南京冬季典型植被光谱特征分析

Research on Spectral Characteristics of Winter Typical Vegetation in Nanjing

利用FieldSpec4便携式地物光谱仪和ASD积分球,于2014年7月和12月对研究区6种典型植被进行光谱数据采集与处理,分析植被冠层和落叶的光谱特征及其变化规律,同时分析坡度因素、测量方法对植被光谱反射率的影响。结果表明:不同季节常绿植被光谱存在差异,不同植被光谱反射率的季节变化也不同。冬季常绿植被具有相似的光谱特征,但是不同植被类型之间也存在明显的差异。冬季植被冠层光谱呈现出先降低后稳定的特点;植被落叶层光谱由于受叶片色素、含水量、土壤背景等因素的影响,在衰老腐化的过程中并未出现明显的规律性变化。一定坡度范围内,植被光谱反射率随坡度的增大而升高。不同的测量方法获取的植被光谱反射率不同,但是光谱变化规律相同。

At present,the study on spectral characteristics of vegetation at home and abroad is more concentrated in summer or autumn,while this study on winter is relatively rare.In this paper,the Fieldspec4 portable spectrometer and ASD integrating sphere were adopted to collect spectrum data of the 6typical vegetation in July and December,2014.Then canopy and defoliation reflectance of these vegetation were acquired.The spectral characteristics and variations of canopy and defoliation were analyzed,and the effects slope factor and measurement methods having on vegetation spectral reflectance also were investigated.The results indicated that evergreen vegetation had a difference in different seasons and the seasonal changes of different vegetation canopy spectrum were different.Winter evergreen vegetation with similar spectral features,whereas different vegetation had obvious differences.In winter,vegetation canopy spectrum first decreased and then stabilized.Because of being affected by several factors such as leaf pigment content,water content and soil background,vegetation defoliation spectrum didn＇t show apparent regular changes during its senescence period.Within a certain slope range,vegetation spectral reflectance increased with increasing slope.The reflectance of vegetation spectrum by different measurement methods differed,while their variations kept the same.