利用普通数码相机估测松林叶面积指数与标准误

Leaf area index and standard error of pine forests estimated with common digital camera

叶面积指数(LAI)与叶面积指数标准误(SEL)是植被的重要结构变量,可为森林经营管理、开展病虫害防治检疫工作提供数据参考。针对条件复杂区域LAI与SEL测定仪法应用的限制性,提出利用数码相机拍摄松林林冠图像,经特征指数2G B计算图像叶覆盖度(用Cover表示)与叶覆盖度标准差(用Cover SD表示)两个指标,构建LAI-Cover、SEL-Cover SD关系模型,实现松林LAI与SEL的估测。利用福建省13个县(市)65组数据对该方法进行试验,结果表明:Cover与LAI、Cover SD与SEL均呈极显著正相关关系,可以用CoverLAI3.0955 0.1926e准确估测松林LAI,用SEL 1.1059CoverSD 0.0674估测SEL,两模型的R2分别为0.613 5、0.493 5,估测精度达0.894 6、0.798 5。由此可见,利用普通数码相机估测松林LAI与SEL具有较高的可行性与准确性,可将该方法推广应用。

Both leaf area index（LAI） and standard error（SEL） have been used as important structural variables of vegetation.These variables have been used as reference data in the performance of forest management,pest control and quarantine.Several studies have reported retrieval of LAI but few have retrieved the related SEL,another significant index in sustainable forest management.This study proposed a method for the applications of LAI and SEL measured with testers in complex conditions.In the study,pictures of pine forest canopy were taken with a common digital camera.The pictures were used to calculate two forest indicators — leaf coverage（Cover） and leaf coverage standard deviation（Cover SD） — via 2G B characteristic index.The correlation models of LAI-Cover and SEL-Cover SD were constructed,from which LAI and SEL of the pine forest were estimated.The results showed highly significant positive correlations between leaf coverage and LAI,and then between leaf coverage standard deviation and SEL.The analysis showed that it was possible to accurately estimate the indexes of pine forests from the models 3.095 5 0.192 6e Cover LAI（R2= 0.613 5） for LAI and SEL 1.105 9C over SD 0.067 4（R2 = 0.493 5） for SEL.The estimation accuracy reached 0.894 6 and 0.798 5,respectively.It was therefore highly feasible and accurate to estimate LAI and SEL of pine forests using common digital cameras.This gadget does not require much outside light conditions and is very convenient,especially in restricted measurement conditions.The proposed method was suitable for solving inaccuracy measurement issues and saving manpower and material resources.Thus it was concluded that the method should be given high-profile promotion to facilitate a wide application.