【摘要】 雪灾是森林生态系统的严重生态干扰之一,会严重影响林木生长并降低生态系统功能。利用2000-2011年SPOT NDVI长时间序列影像数据,基于SG滤波函数进行时序重建,采用灾后同期影像的图像阈值法,以常年多灾的云南省2008年雪灾为例,进行雪灾森林植被受损评估。评估结果与全国灾情月报中的云南省雪灾范围基本一致,全省森林雪灾受损面积达12.09%,主要分布在滇西北的迪庆州、怒江州。对森林雪灾受损程度分析表明,全省重度受灾县7个,中度受灾县13个,轻度受灾县45个。对海拔、坡度、坡向、坡位等地形条件的叠加分析表明,海拔3300~4000 m、坡度5~15°、处于东坡或东北坡中坡位的森林植被受损最严重。本研究有助于实现森林雪灾损失的快速评估,对有效规避次生灾害、开展灾后恢复重建规划具有重要意义。更多还原

【Abstract】 Ice storms are one of the severe disruptions to forest ecological systems,causing vegetation loss and reduction of the ecological systems’ functions.For this reason it is vital to assess the damages to forests after ice storms.Using SPOT Normalized Difference Vegetation Index(NDVI) time serial images of Yunnan Province of China during 2000-2011,forest damage caused by ice storms in 2008 was assessed based on image thresholding techniques of post-storm NDVI time series after Savitzky-Golay filtering by TIMESAT software.The damage threshold was determined by the difference of standard deviation between the years with ice storms and those without,which eventually turned out to be 21%.The range of extracted forest damage is almost consistent with the ice storm extent of Yunnan in the national monthly disaster report,therefore the result is reliable.The destroyed vegetation accounted for 12.09% of the total area of forest.Forest within Diqing County and Nujiang County,in northwest Yunnan,suffered the most losses.On the whole,seven counties took the worst hit by the natural adversity,while thirteen were moderately affected and forty five slightly affected.The most severe damage of forest occurred at the elevation of 3300 m to 4000 m,the slope of 5 to 15 degree,the middle slope position and the east or northeast aspect.Even so,it had little to do with slope position because the most of vegetation is located in the middle slope position.In-situ measurement was not employed here to verify the results because of time and money limits,which compromised the overall accuracy.However,with the acceptable precision,the research method can be used as a real-time forest loss assessment,which is of great significance for taking effective measures to avoid secondary impacts and starting the process of recovery.更多还原