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The boreal forest is one of the world's largest terrestrial biome and plays crucial roles in global biogeochemical cycles, such as carbon (C) sequestration in vegetation and soil. However, the impacts of decades of N deposition on N‐limited ecosystems, like the eastern Canadian boreal forest, remain unclear. For 13 years, N deposition was simulated by periodically adding ammonium nitrate on soils of two boreal coniferous forests (i.e., balsam fir and black spruce) of eastern Canada, at low (LN) and high (HN) rates, corresponding to 3 and 10 times the ambient N deposition, respectively. We show that more than a decade of N addition had no strong effects on mineral soil C, N, P, and cation concentrations and on foliar total Ca, K, Mg, and Mn concentrations. In organic soil, C stock was not affected by N addition while N stock increased, and exchangeable Ca2+ and Mg2+ decreased at the balsam fir site under HN treatment. At both sites, LN treatment had nearly no impact on foliage and soil chemistry but foliar N and N:P significantly increased under HN treatment, potentially leading to foliar nutrient imbalance. Overall, our work indicates that, in the eastern Canadian boreal forest, soil and foliar nutrient concentrations and stocks are resilient to increasing N deposition potentially because, in the context of N limitation, extra N would be rapidly immobilized by soil micro‐organisms and vegetation. These findings could improve modeling future boreal forest soil C stocks and biomass growth and could help in planning forest management strategies in eastern Canada. [ABSTRACT FROM AUTHOR]

We, four teachers in Ojibwe or majority-Ojibwe schools and three teachers in teacher preparation at a small ecologically focused liberal arts college, tell stories to reorient ourselves, centering place in ways accessible to our emerging practice. In these narratives, anchored in the seasons, we describe our challenges and successes in adapting education programs to better evoke the lifeways that predominate in our shared part of rural northern Wisconsin immersed in the lands of the Ojibwe. We relied on experiences, both ours and of Ojibwe learners, to illuminate the rhythms of our place and the seasons of learning defined by boreal forest, an inland sea, the sugar bush, and the wild rice harvest, in the hope of better outcomes for Indigenous and non-Indigenous teacher candidates (and their future students) in our evolving program. This narrative work cobbles a frame enabling connection to create rural, fugitive, decolonized teacher preparation that centers respect, reciprocity, and agency. [ABSTRACT FROM AUTHOR]

Intensive forestry practices have had a negative impact on boreal forest biodiversity; as a consequence, the need for restoration is pressing. Polypores (wood‐inhabiting fungi) are key decomposers of dead wood, but, due to a lack of coarse woody debris (CWD) in forest ecosystems, many species are under threat. Here, we study the long‐term effects on polypore diversity of two restoration treatments: creating CWD by felling whole trees and prescribed burning. This large‐scale experiment is located in spruce‐dominated boreal forests in southern Finland. The experiment has a factorial design (n = 3) including three levels of created CWD (5, 30, and 60 m3 ha−1) crossed with burning or no burning. In 2018, 16 years after launching the experiment, we inventoried polypores on 10 experimentally cut logs and 10 naturally fallen logs per stand. We found that overall polypore community composition differed between burned and unburned stands. However, only red‐listed species abundances and richness were positively affected by prescribed burning. We found no effects of CWD levels created mechanically by felling of trees. We show, for the first time, that prescribed burning is an effective measure for restoring polypore diversity in a late‐successional Norway spruce forest. Burning creates CWD with certain characteristics that differ from what is created by CWD restoration by felling trees. Prescribed burning promotes primarily red‐listed species, demonstrating its effectiveness as a restoration measure to promote diversity of threatened polypore species in boreal forests. However, because the CWD that the burning creates will decrease over time, to be functional, prescribed burns need to be applied regularly on the landscape scale. Large‐scale and long‐term experimental studies, such as this one, are invaluable for establishing evidence‐based restoration strategies. [ABSTRACT FROM AUTHOR]

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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.)

Understanding long-term effects of clear-cutting on current soil carbon (C) fluxes in boreal forests is important in the perspective of global C cycling and future forest management decisions. We studied twelve pairs of forest stands in South-Eastern Norway, each comprised of one previously clear-cut stand and one near-natural stand with similar macroclimate, topography and soil properties. We measured aboveground tree litterfall continuously during two consecutive years and soil respiration fluxes monthly during the snow-free period of one year. Ground vegetation litterfall was estimated from destructive biomass sampling. The previously clear-cut stands had on average 12 % higher annual soil respiration rates, 20 % greater tree litterfall, and tended to have greater total aboveground litterfall (12 %), while the near-natural stands had greater litterfall from ground vegetation (45 %). Litterfall from ground vegetation was strongly linked with below-canopy light transmission, but the contribution of this flux to the total aboveground litterfall was minor. Soil respiration rates were related to microclimate, nitrogen concentration in aboveground tree litter and tree basal area. Though, only basal area could be linked to management type differences in soil respiration, that likely has additional unidentified drivers. We found similar temperature sensitivities of soil respiration in the two management types. We emphasise that age of the dominating trees is an integrated part of the differences between these two types of forest stands. Jointly, our results suggest limited differences in the current net soil C balance of near-natural and previously clear-cut stands. • We compared twelve pairs of near-natural and previously clear-cut stands. • Previously clear-cut stands had greater tree litterfall and soil respiration rates. • Differences in soil respiration rates were partly linked to overstory dynamics. • Near-natural stands had greater litterfall from ground vegetation. • Management history did not affect overall soil carbon balance. [ABSTRACT FROM AUTHOR]

Forest management can impact forest carbon stocks, above- and belowground. The even-aged management practice removes the aboveground carbon stock at harvest, which is thereafter restored as the new forest stand establishes. The effects of even-aged management on forest soils in earlier unmanaged stands are however less well understood, and it has been suggested that large carbon losses may occur. In this study we use a unique paired sampling approach of stands in north inland Sweden. Half of the sampled stands had been clear cut within the previous 54 years, and half were left unmanaged. Our results show that clear-cut harvesting and subsequent transformation of unmanaged stands into even-aged management resulted in lower aboveground carbon stock in the living trees. For the soil there was weak evidence for a loss of c. 15 % of the carbon stock in the organic layer. No evidence of an effect in the more stabilized soil organic carbon within the mineral soil layers was found. • C stocks of boreal forests were assessed under even-aged vs no management. • We found weak evidence that even-aged management reduced organic horizon C. • We found no evidence even-aged management reduced mineral soil C. • Above ground C stocks were lower in managed boreal forests. [ABSTRACT FROM AUTHOR]

