based on remote sensing data during 2000-2015. Furthermore, the condition, evolution trend and frequency of droughts in different morphological areas are discussed. The results show as follows: 1) The SDCI modes is the most applicable model for drought monitoring at month scale in mountain areas, which can be described as SDCI=0.25×VCI+0.5×TRM+0.25×TCI. This model embodies the importance of precipitation in drought monitoring. 2) In temporal scale, the intensities of droughts in July are the strongest, while those in August become weaker. In spatial scale, the intensities of droughts in East Sichuan Basin are the strongest in both July and August, then followed by those in the transition area between Plateau and Basin, while those in plateau area in west of Sichuan is the weakest. 3) In greatly, the summer drought in July becomes weaker while the summer drought in August becomes more severe. However, it shows spatial difference. The summer drought in east Sichuan Province becomes aggravated in July but weaker in August; while in plateau and basin transition zone and western Sichuan Plateau, the summer drought becomes weaker in July but aggravated in August. 4) The frequency of occurrence of droughts is the highest in the eastern Sichuan Basin, followed by the plateau and basin transition zone, and then the western Sichuan Plateau. Moderate droughts occurred frequently in eastern Sichuan Basin and Plateau and Basin transition zone, while mild droughts occurred frequently in the Western Sichuan Plateau.
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    Cellular Automaton Simulation of the Effect of Low Impact Development on Urban Water-logging Reduction
    YANG Fan, XU Jian-gang, LIN Wei
    2017, 32 (7):  1158-1169.  doi: 10.11849/zrzyxb.20160718
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    Low Impact Development (LID) is an important measure to solve urban water-logging problem. To assess prevention and control effect of LID on urban water-logging, the urban area of Changting County in Fujian Province is taken as a case for study. Proper measures of LID for this area, including porous pavement, low elevation greenbelt and rainwater tanks, are proposed. The runoff generation module of SCS model and urban water-logging model based on Cellular Automaton (CA) model are used for simulation and verification. Results show that the urban water-logging model based on CA can simulate the process of urban water-logging effectively under the complex underlying surface scenarios of urban area. By comparing the water-logging simulation results before and after implementation of LID measures, the following conclusions can be drawn: 1) LID measures can reduce water-logging amount by over 50% under condition of different return period, and the reduction effect decline when the return period of storm is longer. 2) The spatial distribution and variation feature of water-logging area before and after LID measures are analyzed: After LID measures, water-logging amount reduces significantly in most water-logging areas, but the reduction is less in water-logging areas of northern Mountain Wolong and left bank of Tingjiang main stream, which means infrastructure construction such as drainage pipe networks should be strengthened in these areas. 3) The areas where LID has the best effect are areas where the water-logging depth is lower than 0.2 m, followed by areas where the water-logging depth is higher than 0.5 m. For those area where water-logging depth is between 0.2 m and 0.5 m, the reduction is not obvious. As the study shows, LID measures can control the water-logging disaster in a certain extent. Therefore, LID measures can be utilized as an effective complement to urban flood control and drainage engineering measures.
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    Relations between Land Use Carbon Budget and Economic Development at County Level in Chengdu City
    WANG Gang, ZHANG Hua-bing, XUE Fei, ZHEN Yan
    2017, 32 (7):  1170-1182.  doi: 10.11849/zrzyxb.20160677
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    Based on the land use map interoperated from remote sensing image and energy consumption data of 2014 at county level in Chengdu city, spatial distribution characteristic of the carbon budget was analyzed. Furthermore, coordinative relations among carbon budget, land use and economic development were studied by establishing regression model. The result shows: 1) The area proportion of carbon sink was 56.97%, higher than that of carbon source. There were remarkable spatial differences of carbon sources and carbon sinks in Chengdu city. Land use intensity county was between 2.40-3.33 at county level, and its spatial distribution presents characteristic of “high in the east and low in the west, while the highest in the middle”. 2) Net carbon emission was 2.43×107 t, with the characteristic of “high in the east and low in the west, while the highest in the middle”. Carbon compensation ratio and ecological support coefficient of each county were between 0.06%-11.58% and 0.05-8.60, respectively, and both presented the characteristic of “low in the east and hig in the west, while the lowest in the middle”. 3) Economy contribution coefficient was between 0.26-1.45, and it demonstrated a trend from high in the center to low in the peripheral area. 4) Net carbon emission was significantly positively correlated with GDP (P<0.01). ESC was significantly negatively correlated with land use intensity (P<0.01). The coupling coordination degree of economy contribution coefficient and land use intensity at each level was 0.56. According to the established regression model, we found that economic development and coupling coordination degree have significant correlation (P<0.01).
