Modelling Aboveground Stand Biomass In Commercial Logs And Harvest Residues

Studying the aboveground stand biomass in commercial logs and harvest residues and paying attention to the distribution of biomass removed from the forest during harvesting operations can not only provide a basis for monitoring the changes of biomass in the forest and estimating the value of forest residues,It can also promote the sustainable development of bioenergy.This paper taken the Australian Pinus radiata plantation as an example,two sets of stand biomass models were constructed.One set was to calculate the stand biomass in two steps.First,a non-linear additive biomass model of total stand,products and residues was established,and then allocative biomass models were constructed to calculate the subdivision of products and residues separately;the other was a non-linear additive biomass model that directly calculated the total biomass and its components of the stand,which performs better,especially in the branch part.The generalized moment estimation method was used to fit the model parameters.The residual variance function and the confidence interval based on the predicted mean curve covering 90% of the observed values were calculated to explain the uncertainty of the model prediction.In order to further explore the rationality of the model form of total amount limitation,this paper compared three model forms: individual component equations were fitted individually,system equations without total limit and system equations with total limit,least squares estimation was used to separately fit component equations,weighted irrelevant regression estimates and generalized moment estimation were fitted system model parameters.The stand biomass models established in this study can provide a good estimate of the forest biomass of Pinus radiata plantations in Australia.