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    20 December 2012, Volume 27 Issue 12 Previous Issue    Next Issue
    Resources Utilization and Management
    Provincial Pattern of China’s Natural Capital Use: A Modification and Application of Ecological Footprint Depth and Size
    FANG Kai, LI Huan-cheng
    2012, 27 (12):  1995-2005.  doi: 10.11849/zrzyxb.2012.12.001
    Abstract ( )   PDF (2208KB) ( )   Save

    Distinguishing and measuring natural capital use is one of the key research priorities for sustainable community. Two modified indictors-regional footprint depth and regional footprint size, as the basis for accounting for depletion of natural capital stocks and appropriation of natural capital flows, respectively, were selected to represent the provincial pattern of China’s natural capital use in 2008. Then cluster analysis was conducted to classify China’s provincial regions (not including Tibet, Hong Kong, Macao and Taiwan due to no data) according to the above attributes. The results are drawn as follows: 1) Obviously there is a geographical complementarity between the depletion of stocks and the appropriation of flows. From the western region to the eastern region, the former (footprint depth) shows an ascending trend from 1.58 in Gansu to 9.48 in Tianjin, while the latter (footprint size) indicates a descending trend from 3.05 hm2 in Inner Mongolia to 0.12 hm2 in Shanghai. 2) Thirty provinces are classified into four patterns, i.e., the natural capital heavily used (one province is involved), the natural capital moderately used (17 provinces are involved), the natural capital slightly used (four provinces are involved), and the stocks relatively slowly depleted (eight provinces are involved). 3) The provincial pattern of natural capital use presents a significant geographical clustering. The eastern and central regions mainly belong to the area of natural capital moderately used, while the northwestern region basically belongs to the area of stocks relatively slowly depleted, and a majority of the southeastern region belongs to the natural capital slightly used. It is indicated that factors leading to provincial pattern of natural capital use are rather complicated, in particular the resources endowment, economic level, land use and industrial allocation. To achieve an optimal allocation of China’s natural capital in the coming decades, it first requires a policy of regional management that builds on the distribution characteristics of natural capital rather than the administrative boundaries.

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    Spatio-temporal Scale Analysis on the Equality of Energy Consumption Carbon Emission Distribution in China
    LU Jun-yu, HUANG Xin-jin, DAI Liang, CHEN Zhi-gang, LI Yue
    2012, 27 (12):  2006-2017.  doi: 10.11849/zrzyxb.2012.12.002
    Abstract ( )   PDF (2339KB) ( )   Save

    In order to make a profound acquaintance of the regional differences and equality of carbon emissions, this article attempted to create Carbon Emission Ecological Pressure Model and Carbon Emission Economic Efficiency Model to calculate the economic and ecological Gini Coefficient of energy consumption carbon emissions from 1996 to 2008 based on the extension of Gini Coefficient original connotation. The results indicated that, from the ecological point of view, the level of inequality decreased gradually which remained at an extremely unequal state. However, from the economic point of view the degree of inequality increased in the earlier period and then declined and the degree remained at a relatively coordinate state. In addition, this article put forward Economy Contributive Coefficient and Ecological Support Coefficient to evaluate equality and reasonability of the carbon emissions in different provinces. Then this paper, through classifying the 30 different provincial regions (not including Tibet, Hong Kong, Macao and Taiwan due to no data) into four categories and analyzing the characteristics of different categories, expected to provide evidence to help the country establish the policy of carbon reduction, promote the capacity to confront with the climate change and pave the way to sustainable development. The category table showed that Guangxi and some other areas not only had relatively higher economic efficiency but also higher carbon ecological capacity; Shanghai and some developed areas had relatively higher economic efficiency but lower ecological carbon capacity while Yunnan and some areas were in the opposite side; Shanxi and some areas not only had relatively lower economic efficiency but also lower carbon ecological capacity.

