Hans Williams, Stephen F. Austin State University, hwilliams@sfasu.edu (Presenter)
I-Kuai Hung, Arthur Temple College of Forestry and Agriculture, hungi@sfasu.edu
Daniel Unger, Stephen F. Austin State University Arthur Temple College of Forestry and Agriculture, unger@sfasu.edu
Dennis Gravatt, Stephen F. Austin State University, dgravatt@sfasu.edu
Karen Malone , Stephen F. Austin State University, karen_mal@msn.com


This study examined the effectiveness of Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery at a regional scale to determine the start of growing season (green-up) in bottomland hardwood wetlands of east Texas. Fifty percent (0.5) of the normalized difference vegetation index (NDVI) value was set as the threshold for the start of growing season. Spring 2009 and 2010 ground observations of bud burst were compared to corresponding spring MODIS Normalized Difference in Vegetation Index (NDVI) calculations. Bud burst was measured using a zero to three measurement scale. The available MODIS imagery indicated an NDVI measurement greater than the 0.5 threshold year-round. This supports prior wetland studies indicating the growing season occurs year-round in the southern and coastal regions of the United States. Based on the method utilized to select the MODIS satellite images, it was determined the data collected is an accurate reflection of the biological indication of bud-break (the chosen biological activity indicator), but not an accurate assessment of start of growing season for East Texas bottomland hardwood wetlands.