Land surface phenology as a coarse-filter indicator of disturbance and climatic effects across the coast redwood rangeThis article is part of a larger document. View the larger document here.
Satellite-based measurements provide a systematic measure of the seasonal fluctuations and general condition of forest vegetation, including that of the coast redwood region. Year-toyear variation in greenness may be caused by gradual disturbances, successional recovery or climatic variation, while within-year variation reflects disturbance events and the response of vegetation types to seasonal change. Here we show how inter- and intra-year redwood forest vigor is captured by the Normalized Difference Vegetation Index (NDVI) using a MODISbased vegetation change model developed as part of the USDA Forest Service's Threat Assessment Centers' Early Warning System. Results show how the land surface phenology of mature and young forests changed before and after wildfire. Following the 2003 Canoe Fire, the productivity of young forests reversed from being higher to lower than mature forests. The early summer 2008 wildfires in Mendocino County did not cause this reversal, presumably because fire effects in second growth were less severe. The August 2009 Lockheed Fire in Santa Cruz County experienced a sharp drop in second growth productivity, as did the early season 2008 wildfires to the south. As a coarse-filter monitoring tool, this product reflects this variation across vegetation types caused by climate and disturbances for the entire conterminous United States.