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This document is a comment on a previous article discussing the regulatory design of the Water Sustainability Act (WSA) in British Columbia, Canada. The comment argues that the WSA's regulatory design took a science-forward approach and considered specific regional factors. It addresses criticisms of the WSA and emphasizes the importance of licensing groundwater use for assessing environmental impacts. The WSA allows for nuanced water management through regulation-making authorities, but challenges remain in implementing the regulations, including Indigenous water rights and government resources. Recommendations for improving the WSA's design include defining sustainability goals, regionalizing regulatory action, and long-term planning. Ongoing resourcing and consideration of Indigenous rights are necessary for the effective implementation of the WSA. [Extracted from the article]

This paper presents an analysis of fisheries and forestry governance in the Canadian provinces surrounding the Gulf of Saint Lawrence. It serves two purposes. The first is to produce a portrait of the trends challenging the hypothesis of a shrinking natural resources economy in these territories, in order to underline both the complexity of the struggles taking place around their ressourcist vocation, and the political tensions shaping the recasting of the extractivist model of development. The second, more theoretical and methodological contribution, is a reflection on the conceptual framework developed here: it aims to show the scope and utility of a combination of (1) a sectoral governance analysis and (2) a territorialized analysis of collective action around resource governance. This combination offers an interesting insight into the struggles and political tensions surrounding the tentative restructuring of the Canadian extractivist model. To do so, we examine the two sectoral trajectories showing signs of indecisiveness and adopt a territorial approach which reveals the numerous and various pressures on territories. A disconnection is thus observed between the sectoral and territorial levels: major frames of reference are gradually opening to encompass social and environmental issues, but this relative opening is not being directly and efficiently translated into practices, despite various innovations and indications of openness in governance processes. This fault line leads us to question the power relationships and power imbalances at work within these governance mechanisms and see how these scenes of struggle provide insights into the ambivalence of the current development trajectory. [ABSTRACT FROM AUTHOR]

The Canadian Fire Weather Index (FWI) is one of the most used tools to forecast forest fire hazard. In this paper, we propose an adaptation of the FWI to take into account the Mediterranean vegetation and climate, to improve FWI performances for areas with these characteristics. In particular, the FWI has been calibrated for two Mediterranean regions (Algarve, Portugal and Peloponnese, Greece) by fitting the experimental data, collected in the field, for the forest fuel moisture content, with the values expected by the application of the original Canadian FWI. Field data were collected during the 2010 and 2011 fire seasons. The satisfactory results obtained by the adaptation of parameters from the original FWI, in spite of the small sample areas and limited time of collection, allowed us to verify the usefulness of the method in describing the fuel moisture dynamics and obtaining indexes closer to the characteristics of the Mediterranean forests considered. The adapted FWI, if further tested and extended to other sample areas, may help in a more detailed and precise application of the FWI index by improving the daily forest fire hazard forecast, to become also a better support for the Civil Protection Agency of Mediterranean countries. [ABSTRACT FROM AUTHOR]

Forests have the potential to be a sink in the global carbon (C) budget and thus play an important role in mitigating climate change. However, large-scale management of forests to their sink potential requires understanding of factors responsible for changes in forest C stocks. In this paper, we quantify the effects of initial forest landscape condition and disturbance rates on landscape-level changes in forest C stocks using predictions for managed forests in Ontario, Canada. Ten-year changes in C stocks in public forests managed for wood fibre production were simulated under four scenarios reflecting the range of volume harvested between 1998 and 2007. Changes in forest C stocks varied across Ontario and with harvest rate, resulting in the forest ranging from being a source of 0.767 tC ha year to a sink of 0.656 tC ha year. Simulation results were used to develop a predictive equation explaining over 93 % of the variation in forest C stocks. Variables included in the equation, in descending order of their effect on changes in forest C stocks, were relative harvest rate, forest growth rate, natural disturbance rate, and initial forest C stocks. A reduced equation, including only the first three variables, explained nearly 89 % of the variation in forest C stocks. The results indicate that short-term changes in C stocks depend on initial forest condition and that there are limits to how much these changes can be manipulated by altering harvest and disturbance rates. [ABSTRACT FROM AUTHOR]

Vast areas of hardwood and mixedwood forests of eastern North America have been high-graded in the past and need silvicultural treatments to increase their value and productivity. To rehabilitate a high-graded temperate mixedwood stand, in Quebec, Canada, we used a split–split-split plot design with three replicates to assess different seed-tree and strip cutting systems, in combination with scarification and planting. The experiment consisted of three regeneration cuts in main plots: 10 seed-trees/ha, 40 seed-trees/ha and a 40-m wide strip clearcut (0 seed-tree/ha) with 60 seed-trees/ha in leave strips, thereby resulting in four levels of tree retention, and all included understory brushing. We applied two types of scarification (patch scarification or disk-trenching) to subplots, two regeneration modes (natural regeneration or planting with white spruce [Picea glauca]) to sub-subplots and two mechanical release treatments (softwood or mixedwood production) to planted sub–sub-subplots. Density of seed-trees did not affect the natural regeneration dynamics after 5 years, but disk-trenching was more efficient for the establishment of yellow birch (Betula alleghaniensis) and sugar maple (Acer saccharum). Few seed-trees of desirable white spruce were present and most died standing, confirming the importance of supplemental planting. Height growth of planted seedlings was 15% higher in the 0 and 10 (26–27 cm/year) than in the 40 and 60 (23 cm/year) seed-trees/ha treatments, and release doubled mean height growth (33.1 vs. 16.6 cm/year). Despite intensive site preparation, pre-established beaked hazel (Corylus cornuta) and mountain maple (Acer spicatum) were present at high densities in the regeneration stratum. Controlling this recalcitrant layer might be the greatest challenge for rehabilitating degraded stands of the mixedwood forest, especially since the use of herbicides is prohibited on Quebec's public lands. [ABSTRACT FROM AUTHOR]

Aerial application of herbicides continues to be a dominant method of vegetation control in Canadian forest management. In this paper, we describe a suite of relatively modern technologies and emphasize their potential for integrated use in optimization of aerial herbicide treatments. The potential is illustrated using several case studies involving fixed-wing applications of glyphosate-based herbicide in the boreal forest region of Ontario, Canada. Results indicate that integration of geographic information systems, differential global positioning, electronic-guidance, on-site meteorological monitoring and remote sensing can be used to effectively plan, enhance application control and provide detailed post-treatment assessment and archival data for herbicide spray programs. SprayAdvisor, a GIS-based decision support system with the capacity to directly integrate all of these elements is briefly described. [ABSTRACT FROM AUTHOR]

