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In targeting mature and over-mature forests for harvesting, management in the boreal forest has resulted in a net loss of older forests that often exhibit complex structural variation and multiple cohorts of trees. Multi-cohort forest management has been proposed as a management approach for these older forests that maintains structural wildlife habitat attributes. At the stand level, the approach relies on various partial harvest techniques to emulate the range of structural variation found in natural boreal landscapes. Here, we examine the extent to which boreal bird communities respond to multi-cohort-related structural variation in boreal mixedwood forests. In particular, we test the utility of parameters of Weibull distributions fitted to stand stem diameter distributions, which have figured prominently in methods to characterize multi-cohort structure, to explain variation in the entire bird community and in various species groupings defined by feeding guilds and forest-type associations. We also compare the explanatory power of the two Weibull parameters against 21 forest structure variables and stand age. In general, Weibull parameters outperformed stand age as a correlate of bird community variation and they were significant explanatory variables for the matrix of all species and for four species groupings, whereas age was significant for only one species grouping. When one or the other Weibull parameter was significant, it also tended to be significant even when variation due to the other was partialled out, supporting the importance not only of forest stature, but also of forest heterogeneity in understanding bird community composition. Thus, we found that multi-cohort-associated structural variation was important in explaining variation among boreal bird communities, supporting the idea of silvicultural approaches that aim at diversifying stand structural characteristics.
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... More recent studies have expanded upon the MCM approach to classify stand structure (Kuttner et al. 2013;Latrémouille et al. 2013;Malcolm and Harvey 2013), however, little is known about the potential of MCM to improve upon existing forest management strategies in terms of biodiversity conservation (Etheridge and Kayahara 2013;Malcolm and Harvey 2013). In a recent study, Burrell et al. (2013) showed that four classes of structural variation associated with MCM were relevant in explaining variation among boreal bird communities, but to date, the responses of other faunal communities remains unexplored. ...
... Mixedwood forest sites were all of type MS2 (as classified by the Ontario Ministry of Natural Resources) and were composed of poplar (Populus spp.), white birch, white spruce, black spruce, and balsam fir, such that 21-72 % of stems C10 cm diameter at breast height (DBH) were deciduous, with all sites having at least some poplar (1-65 %) and spruce (1-61 %; Table 1). Sites ranged from 35 to 130 years since last disturbance and, following Burrell et al. (2013), were classified based on their stem-diameter distribution as either, Cohort Class 1 (n = 4), Cohort Class 2 (n = 3), Cohort Class 3 (n = 5) or Cohort Class 4 (n = 6). Stands that were dated prior to when logging began in the region were considered unlogged. ...
... Weibull parameters from the diameter distribution of all stems were better predictors of ground beetle abundance and community attributes than any other habitat variables measured in this study. Similar results were found when analyzing boreal bird community responses to multi-cohort related structural variation in boreal mixedwood forests (Burrell et al. 2013). This predictive power appears to be related primarily to the scale parameter, which in turn was correlated with the grain of the understory vegetation, canopy height, and shrub openness. ...
Multi-cohort management (MCM) that retains a range of stand structures (age and size class) has been proposed to emulate natural disturbance and improve management in the Nearctic boreal forest. Although MCM forests contain both single- and multi-aged stands of mixed tree sizes, little is known about how variable stand structure affects associated fauna and biodiversity. Here, we examine the relationship between ground beetle (Coleoptera, Carabidae) communities and stand characteristics across a range of forest structure (=cohort classes). Given that MCM classes are defined by the distribution of their tree–stem diameters, we ask whether parameters associated with these distributions (Weibull) could explain observed variation in carabid communities, and if so, how this compares to traditional habitat variables such as stand age, foliage complexity or volume of downed woody debris. We sampled carabids using weekly pitfall collections and compared these with structural habitat variables across a range of cohort classes (stand structure and age since disturbance) in 18 sites of upland mixed boreal forests from central Canada. Results showed that richness and diversity of carabid communities were similar among cohort classes. Weibull parameters from the diameter distribution of all stems were the strongest predictors of variation in carabid communities among sites, but vertical foliage complexity, understory thickness, and percentage of deciduous composition were also significant. The abundance of several carabid forest specialists was strongly correlated with tree canopy height, the presence of large trees, and high vertical foliage complexity. Our results demonstrate that variable forest structure, as expected under MCM, may be useful in retaining the natural range of ground beetle species across the central Nearctic boreal forest.
Multi-cohort forest management (MFM) is a natural disturbance emulation strategy for boreal forests that recommends a diversification of silvicultural techniques to emulate three broad successive phases of post-fire development, termed "cohort classes" Here, for boreal mixedwood (n = 308) and black spruce (n = 108) stands of northeastern Ontario, we: 1) present a multivariate approach to classify the three cohort classes based on a broad set of stand structural variables related to live-tree diameters, densities, and measures of canopy stratification and 2) investigate variation in stand age, mode of stand origin (including horse- And mechanically logged and natural-origin stands), and deadwood features among the cohort classes. In both forest types, average stem diameter distributions in cohort class 1 were normally distributed, those in class 2 showed broader normal distributions, and those in class 3 showed inverse-J distributions. Mean stand age increased with cohort class, and was positively correlated with cohort class in both forest types. Overall, variation in age and deadwood features as a function of cohort class in both forest types provided strong support for developmental aspects of our cohort classifications. Previously logged stands were primarily associated with lower cohort classes, whereas natural-origin stands were strongly associated with complex cohort class 3 stand structures, especially in mixedwoods. As it is primarily the silvicultural manipulation of stand structure that has been proposed to emulate age-related multi-cohort development, our structural cohort classification approach is particularly relevant to the application of MFM in Ontario.
Despite its role as a keystone species, few studies have investigated the habitat requirements of the Yellow-bellied Sapsucker (Sphyrapicus varius (L., 1766)) in the northwestern part of its range, where the current forest harvesting rotation schedule and targets for reducing the prevalence of old and mixedwood stands may reduce the optimal habitat for this species. We studied nesting and foraging habitat requirements of nesting sapsuckers in a boreal mixedwood forest of northwestern Canada by collecting data on nesting sites and foraging substrates on twenty-four 16- to 56-ha plots distributed among four habitat types in 1998 and 2002. Nests (n = 68) were generally found in large (>= 22 cm diameter at breast height) trembling aspen (Populus tremuloides Michx) that were alive but declining and that showed high incidence (81.1%) of heartwood rot infection (Phellinus tremulae (Bondarzev) Bondarzev & Borisov in Bondarzev). Nest-site use by sapsuckers was predicted mainly by the presence of external fungal conks and tree diameter. Among tree species used as foraging substrates, paper birch (Betula papyrifera Marsh.) (65.6%) and green alder (Alnus viridis (Vill.) Lam. & DC.) (21.3%) were used most frequently. The use of birch was strongly correlated with its availability. Mature forests had higher densities of nesting sites and foraging substrates than immature aspen stands. In addition to reconfirming the importance of mature mixedwood forests for Yellow-bellied Sapsuckers, our study also indicates that forest harvest rotations in northwestern Canada should exceed 90 years to promote the keystone role of this species.