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    Study on the Aboveground Biomass of Natural Grassland and Balance between Forage and Livestock in Qilian County
    ZHANG Fu-ping, WANG Hu-wei, ZHU Yi-wen, ZHANG Zhi-zhi, LI Xiao-juan
    2017, 32 (7):  1183-1192.  doi: 10.11849/zrzyxb.20160770
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    By use of statistical yearbook data, years precipitation data, grassland investigation data and MOD13Q1 during 2013-2014 in Qilian County, the models of monitoring grassland aboveground biomass (GAB) and theoretic livestock carrying capacity in different grazing seasons were established. Changes of available grassland yield and livestock carrying capacity were analyzed. Results suggested that the exponential function of MODIS-EVI (Enhanced Vegetation Index) can best simulate the green yield of GAB in Qilian. The average precision of the monitoring model was 71.0%. The monthly dynamic growth of forage during the year was featured by a unimodal curve. The edible grass yield reached a peak of 2 322.61 kg/hm2 in July, and got to the lowest of 702.06 kg/hm2 in December. Average green yields in cold and warm seasons were 1 728.14 and 1 604.7 kg/hm2, respectively. The total available green forage yield in Qilian County were 15.56×108 kg, in which warm seasonal grazing rangeland was 7.74×108 kg, cool seasonal grazing rangeland was 7.82×108 kg. The theoretical carrying capacity of grassland in cold season, warm season and the whole year were 1.517 8, 0.637 0 and 0.931 4 sheep unit/hm2, respectively. The overgrazing rate was 101.7% in warm season, 261.19% in cold season and 149.22% in the whole year. If the overgrazing livestock cannot be fully decreased, about 0.36×108 and 7.17×108 kg of forage should be supplemented in cold and warm season, respectively. If keep the existing grassland, 6.68×104 and 53.64×104 sheep units should be reduced in cold and warm season, respectively. Even if the overgrazing livestock is decreased by 40% in cold season, about 1.17×108 kg of forage should be supplemented.
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    Extracting Tree Species Distribution with Landsat 8 OLI Data
    CHI Yu-feng, LAI Ri-wen, YU Li-li, ZHANG Ze-jun, SU Yan-qin, YING Xing-liang
    2017, 32 (7):  1193-1203.  doi: 10.11849/zrzyxb.20160730
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    Investigation the distribution of the tree species is significant in the forestry work, and extracting the tree species information from remote sensing images plays an important role. Changting County is located in southwest part of Fujian Province, China. The topography in Changting is characterized by mountains and hills. The climate is humid. The mean temperature is 18 ℃, and the annual precipitation is 1 742.8 mm. Forests cover large proportion of the area in Changting County, more than 80%. In this study, multispectral Landsat-8 OLI imagery data obtained on 22 March 2016 were used. Normalized difference vegetation index (NDVI) was used to distinguish the distribution of the vegetations. From December 2015 to February 2016, 550 sample points were detected which contained four different tree species. One hundred points were used to build knowledge based system (KBS), and the rest 450 points were taken to verify the accuracy of the classification. For the KBS, different tree species have different means of spectral threshold values. Half standard deviation of the threshold value of the 100 points was taken to build the initial KBS, and then it was modified by the good result of the classification. Image expansion method was used to classify the forests. The results of the classification were validated with ground verification data, and compared with results derived from expert knowledge classification. The results show that image expansion method combining spectral and spatial characteristics of different tree species improve the classification accuracy. The overall accuracy and Kappa coefficient were 83.01% and 0.77, respectively, increased by 8.25% and 0.11 when compared with expert knowledge classification. The presented study could provide a reference for distinguishing tree species for forestry investigation with Landsat 8 OLI data.
