Changes in Phenological Characteristics of Populus tremuloides in Response to Early Frost

-- Albert Adjesiwor, Michael Flaherty, Ben Butkus, Ariana Potetz

Quaking aspen (Populus tremuloides Michx.) is an important forest tree species in North America. The changing global climate is expected to result in inclement weather conditions such as severe frost. Wyoming is characterized by high summer temperatures and extremely low winter temperatures. A study was conducted to evaluate the response of a young quaking aspen tree to early fall frost. 

Leaf NDVI changes in young aspen from early to late fall 2014

It was observed that frost and cold temperatures (Fig 1) resulted in early leaf senescence and abscission which affected how leaves interact with electromagnetic radiation (EMR). Leaf senescence due to frost resulted in decreased chlorophyll content of leaves and reduced photosynthetic activity. 

This resulted in reduced plant vigor (Fig 2) as measured by the normalized difference vegetation index (NDVI) shown in Figure 1. Remote sensing will be a good tool for assessing how young aspen trees respond to frost damage.