In Canada, there are still extensive tracts of boreal forest consisting of stands that have resulted from natural disturbances. The country's forests are a mosaic made up to a large extent of old-growth forest that is beyond commercial harvesting age, especially in the boreal forest of eastern Canada. As areas of boreal forest under management steadily expand, as demand for forest products continues to grow and as rotation periods become shorter in response to silvicultural practices, the forest cover will inevitably become younger, causing changes to the structure and composition of the mosaic of forest stands that will affect the aspect of entire landscapes. These changes may have an adverse impact on biological diversity. Forest birds are one group of living organisms that may respond quickly to the advent of younger forest landscapes, thereby acting as a biological indicator. In this paper, we discuss some of the problems that birds face as a result of the truncation of the age-class distribution of managed forest landscapes in eastern Canada's coniferous boreal forest, using data obtained from our research in the Clay Belt region of Quebec and Ontario. More specifically, we look at how birds respond to changes in forest structure and composition in terms of time since natural disturbances, and to variation in dead trees availability. We then consider the impact of the prospective rejuvenation of the forest cover in managed forest landscapes, and possible solutions aimed at mitigating that impact through new management strategies based on the maintenance of forest ecosystem diversity. The ability of these new management strategies to maintain the ecological integrity of bird communities provides an indication of their potential as tools for contributing to the maintenance of biological diversity in a broader sense. Key words: bird communities, old black spruce forests, natural landscape age structure, stand structure, dead wood, multicohort management
Presettlement forest composition along a 278 km long transect through central Ontario was recreated from Ontario land survey notes (1857) and compared with existing forest composition as derived from Forest Resource Inventories (1981-1995). Trends through time were analyzed by means of detrended correspondence analysis and univariate statistics (paired t tests and Wilcoxon matched-pair signed-ranks tests). Ordinations based on the first tree taxon listed in a stand and on all tree taxa provided similar results. The eastern half of the transect was initially dominated by boreal conifers, whereas the western half supported stands typical of Ontario's Great Lakes - St. Lawrence (GLSL) region. Significant reductions of yellow birch (Betula alleghaniensis Britt.), balsam fir (Abies balsamea (L.) Mill.), and eastern white cedar (Thuja occidentalis L.) and significant increases of poplar (Populus spp.) and white birch (Betula papyrifera Marsh.) were observed within the boreal half. A significant reduction in eastern white cedar and an increase poplar were observed in the western half. Changes in the boreal region strongly support previous studies conducted over shorter time periods and may be attributed to clear-cut harvesting. The persistence of shade-tolerant hardwoods within the GLSL region can be attributed to the prevalence of small-scale disturbances associated with partial-cut harvesting systems.
Balsam fir (Abies balsamea (L.) Mill.) mortality caused by the last spruce budworm (Choristoneura fumiferana (Clem.)) outbreak (1970-1987) was studied in 624 sites belonging to a complex natural forest mosaic originating from different fires in northwestern Quebec. Multiple regression analyses were used to assess the respective effects of stand structure, species composition, site characteristics, and the forest composition surrounding the stand on observed stand mortality. Mortality was observed to increase in relation to diameter of the trees, basal area of balsam fir, and the number of stands dominated by conifers in the forest mosaic. All of these factors showed significant independent effects, but 60% of the variance remained unexplained. Site characteristics, however, did not show a significant relationship to stand mortality. The results suggest that forest composition at both the stand and the forest mosaic levels may be responsible for differing degrees of defoliation that result in differences in stand mortality. Forest management strategies that favor the presence of mixed compositions both at the stand level and at the mosaic level may contribute to decreased stand vulnerability.
Fire is fundamental to the natural dynamics of the North American boreal forest. It is therefore often suggested that the impacts of anthropogenic disturbances (eg logging) on a managed landscape are attenuated if the patterns and processes created by these events resemble those of natural disturbances (eg fire). To provide forest management guidelines, we investigate the long-term variability in the mean fire interval (MFI) of a boreal landscape in eastern North America, as reconstructed from lacustrine (lake-associated) sedimentary charcoal. We translate the natural variability in MFI into a range of landscape age structures, using a simple modeling approach. Although using the array of possible forest age structures provides managers with some flexibility, an assessment of the current state of the landscape suggests that logging has already caused a shift in the age-class distribution toward a stronger representation of young stands with a concurrent decrease in old-growth stands. Logging is indeed quickly forcing the studied landscape outside of its long-term natural range of variability, implying that substantial changes in management practices are required, if we collectively decide to maintain these fundamental attributes of the boreal forest.
Two common methods of measuring forest stand woody stem attributes include prism plots for basal area and modified point-distance for stem density. The data from each method can be used for the other calculation; that is, prism data can provide stem density, and point-distance data can provide estimated basal area. We examined data from the same 10 stands using the two techniques to determine whether the results for each calculation were comparable and/or consistent. There was a significant correlation between the estimated tree (defined as stems >10 cm) basal areas, and between tree stem densities, derived from the two methods (P < 0.01). Prism plots provided significantly higher estimated tree stem densities (+23.5%; P < 0.05) compared to estimates from the point-distance technique, but there was no difference between estimated tree basal area. For all stems, that is also including stems <10 cm dbh, there was no difference between the two methods for estimated basal area or stem density. There was no correlation between total stem densities derived from the two methods. This is likely because the prism plot method (two-factor metric prism) sampled relatively few trees with small diameters, whereas the point distance technique, as used, sampled small trees independently from trees using a diameter distinction. When we removed two young stands with <50 trees/ha, there was no difference in estimates of stem density. We concluded that, for boreal forest stands with a normal density of trees (i.e., >10 cm dbh and 900 to 3,000 stems/ha), either method would provide comparable estimates of stem density and basal area. We found no time difference in conducting surveys using either method.
