Estimating the effect of gypsy moth defoliation u.pdf

Remote Sensing of Environment 112 (2008) 3983–3990 Contents lists available at ScienceDirect Remote Sensing of Environment j ourna l homepage: www.e lsev ie / locate / rseEstimating the effect of gypsy moth defoliation using MODIS K.M. de Beurs ?, P.A. Townsend University of Wisconsin – Madison, Department of Forest and Wildlife Ecology, 1630 Linden Drive, Madison, WI 53706, United States? Corresponding author. Current address: Virginia P University, Department of Geography, 107 Major William United States. E-mail addresses: kdebeurs@ (K.M. de Beurs), (P.A. Townsend). 0034-4257/$ – see front matter ? 2008 Elsevier Inc. Al doi:10.1016/j.rse.2008.07.008a b s t r a c ta r t i c l e i n f oArticle history: The area of North American Received 28 February 2008 Received in revised form 10 July 2008 Accepted 21 July 2008 Keywords: MODIS NDWI NDVI NDII Insect disturbance Gypsy moth Forestsforests affected by gypsy moth defoliation continues to expand despite efforts to slow the spread. With the increased area of infestation, ecological, environmental and economic concerns about gypsy moth disturbance remain significant, necessitating coordinated, repeatable and comprehensive monitoring of the areas affected. In this study, our primary objective was to estimate the magnitude of defoliation using Moderate Resolution Imaging Spectroradiometer (MODIS) imagery for a gypsy moth outbreak that occurred in the US central Appalachian Mountains in 2000 and 2001. We focused on determining the appropriate spectral MODIS indices and temporal compositing method to best monitor the effects of gypsy moth defoliation. We tested MODIS-based Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Normalized Difference Water Index (NDWI), and two versions of the Normalized Difference Infrared Index (NDIIb6 and NDIIb7, using the channels centered on 1640 nm and 2130 nm respectively) for their capacity to map defoliation as estimated by ground observations. In addition, we