Table of Content

    25 October 2001, Volume 16 Issue 5 Previous Issue    Next Issue
    Special Column:Celebration of the 70th Anniversary of IGSNRR, CAS
    A summary and perspective of forest vegetation impacts on water yield
    LI Wen hua, HE Yong tao, YANG Li yun
    2001, 16 (5):  398-406.  doi: 10.11849/zrzyxb.2001.05.001
    Abstract ( )   PDF (417KB) ( )   Save
     This summary and review dealt with the history of forest hydrology and catchment research. Most results of the catchment experiments showed that forest clearing would increase the water yield but the impacts of the forest vegetation on water yield were complex,which depen ded on many factors such as topography climate, soil catchment area forest type, management and so on. It is impossible to extrapolate the result from one area to another or from one scale to another because there are many differences between them.A developing trend to study are the combination of data from a number of catchments that have different characteristics and the application of new measurring technics and approaches.
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    Progress of the research on the role of the forest during the past 20 years
    SUN Hui nan
    2001, 16 (5):  407-412.  doi: 10.11849/zrzyxb.2001.05.002
    Abstract ( )   PDF (209KB) ( )   Save
     The famous Chinese Geographer Academician HUANG Bing wei published 2 articles on the role of the forest in 1981 and 1982.These 2 articles had not only promoted the discussion on the role of the forest,but also promoted the research work in this field.Until now they still have their effect of the ecological and environmental reconstruction in China,especially in the development of the western regions of China. In China and in the whole world new progress was witnessed in this field during the last 20 years.The progress was reflected in both experimental and theoretical research. The former has provided more accurate and more credible data, while the latter has made a deeper understanding on the role of the forest,especially on hydrology and climate. Nevertheless, there are still a series of problems awaiting to be tackled because of the complexity of the problems themselves and difficulties in carrying out experiments.
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    Statistical analysis about the changes of forest resource and precipitation in China over the past 50 years
    GE Quan sheng, ZHAO Ming cha, ZHANG Xue qin, ZHENG Jing yun, SUN Hui nan, ZHANG Pi yuan
    2001, 16 (5):  413-419.  doi: 10.11849/zrzyxb.2001.05.003
    Abstract ( )   PDF (621KB) ( )   Save
    There exists much dispute about the influence of forest on precipitation.Presently the research is very weak to analyze the influence of afforestation and deforestation on precipitation at large scale.Therefore,changes of forest resources and precipitation in China over the past 50 years are analyzed in order to find the relation between changes of forest resources and precipitation at large scale. The main conclusions are as follows. (a) The percentage of forest coverage has been tending to increase since the foundation of P.R.China(i.e.,1949),which rose from 8.6% in 1948 to 13.9% within 1989 1993, and 16. 55% in 2001.(b) The average precipitation for forestland is 53.4 mm higher than that for non forestland,while the average precipitation variation in forestland is 9% less than that in non forestland,which indicates that the forest has the function of mitigating variation of precipitation.In addition,the precipitation of the whole country, forestland, and non forestland all tends to drop during the past 50 years.(c)For each period of the forest survey implemented since 1949,the statistical analysis discloses that the relationship between changes of percentage of forest coverage and precipitation is insignificant.The percentage of forest coverage in China is increasing obviously,while the annual precipitation is declining.That means the increasing percentage of forest coverage does not result in the increasing of precipitation at large scale,i.e.,there is no significant relationship between the change of forest resources and the precipitation in China.(d)The research about relationship between the change of forest coverage and precipitation is a complex system, and there also exists much uncertainties (e.g.,the inherent problem of statistical data about forest resources, declining of forest quality,etc.),which will affect the result of this research directly and(or) indirectly.Hence,it is indispensable to probe the influence of forest on precipitation by experimental verification and theoretical discussion.
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    Proper assessment for forest hydrological effect
    ZHOU Xiao feng, ZHAO Hui xun, SUN Hui zhen
    2001, 16 (5):  420-426.  doi: 10.11849/zrzyxb.2001.05.004
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     Only by understanding forest hydrological effect accurately and objectively can we get right direction from these principles. This paper proposes using systematic viewpoint to deal with the relationship between forest and water. Comprehensive adjustment function of forest and the relationship between forest and hydrologic cycle are stated and analyzed systematically depen ding on the long term research results of fixed ecological stations throughout China and similar research projects. It raises that in the development of western regions of China, scientific allotment of water resources should be considered in construction of forest grass vegetations and all industrial development should be moderate.