Bird community response to both landscape-scale and local (forest types) changes in forest cover was studied in three boreal mixed-wood forest landscapes modified by different types of disturbances: (1) a pre-industrial landscape where human settlement, agriculture, and logging activities date back to the early 1930s, (2) an industrial timber managed forest, and (3) a forest dominated by natural disturbances. Birds were sampled at 459 sampling stations distributed among the three landscapes. Local habitat and landscape characteristics of the context surrounding each sampling station (500-m and 1-km radius) were also computed. Bird communities were influenced by landscape-scale changes in forest cover. The higher proportion of early-successional habitats in both human-disturbed landscapes resulted in significantly higher abundance of early- successional bird species and generalists. The mean number of mature forest bird species was significantly lower in the industrial and pre-industrial landscapes than in the natural landscape. Landscape-scale conversion of mature forests from mixed-wood to deciduous cover in human-disturbed landscapes was the main cause of changes in mature forest bird communities. In these landscapes, the abundance of species associated with mixed and coniferous forest cover was lower, whereas species that preferred a deciduous cover were more abundant. Variation in bird community composition determined by the landscape context was as important as local habitat conditions, suggesting that predictions on the regional impact of forest management on songbirds with models solely based on local scale factors could be misleading. Patterns of bird species composition were related to several landscape composition variables (proportions of forest types), but not to configuration variables (e.g., interior habitat, amount of edge). Overall, our results indicated that the large-scale conversion of the southern portion of the boreal forest from a mined to a deciduous cover may be one of the most important threats to the integrity of bird communities in these forest mosaics. Negative effects of changes in bird communities could be attenuated if current forestry practices are modified toward maintaining forest types (deciduous, mixed-wood, and coniferous) at levels similar to those observed under natural disturbances.
In boreal forests, several bird species use standing dead trees for feeding or nesting and depend on them for their survival. Studies on wildlife use of snags have shown that their availability is greatly influenced by the age of the forest and the type of perturbation (natural versus anthropogenic). Accordingly, cavity-nesting birds seem largely affected by these changes in availability of snags. In North American boreal forests, relationships between birds and dead wood availability have predominantly been documented in western forests. The dynamics of dead wood and the distribution patterns of birds associated with this habitat feature remain largely unknown in eastern black spruce forests. Distribution patterns of birds associated with dead wood were documented in the eastern black spruce forest of northwestern Quebec, Canada. Study areas were composed of four forest landscapes (50-100 km 2) that were naturally disturbed by different fire events (1 year, 20 years, 100 years and > 200 years) and two logged landscapes (20 years, 80 years). Birds were surveyed by point counts. Overall, 348 point counts were distributed over the six forest landscapes. Vegetation plots centered at each point count were used to sample live trees and dead wood. In naturally disturbed forest landscapes, species richness and abundance cavity-nesting birds reached a peak in early post-fire and in mature forest landscapes. Standing dead wood availability and abundance patterns of cavity-nesting birds were significantly less in 20-year-old managed forests landscapes than in those of naturally disturbed forests landscapes. This pattern was persistent in mature forests comparisons between 80-year-old horse-logged second-growth forests and mature forests of post-fire origin. Our results suggest that old-growth forests in this portion of the eastern black-spruce forest ecosystem do not play a key role for cavity-nesting birds. Mature and over-mature stands are, however, key habitats for many species of secondary cavity nesters, whereas early post-fire stands are key habitats for primary cavity-nesting birds and represent the main source of recruitment for standing dead wood in this ecosystem. Changes in silvicultural practices designed to maintain specific structure of over-mature stands (increased partial cutting) may provide a means for maintaining cavity-nesting birds at the landscape scale. Intensification of salvage cutting in early post-fire landscapes is another serious concern in black spruce forests. Reduction in the overall availability of dead wood through such forest practice may affect populations of some primary cavity nesters that are restricted to this specific forest type.
Forest ecosystem management, based partly on a greater understanding of natural disturbance regimes, has many variations but is generally considered the most promising approach to accommodating biodiversity concerns in managed forested regions. Using the Lake Duparquet Forest in the southeastern Canadian boreal forest as an example, we demonstrate an approach that attempts to integrate forest and stand-level scales in biodiversity maintenance. The concept of cohorts is used to integrate stand age, composition and structure into broad successional or stand development phases. Mean forest age (MFA), because it partly incorporates historic variability of the regional fire cycle, is used as a target fire cycle. At the landscape level, forest composition and cohort objectives are derived from regional natural disturbance history, ecosystem classification, stand dynamics and a negative exponential age distribution based on a 140 year fire cycle. The resulting multi-cohort structure provides a framework for maintaining the landscape in a semi-natural age structure and composition. At the stand level, the approach relies on diversifying interventions, using both even-aged and uneven-aged silviculture to reflect natural stand dynamics, control the passage (“fluxes”) between forest types of different cohorts and maintain forest-level objectives. Partial and selective harvesting is intended to create the structural and compositional characteristics of mid- to late-successional forest types and, as such, offers an alternative to increasing rotation lengths to maintain ecosystem diversity associated with over-mature and old-growth forests. The approach does not however supplant the necessity for complementary strategies for maintaining biodiversity such as the creation of reserves to protect rare, old or simply natural ecosystems. The emphasis on maintaining the cohort structure and forest type diversity contrasts significantly with current even-aged management in the Canadian boreal forest and has implications for stand-level interventions, notably in necessitating a greater diversification of silvicultural practices including more uneven-aged harvesting regimes. The approach also presents a number of operational challenges and potentially higher risks associated with multiply stand entries, partial cutting and longer intervals between final harvests. There is a need for translating the conceptual model into a more quantitative silvicultural framework. Silvicultural trials have been established to evaluate stand-level responses to treatments and operational aspects of the approach.
A method is proposed to partition the variation of species abundance data into independent components: pure spatial, pure environmental, spatial component of environmental influence, and undetermined. The new method uses pre-existing techniques and computer programs of canonical ordination. The intrinsic spatial component of community structure is partialled out of the species-environment relationship in order to see if the environmental control model still holds. The method is illustrated using oribatid mites in a peat blanket, forest vegetation data, and aquatic heterotrophic bacteria. In this latter example, the new method is shown to be complementary to another approach based on partial Mantel tests.
