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Increased fire severity in boreal forests of Interior Alaska is shifting forest canopy composition from black spruce ( Picea mariana ) to deciduous species, including trembling aspen ( Populus tremuloides ) and Alaska paper birch ( Betula neoalaskana ). Because deciduous trees are less flammable than black spruce, the dominant disturbance regime in deciduous forests could move away from fire to one of gap disturbances. In this study, we quantified forest gap characteristics and vegetation within eight mature (62–119-yr-old) deciduous stands in Interior Alaska. Canopy gaps were generally small (true gap area <50 m 2 ), formed by the mortality of 4–16 gap makers (which were always deciduous trees), and occupied ∼17–29% of the forest except in the oldest stand, where gap fraction exceeded 45%, and in one anomalous 84-yr old stand, where gaps were absent. Canopy openness increased linearly with gap area, but density of both deciduous and evergreen tree recruits was generally low and insufficient to create future stands with densities similar to those currently found in mature stands across the landscape. Canopy openness was instead correlated with decreased leaf litter cover and increased cover of moss, lichen, and evergreen shrubs. Given the low recruitment of trees with canopy gaps and the decreased probability of fire, deciduous stands will likely transition to non-forested areas or low density stands once overstory trees reach maturity and die. This could have numerous implications for ecosystem function, including carbon (C), water, and energy balance, and potential feedbacks to future fire occurrence and regional climate. [ABSTRACT FROM AUTHOR]

Abstract: Postfire tree species compositions are predicted to be the same prior to fire according to the direct regeneration hypothesis (DRH). We studied 94 upland boreal forest stands between 5 and 18 years after fire in Ontario, Canada. Postfire species-specific regeneration density was positively related to prefire stand basal area for Pinus banksiana, Populus spp., Betula papyrifera and Picea mariana, but not for Picea glauca and Abies balsamea. In addition, seedling density of Populus spp., B. papyrifera, P. mariana, P. glauca and A. balsamea were positively affected by build up index and, except Populus spp., their density increased with age of burn. To facilitate testing the DRH, we introduced a term called compositional difference (CD) that is the difference in a species relative percentage between the postfire and prefire stand. The testable null hypothesis is CD=0 for a given species. CD was not different from 0 for P. banksiana, was 19.8% for Populus spp., 10.4% for B. papyrifera, −17.9% for P. mariana, −14.6% for P. glauca, and −14.9% for A. balsamea, indicating fire increases broadleaves at the expenses of mid- and late-successional coniferous species. Compositional increases of Populus spp. and B. papyrifera in postfire stands occurred mostly where these species were a minor component prior to fire. In conclusion, the DRH was supported by the specific positive relationships between postfire regeneration densities and prefire basal area for P. banksiana, Populus spp., B. papyrifera and P. mariana. However, if the DRH is used for predicting postfire composition, P. banksiana is the only species that had the same composition between postfire and prefire stands. Nevertheless, CD for P. banksiana was negatively related to its prefire composition. Similarly, CD for other species was negatively related to their prefire compositions with varying effects of build up index and age of burn. Our results suggest, if fire occurrences increase with global change, the boreal landscape will be more dominated by hardwoods and mixtures of conifers and hardwoods. [Copyright &y& Elsevier]

Abstract: This paper provides an account of ‘vital ecosystem security’. The central claim is that ‘vital ecosystem security’ and the processual ontology of ‘complex adaptive becoming’ provide useful terms with which to think environmental citizenship biopolitically within the contingent matrix of climate change. The paper identifies how complex adaptation, the operative form of vital ecosystem security, defines an emerging form of environmental citizenship, which can be found operating at the interface of a new type of forestry and the global carbon cycle. The specific case developed here concerns the boreal forest of northern Canada. [Copyright &y& Elsevier]