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    Calculation and Analysis on Indirect Carbon Emissions from Residential Consumption Based on Input-Output Model
    ZHU Qin, PENG Xi-zhe, WU Kai-ya
    2012, 27 (12):  2018-2029.  doi: 10.11849/zrzyxb.2012.12.003
    Abstract ( )   PDF (2503KB) ( )   Save

    In this paper, the indirect carbon emissions from residential consumption in China during 1992-2005 are calculated and analyzed using the input-output model based on the comparable price input-output tables. The empirical results show that the indirect residential carbon emissions in China rose up from 3.3876×108 t C to 6.7940×108 t C with the growth rate of 100%; the indirect residential carbon emission per capita rose up from 289.1 kg C to 519.6 kg C with the growth rate of 79.7%. Both of these growth rates were much lower than that of residential consumption scale, and the ratio of residential emissions to that of the whole national carbon emission tended to fluctuant decline. The proportion of emissions from agriculture and foods dropped considerably, while that from service sector, such as residence, transportation, and information service, rose sharply during this period. The gap of emission scale between urban and rural residents tended to be widened, with the ratio of urban residential emission per capita to the rural ranging from 2.4 to 4.0, even though changes in emission structure of both areas showed some homogenous trend. Compared with developed countries, the indirect carbon emission per capita from residential consumption in China was only 1/14 to that in the USA in the 1990s, as well as 1/5 to 1/2 to that in European countries, showing that the residential emission level in China remains still in fairly low in meeting basic needs, and needs to be improved reasonably. These results imply that it is possible for China in the future that people’s living standard may be improved continuously while carbon emissions may be slowed effectively by upgrading residential consumption structure to adjust industrial structure, as well as to reduce carbon intensity.

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    Adaptation of Tibetan Nomadism to Climate Change in the Source Region of the Yellow River
    BAI Wan-qi, ZHANG Yi-li, LIU Lin-shan, ZHANG Qin-qin, DU Chang-jiang
    2012, 27 (12):  2030-2038.  doi: 10.11849/zrzyxb.2012.12.004
    Abstract ( )   PDF (2356KB) ( )   Save

    Based on family questionnaire, meteorological and statistical data,remote sensing and field survey, a case study of Darlag County in the source region of the Yellow River has been conducted to understand the process of alpine grassland degradation and the behaviors of Tibetan nomads’response and adaptation to climate warming. The results show that there was an increase of 0.29℃/10 a on average in annual temperature during 1956-2009 in Darlag County, which indicated more obvious warming effect than that in the Tibetan Plateau and the whole country. With the impacts of climate warming and grazing, 29.39% grassland degraded between the 1970s and 2000. For dealing with the consequences of grassland degradation, local nomads have taken various adaptive measures in livestock production, such as earlier moving from summer pasture to winter pasture, making fence for pasture, adjusting the amount and structure of livestock, increasing the amount and ratio of livestock for sale, supplementing fodder in winter, planting grasses, etc., and simultaneously changes in lifestyle and ideology have also happened correspondingly. This demonstrates that the Tibetan nomadism essentially possesses the nature and mechanism of adaptation to climate change, and is capable of adjusting production and living to a certain extent actively or passively. Therefore, with adaptive modification Tibetan nomadism will prove to be an important adaptation mode of climate change in the source region of the Yellow River.

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    Resources Security
    Urban Development Security Warning of Jiangsu Province under Water Restriction
    DAI Liang, CHEN Dong-xiang, WU Shao-hua, LI Ru-hai, ZHOU Sheng-lu, CHEN Yi, HUANG Xian-jin
    2012, 27 (12):  2039-2047.  doi: 10.11849/zrzyxb.2012.12.005
    Abstract ( )   PDF (2833KB) ( )   Save

    Urban expansion can’t go on without water resources, as water resources carrying capacity is an crucial factor to urban development. In this article, we put forward a method of calculating urban development degree threshold based on water constraints and urban development security warning. Taken Jiangsu Province for example, we made a research on urban development security warning from aspects of status, trends and effects, and then we made a division of comprehensive early warning partition. The results show that: by 2020, Suzhou, Wuxi, Changzhou and Nanjing will be severe warning area. Xuzhou and Lianyungang will be high warning area and Zhenjiang, Yangzhou, Taizhou and Nantong will be moderate warning area, while Huaian, Yancheng and Suqian will be mild warning area. Through GM(1, 1) model and related equations, we defined and quantified the indexes of urban development degree, development capacity, development critical point, population and temperature changes after development. We aim at simulating the whole process of urban development, reflecting the dynamic of urban development in order to provide scientific basis and theoretic support for government in formulating diverse urban development policies and warning measures.