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    Effects of forest on water circle on the Loess Plateau
    LI Yu shan
    2001, 16 (5):  427-432.  doi: 10.11849/zrzyxb.2001.05.005
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     From the research results on soil hydrology, the effects of forest hydrology on the total runoff and the surface water transferred into ground water were analyzed.It was found out that there exits an underlying drying layer of soil underneath forestland at a depth of more than 1 to 3 m from the soil surface.The distribution of the drying layer and causes why it exits are expounded, as related to ecological attributes of the Loess Plateau. It was believed that the drying layer is in great water deficit caused by evapotranspiration,which prevents gravitational infiltration of water and the replenishment of ground water.It is determined that a forestland on the Loess Plateau reduces the total runoff as the results of the increased retention of runoff and of the reduced recharged into ground water.
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    Soil water resources and afforestation in Loess Plateau
    YANG Wen zhi
    2001, 16 (5):  433-438.  doi: 10.11849/zrzyxb.2001.05.006
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     Based on analysis of the inborn condition of soil water resource and soil water cycle and balance in Loess Plateau,soil hydrological efficiency in artificial forest system, soil desiccation—the formation of soil arid layer and the problem of afforestation were discussed in this paper.
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    Impacts of forest vegetation on watershed runoff in dryland areas
    WANG Li xian, ZHANG Zhi qiang
    2001, 16 (5):  439-444.  doi: 10.11849/zrzyxb.2001.05.007
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    :Watershed runoff is impacted by forest vegetation in the ways of runoff generation mechanisms,total amount of stream flow,the temporal variations of annual runoff,and water quality of the runoff.This paper presents the authors and their colleagues research results carried out with this regards in dryland area throughout the world.The analyses show thatalong with the increase of forest coverage,the total annual volume of runoff could be reduced,the peak flow reduced dramatically in small spatial scaleswater quality of runoff improved to great extent.On the basis of research results, it was estimated that the water use for ecological sustainability is up to 16 billion m3 in terms of forestry ecological engineering in dryland area of China.Some future research chanlleges were also proposed in the last section of the paper.
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    A discussion on the application of plant physiological model to the hydro climatic effects of forest
    WANG Tian duo
    2001, 16 (5):  445-450.  doi: 10.11849/zrzyxb.2001.05.008
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     The role which plant physiological simulation can play in the assessment of the effects of forests(and their undergrowth) on hydrology and climates is analyzed.This is an essential practice because of the complexity of forest structure function and the landscape. Forests are parti cularly important in soil conservation on steep slopes but it is at the expense of water supply to downstream areas. Plant physiological models should be used in combination with models of soil and meteorological processes.
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    Hydrological functions of forest vegetation in upper reaches of the Yangtze River
    LIU Shi rong, SUN Peng sen, WANG Jin xi, CHEN Lin wu
    2001, 16 (5):  451-456.  doi: 10.11849/zrzyxb.2001.05.009
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    : The canopy density and the interception rate of Sichuan Miyaluo subalpine forest are in positive correlation,the interception rate reaches 24% when the canopy density is 0.7 and decreases to 9.5% when the canopy density is 0.3(measured during May and July)litter of arrow bamboo fir mixed stand has the maximum water retaining capacity(6.0 mm)and music fir mixed stand has the minimum(2.8mm),because the former has more associated broad leaf trees and shrubs.The maximum soil water holding capacity,maximum litter water holding capacity and maximum moss layer water holding capacity of the primitive fir forest of Minjiang is much greater than that of the other vegetation types such as secondary growth after cutting.The runoff of the well coverd valley is greater than that of wasteland or open forestland.As to different cutting methods,the runoff increment is:clear cutting> selection cutting>no cutting.Compared with other forest types of China,the relative forest evapotranspiration ratio(Evapotranspiration/preci pitation)of the upper reaches of the Yangtze River is relatively low(30~40%)because of the high altitude and the greater amount of precipitation.
