Stem Analysis component:

Regeneration, growth, and productivity in hypermaritime forests of coastal British Columbia is one component of the large interdisciplinary project (The HyP3 Project) aimed at developing guidelines for the sustainable management of the poor- and low-site cedar – hemlock forests that dominate much of the outer coastal landscape.  The purpose of the stem analysis component of the HyP3 trial is to determine the historical tree and stand development patterns of these sites.  While there is much uncertainty surrounding the feasibility and sustainability of harvesting such wet, slow growing forests, it is believed that the potential exists to improve the long term growth rates of commercial timber species on sites.  The natural disturbance pattern of these forested sites is primarily small scale, usually as a result of landslides or windthow.  This means a few individuals or small groups of trees are removed in a particular area but the pattern is repeated over a very large area.

Old landslide track on the north coast.

While individual trees in a stand may vary in age from less than 200 to more than 600 years, the stand as a whole has probably not been disturbed for several thousands of years.  Over this amount of time, the organic layers on the forest floor build up to the point where they act like insulating blankets that impede soil drainage, soil warming, and nutrient availability.  These conditions tend to depress growing conditions for conifers and forest growth essentially stagnates.  It is possible that disturbing these sites through harvesting, combined with some form of site preparation, may improve current growing conditions.

Deep organic material over mineral soil layer.

A total of 38 trees were selected from inside the treatment units at the Oona River operational trial: 25 western redcedar, 6 yellow cedar and 7 lodgepole pine.  Sample disks were cut at 0.7, 1.3, and 2.0 m above the point of germination and at 5 m intervals there after (an interval equivalent to a board length), decreasing to 2 m intervals above 20 m (or a height where the diameter is to small to mill).  A sub-set of trees were sampled entirely at 2 m intervals to collect a more complete data set that can be used to produce detailed growth curves.  All sample disks were air dried for a minimum of 2 weeks prior to any surface preparation.  After drying, the disks were passed through a surface planer to achieve a uniform thickness and produce a clean face for counting and measuring.  Ring counting and measuring was done using a 40X stereo microscope connected to a high resolution, colour video camera in combination with a Calcomp digitizing pad.  The system is capable of detecting and measuring rings at a resolution of 0.0025mm and all information is automatically recorded in a digital file.

Sample tree marked for  cutting.

Initial results have reinforced our belief that site enhancement is possible on the lower productivity sites we have examined.  The sample trees collected at Oona River showed that the current stand of redcedar took an average of 36 years to reach breast height (1.3 m) with some trees taking more than 100 years.  The average site index (height at 50 years from breast height) of these redcedar was only 5.1 meters.  When we examined second growth stands of the same site series that had been logged on the north coast, we found that the average length of time to reach breast height was reduced to 6 years and the average site index had increased to 17.6 m.  These values indicate an 83% reduction in the average time required to reach breast height and a 345% increase in the average site index following a man-made disturbance.  None of the second growth stands we sampled had received any form of site treatment which we believe could further improve the growing conditions.  Analysis of the planted seedlings at Oona River over the next 5 - 10 years will add significant information about the early stages of stand development on  these coastal sites.

19 year old redcedar on a logged '01' site near Prince Rupert.