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    Resources Ecology
    Theory Construction and Its Application to Ecological Environment Compensation Based on Ecological Land Rent
    LONG Kai-sheng, CHEN Li-gen
    2012, 27 (12):  2048-2056.  doi: 10.11849/zrzyxb.2012.12.006
    Abstract ( )   PDF (1218KB) ( )   Save

    Ecological environment compensation is an urgent problem need to be resolved in the field of natural resource and ecological management. As a new idea, ecological land rent has enriched the methodology and theory of ecological environment compensation. Essentially, ecological land rent is excessive profits generated from scarcity of ecological resources, and the profits be used to pay for ecological environment compensation wouldn’t decrease the necessary income of social producers. So, it is a feasible way to perfect the theory and practice of ecological environment compensation based on ecological land rent.
    Taking "resource scarcity-ecological land rent-ecological environment compensation" as logic route, discussing the formation process of ecological land rent I and ecological land rent Ⅱ, and according to allocation of ecological land rent, this paper distinguished ecological environment compensation I related to ecological resource consumption from ecological environment compensation Ⅱ related to improvement of production efficiency. And theoretical framework of ecological environment compensation based on ecological land rent was constructed and new idea of ecological environment compensation was put forward. Then, based on the data of ecological footprint and input-output table, the quantity of ecological environment compensation in per unit economy output of China was counted. The result shows, in China, during 1997 to 2007, the total ecological environment compensation I increased from 2781×108 yuan to 9900×108 yuan, and ecological environment compensation Ⅱ increased from 26318×108 yuan to 68262×108 yuan. This implied the serious condition of ecological environment protection and it is anxious to compensate ecological environment in China. In future, as the consumption of ecological resource increasing, the quantity of ecological environment compensation will increase at the same time. In order to ensure sustainable use of ecological resources, it is necessary to pay enough compensation fund to govern ecological environment and reward contributors of ecological environment protection. Accordingly, ecological environment compensation I will be used to cover scarcity of ecological resources and ecological environment compensation Ⅱ will be used to encourage producers to improve production efficiency and adopt advanced technologies.
    The research of ecological environment compensation from the perspective of ecological land rent provides new ideas to make policies to resolve ecological problem. Finally, this paper suggests some ways to realize ecological environment compensation I and Ⅱ such as to establish ecological tax system, reform price mechanism of resource-based products and perfect incentive system of environment protection and so on.

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    The Regulation of Soil Temperature and Water on Ecosystem Respiration of a Subtropical Plantation under the Seasonal Drought
    ZHANG Shu, SHEN Shuang-he, WEN Xue-fa, ZHANG Xin-yu, SUN Xiao-min, WANG Hui-min
    2012, 27 (12):  2057-2070.  doi: 10.11849/zrzyxb.2012.12.007
    Abstract ( )   PDF (3755KB) ( )   Save

    The carbon balance has been affected by altered precipitation patterns caused by global climate changes. The carbon sequestrated by terrestrial ecosystems returns to the atmosphere mainly through respiration, of which temperature and water are two essential factors in regulating ecosystem respiration (Reco). Seasonal drought caused by the imbalance of heat and rain provides natural experimental conditions to investigate the regulation of temperature and water on ecosystem respiration in the ChinaFLUX Qianyanzhou subtropical plantation. Based on the eddy covariance and conventional meteorological data collected from 2003 to 2010, this study analyzed the response of ecosystem respiration to temperature and soil water content, and explored the effects of temperature or both temperature and soil water content on ecosystem respiration seasonality and annual respiration. The study showed that the seasonal variations of ecosystem respiration were mainly controlled by soil temperature, and Reco was an exponential function of soil temperature. Only under drought condition can soil water content play a significant role in regulation. With only temperature taken into account, the ecosystem respiration rate at the reference temperature (Rref) was significantly affected by soil water content; while with temperature and soil water content taken into account, the ecosystem respiration under reference temperature was not affected by soil water content. There was no evident difference between considering temperature alone and both temperature and soil water content, the ecosystem respiration amount was 1289.4±73.9 g C·m-2·a-1. But the seasonal variations of ecosystem respiration had significant differences between 2003 and 2010 whether a seasonal drought existed or not.

