Impact of Clostera anachoreta and Micromelalopha troglodyta insect-induced damage on the hyperspectral features of Populus×canadesis cv.‘I-214’

Clostera anachoreta and Micromelalopha troglodyta are the two primary defoliators feeding upon the leaves of Populus×canadesis cv.‘I-214’.The purpose of this investigation is to determine the impact of C.anachoreta and M. troglodyta insect-induced damage on the hyperspectral features of P.×canadesis cv.‘I-214’ and to provide basic data for remote sensing monitoring.The experiment was carried out at the canopy and leaf levels in six-year-old stands at the induced-damage and control plots from May to August in 2003.The hyperspectral reflectance and biochemical and physiological parameters consisting of photosynthetic pigments,nitrogen and relative water content were measured when P.×canadesis cv.‘I-214’ defoliation rate was 48% caused by insect-damage.The raw hyperspectral data,their derivatives,and t test were used.The results showed that the spectral reflectance of P.×canadesis cv.‘I-214’ insect-induced damage by C.anachoreta and M. troglodyta decreased regardless of the leaf or canopy level.There were double red edge peaks.The canopy spectral reflectance had high sensitivity and discrimination in the visible-NIR region.The sensitive ranges included 449.1-466.1 nm,798.6-801.4 nm,and 826.8-833.9 nm.The red edge positions(REP) in canopy and leaf spectral reflectance shifted to blue,and the slope and area of red-edge decreased.The REP of test and CK of the canopy were 719.3 and 725.0 nm,respectively,the REP of the leaves of test and CK were 709.4 and 719.3 nm,respectively.In addition,after P.×canadesis cv.‘I-214’ being damaged by C.anachoreta and M. troglodyta,the leaf area,concentrations of chlorophyll a,b and total chlorophyll,carotenoid,leaf nitrogen content and relative water content all decreased evidently.