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    The effects of forest rehabilitation on microclimate in red earth hilly area of China
    LIU Yun fen, LI Jia yong, CHEN Yong rui, LIN Yao ming
    2001, 16 (5):  457-461.  doi: 10.11849/zrzyxb.2001.05.010
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     This study was conducted at Qianyanzhou Experimental Station of the Chinese Academy of Scienceswhich is located in typical red earth hilly area of southern China.Since the 1980sland use in the area has been transformed from mainly wasteland and farmland into woodland and orchard land.The forest cover rate was increased from 2.06% in 1983 to 78.21% in 1998.With forest rehabilitationthe microclimate has obviously changed.The observation data showed that the through fall and stem flow account for about 90% of the precipitationthe moisture inside of the forest is always higher than that outsidethe temperature and soil temperature in inside of the forest are always lower than that outside.It is evident that forest plays an important role in adjusting the moisture and temperature.
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    Conservation of natural forest and flood control strategies in Northeast China
    TAN Feng wu, WU Jia bing, PEI Tie fan
    2001, 16 (5):  462-466.  doi: 10.11849/zrzyxb.2001.05.011
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     In light with the hydrological function of natural foreststhis paper analyzes the relationship between the reduction of natural forests and flood damage in Northeast China.Based on itstrategies for flood protection are put forward.In additionsuggestions on establishing flood control information systemimproving rainstorm and flood forecast accuracy as well as establishing flood protection insurance and post flood reconstruction system are also identified.
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    Effects of forest on regional precipitation results from some different analyses and their comparisons
    MIN Qing wen, YUAN Jia zu
    2001, 16 (5):  467-473.  doi: 10.11849/zrzyxb.2001.05.012
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     The problem of forest effects on regional precipitation is very complex which has been existing in the fields of forestry ecology, forestry meteorology and forestry hydrology for over one hundred years.Any wrong analytical result will lead to much confusion in ideology and misplay in practice. Therefore, the researches and disputes to the problem are significant in both theory and practice. Viewing from paralleling observations, statistical analysis and simulative modeling used in some typical literatures,the primary and qualitative results were obtained.The results show that there exist big differences between different research methods due to subjectivities in almost every method. The further search should not only be focused on the physical mechanisms of atmospheric boundary but also physiological and ecological characteristics of forests and grass and soil water balance as well.Especially,with the variations in vegetation coverage,water consumption of vegetation,dynamics of soil water,and possible changes of regional water resources should be paid more attention to,which is much more important in regional ecological restoration and construction.
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    The impact of forest change on watershed hydrology ──Discussing some controversies on forest hydrology
    CHEN Jun feng, LI Xiu bin
    2001, 16 (5):  474-480.  doi: 10.11849/zrzyxb.2001.05.013
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     Some controversies on the forest hydrology were analyzed in this article. The controversies focus on(a)Can forests increase rainfall﹖(b)Can forests decrease annual runoff and regulate flows﹖(c)Can forests reduce floods﹖Many evidences and several viewpoints were listed.By the author's point, the effects of forests on precipitation are relatively small forests can reduce annual runoff compared with shorter vegetations and the effects of forest on dry season flow and peak flood mitigation can't be made the last word.The reasons that various and contradictive conclusions exist are due to the limitations of research methodology,the complexity of research object and the difference of region and scale. So, the difference of zonality,scale and species or type of forest should be considered when the effects of forest hydrology be evaluated.
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    Influence of forest cover change on hydrological process and watershed runoff
    SHI Pei li, LI Wen hua
    2001, 16 (5):  481-487.  doi: 10.11849/zrzyxb.2001.05.014
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     Forest cover change plays an important role in regulating water distribution in forest and watershed runoff.Literature review and analysis of the influence of forest cover change on hydrological process and runoff showed that deforestation or forest fire can reduce the capabilities of rainfall interception in canopythroughfall interception and water conservation in litter layer and soil infiltration and water storage.The influence of forest cover change on watershed runoff presented diverse patterns in different regions.Howevera primary conclusion can be reached is that deforestation will reduce forest transpiration and enhance runoff except the Yangtze River showed a contradictory case. With similar effect forest fire will reduce vegetation transpiration and increase watershed runoff.
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    Life cycle analysis of water resources and function response in the process of eco agriculture construction
    LU Bing you
    2001, 16 (5):  488-492.  doi: 10.11849/zrzyxb.2001.05.015
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     A whole life cycle research on water resources utilization is presented in three eco agricultural counties in which good performances have been gained through the implementation of eco agricultural strategy based on a previously severe natural environmentResults show that the progress of the life cycle of water resources usage is influenced by several factors.The development of the process currently features the initiative status in these counties.The integrity of the cycle will improve the ecologicaleconomic and social functions of ecosystems at direct ratio.
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