The development of cooperation depends on the nature of deliberations among and between local stakeholders and the state as well as the context of deliberations, especially whether larger scale governance helps, hinders or overrides deliberative processes. However, the context of deliberations has not been a focus of past research on deliberation. The paper identifies the key context criteria that influenced deliberation and the development of cooperation in a comparative case study of two forest advisory committees in Ontario, Canada. The study uses cognitive mapping and network analysis techniques to identify key context criteria and concludes with five inferences regarding the influence of context on deliberation and cooperation that have implications for deliberation and decentralization theories. [ABSTRACT FROM AUTHOR]

Recent interest in sustainable forest management planning in the Yukon has coincided with growing public awareness of climate change, providing an opportunity to explore how forestry plans are incorporating climate change. In this paper, the Strategic Forest Management Plans for the Champagne and Aishihik First Nations Traditional Territory (CATT) and the Teslin Tlingit Traditional Territory (TTTT) are examined for evidence of adaptation to climate change. For each plan, management policies and practices that are also recognized as ways to adapt to climate change are identified to provide information on the incremental costs and benefits of additional adaptation efforts. A typology for classifying sustainable forest management plans according to how they address climate change is proposed and applied to the CATT and TTTT plans. This typology, which may be useful to any future retrospective assessments on how successful these or other sustainable forest management plans have been in addressing and managing the risks posed by climate change, consists of a matrix that categorizes plans into one of four types; (1) proactive-direct, (2) proactive-indirect, (3) reactive-direct, and (4) reactive-indirect. Neither of the plans available for the southern Yukon explicitly identifies climate change vulnerabilities and actions that will be taken to reduce those vulnerabilities and manage risks. However, both plans have incorporated some examples of 'best management practices' for sustainable forest management that are also consistent with appropriate climate adaptation responses. Even in a jurisdiction facing rapid ecological changes driven by climate change, where there is a relatively high level of awareness of climate change and its implications, forestry planning processes have yet to grapple directly with the risks that climate change may pose to the ability of forest managers to achieve the stated goals and objectives of sustainable forest management plans. [ABSTRACT FROM AUTHOR]

Determining the feasibility of a large-scale afforestation program is one approach being investigated by the Government of Canada to increase Canada’s potential to sequester carbon from the atmosphere. Large-scale afforestation, however, requires knowledge of where it is suitable to establish and grow trees. Spatial models based on Boolean logic and/or statistical models within a geographic information system may be used for this purpose, but empirical environmental data are often lacking, and the association of these data to land suitability is most often a subjective process. As a solution to this problem, this paper presents a fuzzy-logic modeling approach to assess land suitability for afforestation of hybrid poplar ( Populus spp.) over the Prairie Provinces of Canada. Expert knowledge regarding the selection and magnitudes of environmental variables were integrated into fuzzy rule sets from which estimates of land suitability were generated and presented in map form. The environmental variables selected included growing season precipitation, climate moisture index, growing degree days, and Canada Land Inventory capability for agriculture and elevation. Approximately 150,000 km2, or 28% of the eligible land base within the Prairie Provinces was found to be suitable for afforestation. Accuracy assessments conducted with fuzzy accuracy methods provided a more descriptive assessment of the resulting land suitability map than figures generated from a more conventional Boolean-based accuracy measure. Modeling, mapping and accuracy assessment issues were identified for future extension of this work to map hybrid poplar land suitability over Canada. [ABSTRACT FROM AUTHOR]

This paper describes the emergence of a de-centered and privatized mode of governance in the Canadian forest sector. Using deliberative democratic theory as a descriptive foundation, it explores two key social facts that are arguably central to any historical analysis of this trend. First, increasing cultural pluralism challenges contemporary society to create new institutional arrangements that can incorporate a much larger, and often contested, array of public values into decision-making processes. Second, as management systems become more complex and science-driven, decision makers are finding it increasingly difficult to resolve issues of uncertainty and conflicting scientific evidence. De-centered forms of public participation provide important opportunities for government and industry to overcome these contemporary challenges, but certain side effects are also apparent. From the steering tactics of sponsoring agencies and corporations to the “ghettoizing” of environmental discourses, several implications are discussed. [ABSTRACT FROM AUTHOR]

Although succession may follow multiple pathways in a given environment, the causes of such variation are often elusive. This paper describes how changes in fire interval mediate successional trajectory in conifer-dominated boreal forests of northwestern Canada. Tree densities were measured 5 and 19 years after fire in permanent plots and related to pre-fire vegetation, site and fire characteristics. In stands that were greater than 75 years of age when they burned, recruitment density of conifers was significantly correlated with pre-fire species basal area, supporting the expectation of stand self-replacement as the most common successional pathway in these forests. In contrast, stands that were under 25 years of age at the time of burning had significantly reduced conifer recruitment, but showed no change in recruitment of trembling aspen ( Populus tremuloides). As a result, young-burned stands had a much higher probability of regenerating to deciduous dominance than mature-burned stands, despite the dominance of both groups by spruce ( Picea mariana and Picea glauca) and pine ( Pinus contorta) before the fire. Once initiated, deciduous-dominated stands may be maintained across subsequent fire cycles through mechanisms such as low on-site availability of conifer seed, competition with the aspen canopy, and rapid asexual regeneration of aspen after fire. We suggest that climate-related increases in fire frequency could trigger more frequent shifts from conifer to deciduous-dominated successional trajectories in the future, with consequent effects on multiple ecosystem processes. [ABSTRACT FROM AUTHOR]

Seasonal forest pools (SFPs) are geographically- and hydrologically-isolated ponded wetlands, in that they are topographically isolated from other surface waters. SFPs occur commonly throughout the temperate forests of the eastern United States and adjacent Canada. SFPs are ephemeral in occurrence, typically drying annually. The regular drying of SFPs excludes fish from these habitats, and as a result, they are the preferred breeding habitat of some amphibians, notably ambystomid (‘mole’) salamanders and wood frogs ( Rana sylvatica Le Conte). The pools also support a rich and diverse invertebrate fauna. The duration of the wet phase, or hydroperiod of SFPs, has been repeatedly shown to be the dominant influence on the composition and fitness of the faunal community of the pools. Despite the importance of SFP hydrology, it is a poorly studied subject. This paper reviews the limited state-of-knowledge of seasonal forest pool hydrology and associated basin morphology. The review discusses findings from studies of other isolated ponded wetlands that could be applicable to our understanding of the hydrology of SFPs. [ABSTRACT FROM AUTHOR]

