Will Kessler, M.S. student
Natural Resources

Research Title: Assessment of Remote Sensing as a Tool to Detect Calcium in Northeastern Red Spruce Forests

Advisor: Dr. Barrett Rock

Description of Research

Calcium (Ca) is an important macronutrient in trees, and likely plays a significant role in forests via its influence on stand vigor, regeneration, and net primary productivity (NPP).  There have certainly been leaching and losses of Ca in acidified soils across the Northeastern U.S., and it may be an important limiter of growth and vitality in coniferous species like red spruce (Picea rubens Sarg.).  Many studies have focused on tree physiology and forest ecology in Ca-depleted soils, and some have reported improved tree health in Ca-fertilized areas, such as experimental watershed 1 at the Hubbard Brook Experimental Forest (HBEF) in Thornton, NH.

Recent studies have reported a tight link between tree vigor and total foliar Ca, although the respective importance of different forms of this Ca is not well understood.  There is evidence that membrane regulatory Ca plays an important role in needle tissue function, and a lack thereof may lead to winter needle mortality.  There has also been considerable interest in the precipitation of Ca-oxalate crystals in foliage, observed in connection with factors as varying as soil Ca availability, needle age, atmospheric pollution level, and general tree stress level. 

I plan to explore remote sensing techniques as a tool to map Ca sensitive areas of the northeastern forests.  Remote sensing of foliar reflectance patterns has been applied to questions of forest nutrition and health, at both small, and large scales.  This approach relies on the variation within a needle’s reflectance of energy (i.e. it’s spectrum) to detect physiological differences therein.  I hypothesize that, with successful incorporation of the Ca fertilization into red spruce foliage at HBEF, will come both increased tree vigor, and observable changes in needle reflectance spectra.  By measuring foliar Ca, Ca-oxalate abundance, as well as needle spectra at close and long range in trees from both the amended and reference watersheds, I hope to assess the potential for remote sensing techniques to be used for large-scale questions of Ca biogeochemistry.