Increased tree mortality rates have been observed worldwide in connection to climate warming-related processes, such as drought, heat, fire, and insect pest outbreaks. An understanding of the drivers of tree mortality during the Anthropocene is urgently needed to estimate forest vulnerability in a warmer climate. In this study, we assessed the drivers of tree mortality in an urban recreational boreal forest area in Helsinki, Finland, of approximately 830 ha, where increased tree mortality rates have been recently observed. A time series of aerial images was used to quantify tree mortality over the area to detect dead trees from 2005 to 2021 at seven timestamps. In total, 6008 dead trees were observed from the aerial images collected during the monitoring period. Forest environmental and climatic variables were used to explore the tree mortality drivers for individual trees and tree communities using logistic regression and correlation analysis. Our results showed that drought-related variables, i.e., the standardised precipitation evapotranspiration index and the Palmer drought severity index, were linked with increased tree mortality rates. We found that the stand-level basal area predicted tree mortality risk and was linked to site type; smaller basal area stands were located on rocky dry soils, resulting in a greater probability of tree mortality. We also observed that trees at high elevations or on steep slopes showed a greater mortality risk. Our results can increase the understanding of tree mortality in urban areas and help the planning of built and green areas in a changing climate. • A 16-y time series of individual tree mortality investigated in a boreal forest. • Trees on dry soils where growth is limited showed high mortality risk. • Drought and warmer temperatures increased tree mortality. • Stand-level basal area and site type predicted tree mortality risk. [ABSTRACT FROM AUTHOR]

• Optimal size and spatial aggregation in forest conservation remains unresolved. • We reviewed the impact of patch size and aggregation on boreal forest biodiversity. • Limited studies examined patch size effect, yielding mixed results. • Knowledge gap exists in landscape-scale boreal forest conservation strategies. Area-based conservation measures are the main approach to preserve forest biodiversity. However, there is no common view on the best strategy in relation to spatial aggregation of conservation areas, for a given total area preserved. We conducted a systematic literature review to evaluate the effect of mean patch size and aggregation of conservation areas on landscape-scale biodiversity in boreal forest. Our main objectives were to find empirical evidence regarding whether few large or several small conservation areas protect more biodiversity and investigate how the spatial aggregation of conservation areas affects biodiversity. We searched specifically for studies comparing biodiversity across many small vs. few large and dispersed vs. aggregated conservation areas, controlling for total area protected. Although our initial search resulted in a large number of articles, not a single study assessed landscape-scale biodiversity in many small vs. few large, or dispersed vs. aggregated conservation areas, of a spatial scale relevant to average-sized or even small nature reserves (i.e. ≥ 10 ha). We did find 5 studies comparing many small vs. few large conservation patches within clear-cuts, and one study of forest patches within a national park (ca 7 ha). The conservation areas on clear-cuts were patches of retained trees, with the smallest patches being single trees. The effect of patch size on biodiversity varied among studies, mostly indicating neutral effects of patch size. While the results of these studies are relevant to clear-cuts, their relatively small spatial extent (the largest retained patch being 1.2 ha) precludes extrapolation to scales relevant to reserves in boreal forest. Our review exposes an extensive knowledge gap regarding consequences of the sizes of conservation areas on landscape-scale boreal forest biodiversity. Until such information is available, we recommend a combined approach involving both small and large conservation areas in boreal forest. [ABSTRACT FROM AUTHOR]

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd 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.)

Impoundment of hydroelectric reservoirs deeply modifies habitats available for waterfowl because it involves transforming a fast-flowing river, its tributaries and nearby ponds and wetlands into a large body of water. Using a Before-After-Control-Impact design, we evaluated whether the creation of the Péribonka reservoir, a steep-sloped hydroelectric reservoir with low water level fluctuations, affected the abundance and species composition of waterfowl breeding pairs and broods in the area. We used helicopter-based waterfowl survey data covering a period of 2 years before and a period of 10 years after the creation of the reservoir. We also used 9 5x5 km plots and 72 km of river as control sites. Our results show that breeding pair density slightly increased after impoundment, while brood density increased significantly (sixfold), especially for Common Goldeneye (Bucephala clangula). This suggests that there were favorable habitat gains for waterfowl after impoundment, probably due to low water level fluctuations and localized areas of shallow water, and that mitigation measures likely helped to reduce the impact of the project. Because this BACI study ended 10 years after impoundment, it remains difficult to ascertain whether conditions in the Péribonka reservoir have stabilized or are still evolving. [ABSTRACT FROM AUTHOR]

Managers designing infrastructure in fire‐prone wildland areas require assessments of wildfire threat to quantify uncertainty due to future vegetation and climatic conditions. In this study, we combine wildfire simulation and forest landscape composition modeling to identify areas that would be highly susceptible to wildfire around a proposed conservation corridor in Québec, Canada. In this measure, managers have proposed raising the conductors of a new 735‐kV hydroelectric powerline above the forest canopy within a wildlife connectivity corridor to mitigate the impacts to threatened boreal woodland caribou (Rangifer tarandus). Retention of coniferous vegetation, however, can increase the likelihood of an intense wildfire damaging powerline infrastructure. To assess the likelihood of high‐intensity wildfires for the next 100 years, we evaluated three time periods (2020, 2070, 2120), three climate scenarios (observed, RCP 4.5, RCP 8.5), and four vegetation projections (static, no harvest, extensive harvesting, harvesting excluded in protected areas). Under present‐day conditions, we found a lower probability of high‐intensity wildfire within the corridor than in other parts of the study area, due to the protective influence of a nearby, poorly regenerated burned area. Wildfire probability will increase into the future, with strong, weather‐induced inflation in the number of annual ignitions and wildfire spread potential. However, a conversion to less‐flammable vegetation triggered by interactions between climate change and disturbance may attenuate this trend. By addressing the range of uncertainty of future conditions, we present a robust strategy to assist in decision‐making about long‐term risk management for both the proposed conservation measure and the powerline. [ABSTRACT FROM AUTHOR]

Wetland degradation throughout the interior of North America has resulted in a loss of breeding habitat for many waterbird species. The Black Tern (Chlidonias niger) is an obligate marsh-breeding colonial waterbird that has experienced widespread, long-term population declines. Habitat loss and degradation through agricultural conversion, wetland drainage, and agrochemical runoff have been identified as key threats, and studies have suggested that a decline in breeding habitat may be a contributing factor to population declines. Habitat association studies have noted relationships between Black Terns and wetland characteristics, including both local-scale factors such as vegetation type, and landscape-scale factors such as wetland density. However, similar studies have not been conducted in Saskatchewan, the core of the species range in North America. We used high-resolution remotely-sensed imagery to relate habitat, land use, and geographic covariates at wetlands in Saskatchewan to the occurrence of breeding Black Terns and numbers at their colonies. We found that colony occurrence was positively associated with the extent of emergent aquatic vegetation present at a wetland. There was a strong non-linear effect of latitude, whereby colony occurrence and abundance were highest at mid-latitudes in Saskatchewan, corresponding to the boreal transition zone between the prairies to the south and boreal forest to the north. Our results suggest that Black Terns may be first selecting habitat at the landscape scale, perhaps in relation to wetland density, then occupying specific breeding colonies based on wetland characteristics. [ABSTRACT FROM AUTHOR]