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    Comparison of Water Consumption Characteristics of Three Fast-growing Timber Species Sapling under Different Soil Water Conditions
    HU Hong-ling, ZHANG Jian, HU Ting-xing, CHEN Hong, WU Xiu-hua, PAN Yong-xiang, ZENG Fan-ming
    2012, 27 (12):  2071-2080.  doi: 10.11849/zrzyxb.2012.12.008
    Abstract ( )   PDF (938KB) ( )   Save

    A pot experiment with controlled water supply was performed to analyze and compare the water consumption characteristics of three fast-growing timber species (Eucalyptus grandis, bamboo willow (a hybrid of Salix) and Alnus cremastogyne under three soil water conditions (e.g., the soil water content was controlled at 85%-80%, 55%-50%, and 35%-30% field capacity, respectively). The results are as follows: 1) Under the same weather and soil water condition, the transpiration rate, interval water consumption, diurnal water consumption and total water consumption most presented the trend that E.grandis>bamboo willow>A.cremastogyne. 2) There was no significant difference between E.grandis and bamboo willow in terms of the diurnal water consumption rate (P>0.05), but both were obviously higher than A. cremastogyne. 3) Relatively larger total leaf area and the different drought avoid strategies were the main reasons for E.grandis consuming more water than the remaining two species. 4) The capacity of water consumption of a tree species was closely correlated to its assimilation ability and growth rate. No matter which species, the net photosynthetic rate, total leaf area, height and surface diameter increment all declined with the decrease of water consumption. However, compared with bamboo willow and A.cremastogyne, the assimilation and water consumption ability of E.grandis were more difficult to be affected by drought. 5) We came to the conclusion that E.grandis and bamboo willow are more suitable for the regions which have sufficient precipitation with even annual rainfall distribution, while A.cremastogyne is recommended to be planted in areas which often suffered water-deficient or seasonal drought.

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    Effects of Different Land Use Patterns on Soil Nutrients and Soil Active Organic Carbon Components in Karst Mountain Area
    LIAO Hong-kai, LONG Jian, LI Juan
    2012, 27 (12):  2081-2090.  doi: 10.11849/zrzyxb.2012.12.009
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    Soil nutrients and six active components (microbial biomass C, N, P, basal respiration, easily oxidized organic carbon and dissolved organic carbon) under five typical land use patterns (forest, Chinese prickly ash orchard, pitaya orchard, grassland returning from farmland and dry land ) were measured to discuss soil quality in response to different land use patterns, providing scientific basis for selecting rational land use patterns and rocky desertification control in karst mountain areas. The results showed that the contents of soil nutrient and active component were the highest in forest, where soil organic carbon, microbial biomass C, N, P, easily oxidized organic carbon and dissolved organic carbon contents were 44.80 g·kg-1, 477.86 mg·kg-1, 102.87 mg·kg-1, 17.54 mg·kg-1, 7.72 g·kg-1 and 166.43 mg·kg-1, respectively, soil nutrient and active component contents were decreased in the order of Chinese prickly ash orchard, pitaya orchard, grassland returning from farmland and dry land. Except soil nutrient and active component contents in dry land were closer to grassland returning from farmland which had naturally recovered 15 a, mostly below the significant difference level, however, significantly differences in soil nutrient and active component were detected in other land uses. The RAD showed that soil organic carbon is a main impact factor to the active component. The cumulative effect to soil nutrients and active component in Chinese prickly ash orchard was only next to forest, but obviously higher than that in pitaya orchard and dry land. This study clarified that natural repair is a slow process which needs necessary afforestation measures in karst soil, and Chinese prickly ash orchard can be used as a priority vegetation in agricultural production or ecological restoration in karst mountain areas.

