Drought and cold stress-induced morphometric changes in tree rings of red spruce

Jagels, Richard; Hornbeck, James; Marden, Susan

Field work was conducted on two sites on Isle au Haut (Head Harbor and Eastern Head). Notes that fog pH on Isle au Haut averaged 3.26 (Min = 2.90). Average age of Red Spruces at Head Harbor were 63 years (36-98) and at Eastern Head were 78 years (46-105). The following is taken (in part) from concluding remarks: 'The initial premise that morphometric analysis master curves would provide unique fingerprints for narrow rings produced during different environmental stimuli proved to be too optimistic. The between-tree variation was too great (particularly in the transition zone between earlywood and latewood) to permit generating meaningful master curves for a particular year, even on a per site basis. In part, this variability reflects genetic heterogeneity but in addition, tree vigor and microstie differences may play important roles. Therefore, the effect of a drought is not manifested uniformly throughout a stand. Even ring width varies considerably within a stand for a particular year, but the mean is an indicator of general stand response. Quantitative analysis of selected parts of the morphometric curves proved useful in delineating stand response. In this study, CAL was the most sensitive to drought and permitted us to distinguish narrow rings produced by drought from those produced by winter stress. For other environmental stresses, different morphometric features might be useful....' /STUDY LOCATIONS:/ /ISLE AU HAUT/Head Harbor/Eastern Head/