1. Studies on the variability of natural fire regimes are needed to understand plant responses in a changing environment. Since vegetation changes might follow or trigger changes in fire frequency, climate models suggest that changes in water balance will accompany current global warming, and the response of fire regimes to Holocene hydro-climate changes and vegetation switches may thus serve as a useful analogue for current change. 2. We present high-resolution charcoal records from laminated cores from three small kettle lakes located in mixed-boreal and coniferous-boreal forest. Comparison with some pollen diagrams from the lakes is used to evaluate the role of the local vegetation in the fire history. Fire frequency was reconstructed by measuring the separation of peaks after detrending the charcoal accumulation rate from any background. 3. Several distinct periods of fire regime were detected with fire intervals. Between c. 7000-3000 cal. year BP, fire intervals were double those in the last 2000 years. Fire frequency changed 1000 years earlier in the coniferous-boreal forest than in the mixed-boreal forest to the south. The absence of changes in combustibility species in the pollen data that could explain the fire frequency transition suggests that the vegetation does not control the long-term fire regime in the boreal forest. 4. Climate appears to be the main process triggering fire. The increased frequency may be the result of more frequent drought due to the increasing influence of cool dry westerly Pacific air-masses from mid to late Holocene, and thus of conditions conducive to ignition and fire spread. In east Canada, this change matches other long-term climate proxies and suggests that a switch in atmospheric circulation 2-3000 years ago triggered a less stable climate with more dry summers. Future warming is moreover likely to reduce fire frequency.
Silvicultural practices following clearcutting in boreal forest may encourage the creation of monospecific, single-aged stands having less vegetation heterogeneity and diversity than original stands. We conducted point counts in central Saskatchewan, Canada, 1993-1995, in pure and mixedwood stands dominated by black spruce (Picea mariana), jackpine (Pinus banksiana), trembling aspen (Populus tremuloides), or white spruce (Picea glauca). Mixedwood stands supported more individuals and more species than pure stands. Higher abundance in mixedwood stands relative to pure stands was consistent among nesting guilds and migration strategies. Rarefaction revealed similar patterns, although pure trem- bling aspen stands were predicted to support more species than aspen-dominated mixedwood stands. Increased avian diversity in mixedwood stands was not solely the result of the mixing of bird species associated with coniferous or deciduous forest types. Chipping Sparrow (Spizella passerina), Pine Siskin (Carduelis pinus), White-winged Crossbill (Loxia leucop- tera), Red-breasted Nuthatch (Sitta canadensis), Swainson's Thrush ( Catharus ustulatus), and Tennessee Warbler (Vermivora peregrina) were more abundant in mixedwood stands than pure stands. Black-throated Green Warbler (Dendroica virens), Magnolia Warbler (D. magnolia), and Blackburnian Warbler (D. fusca) were abundant in stands dominated by white spruce but were absent from jackpine or black spruce. Other species such as American Redstart (Setophaga ruticilla) and Chestnut-sided Warbler (D. pensylvanica) relied exclu- sively on pure trembling aspen, particularly stands with dense shrub cover. Several bird species in the boreal forest will be adversely affected by forestry practices that target mature to old aspen and white spruce mixedwoods and promote reduction in mixedwood compo- sitions of regenerating stands.
Emulation silviculture is the use of silvicultural techniques that try to imitate natural disturbances such as wildfire. Emulation silviculture is becoming increasingly popular in Canada because it may help circumvent the political and environmental difficulties associated with intensive forest harvesting practices. In this review we summarize empirical evidence that illustrates disparities between forest harvesting and wildfire. As a rule, harvesting and wildfire affect biodiversity in different ways, which vary a great deal among ecosystem types, harvesting practices, and scale of disturbance. The scales of disturbance are different in that patch sizes created by logging are a small subset of the range of those of wildfire. In particular, typical forestry does not result in the large numbers of small disturbances and the small number of extremely large disturbances created by wildfires. Moreover, the frequency of timber harvesting is generally different from typical fire return intervals. The latter varies widely, with stand-replacing fires occurring in the range of 20 to 500 years in Canada. In contrast, harvest frequencies are dictated primarily by the rotational age at merchantable size, which typically ranges from 40 to 100 years. Forest harvesting does not maintain the natural stand-age distributions associated with wildfire in many regions, especially in the oldest age classes. The occurrence of fire on the landscape is largely a function of stand age and flammability, slope, aspect, valley orientation, and the location of a timely ignition event. These factors result in a complex mosaic of stand types and ages on the landscape. Timber harvesting does not generally emulate these ecological influences. The shape of cut blocks does not follow the general ellipse pattern of wind driven fires, nor do harvested stands have the ragged edges and unburned patches typically found in stand-replacing fires. Wildfire also leaves large numbers of snags and abundant coarse woody debris, while some types of harvesting typically leave few standing trees and not much large debris. Successional pathways following logging and fire often differ. Harvesting tends to favor angiosperm trees and results in less dominance by conifers. Also, understory species richness and cover do not always recover to the pre-harvest condition during the rotation periods used in typical logging, especially in eastern Canada and in old-growth forests. As well, animal species that depend on conifers or old-growth forests are affected negatively by forest harvesting in ways that may not occur after wildfire. The road networks developed for timber extraction cause erosion, reduce the areas available for reforestation, fragment the landscape for some species and ecological functions, and allow easier access by humans, whereas there is no such equivalency in a fire-disturbed forest.
Forest stand structure is an important element for biodiversity and, from a sustainable forest management perspective, uneven-sized stands should be managed in order to maintain the structural diversity over the landscape. The first objective of this study is to develop a statistical tool to characterize stand structure that can be used in forest management planning. The second objective is to classify the stand structure of two regions to illustrate a possible use for the tool. The statistical tool for characterizing stand structure has been developed from forest inventory data gathered by the ministèe des Ressources naturelles du Québec, using discriminant analysis. The analysis makes it possible to classify the stands into three types of structure, even-sized, uneven-sized and inverse J-shaped, with an error rate estimated at only 7%. Proportions of different structure types in Quebec's eastern black spruce forest region have been compared with those found in the western black spruce forest region. Nearly 90% of the western black spruce forest region is composed of pure black spruce stands, contrary to the eastern black spruce region, where there are more pure fir and mixed spruce-fir stands. Most of the western black spruce forest stands are even-sized (62%), while almost 70% of the eastern black spruce forest stands are uneven-sized or inverse J-shaped. Pure black spruce stands are more even-sized than pure fir stands, but regional differences are also found within pure black spruce stands. Our results show that it is possible to develop a robust tool that makes it possible to classify thousands of stands rapidly. Such tools are required if we want to consider stand structure for appropriate management prescriptions in the boreal forest.
