中国南方冰雪灾害对森林可燃物影响的数量化分析--以湖南为例

Quantity Analysis of Forest Fuel Under the Impacts of Snow Damage in South of China—Case Study in Hunan Province

利用遥感数据、地面调查数据及植被分布图,将可燃物分为6种类型:阔叶林、马尾松林、杉木林、混交林、其他针叶林和竹林。通过地面调查和遥感分析对森林受害程度进行分级,根据冰雪前后同期卫星数据NDVI值的差异可以对林木受害程度进行分级,对不同结构层次可燃物增减情况进行分析,根据NDVI变化和地面调查将受害程度分为4级。结果表明:Ⅰ级受害面积400.07万hm2,占总森林面积41.68%,Ⅱ级受害面积403.95万hm2,占总森林面积41.93%,Ⅲ级受害面积100.90万hm2,占总森林面积10.42%,Ⅳ级受害面积57.76万hm2,占总森林面积5.96%。林木受害后主要表现为地表可燃物载量急剧增加,对于不同可燃物、不同受害程度增加的量有很大不同,地表可燃物载量最大增长倍数为32.81倍,最高地表可燃物载量可达142.82t·hm-2。

We used MODIS 1B dataset,ground truth data and plant distribution data to classify the forest fuel into broadleaf forest,masson pine forest,Chinese fir forest,mixed forest,other coniferous forest,and bamboo forest.We classified the damage level of forests based on ground truth and remote sensing analysis,and analyzed the increased or decreased amount of different fuel.We classified the damage level into 4 classes based on the difference of NDVI change before and after the snow damage.The results showed：the area of class Ⅰ was 4.000 7 million hm^2,account for 41.68% of total area,the area of class Ⅱ was 4.039 5 million hm^2,account for 41.93% of total area,class Ⅲ was 1.009 million hm^2,account for 10.42% of total area,and class Ⅳ was 0.5776 million hm^2,account for 5.96% of total area.After the damage the surface fuel loading increased dramatically,and the increased amount was different for various fuel and various damage levels.The maximal increas of times of surface fuel was 32.81 times,and the maximal fuel loading was 142.82 t·hm^-2.