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Diameter at breast height (DBH) is a unique attribute used to characterize forest growth and development for forest management planning and to understand forest ecology. Forest managers require an array of DBHs of forest stands, which can be reconstructed using selected probability distribution functions (PDFs). However, there is a lack of practices that fit PDFs of sub-dominating species grown in natural mixed forests. This study aimed to fit PDFs and develop predictive models for PDF parameters, so that the predicted distribution would represent dynamic forest structures and compositions in mixed forest stands. We fitted three of the simplest forms of PDFs, log-normal, gamma, and Weibull, for the DBH of eight tree species, namely balsam fir (Abies balsamea [L.] Mill.), eastern white pine (Pinus strobus L.), paper birch (Betula papyrifera Marshall), red maple (Acer rubrum L.), red pine (Pinus resinosa Aiton), sugar maple (Acer saccharum Marshall), trembling aspen (Populus tremuloides Michx), and white spruce (Picea glauca [Moench] Voss), all grown in natural-origin mixed forests in Ontario province, Canada. We estimated the parameters of the PDFs as a function of DBH mean and standard deviation for these species. Our results showed that log-normal fit the best among the three PDFs. We demonstrated that the predictive model could estimate the recovered parameters unbiasedly for all species, which can be used to reconstruct the DBH distributions of these tree species. In addition to prediction, the cross-validated R2 for the DBH mean ranged between 0.76 for red maple and 0.92 for red pine. However, the R2 for the regression of the standard deviation ranged between 0.00 for red pine and 0.69 for sugar maple, although it produced unbiased predictions and a small mean absolute bias. As these mean and standard deviations are regressed with dynamic covariates (such as stem density and stand basal area), in addition to climate and static geographic variables, the predicted DBH distribution can reflect change over time in response to management or any type of disturbance in the regime of the given geography. The predictive model-based DBH distributions can be applied to the design of appropriate silviculture systems for forest management planning. [ABSTRACT FROM AUTHOR]

Methane flux measurements were carried out at a temperate forest (Haliburton Forest and Wildlife Reserve) in central Ontario (45° 170' 11" N, 78° 32' 19" W) from June-October, 2011. Continuous measurements were made by an off-axis integrated cavity output spectrometer Fast Greenhouse Gas Analyzer (FGGA) from Los Gatos Research Inc. that measures methane (CH4) at 10 Hz sampling rates. Fluxes were calculated from the gas measurements in conjunction with wind data collected by a 3-D sonic anemometer using the eddy covariance (EC) method. Observed methane fluxes showed net uptake of CH4 over the measurement period with an average uptake flux (± standard deviation of the mean) of -2.7±0.13 nmolm-2 s-1. Methane fluxes showed a seasonal progression with average rates of uptake increasing from June through September and remaining high in October. This pattern was consistent with a decreasing trend in soil moisture content at the monthly time scale. On the diurnal timescale, there was evidence of increased uptake during the day, when the mid-canopy wind speed was at a maximum. These patterns suggest that substrate supply of CH4 and oxygen to methanotrophs, and in certain cases hypoxic soil conditions supporting methanogenesis in low-slope areas, drive the observed variability in fluxes. A network of soil static chambers used at the tower site showed close agreement with the eddy covariance flux measurements. This suggests that soil-level microbial processes, and not abiological leaf-level CH4 production, drive overall CH4 dynamics in temperate forest ecosystems such as Haliburton Forest. [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]