Identifying the scales of variation in forest structures and the underlying processes are fundamental for understanding forest dynamics. Here, we studied these scale-dependencies in forest structure in naturally dynamic boreal forests on two continents. We identified the spatial scales at which forest structures varied, and analyzed how the scales of variation and the underlying drivers differed among the regions and at particular scales. We studied three 2 km × 2 km landscapes in northeastern Finland and two in eastern Canada. We estimated canopy cover in contiguous 0.1-ha cells from aerial photographs and used scale-derivative analysis to identify characteristic scales of variation in the canopy cover data. We analyzed the patterns of variation at these scales using Bayesian scale space analysis. We identified structural variation at three spatial scales in each landscape. Among landscapes, the largest scale of variation showed the greatest variability (20.1–321.4 ha), related to topography, soil variability, and long-term disturbance history. Superimposed on this large-scale variation, forest structure varied at similar scales (1.3–2.8 ha) in all landscapes. This variation correlated with recent disturbances, soil variability, and topographic position. We also detected intense variation at the smallest scale analyzed (0.1 ha, grain of our data), partly driven by recent disturbances. The distinct scales of variation indicated hierarchical structure in the landscapes studied. Except for the large-scale variation, these scales were remarkably similar among the landscapes. This suggests that boreal forests may display characteristic scales of variation that occur somewhat independent of the tree species characteristics or the disturbance regime. [ABSTRACT FROM AUTHOR]

This article presents historic energy profiles in order to understand the changing roles of three critical energy flows in eastern Canadian agroecosystems. The first flow is the societally useful energy that farms produced in crops, animal products, and forest resources. This flow stabilized after colonization and then intensified with the introduction of fossil fuel inputs. The second flow consists of these external inputs, including human labor and the energy embodied in machinery, fuel, and fertilizers. The final flow is the biomass from within the agroecosystem itself. Farmers removed this biomass from their final produce and recycled it as feed for animals, seed for crops, and fencing for livestock management. This article presents evidence on these energy flows from a set of case studies in Northeastern North America. Prince Edward Island (PEI) offers a study of energy transitions in a frontier agroecosystem at the farm, township, county, and the bounded provincial scales. This study uses time points from the 1881, 1931, 1951, and 1996 censuses, as well other statistics. The energy in land produce remained stable during the socio-ecological transition because of the importance of forest products. Results at the sub-county scale demonstrate complementary components within the larger provincial system, and the example of one farm (1877-1892) illustrates specialized energy strategies within the advanced organic regime. After the socio-ecological transition, external inputs remained lower than expected, but together with the steady growth of livestock, they ensured that biomass energy inputs were more productive in the mineral regime than they had been in the organic period. [ABSTRACT FROM AUTHOR]

Development of high-valued products through an integrated biorefinery approach is essential for the revival of the Canadian forest industry. Utilization of tree bark is one such example with considerable potential. The bark of trees contains a reservoir of phytochemicals that could be harnessed as value-added co-products. The objective of this study was to identify, characterize, and seek commercial potential of phytochemicals present in poplar bark. Industrially harvested poplar bark ( Populus tremuloides) was procured from Quebec. Water-soaked poplar bark was subjected to three steam-explosion treatments (treatments 1 to 3) using a steam-explosion reactor. During the experiment, extracts such as air purge, pre-steam purge, cooked purge, and pressed liquid were collected and subjected to compositional analysis. The results showed that the leftover bark residue even after the treatments was still fit for regular combustion for generating heat. Among the several identified phytochemicals (>100), furfural, 5-HMF, benzoic acid, salicylic acid, and catechol can be obtained as bulk chemicals, and sakuranin present at 15.9 % (extracted with acetone) as a high-valued and fine chemical. Considering the increasing demand for plant-based ingredients, there exists enormous potential to utilize these phytochemicals in agro-pharmaceutical industries. Further end-use studies, however, are required to ascertain the true economic potential of poplar bark phytochemicals. [ABSTRACT FROM AUTHOR]

Corresponding with the increasing global resource demand, harvesting now affects millions of hectares of boreal forest each year, and yet our understanding of harvesting impacts on boreal carbon (C) dynamics relative to wildfire remains unclear. We provide a direct comparison of C stocks following clearcut harvesting and fire over a 27-year chronosequence in the boreal forest of central Canada. Whereas many past studies have lacked measurement of all major C pools, we attempt to provide complete C pool coverage, including live biomass, deadwood, forest floor, and mineral soil C pools. The relative contribution of each C pool to total ecosystem C varied considerably between disturbance types. Live biomass C was significantly higher following harvesting compared with fire because of residual live trees and advanced regeneration. Conversely, most live biomass was killed following fire, and thus post-fire stands contained higher stocks of deadwood C. Snag and stump C mass peaked immediately following fire, but dramatically decreased 8 years after fire as dead trees began to fall over, contributing to the downed woody debris C pool. Forest floor C mass was substantially lower shortly after fire than harvesting, but this pool converged 8 years after fire and harvesting. When total ecosystem C stocks were examined, we found no significant difference during early stand development between harvesting and fire. Maximum total ecosystem C occurred at age 27 years, 185.1 ± 18.2 and 163.6 ± 8.0 Mg C ha for harvesting and fire, respectively. Our results indicate strong differences in individual C pools, but similar total ecosystem C after fire and clearcutting in boreal forests, and shall help improve modeling terrestrial C flux after stand-replacing disturbances. [ABSTRACT FROM AUTHOR]

Forest productivity is driven by a suite of direct climatic and non-climatic factors that are transient or permanent. The kind of productivity driver and the nature of their effects vary by species, and scale dependencies potentially complicate these relationships. This study explored productivity-driver relations in eastern Boreal Canada and determined spatial effects in productivity control when expressed with stand dominant height at a reference age (site index). Data from 4,217 temporary sample plots obtained from boreal mixedwood and conifer bioclimatic domains, and with varied species composition, were used in this study. A single-level global model that assumes equal sensitivities across spatial scales was calibrated and compared with three alternative models reflecting different hypotheses on possible spatial heterogeneities. Alternative models were calibrated by plot-level soil deposit types (microscale), landscape dominant deposits (mesoscale) and bioclimatic domains (macroscale). A marked difference between the global and alternative models was observed, suggesting that a single global model does not sufficiently reflect existing heterogeneity in productivity-driver relationships. A combination of macro- and microscale models provided the best explanation of site index. Results further showed that site index is mainly driven by species composition (complementarity effects of aspen and jack pine compositions) and stand diameter structural diversity effects. It is concluded that successional changes, more than direct climatic effects, drive productivity. [ABSTRACT FROM AUTHOR]

