Canadian Forest Service Publications
Contrasting current and potential productivity and the influence of fire and species composition in the boreal forest: a case study in eastern Canada. 2015. Rapanoela, R.; Raulier, F.; Gauthier, S.; Ouzennou, H.; Saucier, J.-P.; Bergeron, Y. Can. J. For. Res. 45:541-552.
Issued by: Laurentian Forestry Centre
Catalog ID: 35988
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The capacity of a forest stand to produce timber is related to the interactions that exist between its regeneration capacity, physical site characteristics (climate, surficial deposit, drainage), and disturbances. Minimally, to be sustainably managed, a forest needs to be sufficiently productive and able to regenerate after a disturbance so that its productive capacity is maintained or enhanced. To this effect, we evaluated timber productivity over a large area (175 000 km2) covering the latitudinal extent of closed-canopy black spruce (Picea mariana (Mill.) B.S.P) forest. Site index and relative density index were used to identify stands that cannot reach a minimum volume of trees of minimum size over one rotation. A nonparametric method was used to estimate their values for all stands within the study area. This imputation used either physical site attributes alone to assess potential productivity independent of stand history or physical and vegetation site attributes to assess current productivity. The proportion of productive stands was then estimated at the scale of landscapes ranging from 39 to 2491 km2. Physical site factors alone explain 84% of the variability in the percentage of potentially productive stands (78% for currently productive stands); their combination resulted in an abrupt transition in productivity over the study area. However, burn rate alone also explains 63% of variation in the proportion of currently productive stands and 41% of the relative difference between percentages of potentially or currently productive stands. These results have implications for strategic forest management planning at land classification stage, as timber production area is assumed to remain stable through time, whereas it is apparently related to the disturbance rate.
Plain Language Summary
By combining the influence of site characteristics of forest stands (e.g. climate, soil and drainage) with the burn rate, the researchers found an abrupt transition in the proportion of productive stands in the ecological districts of the closed black spruce forest in Northern Quebec. A forest is said to be closed when it mostly comprises stands of 7 or more metres in height and canopy density is higher than 40%.
This study will be used to estimate the capacity of sites to support forest management activities.