Special Column:Celebration of the 70th Anniversary of IGSNRR, CAS
GE Quan sheng, ZHAO Ming cha, ZHANG Xue qin, ZHENG Jing yun, SUN Hui nan, ZHANG Pi yuan
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.