Hair lichens in the genera Alectoria and Bryoria dominate old-growth circumboreal coniferous forests and have important ecosystem functions, particularly for reindeer and caribou. These lichens are sensitive to changes in climate and are unable to maintain a high standing crop in industrial forestry based on clear-cutting, highlighting the need of management models based on continuous cover forestry. We examined how dry mass (DM) growth and CO 2 exchange in hair lichens depended on the balance between growth (carbon gain from photosynthesis) and losses (both carbon loss from respiration and mass loss from fragmentation). Partial cutting trials were conducted in a Picea abies -dominated forest by three levels of basal area (BA) removal (0 %; 33 %; 67 %), with five 80 m × 80 m plots per level. We compared two species with similar functional traits but with different cortical pigments, the pale Alectoria sarmentosa and the dark Bryoria fremontii. Lichens were transplanted within the lower canopy using net cages over a 1-year period to evaluate net growth, loss by thallus fragmentation and gross growth. Canopy openness and transmitted radiation during the growing season were estimated from hemispherical photographs. Canopy temperature, relative humidity, and photosynthetic photon flux density were monitored, with microclimate data subsequently used to model net CO 2 exchange using previously published response matrices describing net photosynthetic and respiratory activity. Net DM growth of A. sarmentosa was higher than in B. fremontii , and increased with level of BA removal, being twice as high in the 67 % BA removal as in the control. In contrast, B. fremontii responded weakly to partial cutting due to high rates of thallus fragmentation. However, gross growth of both species increased with canopy openness and transmitted radiation. The modelled net assimilation showed large seasonal variation, with the largest difference among levels of BA removal in autumn. The estimated DM growth agreed well with observed gross growth in A. sarmentosa but was underestimated in B. fremontii. Modelling of CO 2 exchange can provide a mechanistic understanding of how hair lichens respond to partial cutting and climate change. The response of hair lichens to microclimate in partial cuts depends on the trade-off between growth and losses. Results suggest that the faster lichen growth on residual trees in the one-third removal partial cuts compensated to a significant degree for the loss of lichen mass by the removal of host trees. [Display omitted] • Net growth of Alectoria was doubled in plots with 67 % basal area removal. • Bryoria responded weakly to partial cutting due to high thallus fragmentation. • Gross growth of both species increased with canopy openness and transmitted light. • Gross growth of hair lichens can be predicted from microclimate and CO 2 gas exchange. • Partial cutting has large potential to improve growth of hair lichens on residual trees. [ABSTRACT FROM AUTHOR]

The competitive stress of individual trees can be quantified by considering their positions and dimensions such as diameter at breast height (dbh) and height with respect to their neighbor trees. However, measurements of these attributes in the field limit the number of trees and stands that can be assessed with given resources. In recent years, terrestrial laser scanning (TLS) and airborne laser scanning (ALS) data have become prominent in characterizing three-dimensional forest structures. These data could also provide efficient and reliable tools to assess the competitive stress of trees within a stand. Therefore, we aimed to investigate the capability of TLS and low-altitude ALS in characterizing the competitive stress affecting individual trees in boreal forests. We compared: a) an object-based approach that quantified competition through the identification and characterization of competing neighbor trees from the TLS and ALS point clouds, and b) a point cloud-based approach where the presence of point cloud structures representing competitive vegetation around a target tree was considered. Accordingly, three object-based competition indices (CIs) utilizing dbh (CI dbh), height (CI H), and maximum crown diameter (CI MCD) as weights were calculated using the Hegyi equation. For the point cloud-based approach, the canopy density index (CDI), and the competitive pressure index (CPI) were derived using an upside-down search cone set at 60 % relative tree height, while the CI Cylinder was calculated by counting the number of voxels occupied by the competitive vegetation inside a fixed-radius cylinder. These laser scanning-based CIs were assessed against in situ -based CIs where dbh and height were used as weights in the Hegyi equation. The results showed that the object-based CIs were more correlated (r = 0.33–0.48, p- value < 0.001) with the in situ -based CIs in comparison with the point cloud-based CIs (r = −0.22–0.37). The object-based CIs showed a high correlation (r = 0.65–0.71, p- value < 0.001) when compared between TLS and ALS, while a greater variation was observed for the point cloud-based CIs (r = 0.29–0.53, p- value < 0.001). Tree detection rate and the number of neighboring trees in the field affected how well the CIs derived from the TLS and ALS data were in line with the in situ -based CIs, especially when the competitive stress was assessed using the object-based CIs. In conclusion, the object-based CIs derived using TLS and ALS provided consistent characterization of competition in managed boreal forests compared to the in situ -based CIs. While TLS is ideal for small-scale assessments, low-altitude ALS offers a rather similar capacity for assessing competition but with broader coverage. In complex forest structures, reliable tree detection is essential to avoid underestimating the competitive stress of trees. • Studying the competitive stress of trees helps in understanding the growth patterns. • Competition indices (CIs) computed by the presence of competing trees or vegetation. • We compared CIs estimated using terrestrial (TLS) and airborne laser scanning (ALS). • ALS provided similar estimates to TLS when CIs were based on the Hegyi equation. • Capacity of capturing all relevant competitors determines CI estimation accuracy. [ABSTRACT FROM AUTHOR]

Livestock summer grazing in mountains and forests in Norway is generally considered beneficial to biodiversity. In this study we investigated if this is the case for cattle in boreal production forest. We collected biodiversity data on field layer vegetation, floral resources and flower-visiting insects in young spruce plantations that were planted 2–10 years ago. We picked young spruce plantations inside and outside well-established cattle grazing areas. On each plantation, we sampled fenced and unfenced plots (20 * 20 m each). This study design allowed us to investigate long-term effects of cattle grazing as well as short-term effects of excluding cervids only and short-term effects of excluding cervids and cattle. Long-term cattle grazing reduced the abundance of woody plants and reduced the abundance of flowers. Excluding cervids for two summers led to reduced height of woody plants (shrubs and heather) and to increased flower abundance. In contrast, excluding cervids and cattle for two summers led to increased height of graminoids, herbs and woody plants, to higher abundance of graminoids, higher flower abundance and higher abundance of flower-visiting insects. In conclusion, cattle affected the studied system in different ways and to a larger extent than native cervids. Our study shows that we must be careful when inferring results from cattle grazing studies on grasslands to forest ecosystems. As this study documents a negative effect of cattle on floral resources and flower-visiting insects, and we currently are facing a global pollination crisis, a careful consideration of the current practice of cattle grazing in boreal forest might be needed. [Display omitted] • In Norway, beef cattle are released for summer grazing into boreal production forest. • We investigated how this practice affects plants and flower-visiting insects. • Cattle affected the studied system in different ways and to a larger extent than cervids. • Cattle reduced vegetation height and reduced the abundance of graminoids. • Cattle reduced the abundance of flowers and the abundance of flower-visiting insects. [ABSTRACT FROM AUTHOR]

