In this study

forest background reflectivity was retrieved based on a four-scale model in Jiagedaqi District

northeastern China by using the bidirectional reflectance distribution function product from moderate resolution imaging spectroradiometer. The seasonal variation of forest canopy Bidirectional Reflectance Distribution Function（ BRDF） and background reflectivity were then observed. The results showed that:（1） in the study area

the characteristics of bidirectional reflectivity of the mixed and coniferous forests are similar. In summer

the BRDF of the broadleaf forest was lower than that in the coniferous forest and the mixed forest in the red band

with the opposite trend in the near-infrared band. The BRDF of different forest types presents obvious seasonal variation

especially in the deciduous forest area.（2） The background reflectivity in the red band was low

ranging from 0 to 0. 1 in the study area. The background reflectivity in near-infrared band was mostly more than 0. 3 with high spatial variation.（3） The trends of the seasonal variation of background reflectance in different forest types were similar. However

the amplitudes of the seasonal variation in different forest types differed: the variation of background reflectance of the broadleaf forest was the largest

especially in the near-infrared band.