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    Research on Temporal and Spatial Evolutions of Environmental Cost and Total Factor Productivity of Maize Production in China
    WANG Huan, MU Yue-ying, HOU Ling-ling
    2017, 32 (7):  1204-1216.  doi: 10.11849/zrzyxb.20160673
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    This paper focuses on China’s maize production and makes comparison of maize production in different producing districts. The paper divides 20 maize production provinces in China into three production districts, first main producing district, second main producing district and other producing district, based on the production scale and total yield in each province. After calculating the environmental total factor productivity of maize production in each province from 2004 to 2014, including the environment cost of chemical fertilizer, pesticide, machine and electricity, this paper makes comparison among three producing districts. The main results are as follows. Firstly, although the yield per unit area is increasing, the total factor productivity of corn production shows a downward trend, decreasing at the rate of 3.3% per year on average, which is mainly caused by the lack of production capacity exploitation and labor reservation; and maize production in China is still in extensive mode meanwhile it is experiencing a transition to labor-saving and environment-sustainable production. Secondly, the comparison between three producing districts shows that the first main producing district has the advantages in mechanization level, environmental sustainability and environmental total factor productivity and has high yield both in total and per unit area. As this district supplies about 65% of the total maize production in China, maize production in China can maintain at high level in the future. The second main producing district has advantage in maize production foundation and its technical efficiency increases at the rate of 2% on average, thus this district can ensure maize supply security by optimizing management of inputs. The other producing district has advantages in environment-sustainable transition rate and has high yield per unit area, thus it can make supplement of maize supply by applying advanced technology.
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    Resource Research Method
    Improving the Forest Type Mapping Accuracy in Semiarid Mountainous Areas Based on TM Images—Take the West Mountain of Beijing as an Example
    WANG Xiao-xue, SHEN Hui-tao, LIN Tian-miao, JING Feng, LI Xu-yong, KONG Fan-li
    2017, 32 (7):  1217-1228.  doi: 10.11849/zrzyxb.20160159
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    Since forest is an important indicator of global climate change, the way to extract forest changing should be top priority in forest management and utilization. Especially, the extraction of sub-categories of forest vegetation has always been a difficult point in remote sensing image classification. Therefore, it is important to find a suitable method for forest type mapping, especially in regions with diverse climatic conditions and complex terrain. The present study discussed various methods that could be used to improve the accuracy of forest type classification using Landsat Thematic Mapper (TM) imagery data, taking a semiarid mountainous area in Beijing, China as an example. All classification results were compared with confusion matrices and Kappa statistics. The results showed that: 1) The combination of a digital elevation model (DEM), aspect data, TM4 and TM5, and a synthetic band (TM4-TM2) comprised an optimal dataset when using pixel-based classification. 2) Elevation alone could increase the accuracy by 23% in broad-leaved forest, whereas by 4%-5% in coniferous and mixed forest. Meanwhile, aspect alone could increase the accuracy by 21% in broad-leaved forest, whereas by 13% in coniferous forest and 18% in mixed forest, respectively. Aspect can provide more valuable information for forest mapping than elevation. 3) According to the confusion matrices, the accuracy of pixel-based classifications was slightly higher than that of object-based classification. 4) However, the latter seemed to consist with field investigations better. Our findings implied that integrating distributional characteristics of forests in semiarid regions with Landsat TM imagery could improve the accuracy of forest stand mapping at a regional scale.
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    The Comparison of FY-3A/VIRR and TERRA/MODIS Data for Drought Monitoring
    WANG Feng-jie, FENG Wen-lan, Zha xiyangzong, NIU Xiao-jun, LIU Zhi-hong, WANG Yong-qian
    2017, 32 (7):  1229-1239.  doi: 10.11849/zrzyxb.20160745
    Abstract ( )   HTML ( )   PDF (5985KB) ( )   Save
