Wednesday, August 4, 2010

PS 49-10: A comparison of seasonal post-fire vegetation growth trends in sagebrush systems using MODIS data

Gretchen A. Meier, USGS

Background/Question/Methods

LANDFIRE is a large interagency project designed to provide nationwide spatial data for fire management applications.  As part of the effort, 2000 vintage Landsat data sets were used in conjunction with a large volume of field information to generate detailed vegetation type and structure data sets for the entire United States.  To keep these data sets current and relevant to resource managers, we are developing an approach for updating these products.  The Vegetation Change Tracker (VCT) developed by Huang et al. (2010) was designed to assess change occurring using multitemporal Landsat data (30m resolution).  The VCT easily detects disturbance in forested systems, however it is less effective identifying changes in non-forested systems.  An alternative method for detecting and assessing disturbances in shrub-lands is a time-series analysis of 8-day 250m MODIS data to establish seasonal vegetation growth patterns.  

Results/Conclusions Initial analyses of vegetation indices (NDVI) suggest that disturbed areas show different patterns of recovery and magnitude of change based in part on ages of the stands. Long term, this effort will contribute to a vegetation recovery model that will be useful for updating LANDFIRE vegetation layers in shrub-lands.