Abstract:The result showed that the biomass of five types of forest plantations, i.e. 22-aged Pinus tabulae formis. 24-aged Populus hopeiensis, 17-aged Robinia pseudoacacia, 5-aged P. simonii and 17-aged P. canadensis plantations, was 11. 812 t · ha -1, 16. 540 t · ha-1, 19. 765 t · ha-1 5. 831 t · ha -1 and 124. 882 t · ha-1 respectively, and their net primary productivity (NPP) was0.537t· ha-1 · a -1, 0.689t· ha-1 · a-1. 1.163t· ha-1 · a-1, 1.166t· ha-1 · a-1 and 7. 346 t · ha -1· a-1 respectively; and that the biomass of 20-aged Caragana korshinskii plantation was 8. 241 t · ha-1 with its NPP of 0. 421 t · ha-1 · a-1. The generally lower productivity of various tree and shrub plantations in the region may result from less precipitation, lower field capacity and a serious lack of soil nutrients.