In forestry, the availability of high spatial resolution (<1 m/pixel) imagery from new earth observation satellites like Ikonos favours a shift in the image analysis paradigm from a pixel-based approach towards one dealing directly with the essential structuring element of such images: the individual tree crown (ITC). This paper gives an initial assessment of the effects of 1 m and 4 m/pixel spatial resolutions (panchromatic and multispectral bands, respectively) on the detection, delineation, and classification of the individual tree crowns seen in Ikonos images. Winter and summer Ikonos images of the Hudson plantation of the Petawawa Research Forest, Ontario, Canada were analyzed. The panchromatic images were resampled to 0.5 m/pixel and then smoothed using a 3 × 3 kernel mean filter. A valley-following algorithm and rule-based isolation module were applied to delineate the individual tree crowns. Local maxima within a moving 3 × 3 window (i.e., Tree Tops) were also extracted from the smoothed images for comparison. Crown delineation and detection results were summarised and compared with field tree counts. Overall, the ITC delineation and the local maxima approaches led to tree counts that were on average 15 percent off for both seasons. Visual inspection reveals delineation of clusters of two or three crowns as a common source of error. Crown-based species spectral signatures were generated for six classes representing conifer species, plus a hardwood class and a shrub class. After the ITC-based classification, classification accuracy was ascertained using separate test areas of known species. The overall accuracy was 59 percent. Important confusion exists between red and white spruces, and mature versus immature white pines, but post-classification regroupings into single spruce and white pine classes led to an overall accuracy of 67 percent. [ABSTRACT FROM AUTHOR]

Active adaptive management has recently been advocated for efficiently reducing resource management uncertainties, but no documented applications to forestry issues exist in Ontario. This paper reports the experience of a diverse partnership applying active adaptive management to improve techniques for obtaining desired boreal mixedwood structure and composition in northeastern Ontario. Institutional and economic barriers have been more limiting than technical barriers. Building and maintaining the partnership have required considerable effort, and opportunities for conflict were greatest in the assessment and design steps of the adaptive management cycle. The partnership has maintained its progress by promoting flexibility, trust, and consensus-building. This study demonstrates that classical adaptive management can be simplified for application in local management units. A broader application of active adaptive management in Ontario will require senior decision-makers to endorse a strategy that includes staff retraining, admission of management uncertainties, cooperation among management agencies, stability of long-term funding, encouragement of innovation, and regular adjustment of policies and practices. [ABSTRACT FROM AUTHOR]

Discusses academic freedom in the University of Toronto forestry faculty in the period between World War I and II. Basis for Clifton Durant Howe's approach to carrying out his duties as dean of the faculty; Comprehensive efforts of the faculty to generate the requisite public support for forestry.

An uneven-aged silviculture experiment was established in second-growth peatland black spruce (Picea mariana [Mill.] B.S.P.) stands in the boreal forest of northeastern Ontario, Canada in 1994. Three harvest treatments along with an unharvested control were applied in three replications. Fifteen-year results indicate that light- and medium-intensity harvest treatments maintain stand structure suitable for the continued application of uneven-aged silviculture treatments. Based on basal area growth trends and the development of stand structure, a cutting cycle of 20–25 years appears to be feasible for these treatments. Future harvests will likely yield a higher proportion of larger diameter trees with a greater value. The heavy harvest intensity treatment will result in a greater fluctuation of the growing stock and a longer cutting cycle. Without cutting treatments, the control treatment may eventually develop a stand structure that is unsuitable for the implementation of uneven-aged silviculture. [ABSTRACT FROM PUBLISHER]

In the boreal mixedwood region of Canada, management for conifer regeneration after clearcutting generally involves mechanical site preparation, planting and aerial spraying with glyphosate to minimize post-planting competition from natural broadleaf regeneration. However, the resulting conifer plantations have economic and ecological disadvantages compared with mixedwood stands with healthy and productive broadleaf components. This study examined 10-year growth of planted spruce and natural regeneration after pre- and post-harvest spraying and partial cutting treatments on a boreal mixedwood site in northeastern Ontario, Canada. The treatments were as follows: (1) pre-harvest broadcast spraying with glyphosate to suppress trembling aspen (Populus tremuloides Michx.) regeneration, (2) clearcut (unsprayed) for broadleaf regeneration, (3) partial cut to suppress shade-intolerant vegetation, and (4) post-harvest broadcast spraying to promote conventional conifer plantations. Planted spruce trees were tallest in the pre-harvest spray treatment but had the largest basal diameter in the post-harvest spray treatment; neither of the differences was significant at 0.05. Total broadleaf regeneration density in the pre-harvest spray treatment was similar to that in the partial cut, but higher than that in the post-harvest spray treatment. Additional shade from greater amounts of shrubs and residual overstory trees in the partial cut treatment resulted in higher quality spruce trees than in the spray treatments; based on branch size, branch-free stem length and stem taper, wood quality was generally lowest in the post-harvest spray treatment. Pre-harvest spraying provided a better balance between growth and quality of planted spruce than either post-harvest spraying or partial cutting. [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]