During 2 years (2009, 2010), CO fluxes were measured in an oligotrophic fen located at the ecotonal limit of forest tundra and lichen woodland, in northeastern Canada. Peatlands in this region have registered a rise in surface moisture since Little Ice Age, allowing an increase in their pool size and density. In the studied peatland, 83 % of the surface is covered either with pools (42 %), hollows (28 %) and lawns (13 %) all of which present a mean water table higher than 7 cm. We evaluated how these conditions might influence the CO balance in these poor fens located in the northeastern section of the La Grande river watershed. During the two years measurements, results indicate a net CO source with 404 (±287) and 272 (±250) g CO myear emitted to the atmosphere throughout the growing seasons and winters. Modeled wintertime net ecosystem exchange resulted in a net loss of 150 (±36) and 150 (±37) g CO m year in 2009 and 2010 respectively, while 248 (±248) and 124 (±195) g CO m was emitted during 2009 and 2010 growing seasons. This high CO source can be attributed to three factors: (1) the length of the cold season which represented 210-214 days of net CO loss (2) a high pool/vegetated surface ratio since pools are a net source of CO and presented 38-40 % of the annual spatially weighted CO budget and (3) hydroclimatic conditions during the growing season as dryer and warmer conditions in 2009 reduced photosynthesis and increased respiration rates. [ABSTRACT FROM AUTHOR]

The structure and productivity of boreal forests are key components of the global carbon cycle and impact the resources and habitats available for species. With this research, we characterized the relationship between measurements of forest structure and satellite-derived estimates of gross primary production (GPP) over the Canadian boreal. We acquired stand level indicators of canopy cover, canopy height, and structural complexity from nearly 25,000 km of small-footprint discrete return Light Detection and Ranging (Lidar) data and compared these attributes to GPP estimates derived from the MODerate resolution Imaging Spectroradiometer (MODIS). While limited in our capacity to control for stand age, we removed recently disturbed and managed forests using information on fire history, roads, and anthropogenic change. We found that MODIS GPP was strongly linked to Lidar-derived canopy cover ( r = 0.74, p < 0.01), however was only weakly related to Lidar-derived canopy height and structural complexity as these attributes are largely a function of stand age. A relationship was apparent between MODIS GPP and the maximum sampled heights derived from Lidar as growth rates and resource availability likely limit tree height in the prolonged absence of disturbance. The most structurally complex stands, as measured by the coefficient of variation of Lidar return heights, occurred where MODIS GPP was highest as productive boreal stands are expected to contain a wider range of tree heights and transition to uneven-aged structures faster than less productive stands. While MODIS GPP related near-linearly to Lidar-derived canopy cover, the weaker relationships to Lidar-derived canopy height and structural complexity highlight the importance of stand age in determining the structure of boreal forests. We conclude that an improved quantification of how both productivity and disturbance shape stand structure is needed to better understand the current state of boreal forests in Canada and how these forests are changing in response to changing climate and disturbance regimes. [ABSTRACT FROM AUTHOR]

Studies have shown that tropospheric ozone (O) impacts trees in various ways, including growth reductions. To date, the landscape-level response of Canadian forests carbon (C) to O exposure has not been quantified. We used a modified version of the Carbon Budget Model of the Canadian Forest Sector and data from Aspen FACE to quantify the landscape-level impacts of different O exposure modelling experiments. The main strengths of our approach consisted of using the most complete empirical data available to estimate the amount and location of forest C across Canada, as well as explicitly simulating the consequences of fire, insect, and harvest disturbances on forest C dynamics. These disturbances lead to younger forests and, considering trees sensitivity to O exposure to decrease with age, thus result in higher landscape-level modelled impacts for the same O levels. Despite various sources of uncertainty, our results indicate that even under a modelling experiment where O increases continuously over four decades, the landscape-level impacts on the merchantable biomass and ecosystem C remain limited. Our results also suggest that the current direct impacts of O on Canadian forests are likely below detection at the landscape level. [ABSTRACT FROM AUTHOR]

Canada is a large nation with forested ecosystems that occupy over 60% of the national land base, and knowledge of the patterns of Canada's land cover is important to proper environmental management of this vast resource. To this end, a circa 2000 Landsat-derived land cover map of the forested ecosystems of Canada has created a new window into understanding the composition and configuration of land cover patterns in forested Canada. Strategies for summarizing such large expanses of land cover are increasingly important, as land managers work to study and preserve distinctive areas, as well as to identify representative examples of current land-cover and land-use assemblages. Meanwhile, the development of extremely efficient clustering algorithms has become increasingly important in the world of computer science, in which billions of pieces of information on the internet are continually sifted for meaning for a vast variety of applications. One recently developed clustering algorithm quickly groups large numbers of items of any type in a given data set while simultaneously selecting a representative-or 'exemplar'-from each cluster. In this context, the availability of both advanced data processing methods and a nationally available set of landscape metrics presents an opportunity to identify sets of representative landscapes to better understand landscape pattern, variation, and distribution across the forested area of Canada. In this research, we first identify and provide context for a small, interpretable set of exemplar landscapes that objectively represent land cover in each of Canada's ten forested ecozones. Then, we demonstrate how this approach can be used to identify flagship and satellite long-term study areas inside and outside protected areas in the province of Ontario. These applications aid our understanding of Canada's forest while augmenting its management toolbox, and may signal a broad range of applications for this versatile approach. [ABSTRACT FROM AUTHOR]

