Study On Mechanism Of Fire-preventing Forest Belts Of Schima Superba

In this paper, the author discussed the history and the main content of fire-preventing forest belts of home and abroad. Through the investigation Schima superba forest belt and the neighboring flammable Pinus massomiana and the Cunninghamia lanceolata forests, to the community horizontal and the vertical structure, the fuel loading and the distributing, the forests environment and the microclimate characteristic (s) as well as studying the combustion properties of litter of Schima superba, Pinus massomiana and the Cunninghamia lanceolata with different moisture contents were tested by CONE calorimeter and so on. Comprehensively, systematic researches and main findings of the study were as follows:1 When of Schima superba fire-preventing forest belts started to work? Generalized analysis the growth factors of Schima superba tree high, DBH, crown, height of the lowest branch, obtained the Schima superba start fire protection mature age is 8 years. And proposed the Schima superba fire protection mature age.2 Pair of different types forests community structure and the flammability carry on the cluster analysis resulted in that, the between of Pinus massomiana and the Cunninghamia lanceolata forest community structur and the flammable similarity must compare the Schima superba height of stand.3 The flammability of forests fuel analyses: the difficulty to burn the fuel of Pinus massomiana and the Cunninghamia lanceolata stands are average 65%, but the fuel of Schima superba stand accounted for 90%, the compare flammable and compare difficulty to burn of fuel of Pinus massomiana and the Cunninghamia lanceolata stands were the proportion which the fuel occupies to be higher than Schima superba stand obviously.4 Surfaces litters loading and the moisture content analysis: The litters loading of Pinus massomiana and the Cunninghamia lanceolata were high, and the level distribution assumed the continuous distribution; but Schima superba forest belt then few very many, had the significance difference, moreover the level distribution assumed the intermittent distribution. In the fire protection season, the mature Schima superba growth of leaves and branches, the shade density was generally big, the litters of moisture content compared to the Pinus massomiana and the Cunninghamia lanceolata stands high.5 Litters surely using the CONE calorimeter measurement the flammability:(1)the leaf and the small branch of litters of Schima superba with the different moisture content catches time to ignition (TTI) when the Pinus massomiana and the Cunninghamia lanceolata carried on the comparison with the identical condition under to discover the inflection point, namely along with the moisture content ascension, the Schima superba leaf and the small branch increased quickly compared to the Pinus massomiana and the Cunninghamia lanceolata TTI is bigger than the TTI of Pinus massomiana and the Cunninghamia lanceolata in the humidity 20% about Schima superba leaf and small branch(2)The generalized analysis the heat release rate (HRR), total heat release (THR), ratio pkHRR/TTI of litters of leaf and small branch of Schima superba, Pinus massomiana and the Cunninghamia lanceolata that discovery Schima superba leaf and the small branch was slower than the Pinus massomiana and the Cunninghamia lanceolata HRR speed, THR were few. Indicated the Schima superba compared to the Pinus massomiana and the Cunninghamia lanceolata fire-resistance, being suitable made the fire protection tree seed.6 Through investigation Schima superba forest belt in microclimate factor: The wind speed, the temperature, the humidity and so on, with the neighbor open territory and the Pinus massomiana and the Cunninghamia lanceolata forests microclimate factors carrying on the contrast analysis, obtained in the forest the microclimate was the Schima superba forest belt gets up a protection potency important attribute.