13 results
Search Results
2. An experimental test of niche versus dispersal limitation of the distribution limit of the Ghost Antler Lichen, Pseudevernia cladonia , along a temperate–boreal elevation gradient.
- Author
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Rinas, Christina L. and Vellend, Mark
- Abstract
Understanding the mechanisms underlying species' distribution limits is critical for predicting how species may respond to environmental change. For species restricted to mountain summits, there is concern that climatic changes may result in increasingly restricted distributions. Two central mechanisms govern species distribution limits: (i) niche limitations–environmental conditions beyond distribution limits that are insufficient for survival and reproduction, and (ii) dispersal limitations that prevent colonization of suitable habitat beyond distribution limits. Here, we conducted a transplant experiment to examine the effect of niche versus dispersal limitation on the altitudinal distribution limit of the Ghost Antler Lichen (Pseudevernia cladonia (Tuck.) Hale & Culb.) that, within Québec, Canada, is restricted to high-elevation mountain summits in the southeast. Along an elevation gradient, we transplanted individuals into sites within its distribution, at the edge, and beyond its distribution. We observed that survival and performance were greatest within its distribution and decreased markedly beyond its distribution, supporting our prediction that this lichen is niche limited along the elevation gradient. We suggest that cooler and more humid conditions at the summit are important environmental factors for this species' persistence. Our findings suggest that projected climatic changes in these montane habitats may result in less suitable habitat for this species. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Are operational plantations meeting expectations? A large-scale assessment of realized versus anticipated yield in eastern Canada.
- Author
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Barrette, Martin, Auger, Isabelle, Thiffault, Nelson, and Barrette, Julie
- Subjects
TREE farms ,PLANTATIONS ,CARBON sequestration in forests ,FOREST resilience ,FOREST conservation ,FOREST productivity ,JACK pine - Abstract
Forest plantations play an increasingly important role in meeting global demand for wood. They usually have higher yield than naturally regenerated forests. Thus, plantations can support economically viable wood production, enable forest conservation elsewere, help mitigate climate change by contributing to carbon sequestration and increase forest resilience and resistance to biotic and abiotic stressors. If yield of plantations is not as high as anticipated, then their use could generate important sustainability issues. There are still major gaps in our understanding of the factors that influence yield, even with respect to black spruce, white spruce, and jack pine, three of the most commonly planted tree species in northeastern North America. Our objective was to evaluate the yield of forest plantations of these species over a 416 000 km
2 region that was representative of northeastern North American forests. Contrary to our prediction, realized yield of operational plantations was consistently lower than anticipated. Site index and competition both played a significant role in determining the yield of plantations. In the context of uncertain realized yield of operational plantations, we emphasize the necessity of relying on adaptive management to determine harvest levels that are compatible with sustainable management objectives. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
4. Early influences of tamarack (Larix laricina) on black spruce (Picea mariana) and its immediate environment in plantations.
- Author
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Roy Proulx, Samuel, Leduc, Alain, Thiffault, Nelson, and Laganière, Jérôme
- Subjects
BLACK spruce ,PLANTATIONS ,LARCHES ,TREE growth ,MONOCULTURE agriculture ,SOIL acidity ,TAIGAS - Abstract
Mixed plantations are garnering increased attention due to their potential to provide a broader array of benefits compared to monocultures. Although numerous studies have indicated promising complementarity between black spruce (Picea mariana) and tamarack (Larix laricina), few have delved into individual tree growth interactions to thoroughly assess early growth complementarity. We sampled 119 planted black spruce and their immediate environment to quantify and qualify any differences between two conditions in young plantations: mixed tamarack ("mixtures") and black spruce monocultures ("monocultures") within young plantations. We investigated the effect of neighbouring under four perspectives: tree competition, microenvironment, foliar nutrients, and soil nutrients. Our results showed increased values for black spruce foliar nitrogen total concentration, soil pH, and canopy closure in mixtures compared to monocultures. Furthermore, black spruce stem volume was increased by 38.1% in mixture compared to monoculture. Black spruce stem volume was negatively affected (86% decrease) by the combined effect of shrubs and non-crop trees under high competition pressure, despite the plantation being mechanically released in 2017. Collectively, our results suggest that black spruce growing in mixtures holds a greater growth potential than black spruce in monocultures. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Gamma radiation for the estimation of mineral soil water content in a boreal forest.
