Two methods of pre-harvest inventory were designed and tested on three cutting sites containing a total of 197,500 m3 of wood. These sites were located on flat-ground boreal forest in north-western Quebec, Canada. Both methods studied involved scaling of trees harvested to clear the road path one year (or more) prior to harvest of adjacent cutblocks.
The first method (ROAD) considers the total road right-of-way volume divided by the total road area cleared. The resulting volume per hectare is then multiplied by the total cut-block area scheduled for harvest during the following year to obtain the total estimated cutting volume. The second method (STRATIFIED) also involves scaling of trees cleared from the road. A volume per hectare is calculated for each stretch of road that crosses a single forest stand. This volume per hectare is then multiplied by the remaining area of the same forest stand scheduled for harvest one year later. The sum of all resulting estimated volumes per stand gives the total estimated cutting-volume for all cut-blocks adjacent to the studied road. A third method (MNR) represent the actual existing technique for estimating cutting volume in the province of Quebec. It involves summing the cut volume for all forest stands. The cut volume is estimated by multiplying the area of each stand by its estimated volume per hectare obtained from standard stock tables.
When the resulting total estimated volume per cut-block for all three methods was compared with the actual measured cut-block volume (MEASURED), the analysis showed that MNR volume estimate was 30% higher than MEASURED. However, no significant difference from MEASURED was observed for volume estimates for ROAD and STRATIFIED methods, which respectively estimated cutting volumes 19% and 5% lower than MEASURED.