Isle Royale National Park (IRNP) is an archipelago in west central Lake Superior. In 2010, the National Park Service Great Lakes Inventory and Monitoring Network initiated a long-term monitoring program at IRNP with the goals being to: ( 1 ) determine the current forest structure, (2) assess how succession and climate change will impact species assemblages, and (3) develop realistic management targets related to climate change impacts on IRNP forests. Five forest types were identified, with three of these (sugar maple {Acer saccharum Marsh.)/birch, eastern white cedar {Thuja occidentalis L), and balsam fir {Abies balsamea (L.) Mill.)) being climax types with little likelihood of succeeding into any other type over the next two to three decades. Two forest types (white spruce {Picea glauca (Moench) Voss),/trembling aspen {Populus tremuloides Michx.), and paper birch {Betula papyrifera Marsh.)) were in a state of transition. The long-term (> 50 year) successional pathways of all five forest types will be influenced by climate change, species' migration abilities, and disease. Many dominant species currently on the island, including balsam fir, black spruce {Picea mariana (Mill.) Britton, Sterns & Poggenb.), and white spruce, are expected to become extirpated, while the abundance of other common species, including paper birch and trembling aspen, is expected to decline. The 21 km distance between the mainland and the islands will prohibit timely immigration of new species onto the island in the face of climate change. Immigration will likely be led by avian-dispersed species {Prunus spp., exotic Lonicera spp., and Rhamnus cathartica, another exotic species) with dispersal of other taxa relying on stochastic events or human transport. Managers should consider assisted migration to ensure that species assemblages remain congruent; otherwise, stable ecosystems dominated by a few non-native taxa may result. This is especially relevant on the eastern side of the island where balsam fir forests dominate in shallow, bedrock-derived soils. [ABSTRACT FROM AUTHOR]

• Boreal forest is resilient in the face of repeated disturbances during the Holocene. • Moderate fire frequency leads to a recurrence dynamics. • Resilience remains precarious as shown by lichen woodlands formation. • Climate change is expected to amplify the forest/woodland phenomenon. • Charcoals in mineral soils allow reconstruction of past local tree assemblages. The dynamics of the boreal forest has followed several successional trajectories during the Holocene caused by recurrent stand-scale, abiotic and biotic disturbances. Under stable environmental conditions, site disturbances should favor the regeneration of forest communities enabling the recovery process to produce forests similar to the pre-disturbance states. However, a failure in the post-disturbance recovery process can also occur to shift the forest communities to alternative states. Although fire is the main disturbance factor affecting the dynamics of the boreal forest, long-term resilience of most forest ecosystems remains poorly known because of lack of stand-scale paleoecological evidence. To evaluate the resilience ability of boreal forest ecosystems, we reconstructed their Holocene fire history and documented their successional pathways at the stand scale in two climatically-contrasted regions (western continental versus eastern humid climates of boreal Québec, Canada) based on botanically-identified and 14C-dated soil charcoal remains. Since mid-Holocene, western closed-crown conifer forests were resilient to fire disturbance, but hardwood trees declined significantly. Yet in the eastern region, closed-crown conifer forests similar to that observed today seems to have remained in place since its origin. In both regions, moderate fire frequency leads to a recurrence dynamics that favors renewal of forests stands with the same composition. However, balsam fir – paper birch stands follow a successional pattern characterized by the establishment of paper birch, with subsequent increasing abundance of balsam fir. This allows the maintenance of forests composed of these species, whose dominance fluctuates according to the time elapsed since the last fire. The succession from black spruce to balsam fir stands seems to be an uncommon process that requires a prolonged fire-free period. Although most closed-crown forests are resilient postfire ecosystems which have persisted over several millennia, their resilience is precarious as evidenced by the transformation of some forests into lichen woodlands after fire. [ABSTRACT FROM AUTHOR]