    Drought is the key factor to restrict the development of agriculture and animal husbandry in northern Tibet. Temperature Vegetation Drought Index (TVDI) is one of the commonly used remote sensing methods for monitoring drought, which couples surface temperature (Ts) and vegetation index (VI ). The TERRA/MODIS L1B, MODIS-LST, FY/VIRR L1B and FY/VIRR-LST, at 1 km spatial resolution, are used for the monitoring and analysis. The monitoring period is from 25 July to 4 August 2015. The space of VI-Ts for the whole study area is typically triangular, from which a linear regression analysis is conducted to get the equations of the dry and wet line. TVDI for northern Tibet is extracted. Then, the measured soil moisture data and cumulative total precipitation data in the same period are used to verify the accuracy of TVDI to monitor drought by comparing TVDIE (E represents EVI) and TVDIN (N represents NDVI). The result shows that noise and number of pixels effect monitoring precision, and the precision is better after removing the noise. Small number of fitting pixels will lower their correlation with the equations of the dry and wet line, which affect the accuracy of drought monitoring. There is a significant linear correlation between TVDI and measured soil moisture (P < 0.05), and the coefficients between MODIS-TVDIE, MODIS-TVDIN, FY/VIRR-TVDIE, FY/VIRR-TVDIN and measured soil moisture were 0.611, 0.581, 0.420 and 0.386 respectively. Correlation between MODIS-TVDI and measured soil moisture is higher than that between FY/VIRR-TVDI and measured soil moisture. The correlation between TVDIE and measured soil moisture is also higher than that of TVDIN and measured soil moisture. The coefficients between MODIS-TVDIE, MODIS-TVDIN, FY/VIRR-TVDIE, FY/VIRR-TVDIN and cumulative total precipitation were 0.370, 0.336, 0.275 and 0.171 respectively (P < 0.05). The correlations are consistent with the correlations between TVDI and measured soil moisture. The result suggests that the TVDI based on MODIS and FY/VIRR data are both feasible for drought monitoring in the study area, and TVDIE is better than TVDIN to monitor drought. The monitoring precision of MODIS-TVDI is higher than that of FY/VIRR-TVDI, but FY/VIRR data is also a reliable product for monitoring drought.
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    Comprehensive Discussion
    Responses of Forest Soil Respiration to Human Disturbance
    WANG Hui-lai, LIU Juan, JIANG Pei-kun, ZHOU Guo-mo, LI Yong-fu, WU Jia-sen
    2017, 32 (7):  1240-1255.  doi: 10.11849/zrzyxb.20160667
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    Forest soil is the main source of atmospheric CO2. Human disturbance (fertilization, cutting, burning, undergrowth management and land use change) would react on soil properties and soil micro climate, and thus significantly affect the production and CO2 emission of forest soil. A great deal of research on the influence of human disturbance on forest soil respiration had been accumulated. Human disturbance would stimulate, suppress, or show no effect on soil respiration, depending on forest type, soil conditions, and regional environment and climate factors. In this study, publications relevant to forest soil respiration in bibliographic databases were used. This study briefly described the influence of natural factors (soil temperature, soil moisture) and human disturbances on forest soils respiration, and then systematically explained the response of soil respiration to the human disturbances and associated mechanisms. We pointed out some urgent and key directions in future in order to provide some references and enlightenments for forest management practices under the background of climate change.
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    Review on Soil Cadmium Study and Risk Assessment in Guangxi
    ZHONG Xue-mei, XIA De-shang, SONG Bo, CHEN Tong-bin
    2017, 32 (7):  1256-1270.  doi: 10.11849/zrzyxb.20160689
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    In order to expound the present situation and the potential risk of soil cadmium (Cd) in Guangxi, the paper collected and analyzed literatures about soil Cd in Guangxi which were published in recent 20 years. Based on the uniform criteria, 60 references were selected involving more than 30 areas in Guangxi, 7 090 samples. The paper summarized the distribution of soil Cd content distribution and the situation of soil Cd content exceeding the standard in Guangxi, so as to provide reference for relevant research, environmental policy making and environmental management. Results show that the soil Cd content in Guanxi ranges 0.040-244.1 mg·kg-1, with arithmetic mean and geometric mean 12.23 and 1.884 mg·kg-1, respectively. There were great differences in soil Cd concentration distribution between different functional areas. The average background soil Cd content in the research area is 0.153 mg·kg-1. The geometric mean of Cd content in agricultural soils and urban soils of non-mining areas were 0.467 and 0.320 mg·kg-1, respectively. The geometric mean of Cd content in the soil of mining area and in agricultural soil of mining area were 7.147 and 6.643 mg·kg-1, which were 46.71 and 43.42 times of the background soil Cd content. The majority of farmland soils are maintained at moderate pollution levels. Soils in several counties such as Nandan, Huanjiang, Jinchengjiang and Daxin were greatly affected by the pollution in mining area. There are areas not involved in the collected literatures. We recommend that control measures should be taken in Nandan, Jinchengjiang, Big Huanjiang, Yangshuo and Diaojiang areas, major investigations should be made in Baise Debao, Pingguo, Tiandong and Tianyang aluminum ore producing areas, and monitors on agricultural soil surrounding the mining area should be done.
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