The ultimate object of all evaluation activity in forests is to calculate or estimate the quantity of wood containing in trees and consequently in the crop not only for sale but also for research,predicting future yields,estimating increment to assess return on capital.Therefore,for this study,total volume equations are developed for Dahurian larch(Larix gmelinii Rupr),White birch(Betula platyfylla),Scot pine(Pinus sylvestris var.mongolica),and Poplar(Populus davidiana Dode)in Northeast China.The equations were based on a simple power function and were adapted to the local volumes of the Eastern Daxing’an Mountains for Northeast China.Ten sub-regions(Xilinji(XLJ),Tuqiang(TQ),Amuer(AME),Huzhong(HZ),Xinlin(XL),Tahe(TH),Shibazhan(SBZ),Hanjiayuan(HJY),Songling(SL),Jiagedaqi(JGDQ)included in three regions(Region 1:NWYLHLM,Ragion2:SAYLHLM,Region3:NDXAM)were identified and the volume equations were tested to determine if the differences by ecoregion were statistically significant using the nonlinear extra sum of squares method.Results varied by species,volume type,and ecoregion.These results suggest that:for Dahurian larch,there are significant differences between the three geographic regions and between the sub-regions,depending on local climatic,soil,and ecological conditions.This also implies that regional volume models are not suitable for predicting tree volume at the sub-regional level.Furthermore,using a sub-regional model specific to other sub-regions would result in significant bias in the prediction of total tree volume;the relationship between tree volume and tree diameter of the white birch is not significantly different between the three geographic regions for many sub-regions.The average bias prediction error varied from-4.4%to 9.5%in SL,from-1.9%to 10.5%in JGDQ,from-3.4%to 9.9%in XL,from-0.2%to 11.5%in TH,from-3.8%to 10.3%in HZ,from-2.9%to 9.5%in SBZ and from 13.2%in HJY,from-5.8%to 6.9%in XLJ,from-14.8%in TQ and from-4.2%to 10.1%in AME,and from-1.2%to 7.5%in XL,from-0.8%to 11.7%in TH,from-13.9%to 0.08%in HZ,from-3.5%to 10.3%in SBZ,from-8.9%to 0.9%in HJY,from-2.5%to 10.4%in XLJ,from-11.6%to 9.4%in TQ and from-11.7%to 1.5%in AME for Scot pine.The results varied by species,volume,and ecoregion,which also suggests that the relationship between tree volume and tree diameter of Poplar tree species is significantly different between the two geographic regions within sub-regions(XL against HZ and HZ against SBZ),and no significant difference between sub-regions(XL against TH,XL against SBZ,XL against AME,TH against HZ,TH against SBZ,TH against AME,HZ versus AME,SBZ versus AME)and this because of factors such as soil conditions including local climate,soil,and environment.However,the ecoregion-based volume equations developed in this study could provide more accurate information on tree growth and forest ecosystem development in these three regions to forest managers and planners.This implies that provincial and regional models of volume-diameter relationships are not suitable for predicting trees volume and height at the ecoregional level.The use of a specific ecoregional model will result in a significant bias in the prediction of the total volume of trees.The ecoregion-based volume model equations developed in this study may provide more precise information for the development of forest growth and yield models.