Tree-based intercropping (TBI) systems, combining agricultural alley crops with rows of hardwood trees, are largely absent in Canada. We tested the hypothesis that the roots of 5-8 years old hybrid poplars, growing in two TBI systems in southern Québec, would play a 'safety-net' role of capturing nutrients leaching below the rooting zone of alley crops. TBI research plots at each site were trenched to a depth of 1 m on each side of an alley. Control plots were left with tree roots intact. In each treatment at each site, leachate at 70 cm soil depth was repeatedly sampled over two growing seasons using porous cup tension lysimeters, and analyzed for nutrient concentrations. Daily water percolation rates were estimated with the forest hydrology model ForHyM. Average nutrient concentrations for all days between consecutive sampling dates were multiplied by water percolation rates, yielding daily nutrient leaching loss estimates for each sampling step. We estimated that tree roots in the TBI system established on clay loam soil decreased subsoil NO leaching by 227 kg N ha and 30 kg N ha over two consecutive years, and decreased dissolved organic N (DON) leaching by 156 kg N ha year in the second year of the study. NH leaching losses at the same site were higher when roots were present, but were 1-2 orders of magnitude lower than NO or DON leaching. At the sandy textured site, the safety net role of poplar roots with respect to N leaching was not as effective, perhaps because N leaching rates exceeded root N uptake by a wider margin than at the clay loam site. At the sandy textured site, significant and substantial reductions of sodium leaching were observed where tree roots were present. At both sites, tree roots reduced DON concentrations and the ratio of DON to inorganic N, perhaps by promoting microbial acquisition of DON through rhizodeposition. This study demonstrated a potential safety-net role by poplar roots in 5-8 year-old TBI systems in cold temperate regions. [ABSTRACT FROM AUTHOR]

Many countries undertake a national forest inventory to enable statistically valid monitoring in support of national and international reporting of forest conditions and change. Canada's National Forest Inventory (NFI) program is designed to operate on a 10-year remeasurement cycle, with an interim report produced at the 5-year mid-point. The NFI is a sample-based inventory, with approximately 18,850 2 ×2-km photo plots across the country, distributed on a 20×20-km grid of sample points; these photo plots are the primary data source for the NFI. Capacity to provide annual monitoring information is required to keep policy and decision makers apprised of current forest conditions. In this study, we implemented a multistage monitoring framework and used a Moderate Resolution Imaging Spectroradiometer (MODIS) change product to successfully identify 78% of the changes in forest cover area that were captured with a Landsat change detection approach. Of the NFI photo plots that were identified by both the Landsat and MODIS approaches as having changes in forest cover, the proportion of change area within the plots was similar ( R = 0.78). Approximately 70% of the Landsat-derived change events occupied less than 40% of a single MODIS pixel, and more than 90% of the change events of this size were successfully detected with the MODIS product. Finally, MODIS estimates of the proportion of forest cover change at the NFI photo plot level were comparable to change estimates for the ecoregions as a whole ( R = 0.95). High-temporal, low-spatial resolution imagery such as MODIS, in combination with other remotely sensed data sources, can provide information on disturbance events within a national forest inventory remeasurement cycle, thereby satisfying the interim information needs of policy and decision makers as well as the requirements of national and international reporting commitments. [ABSTRACT FROM AUTHOR]

Habitat configuration has important implications for the persistence of faunal and floral populations at a variety of spatial scales. Forest harvesting alters habitat configurations. However, measuring and predicting such alterations remains challenging, in part because previously developed metrics of habitat configuration are often not statistically independent of habitat amount. Thus, their ability to measure independent effects of habitat configurations and habitat amount on ecosystem components such as wildlife populations has been limited. Here, we evaluate habitat configuration based on newly developed metrics that are independent of habitat amount but do not depend on regression residuals of abundance and configuration relationships on any population of landscapes. We use these new metrics to measure and predict changes in habitat configuration following forest harvesting in the boreal forest of Alberta, Canada. Our findings clearly demonstrate changes in habitat configuration resulting from forest harvesting can be predicted precisely with information about initial habitat patch structure and harvesting patterns. Because forest harvesting has significant implications for habitat configuration, accurately predicting these changes is critical for determining if forest harvesting strategies are sustainable for ecosystem components and processes. This study provides a set of novel, robust metrics for tracking landscape-scale changes in habitat configuration in harvested boreal forests. [ABSTRACT FROM AUTHOR]

This study investigates soil N2O dynamics in forest soils representing early (3-years) and late (>50 years) post-harvest succession in Atlantic Canada over a 9-month snow-free period in order to develop a better understanding of the role of managed forests as sources and sinks of N2O. We couple measurement of surface flux with detailed measurements of subsurface N2O concentrations at four mineral soil depths (0, 5, 20 and 35 cm) at 40 plots located within four sites. Median surface fluxes were similar at all sites regardless of the management stage (−5 to +19 ugN2O–N/m2/day), with all sites behaving as net sinks and sources of N2O over the measurement period. Subsurface mineral soil N2O concentrations at early (3-year) post-harvest succession sites, which ranged from median values of 362 ppbv at 0 cm to 1783 ppbv at 35 cm depth, were significantly higher than late post-harvest succession sites where median concentrations ranged from 329 ppbv at 0 cm to 460 ppbv at 35 cm depth. Examination of relationships between subsurface gas storage and surface flux magnitudes, suggested although recently harvested forest soils may be producing N2O at a greater rate than mature forest soils, observed patterns are consistent with a strong sink for this gas that prevents its conservative transport through the soil profile, and ultimate emission to the atmosphere through the majority of the measurement period. [ABSTRACT FROM AUTHOR]

The relationship between outbreak characteristics of the spruce budworm and the combination of climate, forest composition, and spatial location was examined in eastern Canada by the method of constrained ordination. Approximately 54% of the spatial variability in outbreak pattern, as described by a matrix of four outbreak characteristics, was explained by the spatial pattern of the climate (a matrix of six variables), forest composition (a matrix of seven variables), and spatial location (a matrix of two variables). The relationships between outbreak variables and climate variables were highlighted, and future outbreak characteristics of the spruce budworm were projected using simulations of a global circulation model for the period 2081-2100 where CO2 concentrations reach a maximum of approximately 550 ppm. Future outbreaks are predicted to be an average of approximately 6 years longer with an average of 15% greater defoliation. The methodology is described and the potential effects of climate change on landscape-scale outbreaks of the insect are discussed. [ABSTRACT FROM AUTHOR]

The effects of timber harvesting on stream water quality and efficiency of alternate streamside management zones were evaluated in Pockwock Lake and Five Mile Lake watersheds in central Nova Scotia, Canada. The streamside management zone (SMZ) included a 20 m no cut, 20 m select cut and a 30 m select cut buffer strips along the stream. Water quality of eight streams, six in harvested and two in not-harvested watersheds were monitored for two years before and two years after the harvesting of timber. Nonparametric statistical tests on stream water quality showed that there was significant change in the concentration of potassium in six streams, manganese in five streams, zinc in two streams and total nitrogen in one stream after timber harvesting. There was no significant change in the quality of water in two streams used as control sites in the neighboring watersheds of similar size and hydrological characteristics. The results show that forest management practices were most favorable in streams maintained with 30 m select cut followed by 20 m no cut and 20 m select cut SMZ. The streamside zone width and treatment of select cut or no cut in the zone played an important role in filtering or retaining the minerals in surface water runoff. In buffer zones of similar width, the buffer zone with no cut or forested buffer was relatively more effective at protecting stream water quality than select cut SMZ. The vegetation in the zone may have decreased the flow velocity and increased residence time and thus increased filtration and retention of minerals in the riparian soil. [ABSTRACT FROM AUTHOR]