- Author
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Gélinas, Mathieu and Jutras, Sylvain
- Abstract
Continuous monitoring of water quantities in different soil horizons is necessary to understand the behavior of infiltrated water in the soil. Under certain conditions, using measurements of natural ground gamma radiation can help us estimate soil water content measurements over a 100 m
2 surface within a 15 cm depth. A CS725 sensor can provide up to four daily estimates of soil water content by detecting the natural emission of gamma radiation. However, in boreal forest environments, gamma radiation mitigated by the water in the thick humus layers (litter, fermented, and humic horizon) can bias the underlying mineral soil water content measurements. The objective of this research was to evaluate the accuracy of methods that incorporate variables describing the surface humus layer into calculations of the underlying mineral soil water content, by measuring the soil's natural gamma emission with the CS725. Using raw gamma radiation values obtained by CS725 sensors deployed over various boreal soils, we tested two functions. The first one included variables describing the humus layer and the other excluded these variables (manufacturer's method). The function that included the descriptive humus layer variables showed superior results compared to the function without. The results of this study suggest that the CS725 sensor can adequately estimate mineral soil water content within ±10% absolute of the reference water content when examined with the following humus variables: humus layer thickness, fractioned composition, bulk density, and linear gamma radiation attenuation. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
6. New aboveground biomass equations by components for small black spruce in peatland ecosystems of Western Canada.
- Author
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Wagers, Steven, Castilla, Guillermo, Voicu, Mihai, Rea, Tyler, and Sanchez-Azofeifa, G. Arturo
- Abstract
Black spruce is the most common tree species in Canada, dominating treed peatlands where they are usually stunted. We used 495 destructively sampled trees from 56 plots to develop allometric models of aboveground biomass by components (stem, branches, and needles) for small (<5 m tall) black spruce from peatlands in the Taiga Plains and Boreal Plains Ecozones of Western Canada, for which there were no specific models available of biomass by components. We used leave-one-plot-out cross-validation to assess transferability and compare our models with existing national and ecozone-specific equations. Our models predicted total tree biomass with better accuracy and less biased estimates than the national model (relative RMSE: 30% versus 35% national; relative bias: +1% versus –12% national). Similar results were obtained in other external datasets. Existing ecozone equations performed worse than either our models or the national ones. When we applied the models at the plot level to predict aboveground biomass density (Mg·ha
−1 ), our models outperformed the national model again (relative RMSE: 15.9% versus 18.6% national, relative bias: +3.5% versus –13.6% national). These results indicate that at least for peatlands of Western Canada, our models provide better aboveground biomass estimates for small black spruce trees than existing models. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
7. Poor regeneration of pine after mountain pine beetle attack in colder boreal regions of Canada.
- Author
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Lieffers, Victor J., Benedik, Julie, Stadt, Ken, and Macdonald, S. Ellen
- Abstract
The recent expansion of mountain pine beetle (MPB, Dendroctonus ponderosae) from its native range in western North America into northern boreal pine forests in Alberta, Canada has resulted in conditions for tree regeneration that are dramatically different from those after wildfire, the predominant natural disturbance in these forests. We assessed natural regeneration post-MPB for northern boreal lodgepole pine sites in Alberta, Canada via intensive surveys of small plots at 33 severely attacked pine stands and using data from 205 permanent sample plots representing various site types and levels of MPB mortality. We used model selection to identify factors explaining regeneration. Overall, pine regeneration was very poor 6–9 years post-MPB; only 42% of the 33 intensively surveyed plots and only 9% of the 205 permanent plots had pine seedlings. This poor regeneration is attributed to high levels of cone serotiny in these populations, unsuitable regeneration microsites due to undisturbed litter or feathermoss layers, and competition from the residual canopy and understory vegetation. Other species (aspen, birch, poplar, and black and white spruce) were found on most sites, either as post-attack regeneration or regeneration established in advance. Without intervention, many of these stands will likely transition away from pine, to broadleaf and other conifer species. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Effect of forest understorey stand density on woodland caribou (Rangifer tarandus caribou) habitat selection.