The Chinese boreal forest is an important forest resource in China. However, it has been suffering serious disturbances of forest fires, which were caused equally by natural disasters (e.g., lightning) and human activities. The literature on human-caused fires indicates that climate, topography, vegetation, and human infrastructure are significant factors that impact the occurrence and spread of human-caused fires. But the studies on human-caused fires in the boreal forest of northern China are limited and less comprehensive. This paper applied the spatial analysis tools in ArcGIS 10.0 and Logistic regression model to investigate the driving factors of human-caused fires. Our data included the geographic coordinates of human-caused fires, climate factors during year 1974-2009, topographic information, and forest map. The results indicated that distance to railway (x1) and average relative humidity (x2) significantly impacted the occurrence of human-caused fire in the study area. The logistic model for predicting the fire occurrence probability was formulated as P=1/[1+e-(3.026-0.00011x1-0.047x2)] with an accuracy rate of 80%. The above model was used to predict the monthly fire occurrence during the fire season of 2015 based on the HADCM2 future weather data. The prediction results showed that the high risk of human-caused fire occurrence concentrated in the months of April, May, June and August, while April and May had higher risk of fire occurrence than other months. According to the spatial distribution of possibility of fire occurrence, the high fire risk zones were mainly in the west and southwest of Tahe, where the major railways were located. [ABSTRACT FROM AUTHOR]

Northern forested ecosystems are predicted to change dramatically in response to climate change during the next century. The purpose of this paper was to use logistic regression analysis to model the effects of climate and topography on the spatial distribution of the northern forest around Churchill, Manitoba, Canada. Climate maps were modeled using kriging interpolation of actual climate data collected from 34 long-term monitoring sites distributed throughout the study area, and topographic information was derived from commercially available digital elevation models. Five of the 18 independent variables contributed appreciably (p < 0.15) to the final logistic regression model: distance from the Hudson Bay coast, summer soil temperature, snow density, slope, and snow water equivalent. Current forest distribution was predicted with 66% accuracy using the final model, and Kappa statistics indicated significant agreement between modeled and actual forest extents. Significant explanatory variables demonstrate important synergistic effects of Hudson Bay, wind, and snow in determining forest distribution. Modeled forest extents were further south than actual forest limits, which suggest that the treeline is not likely in equilibrium with the present climate. [ABSTRACT FROM AUTHOR]

Bitumen recovery from oil sands in northeastern Alberta, Canada produces large volumes of tailings, which are deposited in mining areas that must be reclaimed upon mine closure. A new technology of non-segregated tailings (NST) developed by Canadian Natural Resources Limited (CNRL) was designed to accelerate the process of oil sands fine tailings consolidation. However, effects of these novel tailings on plants used for the reclamation of oil sands mining areas remain to be determined. In the present study, we investigated the effects of NST on seedlings of three species of plants commonly planted in oil sands reclamation sites including paper birch (Betula papyrifera), white spruce (Picea glauca) and green alder (Alnus viridis). In the controlled-environment study, we grew seedlings directly in NST and in the two types of reclamation soils with and without added NST and we measured seedling growth, gas exchange parameters, as well as tissue concentrations of selected elements and foliar chlorophyll. White spruce seedlings suffered from severe mortality when grown directly in NST and their needles contained high concentrations of Na. The growth and physiological processes were also inhibited by NST in green alder and paper birch. However, the addition of top soil and peat mineral soil mix to NST significantly improved the growth of plants, possibly due to a more balanced nutrient uptake. It appears that NST may offer some advantages in terms of site revegetation compared with the traditional oil sands tailings that were used in the past. The results also suggest that, white spruce may be less suitable for planting at reclamation sites containing NST compared with the two studied deciduous tree species. Image 109523 • Non-segregated tailings (NST) is a new oil sands tailings processing technology. • Seedlings of examined boreal plants were stressed by the presence of NST in soil. • The effect of NST was associated with elevated Na levels in plant tissues. • Addition of top soil and peat mineral mix in NST improved seedling growth. The effect of NST was associated with elevated Na levels in plant tissues and addition of top soil and peat mineral mix in NST improved seedling growth. [ABSTRACT FROM AUTHOR]

