Soil organic layer combustion in boreal black spruce and jack pine stands of the Northwest Territories, Canada

2018 ◽  
Vol 27 (2) ◽  
pp. 125 ◽  
Author(s):  
Xanthe J. Walker ◽  
Jennifer L. Baltzer ◽  
Steven G. Cumming ◽  
Nicola J. Day ◽  
Jill F. Johnstone ◽  
...  
Keyword(s):  
Northwest Territories ◽  
Boreal Forests ◽  
Black Spruce ◽  
Jack Pine ◽  
Fire Intensity ◽  
Organic Layer ◽  
Complete Combustion ◽  
Soil Organic Layer ◽  
Pine Stands ◽  
Burn Depth

Increased fire frequency, extent and severity are expected to strongly affect the structure and function of boreal forest ecosystems. In this study, we examined 213 plots in boreal forests dominated by black spruce (Picea mariana) or jack pine (Pinus banksiana) of the Northwest Territories, Canada, after an unprecedentedly large area burned in 2014. Large fire size is associated with high fire intensity and severity, which would manifest as areas with deep burning of the soil organic layer (SOL). Our primary objectives were to estimate burn depth in these fires and then to characterise landscapes vulnerable to deep burning throughout this region. Here we quantify burn depth in black spruce stands using the position of adventitious roots within the soil column, and in jack pine stands using measurements of burned and unburned SOL depths. Using these estimates, we then evaluate how burn depth and the proportion of SOL combusted varies among forest type, ecozone, plot-level moisture and stand density. Our results suggest that most of the SOL was combusted in jack pine stands regardless of plot moisture class, but that black spruce forests experience complete combustion of the SOL only in dry and moderately well-drained landscape positions. The models and calibrations we present in this study should allow future research to more accurately estimate burn depth in Canadian boreal forests.

scholarly journals Increasing fire and the decline of fire adapted black spruce in the boreal forest

2021 ◽  
Vol 118 (45) ◽  
pp. e2024872118
Author(s):  
Jennifer L. Baltzer ◽  
Nicola J. Day ◽  
Xanthe J. Walker ◽  
David Greene ◽  
Michelle C. Mack ◽  
...  
Keyword(s):  
Climate Change ◽  
North America ◽  
Black Spruce ◽  
Wildlife Habitat ◽  
Ecosystem Functions ◽  
Organic Layer ◽  
Complete Combustion ◽  
Postfire Regeneration ◽  
Soil Organic Layer ◽  
Compositional Changes

Intensifying wildfire activity and climate change can drive rapid forest compositional shifts. In boreal North America, black spruce shapes forest flammability and depends on fire for regeneration. This relationship has helped black spruce maintain its dominance through much of the Holocene. However, with climate change and more frequent and severe fires, shifts away from black spruce dominance to broadleaf or pine species are emerging, with implications for ecosystem functions including carbon sequestration, water and energy fluxes, and wildlife habitat. Here, we predict that such reductions in black spruce after fire may already be widespread given current trends in climate and fire. To test this, we synthesize data from 1,538 field sites across boreal North America to evaluate compositional changes in tree species following 58 recent fires (1989 to 2014). While black spruce was resilient following most fires (62%), loss of resilience was common, and spruce regeneration failed completely in 18% of 1,140 black spruce sites. In contrast, postfire regeneration never failed in forests dominated by jack pine, which also possesses an aerial seed bank, or broad-leaved trees. More complete combustion of the soil organic layer, which often occurs in better-drained landscape positions and in dryer duff, promoted compositional changes throughout boreal North America. Forests in western North America, however, were more vulnerable to change due to greater long-term climate moisture deficits. While we find considerable remaining resilience in black spruce forests, predicted increases in climate moisture deficits and fire activity will erode this resilience, pushing the system toward a tipping point that has not been crossed in several thousand years.

Fire, climate change, and forest resilience in interior AlaskaThis article is one of a selection of papers from The Dynamics of Change in Alaska's Boreal Forests: Resilience and Vulnerability in Response to Climate Warming.