The Canadian boreal forest is still lacking investigation into compatible species mixtures that can lead to higher growth rates than monospecific or pure stands. The effect of species mixtures on stand productivity can vary with stem density, species proportion, site characteristics, and climate variation. We investigated mixed stands of black spruce (Picea mariana) and tamarack (Larix laricina) in eastern Canadian boreal forests. Using modern forest survey data, we analyzed stand basal area variation in 756 mature stands exclusively composed of these two species over a study area spanning 535,000 km². We generated a linear relationship between mixed stand basal area and stem density, and the residual of this relation was used as response variable named 'residual basal area'. Positive and negative deviations of residual basal area were analysed with generalized additive models and quantile regressions with tamarack basal area, climate, and site characteristics as explanatory variables. The selected model included tamarack basal area, mean seasonal precipitation, degree days, mean annual temperature, stand age, latitude, longitude, and the type of surficial deposit. Tamarack exhibited a linear positive effect on predicted residual basal area. The most significant effect was observed from the interaction between tamarack basal area and stand age, predicting positive residual basal area of 16 m² ha−1 when stand aged was 150 years old and tamarack basal area was between 12 and 17 m² ha−1. Quantile regressions revealed that tamarack could enhance basal area while increasing black spruce stem size and density. Landscape managers may consider the establishment of mixed black spruce and tamarack stands to favor secondary growth in eastern Canadian boreal forests. • Increasing tamarack proportion linearly increased the basal area in boreal forest mixed stands. • Black spruce mean stem size and stem density were enhanced by the presence of tamarack. • Climate variables had limited effect on mixed stands basal area. • Tamarack and black spruce showed good niche complementarity in the boreal forest. [ABSTRACT FROM AUTHOR]

The natural disturbance model for ecosystem management of timber harvesting promotes the emulation of natural disturbance regimes in the patterns of tree removal. Wildfire is a prominent natural disturbance in boreal forests of western Canada, frequently removing most of the tree canopy from patches of 500–10,000 ha in stand-replacing events. However, fire suppression, coupled with a spatial pattern of timber harvesting dominated by small patch cuts of 10–160 ha, have changed the spatial scale of younger stands away from scales within which boreal organisms evolved. In two regions (Sub-Boreal Spruce biogeoclimatic zone of central British Columbia and Liard Basin of southeast Yukon), we tested the hypothesis that different spatial scales of stand-replacing forest disturbance (wildfire and timber harvesting) result in different amplitudes of change in abundance of snowshoe hare, a keystone boreal forest mammal for which mid-seral stand conditions provide optimal habitat. Landscapes with large patches (>2000 ha) of mid-seral forest following stand-replacing disturbance supported consistently and often significantly more hares, with wider amplitude in cyclic fluctuation, than small patches (20–200 ha) of mid-seral habitat and than mature forest landscapes. Densities of hares high enough to support reproduction by Canada lynx (a specialist hare predator) only occurred in landscapes disturbed at the scale of a moderate to large-sized wildfire (1000 – 10,000 ha). Landscapes unaffected by stand-replacing disturbance for at least 80 years (i.e. mature forests) supported very few hares and without cyclic fluctuations. We recommend that the recent pattern of cutting dominated by small patches (20–200 ha) be shifted to include many larger patches (2000–5000 ha). This can happen with incremental, contiguous patch cutting over a period of years short enough that the completed patch will supply high quality, mid-seral habitat for at least the period of one hare cycle (10 y). In designing relatively large patches, mature green tree retention would be desirable for various values, but would be best as small stands of mature forest dispersed within large patch cuts, similar to the legacy of fire. Silviculture (reforestation and stand tending) should create and sustain a mix of conifer and deciduous regeneration in the mid-seral stands. Emulating spatial patterns of stand-replacing natural disturbance appears necessary to sustain snowshoe hare cycles when most fires are suppressed in intensively managed western Canadian boreal forests. [Display omitted] • Sizes of harvested, western boreal, forest patches are often small (10–200 ha). • Large patches (500–10,000 ha), typical of wildfire, are rare in managed landscapes. • Amplitude of snowshoe hare population fluctuations varies with patch size. • Only large patches support wide amplitudes typical of hare and lynx cycles. • Timber harvesting, in place of fire, should include larger patches (2000–5000 ha). [ABSTRACT FROM AUTHOR]

Litterfall is a major pathway for transferring aboveground biomass to the forest floor and thus plays an important role in building forest soil carbon stocks. However, inter- and intra-annual variability of litterfall remains poorly documented, especially in North American temperate and boreal forests, due to the lack of recent long-term studies at high sampling frequencies. This potentially creates uncertainties in estimates of forest carbon budget models. The objectives of the present study were to 1) quantify the mean annual flux, interannual variability, and seasonality of litterfall in three sites (dominated respectively by sugar maple (Acer saccharum Marsh.), balsam fir (Abies balsamea (L.) Mill. 1768), and black spruce (Picea mariana (Mill.) B.S.P.)) in eastern Canada over a period of 22–32 years, 2) relate the litterfall amounts and temporal variations to the changes in the size of major organic matter pools in these ecosystems, and 3) compare our litterfall estimates with reference values used in national greenhouse gas inventories. Litterfall production decreased from the sugar maple to the balsam fir and black spruce sites, preponderantly due to species composition. Litterfall evolution was related to the aboveground biomass of live trees in both conifer sites; in contrast, in the broadleaf site, changes in forest composition and structure were apparently the main drivers. The litterfall seasonality varied between broadleaf and conifer sites and could be explained by a sigmoidal model. Substantial departures from the seasonality for some given years were likely due to important climatic anomalies. Forest floor biomass remained stable over time at all three sites despite the increase in litterfall at the balsam fir and sugar maple sites and rapid forest floor turnover at the latter site. Our analyses of litterfall suggest that reference values from the literature used for national greenhouse gas inventories underestimate annual litterfall and forest floor carbon stocks for temperate and boreal forests. [Display omitted] • Litterfall evolution was related to aboveground biomass only in conifer sites • Mean annual flux and seasonality of litterfall varied by forest type • Climatic anomalies altered annual litterfall production and seasonality • Carbon budget model underestimated carbon stock of litterfall and forest floor [ABSTRACT FROM AUTHOR]