• Inconsistent reporting of fire characteristics hinders comparisons across studies. • Most fire-wildlife research examines recent burns over short durations. • Many studies rely on simple contrasts that treat fire as a uniform disturbance. • Few studies measure the post-fire population responses needed for management. • Wildfires and prescribed fires are studied mostly at non-overlapping spatial scales. Shifting fire regimes are substantially changing North American forests. It is thus critical to understand how wildfires affect forest wildlife, especially for species managed for harvest and for species at risk of extinction. In particular, many populations of carnivores and ungulates are actively managed, so being able to anticipate their responses to future fires, or as burned forests regenerate, would be valuable for management and conservation. We examine how well the current literature addresses these important needs. We reviewed 131 papers published from 1970 to 2019 that reported carnivore and ungulate responses to fires in North American conifer forests. We evaluated the study designs, fire attributes, species studied, and response variables measured. This literature contains considerable taxonomic bias, inconsistent reporting of fire and landscape characteristics, and a mismatch between research objectives and management needs. Of the 18 carnivore species studied post-fire, just three (grizzly bears Ursus arctos , Canada lynx Lynx canadensis , and American marten Martes americana) comprised nearly half of the literature (47.8%). Few papers reported the spatial extents of fires being studied (32.6% for carnivores and 38.2% for ungulates). Most studies focused on recent burns (<15 years post-fire) and monitored post-fire responses for fewer than five years. Few papers measured true population responses post-fire (6.7% for carnivores and 12.4% for ungulates); the majority of papers focused on animal movements or habitat use (presence/absence or relative activity) rather than estimates of survival, recruitment, or population size. Our review also indicates that studying fires with a more diverse array of spatial extents, ages, and severities would be useful for most species. [ABSTRACT FROM AUTHOR]

• Yield capacity describing forest site productivity was expressed through site index. • Observations from permanent plots in long-term experiments give valid reference estimates of total volume production. • Variations in volume yield levels are explained in a larger extent by basal area levels. • The yield capacity functions can be used to compare tree species' production under similar management regimes. • The functions offer far-reaching support for assessing climate change mitigation potential of boreal forests in northern Europe. Information on forest site productivity is a key component to assess the carbon sequestration potential of boreal forests. While site index (SI) is commonly used to indicate forest site productivity, expressions of SI in the form of yield capacity (potential maximum mean annual volume increment) is desirable since volume yield is central to the economic and ecological analyses of a given species and site. This paper assessed the functional relationship between SI and yield capacity on the basis of yield plot data from long-term experiments measured over several decades for Norway spruce (Picea abies), Scots pine (Pinus sylvestris), Lodgepole pine (Pinus contorta) and Larch (Larix decidua and Larix sibirica) in Sweden. Component models of total basal area and volume yield were also developed. SI was determined by existing height development functions using top height and age, whereas functions for stand-level (m2 ha−1) basal area development were constructed based on age, SI and initial stand density using difference equations and nonlinear mixed-effects models. The relation between volume yield (m3 ha−1) and top height was adjusted with total basal area production through nonlinear mixed-effects models. Species-specific parametric regression models were used to construct functional relationships between SI and yield capacity. The root mean square errors of the species-specific models ranged from 2 to 6% and 10–18% of the average values for the basal area and volume equations, respectively. For the yield capacity functions, the explained variations (R2) were within 80–96%. We compared our yield capacity functions to earlier functions of the species and significant differences were observed in both lower and higher SI classes, especially, for Scots pine and Norway spruce. The new functions give better prediction of yield capacity in current growing conditions; hence, they could later be used for comparing tree species' production under similar site and management regimes in Sweden. [ABSTRACT FROM AUTHOR]

