Project Code: WELD-01-110
Sponsor:Weldwood of Canada Ltd.

Over the past six years, Weldwood’s Hinton Division has established numerous trials under its Enhanced Forest Management program to address concerns regarding the feasibility and implementation of operational fertilization programs. The objective of this re-measurement program was to facilitate the identification of stand responsiveness and help establish a fertilizer benchmark, ultimately improving the management of the forest resource by improving yield forecasting.

Twelve experimental trials were established and fertilized over a period of two years to investigate the responsiveness of mid- to late-rotation, fire-origin lodgepole pine to nitrogenous fertilizer treatments. The trials were established in late-rotation lodgepole pine stands ranging from 40 to approximately 110 years of age, and involved the application of several fertilizer compositions.

Growth response to fertilizers was variable among the tested lodgepole pine stands. Typical volume response was good, but specific stands expressed very small responses or no response at all to the treatments. For those stands that experienced elevated growth rates due to the application of fertilizers, the 4-year total and merchantable gross increment was approximately 7-8 m3, with a maximum of 14m3. Stands located on sites with poor nutrient status were considerably more responsive than those on medium sites, providing greater consistency and magnitude of periodic increment. Unresponsive stands within the trial were easily recognized by the presence of significant alder and herbaceous communities. The most recent year of the trial produced the greatest incremental radial increment. This may not be the maximum annual increment gain resulting from the treatment. Total duration of elevated growth from fertilizer may be up to 10 years. General linear models developed from several easily measured site and stand attributes are able to account for up to 60% of the variation in the trial stands’ growth response to the fertilizer treatments