A study was conducted to determine the characters of soil structure in different water and soil conservation forests in Keshan County,northwest of Heilongjiang Province,China.The soil bulk density,the ratio of non-capillary porosity and capillary porosity（NCP/CP）,and the generalized soil structure index（GSSI） were measured for Fraxinus mandshurica,Larix gmelini,Pinus sylvestris var.mongolica,and Picea koraiensis plantations as well as the abandoned land（as control） adjacent to the forests in typical black soil region.Results show that at soil depth of 0–30cm,the soil bulk density of F.mandshurica forest and L.gmelini forest was lower than that of P.sylvestris var.mongolica forest and P.koraiensis forest,with the relative decrease of 8.04%–11.01%.The soil bulk density of L.gmelini forest was significantly different from that of the P.sylvestris var.mongolica forest and P.koraiensis forest.The NCP/CP values of the four types of plantations were all higher（59.75%–128.82% relatively） than that of abandoned land（p〈0.05）,indicating that the soil aeration and permeability under forest were enhanced,especially under L.gmelini forest.GSSI values of the four types of forests were also relatively higher（2.98%–4.36%） than abandoned land（p〈0.05）,indicating that those soil and water conservation forests,especially the F.mandshurica forest and P.koraiensis forest,can promote soil condition to approximate ideal soil structure.The result of this study can provide theoretical basis for scientifically evaluating the effects of vegetation restoration on soil quality in typical black soil region.
