森林火灾的发生和发展与气象条件有着十分密切的关系。森林中的树木和林下地被物一般是可燃物,它的可燃程度决定于含水量的高低。据试验,林下枯枝落叶的含水量大于25％时,火灾不易发生;17—25％不能发生大火灾;10—17％容易发生火灾;小于10％最容易发生火灾。而林木和地被物 The occurrence and development of forest fires have very close relations with meteorological conditions. Forest trees and undergrowths are generally combustible material, its flammability depends on the level of water content. According to the test, when the water content of under-litter branches is more than 25%, the fire is not easy to occur; 17-25% can not have a big fire; 10-17% is easy to have a fire; and less than 10% is most likely to have a fire. And trees and ground cover