Height-diameter relationships based on stand characteristics (stand density, basal area and site index) were investigated for jack pine and black spruce trees using the data from permanent growth study plots in northern Ontario, Canada. Approximately half of the data was used to estimate model parameters and the rest was used for model evaluation. Multiple Chapman-Richards growth functions with parameters expressed in terms of various stand characteristics were fitted to determine the best models for predicting height. Models providing the most accurate predictors of height included basal area, trees ha -1 and diameter at breast height. The inclusion of site index did not increase predictive accuracy. [ABSTRACT FROM AUTHOR]

A large abandoned tailings deposit at a mine site near Timmins, Ontario, Canada has produced significant damage in an adjacent forest due to contamination and wind stress. Significant forest structure changes were measured between 1997 and 1999. A multivariate image-based forest structure index (FSI) was developed using canonical correlation analysis of 1997 field and airborne digital camera data. FSI included decreasing canopy closure and leaf area index, and increasing blown down and standing dead structure measures associated with image spectral, textural and radiometric fraction variables. An image model predicting FSI achieved an R 2 =0.66. The model equation was then applied to 1999 airborne imagery to predict FSI for each plot. Comparing the 1999 image predicted FSI to that calculated from field data showed that the model was strong in predicting positive or no forest structure changes, but not increased structure degradation. The latter was due to the presence of herbaceous and shrub vegetation that had developed during the two-year period in open plots near the tailings where blow down was significant. The next research phase will derive means to separate these two signals in forests of open overstory. [ABSTRACT FROM AUTHOR]