Accurate canopy cover estimation is essential for mature and early-stage young forests, as it guides forest management and silvicultural activities necessary for their growth and regeneration. However, obtaining precise measurements of canopy cover in the field is time-consuming and challenging, especially at the regional and landscape levels. Remote sensing techniques offer a promising alternative to traditional field-based measurements for estimating forest canopy cover. In this study, our objective is to estimate forest canopy cover using vegetation indices derived from the multispectral bands of PlanetScope (Planet Lab, Inc., San Francisco, CA, USA). To the best of our knowledge, this is the first study to utilise PlanetScope imagery data for estimating canopy cover in young boreal forests. Based on the analysis of four bands (green, blue, red, and near-infrared) from PlanetScope imagery, 43 vegetation indices, including four spectral bands and 13 salinity indices, were computed to select predictors in canopy cover modelling. Six regression models were employed to model canopy cover: linear, elastic net, support vector machine, random forest, extreme gradient boosting, and light gradient boosting machine. All the models demonstrated good performance for both the training dataset (R2 = 0.58–0.69) and the testing dataset (R2 = 0.59–0.64, RMSE = 0.16–0.18, rRMSE = 22%–23%, and MAE = 0.12–0.14). Based on the fit statistics in the training and testing datasets and the paired t -test, our study identified the light gradient boosting machine as the most suitable model for predicting canopy cover in young boreal forests. For the light gradient boosting machine, the R2 value was 0.69 (training), and for testing data, the R2 = 0.64, RMSE = 0.16, rRMSE = 22%, and MAE = 0.12. Therefore, we recommend that future researchers utilise Planet multispectral data and the light gradient boosting machine regression to estimate forest canopy cover at a higher spatial resolution. However, exploring additional machine learning algorithms and explicitly boosting methods when computing forest canopy cover using satellite remote sensing is strongly advised. • We modelled the forest canopy cover using PlanetScope satellite-based 43 vegetation indices. • We used six regression models: linear, Enet, SVM, RF, XGboost, and LightGBM. • The reference forest canopy cover was calculated using Light detection and ranging 3D point clouds data and FUSION software. • The performance of the light gradient boosting machine model was the strongest across the six models. [ABSTRACT FROM AUTHOR]

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd 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.)

Given the large and increasing amount of urban, suburban, and exurban land use on Earth, there is a need to accurately assess net primary productivity (NPP) of urban ecosystems. However, the heterogeneous and dynamic urban mosaic presents challenges to the measurement of NPP, creating landscapes that may appear more similar to a savanna than to the native landscape replaced. Studies of urban biomass have tended to focus on one type of vegetation (e.g., lawns or trees). Yet a focus on the ecology of the city should include the entire urban ecosystem rather than the separate investigation of its parts. Furthermore, few studies have attempted to measure urban aboveground NPP (ANPP) using field‐based methods. Most studies project growth rates from measurements of tree diameter to estimate annual ANPP or use remote sensing approaches. In addition, field‐based methods for measuring NPP do not address any special considerations for adapting such field methods to urban landscapes. Frequent planting and partial or complete removal of herbaceous and woody plants can make it difficult to accurately quantify increments and losses of plant biomass throughout an urban landscape. In this study, we review how ANPP of urban landscapes can be estimated based on field measurements, highlighting the challenges specific to urban areas. We then estimated ANPP of woody and herbaceous vegetation over a 15‐year period for Baltimore, MD, USA using a combination of plot‐based field data and published values from the literature. Baltimore's citywide ANPP was estimated to be 355.8 g m−2, a result that we then put into context through comparison with other North American Long‐Term Ecological Research (LTER) sites and mean annual precipitation. We found our estimate of Baltimore citywide ANPP to be only approximately half as much (or less) than ANPP at forested LTER sites of the eastern United States, and more comparable to grassland, oldfield, desert, or boreal forest ANPP. We also found that Baltimore had low productivity for its level of precipitation. We conclude with a discussion of the significance of accurate assessment of primary productivity of urban ecosystems and critical future research needs. [ABSTRACT FROM AUTHOR]

Climate change will lead to more frequent and more severe fires in some areas of boreal forests, affecting the distribution and availability of late‐successional forest communities. These forest communities help to protect globally significant carbon reserves beneath permafrost layers and provide habitat for many animal species, including forest‐dwelling caribou. Many caribou populations are declining, yet the mechanisms by which changing fire regimes could affect caribou declines are poorly understood. We analyzed resource selection of 686 GPS‐collared female caribou from three ecotypes and 15 populations in a ~600,000 km2 region of northwest Canada and eastern Alaska. These populations span a wide gradient of fire frequency but experience low levels of human‐caused habitat disturbance. We used a mixed‐effects modeling framework to characterize caribou resource selection in response to burns at different seasons and spatiotemporal scales, and to test for functional responses in resource selection to burn availability. We also tested mechanisms driving observed selection patterns using burn severity and lichen cover data. Caribou avoided burns more strongly during winter relative to summer and at larger spatiotemporal scales relative to smaller scales. During the winter, caribou consistently avoided burns at both spatiotemporal scales as burn availability increased, indicating little evidence of a functional response. However, they decreased their avoidance of burns during summer as burn availability increased. Burn availability explained more variation in caribou selection for burns than ecotype. Within burns, caribou strongly avoided severely burned areas in winter, and this avoidance lasted nearly 30 years after a fire. Caribou within burns also selected higher cover of terrestrial lichen (an important caribou food source). We found a negative relationship between burn severity and lichen cover, confirming that caribou avoidance of burns was consistent with lower lichen abundance. Consistent winter avoidance of burns and severely burned areas suggests that caribou will experience increasing winter habitat loss as fire frequency and severity increase. Our results highlight the potential for climate‐induced alteration of natural disturbance regimes to affect boreal biodiversity through habitat loss. We suggest that management strategies prioritizing protection of core winter range habitat with lower burn probabilities would provide important climate‐change refugia for caribou. [ABSTRACT FROM AUTHOR]