Forest stand structure is an important element for biodiversity and, from a sustainable forest management perspective, uneven-sized stands should be managed in order to maintain the structural diversity over the landscape. The first objective of this study is to develop a statistical tool to characterize stand structure that can be used in forest management planning. The second objective is to classify the stand structure of two regions to illustrate a possible use for the tool. The statistical tool for characterizing stand structure has been developed from forest inventory data gathered by the ministère des Ressources naturelles du Québec, using discriminant analysis. The analysis makes it possible to classify the stands into three types of structure, even-sized, uneven-sized and inverse J-shaped, with an error rate estimated at only 7%. Proportions of different structure types in Quebecs eastern black spruce forest region have been compared with those found in the western black spruce forest region. Nearly 90% of the western black spruce forest region is composed of pure black spruce stands, contrary to the eastern black spruce region, where there are more pure fir and mixed spruce-fir stands. Most of the western black spruce forest stands are even-sized (62%), while almost 70% of the eastern black spruce forest stands are uneven-sized or inverse J-shaped. Pure black spruce stands are more even-sized than pure fir stands, but regional differences are also found within pure black spruce stands. Our results show that it is possible to develop a robust tool that makes it possible to classify thousands of stands rapidly. Such tools are required if we want to consider stand structure for appropriate management prescriptions in the boreal forest. Key words: Even- and uneven-sized structure, fire regime, Picea mariana, Abies balsamea, boreal forest, structural diversity
Long-term trends in the 22 most abundant land bird species breeding in N Finland were related to habitat selection patterns. Independent data sets were used to describe long-term population trends (POP), edge preferences (EDGE) and effects of the changing age structure of the forests on bird density (AGE). EDGE and AGE correlated positively though not significantly with POP. When EDGE and AGE were taken into account simultaneously, a significant correlation with POP emerged (67% of the variance). Southern species' population trends, however, depend on changes in S Finland. The sedentary species of old forests have plummeted during the recent decades in N Finland. Results for this group (Parus montanus, P. cristatus, P. cinctus, Certhia familiaris, Perisoreus infaustus) suggest that fragmentation and changes in the age structure of the forests are mainly responsible for the recent trends among the abundant forest birds in the north. Results suggest a close tracking of environmental resources by the bird community, but, as the geographical scale of the study is broad and the temporal scale decades rather than years, a simple saturation hypothesis is not an inevitable inference from the data; and if there is close tracking of the environmental resources, it is in terms of populations, not of the community. An alternative hypothesis is provided by changing numbers of high-quality and low-quality population sites; the regional pattern is here a result of complicated dynamics in a mosaic of local populations. -from Authors
The current provincial-extent digital elevation model (DEM) and corresponding hydrological maps for Ontario have been produced using traditional photogrammetry and aerial photograph interpretation. This process is labour-intensive and requires visual interpretation of stereo image pairs. The ground surface and small hydrological features may be inaccurately delineated in areas where vegetation is dense or the ground is otherwise shielded from aerial view. In an effort to improve and automate delineation of hydrological features, we examined the behaviour and final products of the D8 flowrouting algorithm in 2 software environments (TAS and TauDEM for ArcGIS) operating on a high spatial resolution DEM derived using canopy-penetrating light detection and ranging (LiDAR) technology in a pilot study in the Romeo Malette Forest (41.25°N, 81.50°W). Filtered LiDAR data points (5-m spacing) were interpolated using IDW, TIN, and splines, each resulting in a 2.5-m spatial resolution DEM. Results demonstrate improved realism in the characterization of surficial hydrology by LIDAR derived products as compared to applying identical algorithms on existing coarser provincial data. Benefits include the ability to represent streams of lower Strahler order to define crisp watershed boundaries, and the more accurate identification of local depressions that form potentially wet sites. This approach identifies wet sites that should be avoided during forest operations (e.g., skidder traffic) and can provide additional information for trail layout, road planning, and water crossings. By increasing the number of uses of LiDAR, the capital investment in these data becomes increasingly palatable for forest companies interested in obtaining detailed plans of their forest holdings.
Reconciling tree harvesting with the maintenance of forest bird populations is a major concern of integrated management. Because bird nest predation causes >50% of the nest losses in passerines and is known to vary according to habitat characteristics, we explored some aspects of avian nest predation in relation to forestry practices in a boreal coniferous landscape managed primarily for timber production in Quebec. Using artificial tree and ground nests with Common Quail (Coturnix coturnix) and plasticine eggs, we compared the risk of nest predation (1) in experimental riparian forest strips of different widths (20-m, 40-m, and 60-m unthinned strips; >300-m control strips; and 20-m thinned strips) and (2) in clearcuts experimentally subjected to different regeneration practices (plantations with chemical and mechanical weeding, and naturally regenerated clearcuts) between 1992 and 1995. The risk of ground nest predation was lower in naturally regenerated clearcuts (5% daily probability of predation) than in control forest strips (27%). We found no evidence that chemical and mechanical weeding affected the risk of nest predation in clearcuts. In forest strips, the predation risk was higher in forest strips 40-60 m wide than in 20-m and control strips. Birds accounted for 13% of predation signs, whereas red squirrels (Tamiasciurus hudsonicus) were the dominant mammalian predators, accounting for 36% of the total predation (n = 201 nests preyed upon). In our region, the low predation rates (30% for 24 real nests) and the absence of generalist foragers such as crows, raccoons, and skunks could be attributed to the near absence of human occupation in comparison to forest-dominated landscapes in Europe and northeastern United States.
The relationship between mammal community structure and vertical variation in habitat physiognomy (complexity) and horizontal variation in habitat form (heterogeneity) was examined in the llanos of Venezuela. There was little association between habitat structure and the richness, diversity, abundance, and biomass of small mammals. Abiotic factors, such as the degree of wet-season flooding, probably play an important role in patterns of small mammal distribution and abundance. The total number of mammal species was positively correlated with habitat complexity but not correlated with habitat heterogeneity. Increasing species richness across the complexity gradient was probably accommodated by increasing potential food resources. New species were added to complex communities primarily through guild expansion rather than guild addition.-from Author
Comparisons of the effects of logging and fire as disturbance agents on the composition of bird assemblages in boreal ecosystems are still lacking or are limited to the short-term impacts of clear-cutting. In Quebec, where the boreal forest is largely dominated by black spruce (Picea mariana (Mill.) B.S.P.) stands, we surveyed 140 point-count stations in 3 postlogging and 4 postfire development stages determined according to the height of the regenerating spruce trees. Species richness did not vary among forest development stages, but bird abundance was higher in recent clearcuts. Recently disturbed areas were characterized by open-land bird assemblages dominated by Neotropical migrants, which reached their highest abundance in clearcuts. Moreover, logged stands were distinguished from burned sites by the absence of cavity-nesting birds. Forest-bird assemblages reestablished themselves as soon as young spruces reached the sapling stage. However, the Black-backed Woodpecker (Picoides arcticus), Three-toed Woodpecker (Picoides tridactylus), and Brown Creeper (Certhia americana) were restricted to mature stands or recent burns and are thus likely to be negatively affected by modern forestry, which involves fire suppression and short logging rotations. We suggest that retention of larger areas of continuous mature forest might be essential to maintain these species in managed regions.
