- Spencer, K. J.
University of Maine Graduate School (Forest Resources)
A trajectory of stem wood productivity over time is a principal factor in determining the optimum ages for harvest as well as estimating rates of carbon sequestration in forests. Mechanisms controlling the age-related productivity decline in trees and the genetic foundation for this process are not well understood. We aimed to establish an analysis pipeline that integrated current whole-plant physiological and genomics paradigms for understanding the molecular basis of age-related productivity decline in red spruce. Our overarching hypothesis is that age-related patterns of productivity are not limited by physiological factors restricting carbon assimilation but by the intrinsic genetic programming associated with demand-side sinks restricting carbon allocation to apical and cambial meristems. Age-related differences in growth sink strength may be an important fundamental process in explaining the age-related changed in tree physiology. We assessed changes in sucrose, a non-structural carbohydrate (NSC) and primary transported sugar in trees, and relative expression levels of putative spruce invertases, an enzyme which irreversibly catabolizes sucrose.