ランドサットＴＭデータを用いた森林変化モニタリング指標の検討：スギ林の伐採と成長のモニタリング

Abstract

Twelve Landsat Thematic Mapper (TM) indices were evaluated for their usefulness for monitoring logging and growth in forests. The 12 indices were 5 TM channels (TM2, TM3, TM4, TM5 and TM7), a linear combination of TM2, TM3 and TM7, three normalized indices using TM4 and TM3, TM5 or TM7, and three tasseled cap indices. The second principal component (PC2) was computed for each index using late summer TM images of 1986 and 1992. The usefulness of each index was evaluated by analyzing rlationships between PC2 values and the stand ages of Sugi cedar (Cryptomeria Japonica, D. Don.) by visual interpretation, scattergrams and regression analyses. TM4 and indices using TM4 did not differentiate logging areas from unchanged forests due to spectral changes of TM4 in the course of vegetation growth. Clear cutting areas within 5 years were distinguished from unchanged forests in PC2 of TM3 and TM7. An exponential relationship (γ2>0.8) was found between the stand ages and PC2 of TM3 or TM7 during the early regeneration stage. Changes due to growth could be distinguished for stands with ages up to about 12 years old.