We studied the impacts of low density, exurban housing developments on Wood Thrushes (Hylocichla mustelina) breeding in small forest fragments in two regions of rural southern Ontario. In both regions, Wood Thrushes breeding in woodlots with embedded houses (housing penetrating the forest border) experienced significantly higher rates of parasitism by Brown-headed Cowbirds (Molothrus ater) than Wood Thrushes breeding in woodlots with adjacent houses (houses within 100 m of the forest edge), or undeveloped woodlots (no houses within 100 m of the forest edge). Wood Thrushes breeding in Peterborough area woodlots with embedded or adjacent houses experienced significantly increased rates of nest predation compared to Wood Thrushes breeding in undeveloped woodlots. This increased nest predation resulted in significant reductions in seasonal productivity in developed woodlots. No increase in nest predation was experienced by Wood Thrushes nesting in developed woodlots in the Ottawa region. The effects of housing developments appear to be region-specific and may depend on other factors influencing the overall abundance of cowbirds.
The consequences of forest harvest to birds nesting in spatially and temporally dynamic landscapes are poorly understood. The boreal forests of Newfoundland have a low density of nesting birds, are naturally heterogeneous, and experience extreme annual variation in weather. Against this backdrop, we tested whether breeding success of passerines was affected by forest harvest or whether natural heterogeneity masked potential consequences of harvesting. During 2004 and 2005, we monitored 98 nests and banded 439 hatch-year (HY) birds of three migratory passerines in landscapes that varied in the extent of natural or human-induced heterogeneity: the White-throated Sparrow (Zonotrichia albicollis), Yellow-rumped Warbler (Dendroica coronata), and Blackpoll Warbler (Dendroica striata), We monitored nest-initiation date, clutch size, hatching success, nests' daily survival rates, fledging success, and productivity (ratio of HY to adults captured) relative to proportion of forest harvested within radii of 20 m (local scale), 115 m (neighborhood scale), and 1250 m (landscape scale). Local habitat and year significantly predicted nest-initiation date. Hatching success, fledging success, and productivity were significantly influenced by year and proportion of harvest at all scales, although associations varied by species. Nests' daily survival rates were significantly related to proportion of harvest at all three scales for the White-throated Sparrow; for all species they were consistently higher in 2005, and the direction of the harvest's effect differed by species. Our results reveal that larger scales are important later in breeding and that spatial and temporal heterogeneity may not only conceal consequences of forest harvest, they may also have complex interactions that make predictions difficult in these dynamic landscapes.
The notion that species might exhibit thresholds in their response to habitat alteration is appealing from a conservation perspective. Such thresholds could be used as targets for conservation in managed landscapes. In New Brunswick, Canada, forest management produces mosaics of varying stand age, species composition, and structure. We sampled this gradient in habitat suitability to examine the shape of species response functions and to look for evidence of statistically significant thresholds. We focused our attention on bird species breeding in late-seral forest and surveyed them at 390 point-count stations sampling broad-leaved deciduous to pure coniferous stands and a variety of silvicultural treatments (patch cutting, single-tree selection, spruce plantation [35–45 years old], and no recent treatment). A principal components analysis (PCA) on local vegetation separated stations along two axes reflecting gradients in stand composition and habitat alteration (increasingly open canopy and decreasing density of large trees/snags), respectively. We combined logistic regression and receiver-operating characteristic (ROC) analysis to detect thresholds in species occurrence along these gradients. Of the 42 species frequent enough to be included in the analyses, 13 (31%) showed a significant (p < 0.01) negative response to habitat alteration. Eight of the 13 species sensitive to habitat alteration exhibited thresholds in their occurrence after controlling for the suitability of local habitat. According to curves of the expected number of sensitive species (based on their ROC-derived thresholds), canopy closure and the density of large trees (>30 cm dbh) should be at least 70% and 80 stems/ha, respectively, to expect to find the complete assemblage of bird species. However, these values should be viewed as liberal, given the nature of our response variable. More refined (e.g., fitness) parameters should be used to be conservative. Nonetheless, the approach allowed us to establish preliminary quantitative targets for conservation planning based on time-efficient sampling methods, and to explicitly account for the continuous variability existing within and among silvicultural treatments rather than to assume homogeneity within treatments.Resumen: La noción de que las especies pueden presentar umbrales en su respuesta a las alteraciones del hábitat es atrayente desde una perspectiva de conservación. Tales umbrales podrían ser utilizados como objetivos de conservación en paisajes bajo gestión. En Nuevo Brunswick, Canadá, la gestión de bosques produce mosaicos de bosques de edades, composición y estructura de especies diferentes. Muestreamos este la aptitud del hábitat en este gradiente para examinar la forma de las funciones de respuesta de las especies y para buscar evidencia de umbrales estadísticamente significativos. Centramos nuestra atención en la especies de aves que se reproducen en bosque seral tardío y las muestreamos en 390 estaciones conteo por puntos en bosques deciduos de hoja ancha hasta bosques puros de coníferas y una variedad de tratamientos silvícolas (corte por parches, selección de árbol único, plantación de abetos [35-45 años de edad] y sin tratamiento reciente). Un análisis de componentes principales (ACP) de la vegetación local separó estaciones a lo largo de dos ejes que reflejan los gradientes en composición del bosque y alteración del hábitat (dosel progresivamente abierto y reducción en la densidad de árboles/tocones grandes), respectivamente. Combinamos análisis de regresión logística y de característica receptor–operador (CRO) para detectar umbrales en la ocurrencia de especies a lo largo de estos gradientes. De las 42 especies suficientemente frecuentes para ser incluidas en el análisis, 13 (42%) mostraron una respuesta negativa significativa (p < 0.01) a la alteración del hábitat. Ocho de las 13 especies sensibles a la alteración del hábitat exhibieron umbrales en su ocurrencia después de controlar para la aptitud del hábitat local. De acuerdo con las curvas del número esperado de especies sensibles (con base en sus umbrales derivados del CRO), la cobertura del dosel y la densidad de árboles grandes (>30 cm dap) por lo menos deberían ser de 70% y 80 tallos/ha, respectivamente, para esperar encontrar al ensamble completo de especies de aves. Sin embargo, estos valores deben ser vistos como liberales, dada la naturaleza de nuestra variable de respuesta. Para ser conservadores se deben utilizar parámetros más refinados (e. g. adaptabilidad). Sin embargo, el método nos permitió establecer objetivos cuantitativos preliminares para la planificación de la conservación basada en métodos de muestreo rentables en tiempo y para dar cuenta explícita de la variabilidad continua que existe dentro y entre los tratamientos silvícolas en lugar de asumir que hay homogeneidad dentro de los tratamientos.