Rural communities in the northern boreal forest depend on a suite of wild species for subsistence, including large game animals, furbearers, fish, and plants. Fire is one of the primary ecological disturbances and determinants of landscape pattern in the northern boreal forest. We review responses of key boreal subsistence species to variation and change in post-fire stand age and other characteristics. Available data for 17 species indicate highly varied post-fire habitat requirements. Mosaics of differing stand ages generated by fire could therefore be most effective in supplying a suite of subsistence species to hunting-and-gathering communities. Recent and projected increases in frequency of large-fire years might produce a more homogeneous landscape dominated by younger stand ages. Increases in fire suppression around communities might also produce a more homogenous landscape, but dominated by older stand ages. Neither of these scenarios provides mixed habitats for a diverse suite of subsistence species. We suggest that one aspect of the complex suite of human–fire interactions is an understanding of wildlife and plant species’ response to fire in a subsistence region, in an effort to sustain ecosystem services critical to human well-being. [ABSTRACT FROM AUTHOR]

Changes in climate, atmospheric carbon dioxide concentration and fire regimes have been occurring for decades in the global boreal forest, with future climate change likely to increase fire frequency—the primary disturbance agent in most boreal forests. Previous attempts to assess quantitatively the effect of changing environmental conditions on the net boreal forest carbon balance have not taken into account the competition between different vegetation types on a large scale. Here we use a process model with three competing vascular and non-vascular vegetation types to examine the effects of climate, carbon dioxide concentrations and fire disturbance on net biome production, net primary production and vegetation dominance in 100 Mha of Canadian boreal forest. We find that the carbon balance of this region was driven by changes in fire disturbance from 1948 to 2005. Climate changes affected the variability, but not the mean, of the landscape carbon balance, with precipitation exerting a more significant effect than temperature. We show that more frequent and larger fires in the late twentieth century resulted in deciduous trees and mosses increasing production at the expense of coniferous trees. Our model did not however exhibit the increases in total forest net primary production that have been inferred from satellite data. We find that poor soil drainage decreased the variability of the landscape carbon balance, which suggests that increased climate and hydrological changes have the potential to affect disproportionately the carbon dynamics of these areas. Overall, we conclude that direct ecophysiological changes resulting from global climate change have not yet been felt in this large boreal region. Variations in the landscape carbon balance and vegetation dominance have so far been driven largely by increases in fire frequency. [ABSTRACT FROM AUTHOR]

The need for accurate carbon budgeting, climate change modelling, and sustainable resource management has lead to an increase in the number of large area forest monitoring programs. Large area forest monitoring programs often utilize field and remotely sensed data sources. Sampling, via field or photo plots, enables the collection of data with the desired level of categorical detail in a timely and efficient manner. When sampling, the aim is to collect representative detailed data enabling the statistical reporting upon the characteristics of larger areas. As a consequence, approaches for investigating how well sample data represent larger areas (i.e., the sample neighbourhood and the population) are desired. Presented in this communication is a quantitative approach for assessing the nature of sampled areas in relation to surrounding areas and the overall population of interest. Classified Landsat data is converted to forest/non-forest categories to provide a consistent and uniform data set over a 130,000 km2 study region in central British Columbia, Canada. From this larger study area 322 2 × 2 km photo plots on a 20 × 20 km systematic grid are populated with composition and configuration information for comparison to non-sampled areas. Results indicate that typically, within the study area, the spatial pattern of forest within a photo plot is representative of the forest patterns found within primary and secondary neighbourhoods and over the entire population of the study. These methods have implications for understanding the nature of data used in monitoring programs worldwide. The ability to audit photo and field plot information promotes an increased understanding of the results developed from sampling and provides tools identifying locations of possible bias. [ABSTRACT FROM AUTHOR]

Using a case study of the Lake Abitibi Model Forest (LAMF), this study aims to assess the temporal and spatial variability in carbon storage during 1990-2000, and to present a comprehensive estimation of the carbon budget for LAMF's ecosystems. As well, it provided the information needed by local forest managers to develop ecological and carbon-based indicators and monitor the sustainability of forest ecosystems. Temporal and spatial carbon dynamics were simulated at the landscape level using ecosystem model TRIPLEX1.0 and Geographical Information System (GIS). The simulated net primary productivity (NPP) and carbon storage in forest biomass and soil were compared with field data and results from other studies for Canada's boreal forests. The results show that simulated NPP ranged from 3.26 to 3.34 tC ha-1 yr-1 in the 1990s and was consistent with the range measured during the Boreal Ecosystem-Atmosphere Studies (BOREAS) in central Canada. Modeled NPP was also compared with the estimation from remote sensing data. The density of total above- and belowground biomass was 125.3, 111.8, and 106.5 tC ha-1 for black spruce, trembling aspen, and jack pine in the LAMF ecosystem, respectively. The total carbon density of forested land was estimated at 154.4 tC ha-1 with the proportion of 4:6 for total biomass and soil. The analysis of net carbon balance of ecosystem suggested that the LAMF forest ecosystem was acting as a carbon sink with an allowable harvest in the 1990s. [ABSTRACT FROM AUTHOR]

Historical and future projected landscape patterns and changes caused by harvesting and silviculture were evaluated for a 189,000 ha, intensively managed forest in New Brunswick, Canada. We compared changes in species composition, age classes, and patch characteristics (area, size, density, edge, shape, and core area) between 1945, 2002, and projections to 2027 (based on the landowner's spatial forest management plan). In 1945, the landbase was 40% softwood, 37% mixed hardwood-softwood, 10% hardwood, and 9% softwood-cedar. From 1945 to 2002 and 2027, respectively, softwood forest area increased by 2 and 11%, mixedwood decreased by 19 and 20%, and hardwood area increased by 15 and 14%, and softwood-cedar increased by 6% and then decreased by 7%. In 1945, forest >70 years old comprised 85% of the landscape, but declined to 44% in 2002 and was projected to encompass 41% in 2027. Increased area harvested, decreasing harvest patch size, and protection against natural disturbances resulted in progressively smaller mean and less variable patch sizes from 1945 to 2002. Based upon the 25-year forest management plan, this trend was projected to continue, with the exception of nine patches >1000 ha created by 2027, eight of which were softwood plantations. Stand type successional dynamics were highly variable in both harvested and non-harvested areas, and in some cases were unexpected. Few of the 1945 stand types remained static by 2002, with 42 and 35% of mixedwood shifting to softwood as a result of harvesting, and to hardwood as a result of both harvesting and spruce budworm(Choristoneura fumiferana Clem.) outbreaks in the 1950s and 1970s. This study demonstrates the strong cumulative effect of forest management on landscape patterns, especially the socially mandated drive for smaller clearcuts resulting in the loss of large patches. [ABSTRACT FROM AUTHOR]

