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| Extinction characteristics of artificial forest in removal lands in Datong of Qinghai province |
| Liu Sheng,He Kangning,Wang Zhengning,Chang Guoliang,Li Shirong |
| College of Soil and Water Conservation in Beijing Forestry University; Key Lab of Soil and Water Conservation and Combating Desertification,Ministry of Education 100083,Beijing,China |
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Abstract Based on the observed data of net radiation（Rn）'s distribution of typical sunny day in the canopy in artificial forest community which existed after removing lands from cultivation to afforestation and grassland in Datong county from May to July,the extinction characteristics of the communities of Picea crassifolia,Larix principis-rupp rechtii,Hippohae rha mnoides ssp.Sinensis,Betula platyphylla and Populus cathayana were studied.According to Beer Lambert' equation and considering the dynamic variation of the leaf areas index in the growing season of forest,the daily extinction coefficient in different time,daily minimum extinction coefficient and the daily mean extinction coefficient of typical day were studied.Some researches in the variation of leaf areas index and extinction capacity of different canopy depths in different communities were also done.The results showed that the correlation between daily mean extinction coefficient & minimum extinction coefficient and leaf areas index is obvious and equation was simulated.In different canopy depths of all forests,the（cumulative） distribution curves of leaf areas index were S-shape;the extinction capacity above two thirds of the canopy of the Larix principis-rupp rechtii and Picea crassifolia is higher distinctly than he lower,but the variance of Betula platyphylla and Populus cathayana is not obvious.
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Received: 26 June 2005
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