Summary • In northern Scandinavia there are indications of a long-term decline in the abundance of the three dominant vole species, Clethrionomys glareolus, Clethrionomys rufocanus and Microtus agrestis, since the 1970s. One explanation proposes that intensified clear-cutting has created even-aged and homogeneous forest stands with poor overall conditions for survival and reproduction of the voles. • We investigated the relationship between forest age and structural habitat factors and its implications for the species richness and abundance of small mammals. In particular, we assessed the population dynamics of C. glareolus, a forest-dwelling species with rather general habitat requirements. • Extensive snap-trapping of small mammals was conducted during 1998–2000 on 24 study sites in boreal forests in northern Sweden. Trapping was carried out along transects running from immature forests of six age classes (0–50 years) into adjacent reference sites (> 100 years). At each trapping station we recorded 14 habitat variables that were reduced to three principal components (PCs). The PCs were related to late successional traits, such as forest age and cover of tree layers (PC1), cover of tall vegetation in the field layer (PC2) and structural heterogeneity in the forest floor (PC3). • The species richness of small mammals, as well as the total abundance of C. glareolus, was positively influenced by tall vegetation (PC2) and structural heterogeneity (PC3) but not by late successional traits (PC1). The youngest forests had higher scores for both PC2 and PC3 compared with older forests. • The youngest forests also had the highest species richness and total abundance of C. glareolus. This was associated with a generally higher rate of change in numbers of C. glareolus during summer in the youngest forests compared with adjacent reference sites. In contrast, survival during winter was lower in the youngest forests. We found this result to be consistent with a source–sink scenario where young individuals, primarily born in old forest stands in early summer, migrate into younger forests to breed, but where the probabilities for winter survival are poor. • Our study demonstrates that both the species richness of small mammals and the population dynamics of C. glareolus are influenced to a great extent by structural habitat factors that are altered by common forest management practices in northern Sweden. In order to conserve species richness of small mammals and to minimize population fluctuations of C. glareolus in northern Scandinavia, we outline forest management practices that will provide heterogeneous environments, such as leaving logging residues on site after forest harvesting.
Regional variation in spore deposition and viability was studied for two fungi, Fomitopsis rosea (Alb. & Schwein.: Fr.) P. Karst. and Phlebia centrifuga P. Karst., both confined to old-growth spruce forests in the boreal zone. Seven regions in Sweden were studied along a north-south transect in which the historical impact from forestry increases and the amount old forests decreases towards the south. The two southernmost regions were located outside the distribution border of the species. Spore deposition was measured species specifically as heterokaryotisation of homokaryotic mycelia growing on wood discs. There was a significant decline in spore deposition towards the south for both species. F. rosea deposited an average amount of 111 spores m−2 24 h−1 in the northernmost region compared to less than 1 spore in the four southernmost regions. The corresponding values for P. centrifuga were 27 spores m−2 24 h−1 in the north compared to less than 2 spores in the 4 southernmost regions. No deposition was found south of the distribution borders. The viability of spores from local populations within each region was measured as germination success on nutrient media. Individual fruiting bodies from large populations in the north generally produced spores with higher germinability than fruiting bodies from geographically isolated populations in the central and southern regions. However, there was a high variation among the southern populations. Our data suggest that some populations in mid- and south Sweden may suffer from negative genetic effects, possibly associated with fragmentation and loss of habitat. Thus, the combination of low spore deposition and low germinability of spores may be a threat to the long-term persistence of F. rosea and P. centrifuga in southern Sweden. Several other species may experience the same situation, especially when considering the severe decline of dead wood in Swedish forests.
We studied edge effects on the American three-toed woodpecker (Picoides dorsalis) foraging behaviour in 18 remnant forest edges of black spruce and feather moss forests managed with a dispersed checkerboard pattern of clear-cuts. Our objectives were to assess (1) the characteristics of foraging substrates used by woodpeckers, (2) whether birds foraged according to the availability of high-quality foraging substrates found at varying distances from edges and (3) to characterize the movement patterns of foraging individuals near clear-cut boundaries. Behavioural observations of individuals allowed us to characterize all trees used for foraging according to their DBH, decay state, bark cover, tree species and top condition. We also georeferenced those trees, which allowed us to determine their distance from the edge and the orientation of the bird movements with regards to the edge. We sampled snags and downed woody debris along 80 m line transects that were oriented perpendicularly to the edge. Our results show that woodpeckers foraged in a relatively high proportion of live trees (35%). For live trees, woodpeckers used trees of larger diameter and black spruce was underused with regards to its availability. Among snags, woodpeckers preferred snags with a larger diameter, a lower decay class and a higher bark cover than nearest available snags. The density of high-quality foraging substrates (large recently dead trees) increased near the edge and decreased as we got farther into the forest interior. When comparing the distribution of used foraging snags with the one of available high-quality foraging substrates, our results show that these two distributions are significantly different. High-quality substrates located at 40 m or less from an edge were used less frequently than their availability. Hence, we can conclude that foraging woodpeckers can use snags near edges but are less prone to use these foraging trees even though they become more available than in the interior of remnant stands of managed forests. Nevertheless, bird movements were oriented parallel to the edge as far as 80 m away from the clear-cut boundary. Considering the under-utilisation of high-quality substrates near edges, we suggest that foraging substrate availability cannot explain the results obtained; the hypothesis that edges are acting as movement conduits likely explain woodpecker movement patterns we observed. Finally, the retention of larger tracks of mature and overmature forests would reduce the amount of edge habitat and provide better foraging conditions for American three-toed woodpecker in extensively managed landscapes.
Fire history was reconstructed for an area of 15 000 km 2 located in the transition zone between the mixed and coniferous forests in Quebec's southern boreal forest. We used aerial photographs, archives, and dendroecological data (315 sites) to reconstruct a stand initiation map for the area. The cumulative distribution of burnt area in relation to time since fire suggests that the fire frequency has decreased drastically since the end of the Little Ice Age (about 1850) in the entire region. However, a large part of the area was burned between 1910 and 1920 during intensive colonization and when the climate was very conducive to fire. For the period 1920–1945, large fires have mainly been concentrated in the more populated southern area, while few fires have been observed in the virgin coniferous forest in the north. Despite slight differences between the south and the north, fire cycles or the average number of years since fire are not significantly different. Since 1945, there have been far more fires in the south, but the mean fire size was smaller than in the north. These results suggest that the transition between the mixed and coniferous forests observed in the southern boreal forest cannot be explained by a difference in fire frequency, at least during the last 300 years. As climatic factors and species potential distribution did not vary significantly from south to north, we suggest that the transition from mixedwood to coniferous forests is mainly controlled by fire size and severity. Smaller and less severe fires would favor species associated with the mixedwood forests as many need survivors to reinvade burnt areas. The abundance of deciduous species in mixedwood forests, together with the presence of more lakes that can act as firebreaks, may contribute to decreases in fire size and severity. The transition between the two vegetation zones could be related to the initial setting following the vegetation invasion of the area during the Holocene. In this context, the limit of vegetation zones in systems controlled by disturbance regimes such as fires may not have reached a balance with current climatic conditions. Historical legacies and strong positive feedback between disturbance regimes and com-position may filter and delay the responses to changes in climate.