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    Resources Evaluation
    Economic Analysis on the Spatial Distribution of Nature Reserves in China
    WU Jian, LIU Hao
    2012, 27 (12):  2091-2101.  doi: 10.11849/zrzyxb.2012.12.010
    Abstract ( )   PDF (6444KB) ( )   Save

    By using China’s Nature Reserve Inventory Data of 2008, with spatial analysis tools, this paper reveals the characteristics of the spatial distribution of nature reserves in China and analyzes the relevant socio-economic conditions, especially opportunity cost and financial situation. It finds out that the existing spatial distribution is the reasonable choice of local government under current economic and institutional context, which implies that opportunity cost has a key impact on the designation of nature reserves. The failure of nature reserve management has been rooted with current financial mechanism, especially for national nature reserves. The poor financial situation of the local governments in counties, where national nature reserves are mostly located, could drive the local governments to deal with failure. These conclusions remind us that an integration of nature conservation and local socio-economic conditions is very crucial in forming an effective conservation system, and reforming the current financial mechanism is a must-to-do to remove the institutional root of conservation management failure.

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    Changing Properties, Causes and Impacts of Extreme Stream Flow under the Changing Environment in Beijiang River, China
    YE Chang-qing, CHEN Xiao-hong, ZHANG Jia-ming, ZHANG Li-juan
    2012, 27 (12):  2102-2112.  doi: 10.11849/zrzyxb.2012.12.011
    Abstract ( )   PDF (2299KB) ( )   Save

    We analyzed the statistical properties of hydrologic extreme flow for hydrologic stations of Lishi and Shijiao in Beijiang River using eight probability distribution functions. Estimate of parameters was performed using the maximum likelihood technique. Goodness-of-fit was done based on K-S, A-D, ABS and AIC for the optimal linear frequency distribution before and after environmental change. And the rules and effects of variability for hydrologic extreme flow was discussed. The research results indicate that based on vegetation reduction in the basin, annual maximum flow increased significantly in 1991, the hydrological conditions varied. Heavy tail distribution at Lishi and light tail distribution at Shijiao were found to be the best fitting model. The optimal linear frequency distribution maintain consistency before and after environment change, but the impacts on fitting curve of flood series showed an overall performance as upper tail from "gentle" to"steep", and the designed flood magnitude will become larger. After changes in the hydrological regime, the flood return period estimated before the change is often unable to well describe the flood frequency characteristics after environmental changes. Construction of water conservancy projects in the upper reaches is vital to alleviate the pressure of flood on the middle and lower reaches of the river.

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    Coupling Mechanism of Slope-gully Erosion in Typical Black Soil Area of Northeast China
    WANG Wen-juan, ZHANG Shu-wen, FANG Hai-yan
    2012, 27 (12):  2113-2122.  doi: 10.11849/zrzyxb.2012.12.012
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    Black Soil Area of Northeast China is one of the most important marketable grain bases in China, but serious soil loss bring the crucial challenge to the marketable grain production. In this paper, supportad by Remote Sensing and Geographic Information System, taking typical Black Soil Area of Northeast China which is located in the Wuyuer River and Nemoer River basins as study area, based on USLE model and SPOT 5 imagery, the amount of soil erosion on hillslope and gully distribution data in 2005 were obtained respectively. Then the coupling relations between hillslope erosion and gully erosion of different grades, slopes, aspects and so on were analyzed. The results showed that slight erosion and light erosion were the main hillslope eroded area in the study area. Gully erosion was much serious and had a great potential for development. When the slope was below 5°, slope was the key factor causing gully erosion. However, when the slope was above 5°, slope was no more the important factor causing gully erosion. In addition, it showed that the amount of hillslope erosion on sunny slope was higher than shady slope, but for the gully erosion, aspect was not the key factor affecting the formation of gully erosion in Black Soil Area of Northeast China. In areas with an erosion intensity smaller than 2500 t/(km2·a), erosion gully density increased with the amount of hillslope erosion. However, When it is greater than 2500 t/(km2·a), the erosion gully density would be comparatively stable.