Optical remote sensing methods for mapping of the seasonal snow cover are often obstructed by the masking effect of forest canopy. Therefore, optical algorithms tend to underestimate the amount of snow cover in forested regions. In this paper, we investigate the influence of boreal forest stand characteristics on the observed scene reflectance under full dry snow cover conditions by applying an advantageous experimental setup combining airborne hyperspectral imaging and LIDAR data sets from a test region in Sodankylä, northern Finland. This is particularly useful to the understanding of the composition of the mixed satellite scene reflectance behavior and it is relation to the natural ground targets’ spectral signatures. At first, we demonstrate the effects of varying forest stand characteristics, including Canopy Cover (CC), Tree Height (TH) and the product of the these parameters referred to as CCxTH, on the reflectance measured by airborne imaging spectrometer AisaDUAL. Then, we analyze the effects of the presence of snow on forest canopy on the observed AisaDUAL data. The analysis of the effects of canopy was enabled by the high resolution LIDAR measurements which provide reference information on forest canopy characteristics. According to the results the change in Canopy Cover, as well as in CCxTH, is related to the observed change in reflectance, as well as to changes in such spectral indices as Normalized Difference Snow Index (NDSI) and Normalized Difference Vegetation Index (NDVI). Additionally, NDSI was found to vary extensively particularly in dense forests (CC > 85%), where the relative variation was over 100%. This should be considered when applying NDSI-based snow mapping methods in the case of forested areas. One notable finding was that the relation between the forest characteristics and reflectance was nearly exponential, while with reflectance indices it was linear. Besides, the results show that NDSI was a more effective parameter in detecting snow on canopy (values deviated 0.3 on average) than NDVI (values deviated 0.3 on average) in all Canopy Cover classes. The difference in NDSI between these two cases, snow-covered and snow-free canopy, increased when the canopy coverage increased. [ABSTRACT FROM AUTHOR]

Abstract: Underlying the development and function of aspen forest communities are interactions between aspen and a broad suite of plant species. These plant–plant interactions can be facilitative or antagonistic in nature and their influence varies depending on multiple environmental factors that are changing with human activity. The purpose of this synthesis paper is to identify the patterns, mechanisms and consequences of facilitation and competition in aspen communities and how they vary based on environmental conditions and different aspen forest types. Across its expansive range, aspen commonly associate with conifers to form mixed forests. There is increasing evidence that facilitation in early stand development alters competitive interactions between aspen and conifers in later stages of development. However, the influences of facilitation and competition vary depending on conifer species and aspen forest type. In drier, montane aspen forests of the western US, shade and higher moisture content at the base of aspen trees facilitate the germination and survival of young fir seedlings. This facilitation effect increases the proximity of aspen and fir which over time creates competitive interactions that favor conifer dominance. In the more mesic conditions of eastern Canada, aspen also promotes fir establishment but the facilitation effect occurs at the stand level and is most likely driven by increased light penetration and more optimal edaphic conditions rather than by mitigating moisture limitations. In the western and central boreal forest, successional transitions are primarily driven by competitive effects in which short fire cycles and competitive inhibition of spruce favors aspen dominance. Positive and antagonistic interactions between aspen and associated plant species are influenced by environmental conditions that fluctuate according to nature processes and human perturbations. In this review we discuss the impact that plant invasions, global change factors, fire regimes and herbivory have on plant–plant interactions in aspen forest and how they modify successional outcomes. The literature suggests that aspen’s competitive ability is strongly influenced by rising CO2, temperatures, drought and ozone. Conditions resulting in longer fire cycles will tend to promote losses in aspen cover through competitive exclusion through conifer expansion. Finally, competition alters aspen susceptibility to herbivory which is a major threat to aspen resilience in some parts of its range. Identifying the environmental conditions that create the proper balance between facilitative and competitive interactions is paramount in formulating management approaches that promote resilient aspen forests. [Copyright &y& Elsevier]