Biocontrol of caterpillars by ants is highly variable, and we investigate how the strength of the trophic relationship between ants and an important outbreaking forest pest depends on phenological synchrony and on social foraging. We test the hypothesis that early spring foraging by ants, coupled with eusocial recruitment behavior, could undermine the caterpillar's strategies to achieve either enemy-free space or predator satiation.We use a series of field surveys and experiments in trembling aspen stands (Populus tremuloides) in the boreal forest of eastern Canada to assess the role of ants in early-instar mortality of the outbreaking, gregarious forest tent caterpillar (Malacosoma disstria). We also investigate individual-level mechanisms related to phenology and social behavior that underlie the effectiveness of ants as biocontrol on caterpillars. Our results show that ants climb trees early in the spring and harvest young forest tent caterpillars, suggesting that early phenology does not provide an entirely enemy-free space for caterpillars. Our findings further show that recruitment-based social foraging enables ants to deplete groups of gregarious prey, suggesting that these eusocial insects are particularly effective at generating predation pressure on gregarious herbivores since they do not satiate easily. Finally, a manipulative predator exclusion experiment confirms that ant predation is a significant mortality source for early-instar forest tent caterpillars. Taken together, these results suggest that phenology and sociality could modulate the role of ants as effective caterpillar predators and thus showcase the importance of considering natural history and behavioral traits when studying trophic interactions and their role in population dynamics. [ABSTRACT FROM AUTHOR]

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• Ungulate browsing reduced the abundance of both the bilberry plant and invertebrate consumers feeding on this key forest plant. • The plant biomass was nine times higher and invertebrate abundance, as indexed by leaf-chewing, was three times higher when ungulates were excluded. • The 15-year recordings, with five-year intervals, strongly indicated that insect community fluctuations are dampened when browsing ungulates had access to the forest. Ecological theory predicts the strongest ecosystem effects of herbivory when dominant and ecologically important species are consumed. Bilberry, Vaccinium myrtillus , is such a key plant species, attractive to many other species in the boreal forests, for example ungulate and invertebrate herbivores. Large herbivores may remove substantial biomass and alter plant quality and therefore affect abundance and populations of invertebrate animals sharing the same food plant. We combined experimental exclusion of ungulates with a browsing intensity gradient to investigate the 15-year effect of ungulate (Cervus elaphus and Ovis aries) browsing on bilberry plant size and on bilberry-feeding herbivorous larvae (Lepidoptera and Symphyta), in a Norwegian old growth boreal forest ecosystem. Bilberry ramets in exclosure plots had nearly nine times higher dry mass and three times higher abundance of invertebrates feeding on them than in ungulate-access plots. Sweep-netting data verified these findings as larval numbers were twice as high in exclosure plots. The pattern in the large herbivore effects on bilberry size and abundance of herbivorous larvae were identical along the browsing gradient. Differences in larval abundance between treatments, as indicated by leaf-chewing, increased during the 15-year study period, and the community fluctuations were larger when ungulate herbivores were excluded. The browsing effect was moderated by plant quality as larval densities were lowest on both heavily-browsed and non-browsed plants, and highest on ramets that had 50–74% of annual shoots browsed. Our study supports previous findings in that bilberry is relatively disturbance tolerant and may recover quickly, but that ungulates may compete with herbivorous larvae for food biomass. Additionally, our results strongly indicates that population insect community peaks and fluctuations are dampened by ungulate consumption. Our findings add to the understanding on how ungulates may structure forest ecosystems directly and indirectly. [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.)

In recent decades, increases in severe drought, heat extremes, and pest burden have contributed to increased global tree mortality. These risks are expected to be exacerbated under projected climate change. So far, observations of tree mortality are mainly based on manual field surveys with limited spatial coverage. The lack of accurate tree mortality data over large areas has limited the development and applications of tree mortality models. However, a combination of high-resolution remote sensing data, such as aerial imagery and automated imagery analysis, may provide a solution to this problem. In this study, we analysed the dynamics and drivers of forest canopy mortality in 117 366 ha of boreal forest in Southeast Finland, between 2017 and 2023. For this purpose, we first developed a fully convolutional semantic segmentation model to automatically segment forest canopy mortality from aerial imagery in 2017, 2020, and 2023 with a spatial resolution of 0.5 m. Secondly, we trained the model using a dataset consisting of 32555 canopy mortality segments manually delineated from aerial imagery from various geographic regions in Finland. The trained model showed high accuracy in detecting forest canopy mortality (with an F1 score of 0.86–0.93) when tested using an independent test set. To estimate standing deadwood volume, we combined the observed yearly forest canopy mortality with open forest resource information based on extensive field campaigns and airborne laser scanning. In our study area, forest canopy mortality increased from 23.4 ha (0.02 % of the study area) to 207.8 ha (0.18 %) between 2017 and 2023. Consequently, standing deadwood volume was estimated to increase from 5192 m3 (0.04 m3/ha) to 52800 m3 (0.45 m3/ha) during the study period. Both the volume of standing deadwood and the extent of forest canopy mortality increased exponentially. The majority of the forest canopy mortality occurred in Norway spruce-dominated forests (64.1–77.3 %) on relatively fertile soils (81.6–84.7 %) while 20–25 % of the forest canopy mortality occurred in Scots pine-dominated forests. The average age of stands where mortality was observed was between 60 and 70 years old (2017 = 69.7 years and 2023 = 62.6 years), indicating that mature forests were more susceptible to mortality than younger stands. Our findings highlight an exponential increase in forest canopy mortality over a relatively short time span (6 years). The increasing risk of tree mortality in boreal forests underlines the urgent need for large-scale and spatially accurate monitoring to keep up to date with fast-paced changes in boreal forest mortality. As climate change increases drought, extreme heat and bark beetle outbreaks, consistent canopy mortality mapping is essential for implementing timely risk management measures in forestry. • Forest canopy mortality increased by 788 % between 2017 and 2023. • Distribution of canopy mortality shifted towards younger forest stands. • Forest canopy mortality detected with an F1-score of 0.86–0.93 from aerial imagery. [ABSTRACT FROM AUTHOR]

