2008年南方特大冰雪冻害对森林损毁的NDVI响应分析——以江西省中部山区林地为例

Response of NDVI to Forest Damages Caused by the Severe Snow and Ice Chaos in the South of China,2008——A Case Study of Mountainous Forest in Central Jiangxi Province

通过对江西省井冈-吉泰-于山样带,在2008年初冰雪冻害中,森林损毁的调查,获得调查样点563个,以及每个样点的NDVI。依据各样点林分起源、林龄、树种和林地折损程度信息,对NDVI进行分类,发现林地NDVI均值与折损程度呈显著的线性相关关系。天然林在无折损程度下,NDVI均值比人工林和次生林高,但随着折损程度增加天然林NDVI均值下降幅度相对较大,人工林NDVI均值下降幅度较小。幼龄林、中龄林和成熟林在无折损程度下NDVI均值差距不大,随着折损程度增加,幼龄林NDVI均值下降幅度最大,其次,为中龄林、成熟林NDVI均值下降幅度最小。针阔混交林、杉木、竹林和湿地松,在无折损时NDVI均值较高,马尾松最低。随着折损程度增加,阔叶林NDVI均值下降速率最快,马尾松、湿地松、杉木和针阔混交林NDVI均值下降速率较快,竹林NDVI均值下降速率较慢,针叶混合林NDVI均值下降速率最慢。

Based on the field investigation of forest damages caused by the Severe Snow and Ice Chaos of early 2008 in Jinggang-Jitai-Yushan Transect,Jiangxi Province, we obtained Geographic and ecologic information of 563 survey points. The day-by-day precipitation and daily average temperature from January to February of 6 meteoro- logical sites in the study area from 2000 to 2008 were selected to analyze the characteristics of the Severe Snow and Ice Chaos of the South of China,2008. Under the influence of the Severe Snow and Ice Chaos,mean NDVI of the research area is 0.57. Of 58.2% of this area, the NDVI is above 0.55, .and of 38.4% of this area, the NDVI is between 0.35 -0.55. The NDVI of forests can keep in a high value by the influence of the Severe Snow and Ice Chaos. With techniques of remote sensing and GIS we classified the NDVI of each survey point by species, stand or- igin, storey age and the degree of breaking. The result shows that the mean NDVI of natural forest is higher than plantation and secondary forest in the degree of none-breaking, but it decreases in a larger range than plantation with increasing of the degree of breaking. The mean NDVI of half mature forest is not higher than young forest and mature forest in the degree of none-breaking; and the mean NDVI of young forest decreases in a larger range than half mature forest and mature forest with increasing of the degree of breaking. Mean NDV! of mixed wood, bamboo, Chinese fir and slash pine are higher than broadleaf forest and masson pine in the degree of none-breaking; and with increasing of the degree of breaking, mean NDVI of broadleaf forest declines very quickly, mean NDVI of mas- son pine, slash pine, Chinese fir, mixed wood decline quickly, and mixed coniferous forest and bamboo decline not so quickly.