Remotely sensed vegetation phenology of sky islands in the madrean archipelago

The goal of this work is to develop an assessment of changes in landscape scale phenology (Timing of biological events such as green-up and flowering) for vegetation along elevation gradients for mountain sky islands in the drylands of the Southwest US and Northern Mexico. The main goal is to better understand the variability in climate and vegetation green-up relationships as they vary seasonally and interannually and along the elevation and latitudinal gradients. Land surface phenological time series derived from the MODIS Normalized Difference Vegetation Index data from 2000 to 2010 were processed to characterize the interannual and seasonal variability among different sky islands in the Madrean Archipelago. Representative mountains among the sky islands and elevation clines showed unique recurring and interannual phenological trajectories and spatial patterns related to seasonality, drought, and some wildfire events. The start of the season was generally earlier for the higher elevations, while seasonal productivity generally increased with elevation.