Critical loads of acidity were estimated for upland forests in Eastern Canada using the steady-state Simple Mass Balance (SMB) Model. A consistent methodology was applied to the entire region, although critical loads were estimated separately for the Atlantic provinces (New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland), Quebec and Ontario using different data sources. In this project, critical load estimates and steady-state exceedance values did not include the effect of forest fire and forest harvesting, which could have a considerable impact on critical loads in Eastern Canada. The observed soil pH – base saturation relationship for forest soils indicated that the constants used into the calculation of alkalinity leaching should be set to 10 (M/M) for the molar Bc/Al ratio in soil leachate and 109 (mol L−1)2 for the gibbsite dissolution constant. The area-weighted median critical load for each province varied between 519 (Quebec) and 2063 eq ha−1 y−1 (Prince Edward Island), with a median critical load value for Eastern Canada of 559 eq ha−1 y−1. It is estimated that approximately 52% of the mapped area is exceeded in terms of acidity according to the 1994–1998 average total (wet + dry) atmospheric deposition. Greatest exceedances occurred in Ontario and Quebec and in the south of Nova Scotia, due to low critical loads and high loads of acid deposition. [ABSTRACT FROM AUTHOR]

The task of modeling the distribution of a large number of tree species under future climate scenarios presents unique challenges. First, the model must be robust enough to handle climate data outside the current range without producing unacceptable instability in the output. In addition, the technique should have automatic search mechanisms built in to select the most appropriate values for input model parameters for each species so that minimal effort is required when these parameters are fine-tuned for individual tree species. We evaluated four statistical models—Regression Tree Analysis (RTA), Bagging Trees (BT), Random Forests (RF), and Multivariate Adaptive Regression Splines (MARS)—for predictive vegetation mapping under current and future climate scenarios according to the Canadian Climate Centre global circulation model. To test, we applied these techniques to four tree species common in the eastern United States: loblolly pine ( Pinus taeda), sugar maple ( Acer saccharum), American beech ( Fagus grandifolia), and white oak ( Quercus alba). When the four techniques were assessed with Kappa and fuzzy Kappa statistics, RF and BT were superior in reproducing current importance value (a measure of basal area in addition to abundance) distributions for the four tree species, as derived from approximately 100,000 USDA Forest Service’s Forest Inventory and Analysis plots. Future estimates of suitable habitat after climate change were visually more reasonable with BT and RF, with slightly better performance by RF as assessed by Kappa statistics, correlation estimates, and spatial distribution of importance values. Although RTA did not perform as well as BT and RF, it provided interpretive models for species whose distributions were captured well by our current set of predictors. MARS was adequate for predicting current distributions but unacceptable for future climate. We consider RTA, BT, and RF modeling approaches, especially when used together to take advantage of their individual strengths, to be robust for predictive mapping and recommend their inclusion in the ecological toolbox. [ABSTRACT FROM AUTHOR]

Exotic earthworms invading forests in Canada and northeastern United States that were naturally devoid of large detritivores cause major changes in ecosystem function. To assess their long-term impacts, studies are needed to elucidate the factors that control the patterns of earthworm invasion at the landscape level. We analyzed the distribution patterns of exotic earthworms in a northern hardwood forest in south-central New York (USA), as explained by landscape variables thought to be important in determining earthworm distribution. Forest type, slope angle, elevation, and the distance to agricultural clearings and wet refugia were significant predictors of earthworm presence, whereas local wetness index and the distance to streams and roads were not. Forest type and distance to agricultural clearings were the two most significant predictors. Our data suggest that areas close to agricultural clearings, dominated by mixed hardwoods, and located towards valley bottoms or on gentle slopes are very likely to support communities of exotic earthworms. Steeper slopes, areas dominated by American beech or eastern hemlock, and locations in the core of extensive forest landscapes have lower probabilities of invasion by exotic earthworms. When applied to a nearby area, our statistical model correctly predicted earthworm presence for 67% of 377 sampling points. Most of the mistakes were incorrect predictions of earthworm absence, suggesting that our statistical model slightly underestimated earthworm presence, possibly because of the pervasive influence of active agricultural fields adjacent to the test site. [ABSTRACT FROM AUTHOR]

The rate of carbon accumulation in the atmosphere can be reduced by decreasing emissions from the burning of fossil fuels and by increasing the net uptake (or reducing the net loss) of carbon in terrestrial (and aquatic) ecosystems. The Kyoto Protocol addresses both the release and uptake of carbon. Canada is developing a National Forest Carbon Monitoring, Accounting and Reporting System in support of its international obligations to report greenhouse gas sources and sinks. This system employs forest-inventory data, growth and yield information, and statistics on natural disturbances, management actions and land-use change to estimate forest carbon stocks, changes in carbon stocks, and emissions of non-CO2 greenhouse gases. A key component of the system is the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS). The model is undergoing extensive revisions to enable analyses at four spatial scales (national, provincial, forest management unit and stand) and in annual time steps. The model and the supporting databases can be used to assess carbon-stock changes between 1990 and the present, and to predict future carbon-stock changes based on scenarios of future disturbance rates and management actions. [ABSTRACT FROM AUTHOR]

For effective planning, design, and management of water resources engineering, the probability distribution of annual streamflow is necessary. The method of L-moments is applied to identify the probability distribution type of annual streamflow in different climatic regions of Canada. In the Pacific and southern British Columbia mountains (regions 1 and 2), the generalized extreme value (GEV) distribution fits the observations best with the 3-parameter lognormal (LN3) and log Pearson type III (LP3) as potential candidates. In Yukon and northern British Columbia (region 3), the LN3 distribution corresponds to observations best with the LP3 and P3 as potential candidates. In the northwestern forest (region 5), the LP3 distribution matches observations best with the P3 and GEV as potential candidates. In Arctic Tundra (region 10), the 3-parameter Weibull (W3) is the best one with the LN3 and P3 as potential candidates. The P3 distribution provides a best-fit to observations in the Prairies (region 4), northeastern forest (region 6), great Lakes and St. Lawrence (region 7), Atlantic (region 8), and Mackenzie (region 9) with the LN3, LP3, and GEV as potential candidates. [ABSTRACT FROM AUTHOR]

