Background:Stands having advance regeneration of spruce are logical places to start continuous cover forestry(CCF) in fertile and mesic boreal forests.However,the development of advance regeneration is poorly known.Me...Background:Stands having advance regeneration of spruce are logical places to start continuous cover forestry(CCF) in fertile and mesic boreal forests.However,the development of advance regeneration is poorly known.Methods:This study used regression analysis to model the height increment of spruce understorey as a function of seedling height,site characteristics and canopy structure.Results:An admixture of pine and birch in the main canopy improves the height increment of understorey.When the stand basal area is 20 m2ha-1 height increment is twice as fast under pine and birch canopies,as compared to spruce.Height increment of understorey spruce increases with increasing seedling height.Between-stand and within-stand residual variation in the height increment of understorey spruces is high.The increment of 1/6 fastest-growing seedlings is at least 50%greater than the average.Conclusions:The results of this study help forest managers to regulate the density and species composition of the stand,so as to obtain a sufficient height development of the understorey.In pure and almost pure spruce stands,the stand basal area should be low for a good height increment of the understorey.展开更多
In the new year, the trend of worldwide economic regionalism will continue unabated with the contours of an Europe-America-Asia three-region worldclearer than ever before and heightening inter-regional competition. Ye...In the new year, the trend of worldwide economic regionalism will continue unabated with the contours of an Europe-America-Asia three-region worldclearer than ever before and heightening inter-regional competition. Yet the centraltask for the three diverse regions this year will be: how to put their respectivehouses in order. Remarkable progress marked economic cooperation within all the three in-Creasingly diversifying regions in 1993, thus paving the way for further advance展开更多
文摘Background:Stands having advance regeneration of spruce are logical places to start continuous cover forestry(CCF) in fertile and mesic boreal forests.However,the development of advance regeneration is poorly known.Methods:This study used regression analysis to model the height increment of spruce understorey as a function of seedling height,site characteristics and canopy structure.Results:An admixture of pine and birch in the main canopy improves the height increment of understorey.When the stand basal area is 20 m2ha-1 height increment is twice as fast under pine and birch canopies,as compared to spruce.Height increment of understorey spruce increases with increasing seedling height.Between-stand and within-stand residual variation in the height increment of understorey spruces is high.The increment of 1/6 fastest-growing seedlings is at least 50%greater than the average.Conclusions:The results of this study help forest managers to regulate the density and species composition of the stand,so as to obtain a sufficient height development of the understorey.In pure and almost pure spruce stands,the stand basal area should be low for a good height increment of the understorey.
文摘In the new year, the trend of worldwide economic regionalism will continue unabated with the contours of an Europe-America-Asia three-region worldclearer than ever before and heightening inter-regional competition. Yet the centraltask for the three diverse regions this year will be: how to put their respectivehouses in order. Remarkable progress marked economic cooperation within all the three in-Creasingly diversifying regions in 1993, thus paving the way for further advance
