Formation Mechanism of Large-diameter Timber of Chinese Fir
[Objective]This study clarify the relationships between factors including site,initial planting density,stand age,stand density,competition index and large-diameter timber and analyze the formation mechanism of large-diameter timber of Chinese fir in order to provide a theoretical and technical support for the oriented cultivation of large-diameter timber in Chinese fir.[Method]Using the data from the long-term experiment of Weimin state-owned forest farm in Shaowu,Fujian province over 40 years,the effects of site,initial planting density,stand age,stand density,and competition index on the formation of large-diameter timber of Chinese fir were examined.[Result]The outturn and outturn rate of large-diameter tim-ber increased with the increase in the site class.The initial planting density clearly affected the effects of the site on the outturn of large-diameter timber,and low planting density were more favorable to the site ef-fect.The initial planting density had a minimal impact on the outturn and outturn rate of large-diameter tim-ber at site classes of 12 to 16,and the formation age of large-diameter timber was late.The large-diamet-er timber in the stands of 20～22 site classes was much more affected by initial planting density,and the outturn and outturn rate of large-diameter timber increased with the decrease in initial planting density.Low planting densities led to earlier time of producing large-diameter timber.There was a significant interac-tion among the stand age,site index and initial planting density.The outturn and outturn rate of large-dia-meter timber was not significantly affected by site class in the relatively low site index(12～16)or high site index(20～22),but when site index reached or exceeded the 20 site class,the large-diameter timber out-turn would be significantly increased compared with low site classes(12～16).Large-diameter timber was not significantly affected by initial planting density in the ranges(3 333～6 667 trees·hm-2 or 5 000～10000 trees·hm-2).However,initial planting density significantly reduced the outturn and outturn rate of large-diameter timber when compared with the low initial planting density(1 667 trees·hm-2).The key factors af-fecting large-diameter timber were stand age,stand density,stand density index,and site index,and their combined addition contribution rate was 92％.[Conclusion]Some stands in the site class of 14 maybe pro-duce large-diameter timber.The ideal site condition for producing large-diameter timber was more than the site index 16.Planting density should be smaller than 1 667 trees·hm-2,and the large-diameter timber stand can be formed in about 40 years for site class of 16 and 28 years for site classes of 20～22,with an outturn rate of more than 50％and timber outturn of at least 400 m3·hm-2.
Chinese firlarge-diameter timbertimber outturnsiteinitial planting density
万方数据
维普
