PHOENIX HELIX: A FOREST STAND STRUCTURE MODEL FOR INTERPRETING FIELD DATA ON FOREST HEALTH
PD MANION and DH GRIFFIN
State University of New York, College of Environmental Science and Forestry, Syracuse, NY, 12310, USA
Background and objectives
Materials and methods
Results and conclusions
Numbers of trees within diameter classes fit the natural log function, described above, for the total forest and for each of the ten forest types within. Expected relative mortality for trees to grow 2.5 cm for any diameter class of trees in the Adirondack Park was between 19 and 26% depending on the forest type. The actual relative mortality in the sample was generally below expected for trees less than 50 cm. Traditional interpretation of these data might suggest that the forest is unhealthy since there is currently 20% mortality in this forest. Simple interpretation of the data suggests that the forest is healthy because there is less than expected mortality. Analysis based on stand structure, following the law of de Liocourt, suggests that this healthy- looking forest is out of balance, and that some biological or abiotic disturbance will be needed to return the system to equilibrium. Some excess mortality, greater than expected, is readily explained, e.g. excess mortality in large beech is from beech bark disease and excess mortality in mid-size red spruce and balsam fir is from a recent blow down. However, excess mortality in large yellow birch is unexplained. Interpretation of liability factors provides some indication of the nature and abundance of future mortality balancing factors. These observations suggest that assessment of forest health based on the phoenix helix interpretation of forest stand structure provides a realistic foundation for addressing forest health issues.