Biomass procurement in boreal forests affected by spruce budworm: Effects on regeneration, costs and carbon balance

Biomass procured from forests affected by natural disturbances as a bioenergy source is increasingly considered in the context of climate change mitigation. By comparing clearcuts with and without biomass procurement, we aimed to determine the effects of biomass extraction performed alongside lumber harvesting on regeneration density, number of planting microsites, forest renewal costs, and carbon fluxes, in harvested boreal stands affected by spruce budworm. Results showed that biomass procurement increased regeneration density and number of planting microsites. Reduction of downed woody debris due to biomass procurement lowered site preparation costs by 282.07 CAD•ha-1, equivalent to 14.45 CAD per oven-dry metric tonne (odmt-1) of harvested biomass. Product value from biomass processing had to reach from 13.90–76.84 CAD•odmt-1 to make biomass procurement operations profitable. Since biomass procurement significantly increased stocking and reduced the amount of decaying debris, it also reduced cumulative CO2 emissions relative to scenarios without biomass procurement. However, ensuring forest renewal through site preparation and plantation per se, irrespective of biomass procurement, played a more important role for carbon sequestration and net balance. Integrating biomass harvesting to silviculture could have significant ecological and financial impacts on forest management while supporting mitigation efforts against climate change.

Reforestation policy has constrained options for managing risks on public forests

Strict forest renewal policies in western Canada focus on replicating the stand type that was cut and projecting the growth of young stands forward using simple models based upon past growing conditions. These policies arose from European principles of sustained yield and now limit options for adaptive management at the time of investment in forest renewal of public lands. We assert that such simple and restrictive policies, combined with long-term yield predictions, give a false sense of sustainability in times of increased drought, fires, and insect and disease attacks that accompany climate change. We must undertake comprehensive changes in forest policy that incorporate disturbance in our forest management planning. This is a large task! Options include (i) zoning public forests to vary intensities of management and minimize risk; (ii) changing stand- and forest-level models to increase the diversity of forests regenerated; (iii) widening the sphere of scientific experts that can influence forest policy and risk management; and (iv) reallocating expenditures on forest renewal, protection, and management to minimize negative impacts of disturbance. Such a comprehensive overhaul of forest management will be necessary as the current assumptions of forest sustainability come under further scrutiny by the public and investors.

Partitioning and predicting forage biomass from total aboveground biomass of regenerating tree species using dimensional analyses

Foresters and wildlife biologists use biomass estimates as proxies of habitat structure, productivity, and carrying capacity. Determining biomass, however, is challenging without destructive harvests. We provide a dimensional analysis approach to partition browse biomass (BB) from total aboveground biomass (AGB) of six regenerating hardwoods in the Allegheny forests of Pennsylvania, USA. First, we determined the average diameter of browsed twigs for each species. Then, we created a subset of potential browsable twig and foliage biomass from total AGB in 439 individuals harvested within paired exclosure (fenced) and control (unfenced) plots at 15 sites. We fit species-specific allometric equations to estimate BB and AGB using basal diameter and height as predictors and tested the effects of fencing. Although overall stem height and BB were greater within exclosures, fencing did not significantly affect relationships between either predictor and BB or AGB, thereby enabling general and robust (R2 ≥ 0.80) equations for most species. Our work provides biomass equations for regionally dominant species and size classes that are underrepresented in the literature, yet critical to forest renewal and wildlife. Moreover, by sampling variable sites and levels of browse pressure, reported equations lessen site-specific biases. Finally, our methodology provides a template to generate forage biomass prediction equations for other plant and ungulate species.

Long-term effect of forest renewal on the water regime in the small experimental watershed Červík

The small, fully forested watershed Červík (CE) is situated in the part of the Beskydy Mts called the Zadní hory Mts Since November 1953, water balance has been measured in this place with the goal to find out experimentally the changes of the outflow sums during and after the intensive renewal of the forest with a partly changed wood species composition. The measured data were statistically evaluated by the method of double mass curve. In 1962, the decision was made to divide the watershed area into two separate parts A and B. The research started there in 1966 after a twelve-year long calibration period without timber cutting. The stands in the sub-watershed CE-A were cut down in three times shorter intervals than it is common and were immediately renewed. In the CE-B part, the stands were not tended in order to observe visible differences in the sums of outflow in comparison with those in the CE-A part. The measured data were analysed by double mass curve and revealed only very small differences while influence of the environment appeared to be more significant.

The status of and recent trends in forest sector research in British Columbia

In the decade between 1988 and 1998, expenditures on forest sector research in British Columbia have increased substantially in absolute terms but have fallen in relation to the scale of the province's forestry enterprise. These aggregate trends mask important shifts in funding sources and in the specific fields of research that have been supported. The crown corporation Forest Renewal BC has emerged as the dominant source of support for forestry research, clearly displacing appropriated funds with-in the B.C. Ministry of Forests. As a result of falling stumpage fees and changes in forest policy, this source of support is now declining and the long-term security of the Forest Renewal BC research program is in question. At present, expenditures on forestry research are more or less consistent with expenditures on forestry research in other advanced forested jurisdictions, but the anticipated decline in Forest Renewal BC research support belies this otherwise favourable finding. Expenditures on forest products research in the province have not matched their counterparts elsewhere in the world, and recently have declined precipitously. Forestry – forest conservation, management, products and production processes – is becoming ever more complex. Research activity in the province does not appear adequate to sustain the flow of economic and ecological wealth from forests that British Columbians have always enjoyed and have come to expect.