Abstract

Growth and yield models in forest management are derived from past observations, assuming implicitly that future growth conditions will be similar. Local observations of apparent changes in site index (SI: defined as the top height at 50 years breast height age) of lodgepole pine in Alberta during the 20th century raise serious questions about validity of this assumption. As part of a joint program on climate change in Alberta by Canadian Forest Service and Laval University, this thesis aims at investigating the impacts from climate change on the site index based on a process-based forest growth model, StandLEAP. Data processing techniques, nonlinear regression and time series analysis are conducted to obtain the necessary models. The research involves the calibration of a climate-sensitive site index model. This model is then used to explain Sl variability between 1901 and 2000 for each plot. A significant SI increment of 4 mm/year appears on average. This change is significant over 100 to 200 years, the time period used to check that the projected cut can be sustained by the forest over the long term. Over this time period, stand SI will change from .4 to .8 m, more than half of a site index class. The results suggest that climate is an important factor affecting lodgepole pine productivity in Alberta, and have implications for future forest management under a warmer climate