- Author
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Wilson, Steven F., Nudds, Thomas D., Green, Philip E.J., and de Vries, Andrew
- Abstract
Woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) use older forests that provide abundant terrestrial lichen forage and refuge from predators. However, forest structural characteristics vary widely, differing in forage availability but also, perhaps, in the ability of caribou to move freely to access forage or to escape predation. We conducted a multivariate analysis of habitat in two geographically and biophysically distinct regions to identify the independent effects of various attributes, including forest understorey stand density, defined as standing and downed biomass, on caribou habitat selection. We developed Bayesian network models to predict the probability of habitat selection based on a set of remotely sensed habitat inputs. Caribou in the Bistcho range (northwestern Alberta) selected non-forest/sparsely forested areas, while caribou in the Trout Lake region (northwestern Ontario) selected primarily forested habitats, nevertheless consistent with selection for reduced predation risk in both cases. Caribou also selected forest stands with lower understorey stand density in both regions, consistent with selection for stands that would allow greater ease of movement. The high-resolution satellite data resolved habitat characteristics more consistently and in greater detail than standard forest cover datasets that are most often used for these analyses, and led us to conclude that habitat management may require different treatments in different parts of the species' range to address what are nevertheless common pathways to decline. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
9. The influence of forest harvesting activities on seismic line tree and shrub regeneration in upland mixedwood boreal forests.
- Author
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Van Dongen, Angeline, Jones, Caren, Schoonmaker, Amanda, Harvey, Jill, and Degenhardt, Dani
- Subjects
FOREST regeneration ,TIMBERLINE ,TAIGAS ,FOREST restoration ,TREE planting ,TREE growth - Abstract
Alberta's forests are becoming increasingly disturbed and fragmented by the cumulative effects of anthropogenic disturbances exacerbated by the enduring footprint of seismic lines on the landscape. Forest harvesting and subsequent reforestation activities (e.g., site preparation and tree planting) may facilitate tree growth on seismic lines when forestry companies incorporate them into management areas. In this study, forest regeneration was assessed along transects on and off seismic lines within four cutblocks in northwestern Alberta. Tree, sapling, and shrub characteristics were measured, and tree cookies from a subset of trees on and off seismic lines were used to model height growth. No difference in total tree, sapling, or shrub counts on and off seismic lines was found although trees on seismic lines were growing at slightly slower rates compared to the adjacent cutblock, and Alnus viridis was more abundant on seismic lines. Our results suggest that, despite some species-level differences and modest differences in tree growth rates, trees on seismic lines within cutblocks are regenerating similarly to other trees growing in the post-harvest stand. These findings indicate that forest harvesting, and subsequent reforestation, could represent an important tool in conducting landscape-level restoration in mixedwood forests where seismic lines have not naturally recovered. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