Climate change increases the likelihood of extreme weather events and the risk of damage to seedlings. At the same time, forest growth and thus carbon sequestration should be increased to mitigate climate change. A decrease in the number of forest workers requires an extension of the planting season from the traditional spring to fall. These changes in the operating environment can also affect root growth and early performance of seedlings. Granular arginine phosphate has been developed to improve root growth of tree seedlings and may be a potential tool to improve field performance of seedlings after planting. The aim was to study the effects of arGrow® Granulat (ARG) on the field performance of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) seedlings planted at different planting dates and under different site conditions in boreal forests. Container seedlings were planted in mounds on the forest regeneration sites and under the harsh conditions in the former gravel pits in Central Finland. Pine seedlings were planted in May 2021 and spruce seedlings in May and September 2021 and in June 2022. ARG granules were added to the planting hole for half of the seedlings, while the other half remained the untreated control. In the former gravel pits, there was a lot of drought damage, more in spruce than in pine. Under these harsh conditions, ARG treatment increased root growth in Scots pine seedlings and height growth in both species when damage level was moderate. In the forest sites, the exceptionally warm and dry early summer of 2021 and severe night frosts in June 2023 damaged spruce seedlings in particular, and animals pine seedlings. The ARG treatment affected damage levels only in fall planted spruce, with slightly less severe damage in treated than in untreated seedlings. No other differences in damage levels between seedling treatments were found in forest sites. Damage found at most sites made it difficult to reliably compare seedling treatments, and differences in height between treatments varied. On sites with the least damage, ARG treatment increased seedling height of healthy seedlings in both pine and spruce, but the effects were clearer in pine. In conclusion, it is difficult to study true growth effects of ARG treatment under relevant forest conditions, but there was some evidence that arGrow® could increase seedling growth, more so in pine and under harsh planting conditions. • Arginine phosphate improved growth clearer in Scots pine than in Norway spruce. • Arginine phosphate reduced severe damage in fall-planted Norway spruce seedlings. • Scots pine seedlings were more drought resistant than Norway spruce seedlings. • Pine weevils damaged more fall-planted than summer planted seedlings. [ABSTRACT FROM AUTHOR]

Copyright of Forest Ecology & Management is the property of Elsevier B.V. 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.)

Forest tent caterpillar (Malacosoma disstria Hbn.) is a major forest defoliator in North American boreal forests. This pest periodically affects hardwood trees such as trembling aspen (Populus tremuloides Michx.) and balsam poplar (Populus balsamifera L.) across large areas, causing mortality and altering stand attributes and long-term dynamics. In this study, I quantified the responses of aspen stands to forest tent caterpillar defoliation and overstory dieback, including short-term (5 years after dieback) and long-term (20 years later) dynamics. Results indicate that affected stands fully recovered to pre-dieback density but not basal area. Defoliation caused overstory dieback that stimulated understory growth and regeneration but the hardwood regeneration (mostly aspen) did not adequately replace hardwood trees lost to defoliation, resulting in decreased hardwood composition relative to unaffected stands. The high density in affected stands suggested possible further basal area recovery as regeneration and released understory conifers grew into main canopy, following the general trends of boreal mixedwood succession. The results support earlier projections based on residual stand attributes shortly after dieback and reported boreal species growth and mortality rates that indicate forest tent caterpillar defoliation and subsequent overstory dieback would accelerate aspen stand transition to conifer dominance and delay the availability of stands for harvesting by 40–50 years as stands recover. • Forest tent caterpillar defoliates and kills aspen and other hardwood trees. • Affected stands fully recovered in density 20 years post-dieback. • Affected stands recovered 50% basal area lost to insect defoliation. • Affected stands were lower in hardwood composition than unaffected stands. • Overstory basal area and DBH in affected stands will continue to recover. [ABSTRACT FROM AUTHOR]

After a mine is closed, waste rock storage areas must be revegetated to facilitate the return of ecosystem services and meet legal and social expectations. The restoration of forest ecosystems on waste rock through spontaneous colonization associated with primary succession can take decades and is still poorly studied. Adding a mulch of ramial chipped wood (RCW) could improve the physicochemical properties and microclimate conditions of waste rock, thus facilitating substrate colonization by plants. In 2016, a fully randomized block design was installed on waste rock from a closed gold mine located in the boreal forest in Abitibi-Témiscamingue, Quebec, Canada. The design included four treatments: scarified waste rock as the control (W R), 2 cm of RCW mulch on top of scarified waste rock (RCW/W R), and 10 cm layer of sand on top of scarified waste rock with or without 2 cm of RCW mulch (RCW/S and S, respectively). Over a period of five years, we followed the natural colonization of forest species as well as abiotic (substrate microclimate conditions and physicochemistry) and biotic (herbaceous plant colonization) factors influencing woody plant colonization success. Six boreal woody species spontaneously colonized the area (five individuals per m2, on average, all species combined). Salix sp. and Picea glauca seedlings were more abundant on substrates with RCW mulch (especially sand) than those without mulch, and P. glauca had greater aerial biomasses with RCW mulch. Substrate water content during the growing season and the presence of the weed species Tussilago farfara were determining environmental factors in substrate colonization by Abies balsamea. In the absence of Tussilago farfara , RCW mulch increased A. balsamea colonization. RCW mulch increased the total cover of colonizing herbaceous plants (23.3–58.2%) as compared to mineral substrates alone (4.78–52.3%), which negatively affected the number of A. balsamea individuals. The colonizing herbaceous species were mostly primary succession species, Pilosella caespitosa , Anaphalis margaritacea , and Tussilago farfara being dominant; no exotic species were observed. The results highlight the potential of RCW mulch in promoting forest recolonization on waste rock, including mid-successional species like Picea sp. , which could be useful for facilitating ecosystem succession in post-mining landscapes. • Six boreal woody species were present in the first five years of primary succession. • Willow ramial chipped wood increased the number of Salix and Picea seedlings. • Willow ramial chipped wood increased the cover of colonizing herbaceous plants. • Picea glauca had greater aerial biomasses with ramial chipped wood mulch. • Soil water content and weed cover affected the number of Abies balsamea seedlings. [ABSTRACT FROM AUTHOR]

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd 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 Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd 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.)

Exploration practices for oil sands developments in the boreal forest of western Canada create a network of thousands of kilometers of linear features, particularly seismic lines that dissect these forests posing significant environmental challenges. As wildfire is one of the prevalent stand‐replacing natural disturbances in the Canadian boreal forest, it is an important driver of environmental change and stand development that may contribute to the mitigation of such linear industrial footprint. Here, we evaluate the short‐term cumulative (also known as combined) effects of seismic lines and wildfire on biodiversity and site conditions. One year after the Horse River (Fort McMurray, Alberta, Canada) fire event in the spring of 2016, we compared dissected and undisturbed forests in burned and unburned boreal peatlands, assessing changes in overall stand structure and the responses of a variety of organisms. Soil moisture was significantly higher on seismic lines than in the adjacent forest, suggesting why most of the study sites within the fire perimeter showed little evidence of burning at the line in relation to the adjacent forest. Low fire severity on seismic lines seemed an important driver of local species diversity for ants, beetles, spiders, and plants in disturbed peatlands, resulting in similar species composition on seismic lines both within and outside the burned area, but different assemblages in burned and unburned adjacent forests. Our results suggest that fire did not erase seismic lines; rather, wildfire might increase the influence of this footprint on the recovering adjacent forest. Longer‐term monitoring will be necessary to understand how boreal treed peatlands respond to the cumulative effect of wildfire and linear disturbances. [ABSTRACT FROM AUTHOR]

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd 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 Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd 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.)

