Volume 23, numéro 1, 2012

EN :

Forests are the greatest potential source of energy of any terrestrial biome because of the organic carbon in their biomass, and soils are major sinks for atmospheric carbon. Carbon storage could be enhanced either by increasing forest area (impractical), or by reducing catastrophic losses from wildfire and insects through thinning and other means of fuel reduction. The high energy value and renewability of forest biomass makes it an attractive energy alternative to fossil fuel consumption—particularly if energy harvests can reduce wildfire risk and be sustained without impairing fundamental productivity. Gaining public acceptance for increased biomass removal demands that forest productivity is not degraded, but many of the scientific challenges to increased removal rates rest on simplistic concepts lacking long-term field validation. This paper presents the author’s concept of sustained productivity, issues and problems in assessing it, and the value of coordinated efforts to address the question directly. The International Long-Term Soil Productivity program is described as such an effort, and recommendations are made for sustaining similar long-term studies. Keywords: forest bioenergy, sustained productivity, forest fuels, organic carbon, soil, LTSP. Received 8 November 2010, Revised 3 September 2011, Accepted 4 October 2011.

EN :

Long-term site preparation effects on soil characteristics and Douglas-fir (Pseudotsuga menziesii var. glauca) growth and foliar nutrition were measured over a 24-year period following a ground-based harvest in Northern Idaho, USA. Harvest unit soils were classified as Andisols overlaying metasedimentary parent material within a udic-frigid moisture and temperature regime. Douglas-fir site index at base age 50 was 29 m. Site preparation treatments included undisturbed control, broadcast burn, pile and burn, and mechanical scarification. Periodic soil-site measurements were collected on each treatment at regeneration stand ages 6, 14, and 24 years. Six-and 14-year soil bulk density on scarified treatments were significantly higher at 0-15 and 15-30 cm than all other treatments. At 24 years, scarified soil bulk density at 0-15 and 15-30 cm showed recovery to bulk densities observed in non-scarified soils. Scarified soil organic matter (SOM) and N were significantly reduced by 32% and 42% over control levels 6 years post-harvest. After 24 years, scarified SOM and N were significantly lower than that found in broadcast burn (44% and 54%) and pile and burn (33% and 49%). Douglas-fir needle mass and foliar N and P content on scarified soils were significantly lower than on broadcast burn or pile and burn treatments after 24 years (p<0.1). After 24 years, soil and foliar N content was significantly higher on microsites that received a burn treatment (p<0.1). Tree growth on either burn treatment showed significantly greater diameter (35%), height (14%), and volume (92%) when compared to trees growing on scarified soils after 24 years (p<0.1). These results indicate that tree growth on frigid, ash-mantled forest soils of Northern Idaho, USA, can be significantly reduced following soil compaction and displacement of organic matter and nutrient-rich topsoil. Where soil disturbance was minimized and organic matter retention was coupled with a burn treatment, soil and tree productivity was maintained or enhanced. Keywords: Site preparation, soil disturbance, volcanic ash, Douglas-fir productivity, nutrition. Received 10 October 2010, Revised 6 September 2011, Accepted 15 September 2011.

EN :

Coarse woody debris (CWD) in the boreal ecosystem has been hypothesized to play an important nutritional role following stand-replacing disturbances such as fire or harvest. Sites with shallow soil over bedrock, or those with coarse-textured soils, can be especially susceptible to overstory removal because low carbon and nutrient pools may limit stand productivity in subsequent rotations. On these site types, CWD can provide essential nutrition to the developing second growth stand, prior to internal cycling processes stabilizing at crown closure (15 years to 20 years after stand initiation) through slow and steady decomposition. The current study sites were established in 1994 and in 2008 (14 years following harvesting) and were approaching crown closure. The experimental harvest areas were designed to document carbon loss and nutrient fluxes after the application of four levels of biomass removal from mature black spruce forested stands in northwestern Ontario, Canada. Two soil types (fresh, loamy: dry, sandy), with stand replicates (blocks), were selected to test whether residual CWD represents a source or sink for nutrients, and if the decay pattern varied depending on soil type. Measurement/sampling of CWD was done immediately after the harvest treatments were applied, and again in year 4 and year 14. The biomass removal treatment with the greatest carbon loss and fastest CWD decay rate had the highest initial mass of CWD, indicating possible synergistic decay dynamics. Nitrogen concentration in the CWD continued to increase from the initial measurements to year 14 (from 900 ppm to 2400 ppm), but was largely a function of increasing carbon loss. When converted to N content in CWD (kg ha-1), however, nitrogen exhibited an initial upward trend (i.e., immobilization) through years 1to 4 (from 50 kg ha-1 up to 80 kg ha-1) and a subsequent release in years 5 to 14 (from 80 kg ha-1down to 27 kg ha-1). This trend was more apparent on the dry, sandy sites where N content peaked at almost 100 kg ha-1 at year 4, but then reduced to 26 kg ha-1 by year 14. We compared the average loss of N from CWD in years 4 to 14 (5.3 kg ha-1 yr-1) to the total soil inorganic N pool (based on a fresh K2SO4 extraction), and found that the N loss from CWD represented a substantive portion (80%) of the available N pool, particularly on the dry, sandy sites. After an initial peak in year 4, black spruce foliar N decreased significantly (p<.0001) through to year 10 but began to rebound by year 15. This increase, presumably, was in part the result of the documented release of N from CWD. These results suggest that CWD, although a small contributor to the total N pool, makes a substantial contribution to the relatively small available N pool, especially on dry, sandy soils. The trend of initial N immobilization and subsequent release shows CWD may also serve to buffer the initial leaching of nutrients from the site following harvesting and provide an available source of N to the regenerating stand prior to crown closure. Keywords: coarse woody debris, black spruce, carbon and nitrogen dynamics. Received 23 September 2010, Revised 11 December 2012, Accepted 13 December 2012.

