Research On Potential Surface Fire Behavior And Carbon Storage Of Major Forest Types In Beijing Xishan Forestry

Forest fires posed a great threat to the forest itself update, and released increasely the global forest carbon. Catastrophic forest fire had also affected the sustainable development of ecosystem. Based on the stand of tending thinning, not only increase forest carbon storage capacity, but also regulate the fuel load of stand, and chang distribution of combustibles. Pinus tabulaeformis, Platycladus orientalis and Robinia pseudoacacia as common tree species in north China, and the fire more easily occurred. So analysis of the forest combustible and formulating the reasonable and effective control measures can effectively reduce the probability of forest fires, and control the high-speed spread of forest fire in order to reduce property loss.We investigated forest fuel in Pinus tabulaeformis, Platycladus orientalis and Robinia pseudoacacia with different thinning intensity in Beijing Xishan experimental forest farm, Set up 24 pieces of 20mx20m sample and concluded that surface fuel load and vertical distribution of forest fuel load in stands. The three types of forest surface fire behavior index were calculated, and fire spread rate, calorific value per unit area, fire intensity and flame length were analyzed. At the same time, above ground carbon of three forest types with different thinning intensity after 8 years were calculated. Results showed:(1) Forest fuel load in vertical distribution within different forest types were different, and fuel load in 0-2 m layer, compared with other levels, were the highest. With the increase of tree height, the fuel load within three forest types was increased, and then decreased. Surface fuel load was decreased obviously after thinning. The lowest under branch height in Robinia pseudoacacia was lower than Pinus tabulaeformis, so the surface fire easily became canopy fire.(2) According to different indicators with different thinning intensity in each stand, the main indicators for the surface fuel load and 1h fuel, 10h fuel, 100h fuel, living herbs, shrubs and moisture content, fire behavior index were estimated by Behaveplus index. Results showed:The earth’s surface fire spread rate and fuel loads had close relation. Under the different fire spread rate conditions, fire intensity was closely related to the flame length. Forest fire behavior indicators in three stands was Platycladus orientalis> Pinus tabulaeformis> Robinia pseudoacacia.(3) Fire behavior index with different thinning intensity in Pinus tabulaeformis was different, and the tendency was L> CK> M>H. Low intensity thinning (L) did not reduce the intensity of fire behavior, instead of increased. But with the augmentation of the thinning intensity, fuel load and fuel load at all levels in stands reduced significantly, and the fire behavior index also lowed, as well as fire intensity and calorific value per unit area achieved below safe value. The tendency for forest fire behavior index with different thinning intensity in Platycladus orientalis and Robinia pseudoacacia were CK> L> M>H. With the increase of thinning intensity, fuel load at every level decreased, and fire behavior indexes reached below safe value.(4) The effects of different thinning intensity on various components of the carbon were significant in Platycladus orientalis, Pinus tabulaeformis and Robinia pseudoacacia, and different thinning intensity had effects on growth index. Although thinning improved individual volume, but stand volume with heavy thinning in three stands were lower than other treatment. In the study of Pinus tabulaeformis and Robinia pseudoacacia, moderate thinning (M) had more helpful for the accumulation of carbon stock, while carbon stock within control stand in Robinia pseudoacacia was higher than thinning treatments.According to forest carbon stock with different thinning intensity in three stands research, carbon stock increment with moderate thinning (M) was largest. Buck average crown breadth augmented after thinning, which effectively promoted the growth of forest tree diameter at breast height, individual volume. This showed moderate thinning (M) was beneficial to the accumulation of stand volume, and to high quality, high yield and high efficiency cultivation of wood. Although high intensity thinning (H) could effectively reduce the probability of forest fire, which retained fewer wood, but it was not conducive to the accumulation of carbon. So when regulating forest fuel load, we can choose moderate thinning (M), which can effectively prevent the occurrence of forest fire, and also achieve the goal for silviculture. Due to the changes of stand spatial structure, we need to further the analysis of the effect of thinning on canopy fire.