10. Low-impact line construction retains and speeds recovery of trees on seismic lines in forested peatlands.
- Author
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Filicetti, Angelo T., Tigner, Jesse, Nielsen, Scott E., Wolfenden, Katherine, Taylor, Murdoch, and Bentham, Paula
- Subjects
TIMBERLINE ,PEATLANDS ,BIOGEOCHEMICAL cycles ,PREDATION ,SEISMIC prospecting - Abstract
Seismic lines are linear features created by the oil and gas industry for energy exploration. Though individually narrow, collectively seismic lines are a pervasive management challenge, resulting in changes to biogeochemical cycles, plant and animal abundance and behaviour, predator–prey relationships, and forest successional trajectories. These impacts arise from historical construction methods that used bulldozers to remove vegetation and substrate leaving lines as persistent openings in a state of arrested succession. In the mid-1990s, "low-impact seismic" (LIS) line construction began, using mulchers to remove vegetation aboveground to minimize impacts and hasten reforestation. Here, we evaluated the effectiveness of LIS in retention, recruitment, and growth of seedlings in forested peatlands in northeast British Columbia. Retained and recruited trees on LIS lines were found at 69% and 64% of sites, had mean densities of 3400 and 6000 stems/ha, and mean heights of 42 and 11 cm, respectively. These LIS lines appeared to recover along expected trajectories toward tree cover, thereby mitigating challenges typical of older seismic exploration. Our results suggest it is feasible to further fast-forward line recovery by ensuring mulcher drums are kept as high as possible to increase the number and height of trees through the mulching process. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
11. Combining community observations and remote sensing to examine the effects of roads on wildfires in the East Siberian boreal forest
- Author
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Vera Kuklina, Oleg Sizov, Victor Bogdanov, Natalia Krasnoshtanova, Arina Morozova, and Andrey N. Petrov
- Subjects
wildfires ,Siberia ,boreal forest ,community observations ,remote sensing ,Environmental sciences ,GE1-350 ,Environmental engineering ,TA170-171 - Abstract
The paper is aimed at assessing the associations between the road networks geography and dynamics of wildfire events in the East Siberian boreal forest. We examined the relationship between the function of roads, their use, and management and the wildfire ignition, propagation, and termination during the catastrophic fire season of 2016 in the Irkutsk Region of Russia. Document analysis and interviews were utilized to identify main forest users and road infrastructure functional types and examine wildfire management practices. We combined community observations and satellite remotely sensed data to assess relationships between the location, extent, and timing of wildfires and different types of roads as fire sources, barriers, and suppression access points. Our study confirms a strong spatial relationship between the wildfire ignition points and roads differentiated by their types with the highest probability of fire ignition near forestry roads and the lowest near subsistence roads. Roads also play an important role in wildfire suppression, working as both physical barriers and access points for firefighters. Our research illustrates the importance of local and Indigenous observations along the roads for monitoring and understanding wildfires, including “zombie fires”. It also has practical implications for fire management collectively developed by authorities and local communities.
- Published
- 2023
- Full Text
- View/download PDF
12. A regional integrated assessment of the impacts of climate change and of the potential adaptation avenues for Quebec's forests.
- Author
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Boulanger, Yan, Puigdevall, Jesus Pascual, Bélisle, Annie Claude, Bergeron, Yves, Brice, Marie-Hélène, Cyr, Dominic, De Grandpré, Louis, Fortin, Daniel, Gauthier, Sylvie, Grondin, Pierre, Labadie, Guillemette, Leblond, Mathieu, Marchand, Maryse, Splawinski, Tadeusz B., St-Laurent, Martin-Hugues, Thiffault, Evelyne, Tremblay, Junior A., and Yamasaki, Stephen H.
- Abstract
Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing 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.)
- Published
- 2023
- Full Text
- View/download PDF
13. Twenty-year recovery of managed stand, in structure and composition, in boreal mixedwood stands of northwestern Quebec.
- Author
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Noualhaguet, Marion, Work, Timothy T., Soubeyrand, Maxence, and Fenton, Nicole J.
- Subjects
FOREST conservation ,FOREST productivity ,HARVESTING ,FOREST biodiversity ,FIELD research - Abstract
The natural disturbance-based management (NDBM) aims to maintain specific structural and compositional attributes of natural forests in managed stands. Operationally, NDBM relies on diversifying and adapting silvicultural practices, including partial harvesting (PC), to expand the range of options beyond that of simply clearcuts (CC). Established in 1998, the Sylviculture et Aménagement Forestier Écosystémique (SAFE) project evaluates this potential in hardwood, mixedwood, and coniferous stands in northwestern Québec, Canada. Our results confirmed a part of the NDBM objectives, i.e., PC allowed the maintenance of stands with mixed structure and composition, constituting an interesting complement to CC, which reset stand regeneration. However, PC did not accelerate the stand transition to later stages with less intensive harvesting or to earlier stages with more intensive harvesting. We essentially had an initial impact, delaying or stopping the stand evolution that dissipates over time and more quickly with less intensive harvesting. Furthermore, our results did not support the ability of PC to enhance the development of old-growth attributes like deadwood. Despite the 20-year horizon of this study, further field surveys will be required in the future to better understand the impact of different silvicultural treatments on forest productivity and biodiversity preservation throughout a forest rotation. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
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