A whole forest optimisation model was employed to examine economic behaviour as it relates to long term, forest productivity decline in the boreal forests of Ontario, Canada. Our productivity investment model (PIM) incorporated a choice between productivity decline as represented by a drop in forest Site Class, and a fee to `maintain' site productivity. Sensitivity analysis was used to determine the point at which these fees exceeded the value of the differential in timber volume between upper and lower site classes. By varying discount rate, `productivity investment frontiers' were constructed, which highlight the effects of the magnitude in productivity decline, maintenance fees, and harvest flow constraints upon the occurrence and schedule of productivity declines. In presenting this simple approach to exploring the effects of economic choice upon forest productivity decline, the phenomena of `natural capital divestment' within forestry is described. [ABSTRACT FROM AUTHOR]

This article presents an applied framework for selective precision in the insertion of superior data into hybrid regional models where regional purchasing coefficients are absent or unattainable. Due to the lack of regional-level data, crude top-down methods are the most frequently applied methods in Canadian regional studies. However, they may lead to inaccurate policy analysis where significant variation exists between the technical coefficients and trade flows of two economies. This article discusses an alternative, hybrid approach that involves the collection of region-specific information and therefore promises greater accuracy and validity of impact analysis. The robustness of the hybrid model is tested against the results derived from a synthetically regionalized model. The Foothills Model Forest (FMF) in west-central Alberta is used as a case study for the development of a sub-provincial economic database for the purpose of regional impact modeling. [ABSTRACT FROM AUTHOR]

Many recent trail degradation problems have been attributed to mountain biking because of its alleged capacity to do more damage than other activities, particularly hiking. This study compared the effects of experimentally applied mountain biking and hiking on the understory vegetation and soil of a deciduous forest. Five different intensities of biking and hiking (i.e., 0, 25, 75, 200 and 500 passes) were applied to 4-m-long × 1-m-wide lanes in Boyne Valley Provincial Park, Ontario, Canada. Measurements of plant stem density, species richness, and soil exposure were made before treatment, two weeks after treatment, and again one year after treatment. Biking and hiking generally had similar effects on vegetation and soil. Two weeks after treatment, stem density and species richness were reduced by up to 100% of pretreatment values. In addition, the amount of soil exposed increased by up to 54%. One year later, these treatment effects were no longer detectable. These results indicate that at a similar intensity of activity, the short-term impacts of mountain biking and hiking may not differ greatly in the undisturbed area of a deciduous forest habitat. The immediate impacts of both activities can be severe but rapid recovery should be expected when the activities are not allowed to continue. Implications of these results for trail recreation are discussed. [ABSTRACT FROM AUTHOR]

Canada's current National Forest Inventory is a periodic compilation of existing inventory material from across the country. While the current approach has many advantages, it lacks information on the nature and rate of changes to the resource, and does not permit projections or forecasts. Being a compilation of inventories of different dates, the current national forest inventory cannot reflect the current state of the forests and therefore cannot be used as a satisfactory baseline for monitoring change. The current format of Canada's National Forest Inventory has served its purpose by providing national statistical compilations and reporting. However, its useful life is coming to a conclusion. To meet new demands, Canada is considering a new National Forest Inventory design consisting of a plot-based system of permanent observational units located on a national grid. The objective of the new inventory design is to assess and monitor the extent, state and sustainability of Canada's forests in a timely and accurate manner. Details of the new inventory design are described. A strategy to respond to Canada's national and international forest reporting commitments through a National Forest Information System is also discussed. [ABSTRACT FROM AUTHOR]

Examines the potential for carbon sequestration in selected Canadian forest settings and prairie agroecosystems under several management scenarios. Development of a simple carbon budget model to quantitatively examine carbon sequestration potential; Establishment of protected forest-carbon reserves for carbon sequestration opportunities; Constraints in offsetting green house gas emissions by increasing carbon storage in forests and agroecosystems.

An attempt to amalgamate a wide variety of land environmental data in Canada is presented. The data are shown in the form of indices, which can be defined as the comparison of a measured quantity to a standard. The indices are divided into six parts, dealing with forestry, urban overcrowding, erosion, parkland, strip mining, and sedimentation. In addition, changes in urban land use are considered. The information is primarily quantitative rather than qualitative, and national as opposed to solely local or regional. This effort marks one of the first times the land quality of an entire nation has been evaluated. Implications for policy decisions are discussed. [ABSTRACT FROM AUTHOR]

Using an Integrated Terrestrial Ecosystem C-budget model (InTEC), wesimulated the carbon (C) offset potentials of four alternative forest management strategies in Canada: afforestation, reforestation, nitrogen (N) fertilization, and substitution of fossil fuel with wood, under different climatic and disturbance scenarios. C offset potential is defined as additional C uptake by forest ecosystems or reduced fossil C emissions when a strategy is implemented to the theoretical maximum possible extent. The simulations provided the following estimated gains from management: (1) Afforesting all the estimated ? 7.2 Mha of marginal agricultural land and urban areas in 1999 would create anaverage C offset potential of ? 8 Tg C y-1 during 1999-2100, at a cost of 3.4 Tg fossil C emission in 1999. (2) Prompt reforestation of all forest lands disturbed in the previous year during 1999-2100 would produce an average C offset potential of ? 57 Tg C y-1 for this period, at a cost of 1.33 Tg C y-1. (3) Application of N fertilization (at the low rate of 5 kg N ha-1 y-1) to the ? 125 Mha of semi-mature forest during 1999-2100 would create an average C offset of ?58 Tg C y-1 for this period, at a cost of ?0.24 Tg C y-1. (4) Increasing forest harvesting by 20% above current average rates during 1999-2100, and using the extra wood products to substitute for fossil energywould reduce average emissions by ?11 Tg C y-1, at a costof 0.54 Tg C y-1. If implemented to the maximum extent, the combined C offset potential of all four strategies would be 2-7 times the GHG emission reductions projected for the National Action Plan for Climate Change (NAPCC) initiatives during 2000-2020, and an order of magnitude larger than the projected increase in C uptake by Canada's agricultural soils due to improved agricultural practices during 2000-2010. [ABSTRACT FROM AUTHOR]