Comparing autumn senescence from trends in NDVI for two aspen trees in Laramie, WY

--- Erika Alderete, Barbara Jean Bender, Kirk Scheffler, Jennie Schoedel

Aspen trees (Populous tremuloides) are one of the many varieties of deciduous tree that experience visible pigmentation change from green chlorophyll dominant to yellow/red carotene/anthocyanin dominant throughout the fall season.  Although many aspen phenology studies have been done to investigate why and how annual senescence occurs, there is a lack of research detailing how location attributes of different yet nearby trees affect the progression of aspen senescence.

Aspen #1 (clump), Aspen #2 (solo) trees selected for this study

Previous studies range from tracking the timing of pigment changes to identifying other natural stressors contributing to leaf death.  In our experiment we explored the effect of proximity to other aspen trees for autumn senescence and leaf loss.  We chose two aspen trees to collect data from to determine this effect, one in a stand of five trees and another completely isolated from any other aspen trees.

Changes in the NDVI values of the clumped (brown) and solo (blue) aspen trees

Our results indicate that although the onset of dormancy was earlier for the secluded tree, there were in fact no statistically significant differences in senescence timing or rate.