Abstract: Are current estimates of silicate minerals weathering rates precise enough to predict whether nutrient pools will recover after forest harvesting? Answering this question seems crucial for sustainable forestry practices on silicate dominated soils. In this paper, we synthesize estimated Ca and K weathering rates (derived using seven different approaches) from a forested area in northern Sweden (the Svartberget–Krycklan catchment) to evaluate the precision of weathering rate estimates. The methods were: mass-balance budgets (catchment and pedon-scale); long-term weathering losses inferred from weathered soil profiles (using zirconium as a conservative tracer); strontium isotopes (86Sr/85Sr) as proxy for catchment export of geogenic Ca; climate based regressions; a steady-state, process-based weathering model (PROFILE) and a dynamic, conceptual catchment geochemistry model (MAGIC). The different methods predict average weathering rates of 0.67±0.71gCam−2 year−1 (mean±stdev) and 0.39±0.38gKm−2 year−1, suggesting a cumulative weathering release during a forest rotation period of 100 years that is the same magnitude as losses induced by forest harvesting at the end of the period. Clearly, forestry practices have the capacity to significantly alter the long-term nutrient status of the soil and cation concentrations in soil–water runoff. However, the precision in weathering estimates are lower than that needed to distinguish between effects on nutrient pools by different forest practices (complete-tree harvesting versus conventional stem only harvest). Therefore, we argue that nutrient budgets, where weathering rates play a crucial role, cannot be used as basis for resolving whether different harvesting techniques will allow nutrient pools to recover within one rotation period. Clearly, this hampers the prerequisite for sound decision making regarding forestry practices on silicate mineral dominated soils. [Copyright &y& Elsevier]

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Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• The ecosystem carbon pool of late-successional and pioneer forests was compared. • Larch, birch and mixed larch-birch stands were studied in the southern boreal zone. • Biomass C stock density was reduced by 7 and 19% in mixed or birch forest. • Soil organic C density remained stable despite disturbance. The boreal forest biome is prominent for its high organic carbon pools, the stability of which is important for climate change mitigation. Natural and anthropogenic disturbance is converting boreal forests from late-successional conifer stands to broadleaved pioneer forests. The present paper analyzes how the degradation of Larix sibirica forest to mixed Betula platyphylla-L. sibirica stands or finally to monospecific B. platyphylla forest affects organic carbon stock density in Mongolia's boreal forests, which are representative of large forest areas at the southern fringe of this biome in Inner Asia. Conversion of larch forest to mixed forest with 60% larch and 40% birch resulted in the reduction of carbon stock density by 7%, whereas the complete replacement of larch by birch reduced ecosystem carbon stock density by 19%. These reductions only referred to biomass stocks, whereas the soil organic carbon stock remained stable indicating that losses during and after the disturbance were offset by carbon sequestration in the highly productive initial stages of pioneer forests. The magnitude of carbon stock degradation by conversion into broadleaved pioneer forest suggests that the existing estimate of 1.5–1.7 Pg C for the total organic carbon pool in Mongolia's boreal forest is not substantially affected by the present level of forest conversion resulting in a share of 6.4% of birch in Mongolia's total forest area, but could become more relevant with progressive degradation of late-successional forests. [ABSTRACT FROM AUTHOR]

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article focuses on lichen colonization. Branches are well suited for studying lichen colonization as new substrate is added to the branch each year. However, few papers have focused on ecology and dynamics of lichen colonization, and no earlier publications have focused on how environmental changes, caused by logging, influence diaspore attachment and establishment in boreal spruce forests. Increased knowledge about how forestry influences lichen colonization is a prerequisite for developing appropriate forestry methods aimed to maintain species diversity. The survival of a lichen population is influenced by the species' ability to reproduce, to colonize new substratum, and to grow under changing environmental conditions. Foliose and fruticose epiphytic lichens in boreal spruce forest reproduce mainly asexually by dispersal of vegetative diaspores. Vegetative diaspores, such as soredia and isidia, are generally considered advantageous for rapid colonization on the substratum. However, poor dispersal of diaspores has often been postulated as limiting for development of populations of different epiphytic species.