2010 ◽  
Vol 40 (7) ◽  
pp. 1302-1312 ◽  
Author(s):  
Jill F. Johnstone ◽  
F. Stuart Chapin ◽  
Teresa N. Hollingsworth ◽  
Michelle C. Mack ◽  
Vladimir Romanovsky ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Forest Cover ◽  
Fire Regime ◽  
Forest Community ◽  
Landscape Configuration ◽  
Soil Conditions ◽  
Organic Layer ◽  
Forest Stands ◽  
Regional Patterns ◽  
Soil Organic Layer

In the boreal forests of interior Alaska, feedbacks that link forest soils, fire characteristics, and plant traits have supported stable cycles of forest succession for the past 6000 years. This high resilience of forest stands to fire disturbance is supported by two interrelated feedback cycles: (i) interactions among disturbance regime and plant–soil–microbial feedbacks that regulate soil organic layer thickness and the cycling of energy and materials, and (ii) interactions among soil conditions, plant regeneration traits, and plant effects on the environment that maintain stable cycles of forest community composition. Unusual fire events can disrupt these cycles and trigger a regime shift of forest stands from one stability domain to another (e.g., from conifer to deciduous forest dominance). This may lead to abrupt shifts in forest cover in response to changing climate and fire regime, particularly at sites with intermediate levels of moisture availability where stand-scale feedback cycles are only weakly constrained by environmental conditions. However, the loss of resilience in individual stands may foster resilience at the landscape scale, if changes in the landscape configuration of forest cover types feedback to stabilize regional patterns of fire behavior and climate conditions.

scholarly journals Thinning effects on jack pine and black spruce photosynthesis in eastern boreal forests of Canada

Silva Fennica ◽  
2011 ◽  
Vol 45 (4) ◽  
Author(s):  
Venceslas Goudiaby ◽  
Suzanne Brais ◽  
Yvon Grenier ◽  
Frank Berninger
Keyword(s):  
Boreal Forests ◽  
Black Spruce ◽  
Jack Pine

Windthrow hazard modelling in boreal forests of black spruce and jack pine

2005 ◽  
Vol 35 (11) ◽  
pp. 2655-2663 ◽  
Author(s):  
Jean-Gabriel Elie ◽  
Jean-Claude Ruel
Keyword(s):  
Boreal Forests ◽  
Pinus Banksiana ◽  
Forest Cover ◽  
Black Spruce ◽  
Jack Pine ◽  
Soil Conditions ◽  
Mechanical Resistance ◽  
Mixed Stands ◽  
Tree Stability ◽  
Tree Resistance

In this study we compare the mechanical resistance of black spruce (Picea mariana (Mill.) BSP) and jack pine (Pinus banksiana Lamb.) and quantify the effect of species, forest cover type, and soil conditions on tree stability. To measure tree resistance to an applied load, 85 trees were pulled over using a cable and winch system. Predictive equations for the maximum turning moment that a tree can withstand (Mc) were developed with stem mass, and the other factors were used as explanatory variables. The presence of jack pine within the stand negatively affected black spruce resistance. In mixed stands, Mc was significantly influenced by the interaction between tree species and soil type. Jack pine was the only species with significantly lower resistance when grown on shallow and stony soils, which are likely to restrict root development. Black spruce resistance was not affected by soil conditions. Preliminary calculations of critical wind speeds required to cause damage using an adaptation of the ForestGALES model were much lower than those previously published for black spruce.

Effects of topography and thickness of organic layer on productivity of black spruce boreal forests of the Canadian Clay Belt region

2014 ◽  
Vol 330 ◽  
pp. 144-157 ◽  
Author(s):  
Ahmed Laamrani ◽  
Osvaldo Valeria ◽  
Yves Bergeron ◽  
Nicole Fenton ◽  
Li Zhen Cheng ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Black Spruce ◽  
Organic Layer

scholarly journals Effect of Organic Layer Thickness on Black Spruce Aging Mistakes in Canadian Boreal Forests

Forests ◽  
2016 ◽  
Vol 7 (12) ◽  
pp. 69 ◽  
Author(s):  
Ahmed Laamrani ◽  
Annie DesRochers ◽  
Line Blackburn
Keyword(s):  
Layer Thickness ◽  
Boreal Forests ◽  
Black Spruce ◽  
Organic Layer

scholarly journals Wildfire severity reduces richness and alters composition of soil fungal communities in boreal forests of western Canada

2021 ◽  
Author(s):  
Nicola Day ◽  
KE Dunfield ◽  
JF Johnstone ◽  
MC Mack ◽  
MR Turetsky ◽  
...  
Keyword(s):  
Community Structure ◽  
Community Composition ◽  
Fungal Community ◽  
Boreal Forests ◽  
Fire Severity ◽  
Fungal Communities ◽  
Organic Layer ◽  
Fungal Community Structure ◽  
Soil Organic Layer ◽  
Total Fungi

