Responses Of Radial Growth And Biomass Allocation Of Larix Gmelinii To Climate Warming

The global climate change has brought severe challenges to the terrestrial ecosystem,and the forest in northern China,as one of the northern temperate zones with the most significant climate warming,have also suffered serious impacts.Studying the impact of climate warming on tree growth is of great significance for further exploring the response of forest ecosystems to climate change.The radial growth and biomass allocation of trees are important indicators to measure tree growth.In this paper,we selected Dahurian larch（Larix gmelinii）,the dominant tree species in the Chinese boreal forest as the target tree species.We studied the responses of radical growth and biomass allocation of Dahurian larch to climate warming,providing a theoretical basis for global carbon balance research.In this study,the 8-year-old seedlings of Dahurian larch from four different locations（i.e.,Tahe,Songling,Heihe and Dailing from north to south）were transplanted southward to a common garden at Maoershan forestry research station in Heilongjiang Province to simulate climate warming,the radial growth and biomass allocation of trees in common garden and original sites were measured simultaneously.The results showed that:1.Warming treatment,locations,and their interactions have significant effects on the diameter at breast height（DBH）and diameter at 10 cm from the ground(D₁₀)of Larix gmelinii（P<0.01）.Climate warming significantly promotes the radial growth of trees at Songling and Tahe.DBH,D₁₀,their relative growth rate and relative growth rate of unit warming increased with the increase of warming amplitude.The relative growth rates of DBH in Dailing、Heihe、Songling and Tahe were 7.29%、3.17%、58.62%and 101.49%,and the relative growth rate of unit warming were 4.14%·℃^–1、1.28%·℃^–1、16.11%·℃^–1and 18.79%·℃^–1correspondingly.2.Climate warming also changed the proportion of biomass in different organs of Dahurian larch.Using the diameter at breast height as an independent variable,the allometric growth equations of total biomass and biomass of each component of the tree before and after warming were fitted.The fluctuation range of the correlation coefficient R²was between 0.784and 0.999.Before and after warming treatment,there was a significant difference in the slope of the allometric growth equation between the root and branch biomass of trees and DBH at Tahe site.The proportion of stem biomass increased while the proportions of root and branch biomass decreased under warming treatment for all sites.The proportion of leaf biomass decreased for Tahe site.The reduction of root-shoot ratio increased with the increase of warming degree.Climate warming can affect the radial growth and biomass allocation of Dahurian larch,and this effect varied with the warming degree.