Greater fibre yields may be possible in commercial forests through an increased application of post-harvest silvicultural techniques. In Canadian boreal forests, while basic silvicultural regeneration techniques such as planting, seeding, scarifying, and tending, have been employed since the 1940’s, more intensive techniques (intensive forest management (IFM)) such as increased area planted, pre-commercial and commercial thinning, extra tending events, fertilizing, and short rotations may soon be used. There may be effects of basic and more intensive silviculture on biodiversity in the long-term, compared to natural regeneration following logging or especially stand development following natural disturbances. We reviewed approximately 50 papers that reported studies of the long-term effects of post-harvest silviculture on vertebrate wildlife. In particular, large impacts to biodiversity universally occur when native forest types are replaced by rapidly-growing exotic tree species. However, in boreal forests, native tree species are usually planted, and so any effects on associated wildlife communities may be considerably less than in non-native species plantations. Limited long-term information is available, but published studies of effects of basic silviculture and IFM suggested that loss of structures in forest stands was an important common impact that resulted in vertebrate species responses. Fewer structural features in managed forests compared to in natural forests likely results in reduced numbers of animal species dependent on those structures, such as cavity-using species and species for which large decaying woody debris is important. Simplifying stand structures and species composition may result in systems with low connectivity, making them vulnerable to insect and mammalian herbivory. Concentration of IFM in stands on highly productive sites could exacerbate effects (positive or negative), owing to the positive relationship between forest productivity and animal and plant diversity. Species such as black-backed woodpeckers (Picoides arcticus) may be reduced over large areas by stand conversion to mixedwoods, stand structural changes and especially age-class truncation. On the other hand, IFM may contribute increased habitats to species favoring young to mature coniferous-dominated forests, that normally decline across a landscape following clearcutting in boreal mixed and upland conifer stands. An aspatial model, based on published and local information and expert opinion, suggested that IFM and post-harvest silviculture in Ontario’s boreal forests would produce positive and negative species-specific effects on the vertebrates that we modeled. However, IFM appeared to result in little increased effect over basic post-harvest silviculture. We also expect that stand-level effects of IFM on species would accumulate through time over landscapes, as more stands come under intensive management and the level of effects will be cumulative. [Copyright &y& Elsevier]

Species-habitat models are important tools in conservation and wildlife management today. Models simulating the long-term ecological consequences of forestry on biodiversity have large potential as guidance for management. In this paper, we evaluated a model, lichen biomass spatially explicit model (LIBSEM) that predicts the temporal and spatial distribution of epiphytic lichens in boreal coniferous forests. We assessed model performance by simulating the standing crop of pendulous lichens (Bryoria spp.) over a 50-year period in a managed forest landscape (Bratta˚ker, 4405 ha). We compared the simulated data with independent field data based on sampling of lichen litter in 54 plots stratified by forest age class. Simulated epiphyte standing crop was significantly related to field data but overall model performance was rather poor at the cell level (50 m×50 m cells) with a modelling efficiency of 12%. Results suggest that the model succeeded better in predicting lichen biomass on the landscape level. We used LIBSEM to assess possible long-term consequences on epiphytes of four management scenarios differing in the length of the rotation cycle. The change in epiphyte biomass was projected over a 200-year period. Results show that an even-aged silvicultural system with a normal rotation (110 years) only can support a low amount of pendulous lichens while short rotation (60 years) is very detrimental to epiphyte communities. Thus, to enhance the abundance of epiphytic lichens it is necessary to use extended rotations, preferably in combination with forest reserves. We conclude that spatially explicit landscape models may act as a guide for managing boreal forests to improve conditions for epiphytes. [Copyright &y& Elsevier]