The 20-year successional development of understory vegetation was investigated in jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) BSP) plantations in northern Ontario, in relation to stand species composition, species diversity, and the rate of change in stands of different post-disturbance ages. Detrended correspondence analysis (DCA) ordination of plantation stands using species composition data from 1978 and 1998 indicated variation among stands in directions and rates of change in species composition over time. Rank correlations of environmental variables with the DCA axes suggested a light–moisture gradient along the first axis, driven by soil texture and overstory species, and a gradient representing time since disturbance and stand development along the second axis. Although overall beta diversity among stands remained constant over time, some convergence was found among a smaller group of stands, and divergence was noted between spruce and pine stands. Species composition also became more highly correlated with environmental variables through time. From 1978 to 1998, species richness increased in young, dry pine stands; decreased in older, dry pine stands; and decreased in young spruce stands. The understory vegetation in stands on mesic sites was more diverse than that on dry, sandy sites at both times. The rate of change in understory species composition slowed with time after disturbance, indicating an increasing stability in micro en vi ron men tal conditions as the influence of harvesting disturbance became weaker with time.Le développement sur une période de 20 ans de la succession de la végétation de sous-étage a été étudié dans des plantations de pin gris (Pinusbanksiana Lamb.) et d'épinette noire (Piceamariana (Mill.) BSP) situées dans le Nord de l'Ontario en lien avec la composition en espèces du peuplement, la diversité des espèces et le taux de changement dans des peuplements d'âge différent issus de perturbations. L'ordination des plantations par l'analyse de correspondance en utilisant les données de composition en espèces de 1978 et de 1998 indiquait une variation entre les peuplements dans la direction et le taux de changement dans la composition en espèces en fonction du temps. Les corrélations de rang des variables environnementales avec les axes associés à l'analyse de correspondance suggèrent l'ex istence d'un gradient de lumière et d'humidité le long du premier axe, déterminé par les espèces de l'étage dominant et la texture du sol, ainsi qu'un gradient représentant le développement du peuplement et le temps écoulé depuis la perturbation le long du deuxième axe. Bien que dans l'ensemble la diversité bêta parmi les peuplements soit demeurée constante dans le temps, une certaine convergence a été observée parmi un plus petit groupe de peuplements et une divergence a été notée entre les peuplements d'épinette et de pin. Avec le temps, la composition en espèce est également devenue plus étroitement corrélée avec les variables environnementales. De 1978 à 1998, la richesse en espèces a augmenté dans les jeunes peuplements secs de pin et a diminué dans les plus vieux peuplements secs de pin et les jeunes peuplements d'épinette. La végétation de sous-étage dans les peuplements sur des stations mésiques était plus diversifiée que sur les stations sèches et sableuses aux deux moments. Le taux de changement dans la composition en espèces de sous-étage a diminué avec le temps après la perturbation, reflétant la stabilité croissante des conditions en vironnementales à mesure que l'influence de la perturbation due à la récolte s'atténuait.[Traduit par la Rédaction] [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 study examined variation in winter bird diversity, abundance, biomass and species and guild composition on plots in farmland, rural forests, mixed rural habitat, cities and three categories of urban natural areas in southern Ontario. Small (< 20 g), insectivorous, upper canopy, bark foraging and forest species were more prevalent in rural mixed habitat, urban natural areas and especially rural forests. Larger (20-100 g), ground feeding and omnivorous birds typified cities and farms. Many bird species classified as forest, forest edge and field species during summer also favored these same habitats during winter. The 52 sample plots can be accurately classified into the seven habitat categories through discriminant analysis using the percentages of small species, insectivores, forest species and alien species. Urban natural areas, forests and mixed rural habitat showed the highest diversity while cities and farms showed the lowest diversity. Both bird abundance and biomass were highest in urban natural areas with open water and urban residential and commercial areas, whereas both were lowest in farmland. [ABSTRACT FROM AUTHOR]

Summary • Here, paleoecological studies from southern Ontario, Canada, are detailed to reconstruct vegetation history of the last 13 000 14 C year, with emphasis on late-glacial treeless vegetation. • Two sites (Crawford Lake and Twiss Marl Pond) were investigated using combined pollen and plant–macrofossil stratigraphic data. Comparison of multivariate analysis of pollen data with climate variations inferred independently from oxygen isotopes at the same site facilitated systematic evaluations of climate–vegetation interactions during different stages of vegetation development. • Pollen results show a distinctive successional change from Alnus – Dryas –Cyperaceae sparse tundra or periglacial desert to Salix – Juniperus –Cyperaceae dense tundra, with abundant arctic/alpine plant macrofossils, during the first few centuries after ice retreat. The area around the two sites was then dominated by Picea ( c. 12 000–10 000 14 C BP). Vegetation shifts, summarized by log-contrast principal component analysis of the pollen record, indicated a lagged response of forests to deglacial climate warming. The major vegetation shift at c. 7500 14 C BP from coniferous Pinus -dominated to mixed forests probably corresponded to a major shift from deglacial to full postglacial climates. Vegetation during the mid- and late Holocene responded more directly to natural (drought-triggered pathogen-induced Tsuga decline) and human disturbances (aboriginal and EuroCanadian settlements). • This study demonstrates that bedrock basins most faithfully recorded the earliest vegetation change because they usually experienced a short delay in lake formation after ice retreat. [ABSTRACT FROM AUTHOR]

Presents a study that quantified the difference between disturbed and undisturbed woodland in Ottawa, Ontario. Importance of alvar woodlands; Methodology; Differences in the effects of bulldozing and burning.

Presents information on a study which examined the effects of patch size, local forest cover and regional forest cover on the numbers and species composition of forest birds detected in southern Ontario. Methodology; Results and discussion.

