Abstracts - Posters

Global Change Stresses in a Northern Hardwood

Roger Cox¹, X. B. Zhu1,C-P A. Bourque, D. J. Allen and P. A. Arp
¹Natural Resources Canada
rcox@nrcan.gc.ca

Global change includes dynamics of both the changing physical and chemical climate in which our forests grow. These stresses or agents of change can act singularly, together, or in tandem and their interactions need to be understood to accurately forecast impacts on productivity, functioning, and composition of our forests. Experiments dealing with global change agents and their interactions will be discussed in view of predisposition of northern hardwoods to climate extremes. Bioclimatic analyses of current and historical declines will also be reviewed and their role in identifying and verifying key agents affecting northern hardwood resources will be discussed. Determination of key agents and their effect thresholds is essential for the mining of climatic data- bases for biologically relevant events that can form the bases of temporal and spatial correlations with observed dieback and declines. An example of this approach with birch decline will be presented in the light that, defined winter thaw-freeze events known to be damaging to yellow birch (Betula alleghaniensis Britt.), had an increasing trend in annual frequency and intensity during the last 30 years. The geographic extent of the most severe thaw-freeze events when compared with the extent of previously observed yellow birch decline, showed a coincidence with 83% and was 55% of the geographic range.

2005-04-06