Allelopathic interference of Kalmia angustifolia (Ericaceae) to the growth and establishment of black spruce (Picea mariana) has been suggested by several authors. The greenhouse studies suggested that Kalmia has potential for nutrient interference. However, these studies do not eliminate probable involvement of allelopathy. Field studies indicate that soils associated with Kalmia were nutrient-poor particularly for nitrogen, phosphorus, iron, and manganese, and support the hypothesis that Kalmia has dominated microsites that were nutrient-poor prior to its colonization. The questions addressed in this paper are (i) Is Kalmia interference to black spruce growth explained by allelopathy? (ii) Can Kalmia–black spruce allelochemical interactions be better explained by ecosystem-level approach to allelochemicals rather than disturbance-related regeneration ecology of Kalmia? At present, we do not have compelling direct evidence to support allelopathy as a mechanism of Kalmia interference to black spruce. However, organic molecules released from Kalmia into the environment may influence soil mineralization, mycorrhizae, nutrient dynamics, and soil microbial ecology. We hypothesize that synergistic interaction of ecological factors may better explain the interference mechanism of Kalmia. [Copyright &y& Elsevier]

Summary: This paper presents a synthesis of the dendroecological work conducted in the area of Lake Duparquet in the southern boreal forest of northwestern Quebec (Canada) during the last 15 years. The topics of these syn- and autecological studies encompassed forest dynamics and tree growth related to natural disturbances such as forest fires, insect outbreaks, and flooding, as well as the effects of climate change. Seven major fire events occurred around Lake Duparquet since 1720: 1760, 1797, 1823, 1847, 1870, 1916, and 1944. Post-fire stand dynamics, established by a chronosequence of over 200 years, are characterized by the gradual transition from broadleaf dominated stands towards mixed and finally almost pure conifer stands. After fire, insect outbreaks are the second most important disturbance type in the southern boreal forest. Spruce budworm, the predominating defoliating insect, but also forest tent caterpillar and larch sawfly have major impacts on growth and stand dynamics of their respective host species. Global warming since the end of Little Ice Age around 1850 coincided with increasing precipitation and, hence, decreasing droughts in the southeastern boreal area of North America. The accelerated radial growth of eastern white-cedar and black ash at Lake Duparquet is a direct effect of these wetter climatic conditions. Population dynamics and forest composition, however, are rather indirectly affected by climate change through the alteration of the natural disturbance regimes, i. e., the decreased frequency and size of the forest fires and the increased frequency and amplitude of the spring floods. Potential consequences of future global warming on disturbance dynamics and forest composition are briefly discussed. The results of the dendroecological studies contributed to the elaboration of a natural-disturbance based forest management model for the southern boreal forest of Quebec. [Copyright &y& Elsevier]

We summarized our recently-published papers on greenhouse gas exchanges at two important boreal regions underlain by permafrost: eastern Siberia and interior Alaska. Relevant literatures were also referred to, and future research directions on the high-latitude terrestrial processes were suggested. Long-term monitoring of CO 2 fluxes at the boreal forests revealed that anomalous weather and disturbances changed the CO 2 balance. More than a decade is required to return to a CO 2 sink at burned forests in interior Alaska. Anomalous high precipitation altered the forest structure in eastern Siberia, shifting the overstory/understory contributions to the CO 2 balance. The CH 4 emissions were higher in the two boreal forests than in the other boreal forests. Upscaling the in-situ observations and comparisons with top-down approaches revealed considerable inconsistencies exist among the approaches. We recommend the following directions in future research. First, long-term monitoring is indispensable to detect the effect of climate change on ecosystems. Second, disturbance impacts, including fire, thermokarst, and wet spells, need to be quantified. Third, further observations are necessary for constraining CH 4 exchange models. Finally, reconciling top-down and bottom-up approaches is required to reduce uncertainty. Prompt sharing of observed data and model products is crucial to improve our understanding of high-latitude processes. [ABSTRACT FROM AUTHOR]