The present study was conducted in Shorea robusta (sal), Pinus roxburghii (Chir pine), Tectona grandis (Teak) and Ailanthus excelsa (Ardu) plantations of different ages at different sites in Uttarakhand. Biomass was calculated on the basis of complete tree harvesting method (stratified mean tree technique method). Biomass Expansion Factor (BEF) and root-to-shoot ratio (R) of all these 4 tree species have been calculated and presented in this paper. Sample trees of S. robusta were of 45, 53 and 60 years of age. BEF for all these 3 age series were assessed as 1.3 at 45 years, 1.4 at 53 years and 1.2 at 60 years of age. Similarly, R values were assessed as 0.27, 0.28 and 0.26, respectively, in these 3 age series. BEF and R values assessed for T. grandis (28 years age) as 1.46 and 0.21; and for A. excelsa (39 years age) as 1.23 and 0.23, respectively. BEF for P. roxburghii trees calculated as 2.3 for 13 years age, 1.75 for 20 years, 1.71 for 22 years, 1.5 for 33 years and 1.46 for trees of 45 years of age. Similarly, R values were 0.2 for 13 years, 0.21 for 20 years, 0.12 for 22 years, 0.13 for 33 years and 0.15 for 45 years of age. P. roxburghii sample trees have shown decreasing order of BEF with increasing age, whereas S. robusta has not shown such trend along the chronosequence.