Study On Characteristics Of Plant Communities At Burned Area Of Daxing’ An Mountains

In this study, larix gmelinii forest burned areas were experienced in different fire years, different fire intensities, different forest types and different update modes. The natural regeneration conditions, community structure characteristics, community biodiversity were observed and researched in 2013. The objectives were to demonstrate the trends of larix gmelini forest community vegetation update conditions after forest fire in Daxing’an Mountain.The results showed that:1. Fire disturbance has a promoting effect on the natural regeneration of trees. The number of seedlings was first increase and then decrease with the increase of recovery time. The number of birch seedlings was more than larix gmelinii seedlings in the early stage, but the result reversed with time forward. In the stage of restoration, the age, height, basal diameter and other indicators of birch seedling are in a dominant position in the community. The density of seedling in 3 different forest types burned areas are greater than unburned area and showed a ranking of 2003S-L>2003S-R>2003S-G. The density of seedling in three different update modes in burned areas are greater than unburned area and showed a ranking of 2003S-N>2003S-A>2003S-M.2. The alpha diversity index of community each layer in different restoration stages, different update modes and different types of forest burned areas showed a ranking of herb layer>shrub layer>tree layer.The diversity index of shrub layer and herb layer was first increase and then decrease with the increase of recovery time. The simpson and shannon-wiener index in herb layer in 3 different forest types burned areas are less than unburned area and showed a ranking of 2003S-G>2003S-L>2003S-R, while in the shrub layer are greater than unburned area and showed a ranking of 2003S-G>2003S-R>2003S-L. The simpson and shannon-wiener index in both herb and shrub layers showed a ranking of 2003S-M>2003S-A>2003S-N.3. The total species of community in lightly burned and severely burned forest showed a fluctuating upward trend with time forward. Species of tree and shrub layer change less, while herb layer species was significantly upward trend. After ten years, the species of shrub layer and advantage degree in different update modes and different types of forest burned areas were increased compare with unburned area.