Satellite transmitters were used to describe migration patterns and establish connectivity among breeding and wintering areas for 30 White-winged Scoters (Melanitta deglandi) tagged in August 2010 or August 2012 during remigial molt in the St. Lawrence Estuary, Quebec, Canada. Fourteen potential breeding sites were identified in the boreal forest from Quebec to the Northwest Territories, Canada. Most birds molted at marine sites, except for two females that molted close to their breeding areas and a male that molted in interior Manitoba. Most birds remained near their molting location during fall prior to migrating to their wintering area. Individuals tended to use similar fall migration routes from year to year. Most birds (81%) wintered in the Long Island-Nantucket-Cape Cod region along the eastern seaboard of the USA, while only three birds wintered in Canada. Scoters spent almost half the year on wintering areas, and 83% returned within 150 km of the previous year's site. Spring migration patterns depended on breeding status. Breeding birds covered an average of 6,880 km compared to 2,550 km by non-breeding birds during their annual cycle. The St. Lawrence Estuary in Quebec and the Long Island-Nantucket-Cape Cod region (New York state and Massachusetts) were areas particularly important for tagged birds. [ABSTRACT FROM AUTHOR]

Trenčianske Bohuslavice Gravettian site has been known since the early 1980s, with possibly the longest sequence of Upper Palaeolithic human occupation in the region, including a peculiar assemblage of lithic tools composed of bifacial leaf points. This paper presents the results of the 2017 excavation season that produced new data on the absolute chronology, stratigraphy, paleobotany, archaeology, and archaeozoology of the site. We found that the earliest occupation most probably belongs to the Aurignacian. This is followed by two Late Gravettian layers and the layer that yielded the bifacial leaf points. An Early Epigravettian layer dated to 26 kya seals the sequence. The succession of biological remains and geological evidence enabled the reconstruction of a cooling climate and disappearing boreal forest, which corresponded well with the development of the Last Glacial Maximum. [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.)

Areas affected by forest fires are increasing worldwide, making salvage logging (i.e., harvesting fire-affected trees) an increasingly used practice to reduce the economic impacts of fire on forestry. However, salvage logging can have strong ecological impacts, notably on post-fire forest regeneration and biodiversity. Burn severity (i.e., the degree to which fires impact the vegetation and soil) is also a central element that interacts with pre-fire forest characteristics and salvages logging to control post-fire forest dynamics and biodiversity. In an ecosystem-based forest management context, spatial patterns of burn severity should thus be considered when planning salvage logging operations. This study presents a simple and innovative method to generate burn severity maps with Landsat and Sentinel-2 multispectral imageries to support salvage logging operations rapidly after a fire event. We assembled a unique dataset involving 330 plots from 10 burns (from 2010 to 2020) in which burn severity has been estimated on the field using the composite burn index (CBI) approach in eastern North America. CBI values were modelled as a univariate function of changes in spectral indices using the first cloud-free post-fire satellite images taken after the burns. Our results demonstrate that using free satellite images with straightforward methods can produce reliable and ecologically meaningful burn severity maps within the few weeks following a fire event. The method was then applied to a case study with salvage logging that illustrates how our burn severity maps could be a useful tool for guiding post-fire forestry operations in an ecosystem-based management context. We combined burn severity maps with pre-fire forest composition and age maps to assess immediate post-fire forest. We discuss how such an approach helps to guide salvage planning and maintain residual forests that are representative of the initial post-fire spatial variability in burn severity and pre-fire vegetation. We conclude that rapid mapping of burn severity after a forest fire event may offer many other applications for identifying and managing recently burned forests. • Interactions between salvage logging and burn severity control post-fire dynamics. • Unsalvaged residual forests should represent the variability in burn severity. • Free satellite imagery can rapidly produce burn severity maps after a fire event. • Such maps are powerful tool for guiding post-fire salvage logging operations. [ABSTRACT FROM AUTHOR]

Net primary production in boreal coniferous forests is generally severely limited by N deficiency. Nitrogen fertilization has thus the potential to strongly increase forest tree biomass production in the boreal region and consequently increase the biosphere uptake of atmospheric CO 2. Increased N availability may though increase the production and emission of soil N 2 O, counteracting the climate mitigation potential from increased forest biomass production. Studies in the boreal region on the net effect on the climate mitigation potential from N fertilization are scarcer than in other biomes. Therefore, we explored how N affected soil GHG fluxes in two boreal field N-loading experiments, of which one is a long-term experiment (40 years), and the other established 6 years before investigation. We also estimated whether the increased soil N 2 O emission could offset the N-driven increased C sequestration by the trees. Nitrogen additions affected the soil GHG fluxes in both stands. Soil N 2 O emission was enhanced by N addition at every fertilization rate, though marginally compared to the reduced soil CO 2 emission and the increased atmospheric CO 2 uptake and biomass production. The estimated annual uptake of CH 4 by soil under long-term N addition increased. The magnitude of soil CH 4 uptake was on the same order of magnitude as the increase in soil N 2 O emissions caused by N addition, when compared as CO 2 equivalents. In conclusion, forest N fertilization in boreal areas increased the GHG net uptake and, thus, provides a means to mitigate increasing atmospheric concentrations of GHG. • Effects of N addition (20-60 kg N ha-1 yr-1) on tree growth and soil GHG exchange in Pinus sylvestris stands were studied. • N-addition increased stand carbon sequestration and tree growth. • Annual soil CO 2 efflux was reduced, annual N 2 O emission increased up to seven-fold, while CH 4 exchange was unaffected. • The fraction of annually added N lost as N 2 O agree well with reported IPCC emission factors. • Overall, the increase in soil N 2 O emission are negligible in comparison with the increased C sequestration. [ABSTRACT FROM AUTHOR]

Airborne laser scanning (ALS) is increasingly being used to detect cultural remains in forest landscapes. Boreal forests are challenging, however, since most ancient land use was carried out without major permanent ground disturbances. If this challenge can be met, there is a large potential for surveys through existing nation-wide laser-scanning programs, although their resolutions tend to be low. In this study, we compare the performance of low-resolution (LR) and high-resolution (HR) ALS data in the Krycklan catchment in northern Sweden, an area where ancient land use was small-scale and diverse. About three times as many cultural remains were detected in the HR data set, but the LR set was satisfactory for distinct structures. We analyze how LR data sets can be enhanced at ground-point classification and terrain-model generation and conclude that ALS data have a large potential for the detection and protection of cultural remains in the boreal forest. [ABSTRACT FROM AUTHOR]