Old-growth black spruce (Picea mariana) boreal forest in the Clay Belt region of Ontario and Quebec is an open forest with a low canopy, quite different from what many consider to be "old growth". Here, we provide an overview of the characteristics of old-growth black spruce forest for three different site types on organic, clay, and coarse deposits. Our objectives were (1) to identify the extent of older forests; (2) to describe the structure, composition, and diversity in different age classes; and (3) to identify key processes in old-growth black spruce forest. We sampled canopy composition, deadwood abundance, understorey composition, and nonvascular plant species in 91 forest stands along a chronosequence that extended from 20 to more than 250 years after fire. We used a peak in tree basal area, which occurred at 100 years on clay and coarse sites and at 200 years on organic sites, as a process-based means of defining the start of old-growth forest. Old-growth forests are extensive in the Clay Belt, covering 30–50% of the forested landscape. Black spruce was dominant on all organic sites, and in all older stands. Although there were fewer understorey species and none exclusive to old-growth, these forests were structurally diverse and had greater abundance of Sphagnum, epiphytic lichens, and ericaceous species. Paludification, a process characteristic of old-growth forest stands on clay deposits in this region, causes decreases in tree and deadwood abundance. Old-growth black spruce forests, therefore, lack the large trees and snags that are characteristic of other old-growth forests. Small-scale disturbances such as spruce budworm and windthrow are common, creating numerous gaps. Landscape and stand level management strategies could minimize structural changes caused by harvesting, but unmanaged forest in all stages of development must be preserved in order to conserve all the attributes of old-growth black spruce forest. Key words: boreal forest, old growth, paludification, Picea mariana, structural development, succession.Dans la région de la ceinture d'argile de l`Ontario et du Québec, la forêt boréale ancienne d'épinette noire (Picea mariana) est une forêt ouverte, où la canopée est basse, ce qui diffère considérablement de la perception que le public a d'une « forêt ancienne ». Nous présentons ici un aperçu des caractéristiques de la pessière noire ancienne poussant sur dépôts organiques, argileux et grossiers. Nos objectifs étaient: (1) déterminer l'étendue des forêts plus vieilles; (2) décrire la structure, la composition et la diversité en fonction des classes d'âge; (3) mettre en lumière les processus clés dans la pessière noire ancienne. Nous avons échantillonné la composition de l'étage supérieur, l'abondance de bois mort, la composition du sous-bois et les plantes invasculaires de 91 peuplements forestiers, le long d'une chronoséquence de 20 à plus de 250 ans après feu. Nous avons utilizé le maximum de la surface terrière des arbres, observé à 100 ans sur les dépôts argileux et grossiers et à 200 ans sur les dépôts organiques, pour définir le début de la forêt ancienne. Dans la ceinture d'argile, les forêts anciennes sont abondantes, couvrant de 30 à 50 % du paysage forestier. L'épinette noire domine sur tous les sols organiques, ainsi que dans tous les peuplements plus âgés. Bien que les espèces du sous-bois soient moins nombreuses et qu'aucune d'elles ne leur soit exclusivement liée, les forêts anciennes présentent une structure variée et renferment davantage de Sphagnum, de lichens épiphytes et d'éricacées. La paludification, processus caractéristique des peuplements forestiers anciens sur dépôts argileux dans cette région, entraîne une diminution de l'abondance des arbres et du bois mort. Par conséquent, on ne trouve pas dans les forêts anciennes d'épinette noire, les quantités élevées de gros arbres et de chicots qui caractérisent d'autres forêts anciennes. Des perturbations à petite échelle, comme les épidémies de la tordeuse des bourgeons de l'épinette et les chablis, sont fréquentes et créent de nombreuses trouées. Des stratégies d'aménagement à l'échelle du paysage et du peuplement pourraient réduire les changements structuraux causés par la récolte; cependant, il est essentiel de préserver des peuplements non aménagés à tous les stades de développement pour conserver toutes les caractéristiques d'une pessière noire ancienne. Mots clés : forêt boréale, forêt ancienne, paludification, Picea mariana, développement structurale, succession. [Traduit par la rédaction] [ABSTRACT FROM AUTHOR]