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    Spatial and Temporal Trends of Wind Speed on the Loess Plateau during 1957-2009
    MA Qin, ZHANG Xiao-ping, WAN Long, MA Tong-yu, SUN Yan-ping, XU Jin-peng, LEI Yong-nan
    2012, 27 (12):  2123-2134.  doi: 10.11849/zrzyxb.2012.12.013
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    An analysis of spatial and temporal trends of mean wind speed and maximum wind speed during 1957-2009 was performed on the Loess Plateau based on the monthly observed wind speed data at 88 meteorological stations. The cumulative departure analysis, a five-year moving average and the nonparametric methods of Mann-Kendall test, were used for data analysis. Results indicated that:
    1) The annual mean wind speed(1957-2009)was 2.36 m/s on the Loess Plateau, annual mean wind speeds of water erosion region, wind-water erosion crisscross region and wind erosion region were respectively 2.36 m/s, 2.17 m/s and 2.60 m/s,and the mean wind speeds respectively decreased at the rate of -0.0084 m·s-1·a-1, -0.0094 m·s-1·a-1 and -0.0188 m·s-1·a-1,and respectively showed a significant decreasing trend (P<0.001). And on the seasonal scale, the contribution rates of spring and winter for annual wind speed were higher, summer and autumn were lower. For annual mean wind speeds in the three regions, the change point of the decreasing trend was in 1981, and after the 1970s, the wind speed decreased significantly.
    2) The reason why the mean annual wind speed decreased significantly is that the decreasing of the frequency of the daily maximum wind speed with a scale ≥5. The frequency of the gale on the Loess Plateau showed a significant decreasing trend from the 1970s to the 2000s, the magnitude of decrease is the greatest in wind erosion region, by over 10%. By the 2000s, the frequency of gale in most stations on the Loess Plateau is <2%.
    3) In most parts of wind-water erosion crisscross region and the wind erosion region, the number of gale days is more but it is less in the water erosion region and the east of the Loess Plateau. According to the annual mean frequency of gale days in the Loess Plateau, four sub-regions can be divided. They are fewer gale region (<10 d), more gale region (10-50 d), much more gale region (50-100 d) and frequent region (>100 d). Most parts of the Loess Plateau fall into the more gale region, and then fewer gale region and non-freguent region. From the 1970s to the 1990s, most parts of wind erosion region and wind-water erosion crisscross region belong to much more gale region. The Baotou and Zhongning stations belong to more gale region. After the year 2000, most parts of the Loess Plateau turn to the fewer gale region.

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    Analysis of Drought-flood Spatial-temporal Characteristics Based on Standard Precipitation Index in East Region of Gansu in Recent 40 Years
    WANG Yuan-yuan, ZHANG Bo
    2012, 27 (12):  2135-2144.  doi: 10.11849/zrzyxb.2012.12.014
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    The characteristics of drought and flood in east region of Gansu are shown based on monthly precipitation data of 15 meteorological stations from 1971 to 2010 by means of different scales of standard precipitation index, combined with GIS spatial analysis techniques and mathematical statistical theory. The characteristics of drought and flood were quantitatively analyzed and the evolution of the spatial and temporal change of precipitation was illuminated. The results showed that: over the past 40 years, there was a slow decreasing trend of average monthly standard precipitation index (SPI) and an evolution trend of drought was showed in east region of Gansu. Droughts and floods are frequent in the study area from 1971 to 2000, there were seven drought events and five flood events during the 30 years, but frequency of drought and flood was smaller from 2001 to 2010. The weakly increasing trends of spring, summer and winter drought were shown but drought and flood in fall was in a balanced state. There are three types of spatial distribution of precipitation in the area, and were divided into three regions accordingly, i.e., Southeastern (waterlogging area), Northern (arid area) and Midwest (precipitation comfort zone). Meanwhile, seasonal drought and flood differ greatly in spatial distribution, of which Huanxian and Huachi counties in the north are dry generally in summer, autumn and winter, and Jingning in the west tends to be dry in winter, spring and summer; but there are more rainfall in all seasons and easy to form waterlogging in central Xifeng, Zhenyuan and the southern Jingchuan, Chongxin and Huating.