Extensive even-aged management of the boreal forest and its consequences on the loss of late-seral stages (>100 years) is raising concerns about the future of organisms associated with standing deadwood. The considerable reduction of deadwood not only at the stand but at the landscape level is considered to be one of the principal causes of biodiversity loss in managed forest ecosystems worldwide. Ecosystem-oriented management approaches propose a fundamental change in forestry practices whereby live and dead tree retention becomes an important consideration in forest harvesting. We use woodpecker assemblages and their association with standing deadwood for both nesting and foraging to emphasize the importance of the entire range of snag degradation stages for maintenance of key ecological processes in habitat remnants of managed landscapes. We argue that bridging foraging and nesting knowledge of woodpecker's snag requirements can refine conservation objectives for deadwood retention in the boreal forest.
Clear-cut harvesting can alter ecosystem conditions and dynamics drastically compared to natural disturbance regimes, hence alternative harvesting systems are being developed in an attempt to better mimic natural forest structure. A recent approach is to harvest trees at variable intensities and spatial configurations in what is known as variable retention harvesting. Our study examines the responses of aerial insect assemblages to a gradient of forest retention at the landscape scale, and provides an assessment of the conservation benefits of alternative versus traditional harvesting systems in lowland boreal forest. The experimental design consisted of six treatments representing decreasing levels of structural retention at the landscape scale (with four replicates per treatment): (1) unharvested forest interior; (2) unharvested forest edge; (3) high-structural retention (strip retention harvesting areas at the edge of adjacent areas of unharvested forest); (4) medium-structural retention (strip retention harvesting areas in the interior of contiguous retention harvesting areas); (5) low-structural retention (strip retention harvesting areas adjacent to clear-cutted areas); (6) clear-cut harvesting. Response variables were the abundances of selected families and trophic assemblages of aerial insects, which were sampled with Malaise traps at each site. Univariate and multivariate analyses showed that the structural-retention harvesting influenced the abundance of most families and trophic assemblages. Most insect families and assemblages were most abundant in the strip retention harvested areas, especially in the medium retention treatment. These increases in abundance reflected strong edge effects, as evidenced by the fact that significant treatment effects were observed even within the two major habitat types of the study (cleared or forested habitat). Increasing structural retention favoured some assemblages such as Diapriidae, herbivores, and parasitoids whereas other groups such as predators decreased in abundance. Results support the potential use of high-level taxonomic and trophic assemblages of aerial insects in monitoring the ecological sustainability of forest harvesting practices.
Efforts to preserve biological diversity must focus increasingly at the ecosystem level because of the immense number of species, the majority of which are currently unknown. An ecosystem approach is also the only way to conserve processes and habitats (such as forest canopies, belowground habitats, and hyporheic zones) that, with their constituent species, are poorly known. Continued concern with species is essential, however. Landscape-level issues also need much greater attention. Designing an appropriate system of habitat reserves is one landscape- level concern. Understanding and appropriately manipulating the landscape matrix is at least equal in importance to reserves issues, however, since the matrix itselfis important in maintaining diversity, influences the effectiveness of reserves, and controls landscape connectivity.
Pileated Woodpecker (Dryocopus pileatus ) The Birds of North America Online
Bull, E. and J. Jackson. 1995. Pileated Woodpecker (Dryocopus pileatus ). In A. Poole (ed.). The Birds of North America Online [online].
A Forest Habitat Suitability Matrix for Northeastern Ontario
R G D'eon
W W Watt
D'Eon, R.G. and W.W. Watt. 1994. A Forest Habitat Suitability Matrix
for Northeastern Ontario. Natural Resources Canada, Canadian Forest
Service, Timmins, ON. 83 p.
Ontario forest growth and yield program field manual for establishing and measuring permanent sample plots. Ontario Ministry of Natural Resources
Hayden, J., J. Kerley, D. Carr, T. Kenedi and J. Hallarn. 1995. Ontario forest growth and yield program field manual for establishing and
measuring permanent sample plots. Ontario Ministry of Natural Resources, Ontario Forest Research Institute, Sault Ste. Marie, ON.
Hejl, S., K. Newlon, M. Mcfadzen, J. Young and C. Ghalambor.
2002. Brown Creeper (Certhia americana). In A. Poole (ed.). The Birds
of North America Online [online].
Edge effects in central Amazonian forest fragments
Magurran, A. 1988. Ecological Diversity and its Measurement.
Princeton University Press, Princeton, NJ.
Malcolm, J. 1994. Edge effects in central Amazonian forest fragments.
Ecology. 75: 2438-2445.
Classification of Northern Abitibi' s spruce-moss forest stands according to their internal structure. Preliminary report to the Quebec Ministry of Natural Resources
Nguyen, T. 2000. Classification of Northern Abitibi' s spruce-moss forest stands according to their internal structure. Preliminary report to
the Quebec Ministry of Natural Resources. July 2000. 24 p.
Forest management guide for natural disturbance pattern emulation, Version 3.1. Queen' s Printer for
O N Philips
Ontario Ministry of Natural Resources. 2001. Forest management guide for natural disturbance pattern emulation, Version 3.1.
Queen' s Printer for Ontario, Toronto, ON.
Philips, J., E. Nol, D. Burke and W. Dunford. 2005. Impacts of housing developments on Wood Thrush nesting success in hardwood forest
fragments. Condor. 107: 97-106.
The Birds of North America Online
Poole, A.( ed.). 2009. The Birds of North America Online [online].
Forest Regions of Canada. Rev. edition. Dept. of the Environment. Canadian Forestry Service. Publication, no. 1300 Information Canada
J S Rowe
Rowe, J.S. 1972. Forest Regions of Canada. Rev. edition. Dept. of the
Environment. Canadian Forestry Service. Publication, no. 1300 Information Canada, Ottawa, ON. 172 p.