EN :

Sustainable forest management (SFM) is a cornerstone of forest management, whether the resulting forest products are destined for the manufacturing sector or for the emerging bioenergy feedstock market. In British Columbia, research on the environmental effects of forest management has generated scientific knowledge that has informed two linked areas of government responsibility: 1) a comprehensive set of science-based regulations and policies to ensure soil and water conservation, and 2) a monitoring program to ensure the effectiveness of these regulations and policies. An increasing amount of biomass is being harvested from British Columbia’s forests as a feedstock for bioenergy, and these removals have the potential to incrementally increase machine traffic and organic matter removals from forest sites, compared to harvesting operations focused solely on roundwood for timber or pulp. To the extent that existing standards support SFM, they may be sufficient for ensuring that biomass harvesting is also sustainable. Regardless of the new challenges created by intensive harvesting practices, the principles of soil and biodiversity conservation remain the same. The current framework for BC’s SFM policy is reviewed to examine whether it addresses the major sustainability issues that are likely to arise in the province if intensive biomass harvesting becomes more prevalent. We conclude that intensification of biomass removals will require us to keep focused on stand and landscape sensitivity to coarse woody debris removals and biodiversity requirements, nutrient removals, and cumulative soil disturbance. Keywords: regulations, soil conservation, biodiversity, forest biomass harvesting, mountain pine beetle. Received 30 November 2010, Revised 6 June 2011, Accepted 24 August 2011.

EN :

Various biomass sources can potentially be used for biofuel production, and many of these same biomass sources also have other uses. This raises an important question about biomass utilization allocation. We demonstrate an economic principle for biomass allocation by examining the profitability of woody biomass utilization in a simple two-product case. We then develop a mixed-integer programming model for allocating multiple biomass resources in the production of different biofuels and bioproducts. Our model combines biomass utilization allocation with biofuel supply chain optimization. The model is applied to solving the forest biomass utilization allocation problem for East Texas in the southern United States. We find that besides biofuel prices, production scale and CO2 offset credits also significantly affect biomass utilization allocation. Our findings validate our integrative model approach to addressing biomass allocation and provide useful implications for enhancing the efficient utilization of forest biomass. Keywords: forest biomass, biofuel supply chain, greenhouse gas offset, mathematical programming, southern United States. Received 10 October 2010, Revised 20 July 2012, Accepted 24 October 2012.

EN :

The development of bioenergy offers major possibilities for the reduction of greenhouse gas emissions and fossil fuel dependency, but negative impacts can also occur—e.g., the outcome for food production and biodiversity can be negative. This is a dilemma for policy: how to promote bioenergy developments that can substantially reduce greenhouse gas (GHG) emissions and fossil fuel use without jeopardizing other policy objectives. One major activity within IEA Bioenergy Task 30 and its successor Task 43 concerns strategies to integrate expanding bioenergy systems with the existing land use, in order to reduce land use competition and displacement risks, and with the aim of improving land use productivity and reducing negative environmental impacts of the existing land use. This paper presents the outcome of an activity within this topic area: an evaluation tool that is being developed for comparing alternative ways of producing biofuel feedstocks—here applied on selected approaches that combine fuel production with other objectives. The tool, described as a generalized integrative assessment tool, has been used to evaluate several alternative bioenergy development options: (i) an alternative sugarcane expansion scenario for the Cerrado areas in Brazil, (ii) the use of crop or industrial residues for biogas production in the Netherlands, and (iii) an accelerated agricultural growth scenario generating additional food and biofuel feedstocks while conserving biodiversity areas in Ukraine. The results suggest that the tool can be useful for presenting and evaluating multidimensional effects of bioenergy expansion— by listing, analyzing and depicting all dimensions in a clear and comprehensive way. The evaluations of the three cases show that if biofuel feedstock production systems are developed in ways that do not lead to displacement of the prevailing land use, impacts on local food production capacity and biodiversity can be avoided, or at least significantly reduced, compared to a scenario of bioenergy expansion crowding out other land uses. Integrated bioenergy food systems can offer opportunities for both economic and social development. Keywords: biofuels, land use, bioethanol, biogas, Brazil, Netherlands, Ukraine. Received 9 November 2010, Revised 7 December 2012, Accepted 14 December 2012.

EN :

Developed by FPInnovations, FPInterface is an operational-level simulation platform for forest supply activities from the harvest site to the mill gate. The software can model, simulate and optimize forest operations directly from the GIS planning maps. The analysis is done at the block level for a forest management unit and provides the cost and volumes of all products harvested from the selected blocks. The basic platform allows for cost calculations of harvesting, road construction, transport and regeneration. Additional modules are also available for optimizing transport routes, biomass supply flow and cost estimates, operational scheduling and value chain decisions. The software offers a tactical and operational forest planning tool in the context of Canadian forest operations. FPInterface considers all fossil fuel inputs and biomass outputs based on product specifications, harvesting decisions, equipment selection, road network and stand conditions. Therefore, the software offers an opportunity for the development of functionalities for greenhouse gas emissions accounts and carbon budgets for woody feedstock. The main objective of this paper is to describe the calculation of carbon ratio in a module of the FPInterface software. Furthermore, a scenario analysis was conducted, where the usability of the module was demonstrated. The objectives of the analysis were to show the impact of tree size on carbon emissions and to compare different supply chains for biomass in terms of carbon ratios. Keywords: carbon emissions, forest planning, logging operations, biomass, FPInterface. Received 28 September 2010, Revised 21 January 2013, Accepted 27 January 2013.