Some plant invasions have been mapped with remote sensing, but this
approach has not been applied to invasives under a forest canopy. We used Landsat TM
and ETM+ imagery to distinguish areas of high vs. low cover of Amur honeysuckle
(Lonicera maackii), taking advantage of the early leaf expansion and late leaf retention of
this invasive shrub. L. maackii cover was measured in eight stands and compared to 15
Landsat 5 TM and Landsat 7 ETM+ images from spring and autumn dates from 1999 to
2006. Jeffries-Matusita (JM) Distance calculations showed greater separability between
cover classes (high and low L. maackii) than within density classes on some late fall
images. The Soil Adjusted Atmospheric Resistant Vegetation Index (SARVI2) revealed
higher levels of green biomass in high L. maackii cover plots than low cover plots for
November images only. These findings justify further investigation of the effectiveness
of late fall images to map the historical spread of L. maackii and other forest understory
invasives.