© 2019 John Wiley & Sons Ltd Wildfire is the dominant disturbance in boreal forests and fire activity is increasing in these regions. Soil fungal communities are important for plant growth and nutrient cycling postfire but there is little understanding of how fires impact fungal communities across landscapes, fire severity gradients, and stand types in boreal forests. Understanding relationships between fungal community composition, particularly mycorrhizas, and understory plant composition is therefore important in predicting how future fire regimes may affect vegetation. We used an extreme wildfire event in boreal forests of Canada's Northwest Territories to test drivers of fungal communities and assess relationships with plant communities. We sampled soils from 39 plots 1 year after fire and 8 unburned plots. High-throughput sequencing (MiSeq, ITS) revealed 2,034 fungal operational taxonomic units. We found soil pH and fire severity (proportion soil organic layer combusted), and interactions between these drivers were important for fungal community structure (composition, richness, diversity, functional groups). Where fire severity was low, samples with low pH had higher total fungal, mycorrhizal, and saprotroph richness compared to where severity was high. Increased fire severity caused declines in richness of total fungi, mycorrhizas, and saprotrophs, and declines in diversity of total fungi and mycorrhizas. The importance of stand age (a surrogate for fire return interval) for fungal composition suggests we could detect long-term successional patterns even after fire. Mycorrhizal and plant community composition, richness, and diversity were weakly but significantly correlated. These weak relationships and the distribution of fungi across plots suggest that the underlying driver of fungal community structure is pH, which is modified by fire severity. This study shows the importance of edaphic factors in determining fungal community structure at large scales, but suggests these patterns are mediated by interactions between fire and forest stand composition.

scholarly journals Changes in growth of pristine boreal North American forests from 1950 to 2005 driven by landscape demographics and species traits

2012 ◽  
Vol 9 (1) ◽  
pp. 1021-1053 ◽  
Author(s):  
M. P. Girardin ◽  
X. J. Guo ◽  
P. Y. Bernier ◽  
F. Raulier ◽  
S. Gauthier
Keyword(s):  
North American ◽  
Boreal Forests ◽  
Environmental Changes ◽  
Black Spruce ◽  
Species Traits ◽  
Jack Pine ◽  
Forest Growth ◽  
Climatic Data ◽  
Spruce Stands ◽  
The Many

Abstract. In spite of the many factors that are occurring and known for positively affecting the growth of forests, some boreal forests across North America have recently felt the adverse impacts of environmental changes. Knowledge of causes for productivity declines in North American boreal forests remains limited and this is owed to the large spatial and temporal scales involved, and the many plant processes affected. Here, the response of pristine eastern boreal North American (PEBNA) forests to ongoing climatic changes is examined using in situ data, community ecology statistics, and species-specific model simulations of carbon exchanges forced by contemporary climatic data. To examine trends in forest growth, we used a recently acquired collection of tree-ring width data from 252 sample plots distributed in PEBNA forests dominated by black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.). Results of linear trend analysis on the tree growth data highlight a dominating forest growth decline in overmature forests (age > 120 yr) from 1950 to 2005. In contrast, improving growth conditions are seen in jack pine and mature (70–120 yr) black spruce stands. Multivariate analysis of climate and growth relationships suggests that responses of PEBNA forests to climate are dependent on demographic and species traits via their mediation of temperature and water stress constraints. In support of this hypothesis, the simulation experiment suggests that in old-growth black spruce stands the benefit to growth brought on by a longer growing season may have been low in comparison with the increasing moisture stress and respiration losses caused by warmer summer temperatures. Predicted increases in wildfire frequency in PEBNA forests will likely enhance the positive response of landscape-level forest growth to climate change by shifting the forest distribution to younger age classes while also enhancing the jack pine component.

La Régénération préétablie dans les peuplements forestiers naturels au Québec

1988 ◽  
Vol 64 (2) ◽  
pp. 116-120 ◽  
Author(s):  
René Doucet
Keyword(s):  
Key Words ◽  
Forest Cover ◽  
Black Spruce ◽  
Jack Pine ◽  
Balsam Fir ◽  
Ecological Zone ◽  
Ecological Zones ◽  
Pine Stands ◽  
Mature Stands ◽  
Forest Cover Types

The type and abundance of advance growth has been evaluated in 421 areas representing the major forest cover types in Quebec. Advance growth has been found to be abundant in mature stands of every cover type, except jack pine, and in all ecological zones. However its composition varied with cover types: balsam fir was the main species of advance growth in fir and mixedwood stands, while black spruce dominated advance growth in black spruce and jack pine stands. Most of the black spruce advance growth was from layer origin, especially in the black spruce ecological zone. Key words: Québec, regeneration.

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