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    Climatic Characteristics of Cold Wave and Its Impact on Agriculture in Southern Xinjiang in Recent 60 Years
    Mansur Sabit
    2012, 27 (12):  2145-2152.  doi: 10.11849/zrzyxb.2012.12.015
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    The cold wave is one of the main natural disasters in Xinjiang. Because of sparse vegetation cover, large temperate difference and strong cold air mass to the south, it is easy to form cold wave. This paper analyzed the spatial distribution, seasonal and annual changes and forming reasons of the cold wave based on the data of cold wave frequency, duration and its impact on cropland, livestock and economic damage encompassing from 1949 to 2008 in five districts in southern Xinjiang. The results showed that: 1)In recent 60 years, the occurrence of cold wave in mountain areas in southern Xinjiang is more frequent than that in plain area, northern part more than southern part, and the magnitude of cold wave induced temperature drop at southern foot hills of the Tianshan Mountains is greater than in the northern mountain area. According to special distribution, the maximum frequency of the cold wave took place in Bayingolin Mongol Autonomous Prefecture, and then in Aksu Prefecture, Kizilsu Kirghiz Autonomous Prefecture and Hotan Prefecture in turns. Kashgar Prefecture is in an intermediate place. 2)In recent 60 years, annual variation of cold wave frequency is pronounced, and it displayed a decreasing trend, especially, since 1999. The cold wave is strong from September to May of the next year, April and May reach the maximum in the one year time. Decreasing of the extreme temperature happens from April to May and from September to October. 3)Although, frequency of cold wave has a decreasing trend under climate change, its damages to the agriculture are enormous. With the expansion of crop area and the development of socio-economy in southern Xinjiang, the cold wave disasters to agriculture have an increasing trend.

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    Resources Research Methods
    Effect of Satellite Temporal Resolution on Land Cover Change Detection
    WANG Zheng-xing, WANG Ya-qin
    2012, 27 (12):  2153-2165.  doi: 10.11849/zrzyxb.2012.12.016
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    Temporal consistency is one of the pre-requisite when two satellite images are used for land cover change detection, since both inter-annual (yearly) and intra-annual (seasonal) changes are quite common for some land covers. Global Land Survey (GLS) images, mainly based on Landsat MSS/TM/ETM+, have been widely used for land cover change detection due to its 40-year global coverage, relatively high quality, 30-80 m spatial resolution, and open policy. However, few works have been conducted to investigate the effect of lower temporal resolution on change detection. There may be two reasons for this oversight: for some applications, land cover change can be detected using classification, which may circumvent the temporal inconsistency problem; for others, the difference resulted from minor temporal change may be regarded as negligible. This paper obtained the actual year and date of GLS Landsat data from Global Land Cover Facility (GLCF) for nominal year (epoch) 1975, 1990, 2000 and 2005, and analyzed date inconsistency effect on change detection using 16-day MODIS-NDVI serials. The investigation showed that real year (year-difference, YD) covered 1975±4, 1990±4.5, 2000±1.5 and 2005±1.5 for epoch 1975, 1990, 2000 and 2005, respectively. And the average date difference (DD) was 47 days, roughly 3 composite periods for 16-day MODIS-NDVI. What do the Landsat YD and DD mean to MODIS-NDVI? For YD, the study in NECT using 2000-2008 MODIS-NDVI showed that, 4 years among 9 years, 7% sparse grasslands have a >7% yearly variance. For DD, when using growth peak (mid-summer) as reference, 16-48 d difference may lead to MODIS-NDVI difference over 0.4 for cropland and grassland, 0.1-0.2 for forest, while <16 d difference will lead to <0.1 MODIS-NDVI difference. However, when using actual MODIS-NDVI date as reference, even a DD <16 d may also lead to MODIS-NDVI difference with seasonal patterns: only 2.93% pixels with a more than 0.1 NDVI difference resulted from DD<16 d during July 12 to August 28, indicating a perfect period for change detection. Yet this number increased to 11.42% during June 10-September 29 (excluding July 12 to August 28), showing a worst period for change detection.
    This study concluded that the difference resulted from minor temporal change can not be regarded as negligible in certain cases, and MODIS-like high temporal data can improve change detection using low temporal Landsat-like data, in three aspects: 1) when there are enough high-spatial and low-temporal resolution images, MODIS-like data serials can be used to choose data with optimal time for change detection; 2) when there are not enough such images and second-best data are used, MODIS-like data serials can be used to estimate resulted NDVI difference; and 3) when change is only quantitative and simple classification fails to detect, high temporal bio-physiological parameters such as MODIS-NDVI can be directly used to change detection.

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