Age effect on biomass distribution pattern and optimization of allometric growth equation in Eucalyptus urophylla × E.grandis plantations
[Objective]This study aims to analyze the biomass distribution pattern of Eucalyptus plantations at different ages,so as to provide theoretical basis and data support for accurate assessment of carbon storage and carbon sink in China's Eucalyptus industry.[Method]Eucalyptus urophylla × E.grandis plantation in Leizhou Peninsula was taken as the research object.The whole-plant harvesting method was used to measure the biomass of various organs in 57 trees aged 1,2,3,6 and 10.Using diameter at breast height(DBH),height(H),and diameter at breast height-tree height(D2BHHand DBHH)as independent variables,allometric growth models for organ biomass,aboveground biomass,and total biomass without and with age variables were established,respectively,to screen for the optimal model.[Result]The biomass of different parts of E.urophylla×E.grandis increased with age,but the proportion of each organ to the total biomass varied with age.The proportion of stem biomass increased with age,from 45.21％at 1 year old to 68.25％at 10 years old,whereas the proportion of branch and leaf biomass decreased with forest age,from 19.43％and 16.31％at 1 year old to 10.51％and 2.91％at 10 years old,respectively.The proportion of root biomass first increased from 19.05％at 1 year old to 25.21％at 3 years old,and then gradually decreased to 18.33％at 10 years old.The root to shoot ratio of E.urophylla ×E.grandis ranged from 0.16 to 0.39.In selecting the optimal model for biomass of various organs,the model with DBH as the independent variable(without age variable)had better predictions for root biomass and total biomass than other models.The model with D2BHH plus age as independent variables had the best predictions for leaf biomass and aboveground biomass.The model with DBH,H,and age as independent variables had the best predictions for branch biomass.Regarding the prediction accuracy for stem biomass,there was no significant difference between the prediction models with DBHH and D2BHH plus age as independent variables,and both models could predict stem biomass well.[Conclusion]Forest age has significant impacts on the biomass allocation ratio of various organs in E.urophylla×E.grandis plantations.The prediction accuracy of branch,leaf,and aboveground biomass in E.urophylla×E.grandis plantations significantly improves if forest age is included in the allometric growth model.[Ch,2 fig.4 tab.45 ref.]
Eucalyptus urophylla×E.grandisforest agebiomassdistribution patternallometric growth model
万方数据
维普
