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.

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.

Stand-level effects of soil burn severity on postfire regeneration in a recently burned black spruce forest

2005 ◽  
Vol 35 (9) ◽  
pp. 2151-2163 ◽  
Author(s):  
Jill F Johnstone ◽  
Eric S Kasischke
Keyword(s):  
Plant Growth ◽  
Black Spruce ◽  
Landscape Patterns ◽  
Forest Recovery ◽  
Burn Severity ◽  
Organic Layer ◽  
Growth Forms ◽  
Postfire Regeneration ◽  
Soil Organic Layer ◽  
Soil Burn Severity

This study tested whether variations in soil burn severity (soil organic layer consumption) influenced patterns of early postfire plant regeneration in a black spruce (Picea mariana (Mill.) BSP) forest in interior Alaska. Variations in burn severity were related to measurements of postfire tree seedling establishment and cover of plant growth forms observed 7–8 years after fire. Black spruce and trembling aspen (Populus tremuloides Michx.) showed significant and opposite responses of seedling density to changes in soil burn severity. Positive correlations between burn severity and aspen density and individual seedling biomass led to an increase of over three orders of magnitude in aspen standing biomass (aboveground, g/m2) from the least to most severely burned sites. Variations in aspen productivity and consequent effects on litter production and seedbed quality possibly explain the observed negative response of black spruce density to increasing burn severity. Variations in the cover of several plant growth forms were also strongly correlated with patterns of soil burn severity. Regenerating plant communities in low-severity sites had a greater cover of evergreen shrubs and graminoids, while high-severity sites had increased cover of aspen and acro carp ous mosses. Observations of regeneration patterns in the burn are largely consistent with experimental studies of severity effects and suggest that variations in soil burn severity can have a strong influence on landscape patterns of postfire forest recovery. In this case, increases in burn severity have shifted successional trajectories away from simple conifer self-replacement towards a trajectory of mixed conifer and deciduous dominance.

scholarly journals Impacts of Climatic Variation on the Growth of Black Spruce Across the Forest-Tundra Ecotone: Positive Effects of Warm Growing Seasons and Heat Waves Are Offset by Late Spring Frosts

2020 ◽  
Vol 3 ◽  
Author(s):  
Guillaume Moreau ◽  
Catherine Chagnon ◽  
David Auty ◽  
John Caspersen ◽  
Alexis Achim
Keyword(s):  
Climate Change ◽  
North America ◽  
Black Spruce ◽  
Growing Season ◽  
Late Spring ◽  
Climatic Data ◽  
Northeastern North America ◽  
Forest Tundra ◽  
Growing Seasons ◽  
Spring Frosts

Climate strongly limits the physiological processes of trees near their range limits, leading to increased growth sensitivity. Northeastern North America is experiencing considerable warming, so the growth of trees near the northern treeline represents a key indicator of forest responses to climate change. However, tree-ring series and corresponding climatic data are scarce across the forest-tundra ecotone when compared to southern boreal regions, resulting in fewer studies on growth-climate relationships focused on this ecotone. Using daily climatic data, we identified trends in growing season heat accumulation and the intensity of acute climatic events over the last several decades in the southern and the northern parts of the forest-tundra ecotone in northeastern North America, and investigated their influence on black spruce radial growth. We found that black spruce trees responded positively to the increase in growing season temperatures and heat wave intensity, suggesting that growth is currently limited by suboptimal temperatures. While tree growth in the southern region generally benefited from warm spring temperatures, vulnerability to late spring frosts reduced tree growth in the northern region and increased probability of abrupt growth decline. In this region, late spring frosts offset approximately half of the additional growth that would otherwise occur over the course of a warm growing season. This vulnerability of northern trees may result from local adaptations to short growing seasons, which initiate biological activities at colder temperatures in the spring. Overall, our results highlight the need to explicitly incorporate acute climatic events into modeling efforts in order to refine our understanding of the impact of climate change on forest dynamics.

Paludification dynamics in the boreal forest of the James Bay Lowlands: effect of time since fire and topography

2009 ◽  
Vol 39 (3) ◽  
pp. 546-552 ◽  
Author(s):  
Martin Simard ◽  
Pierre Y. Bernier ◽  
Yves Bergeron ◽  
David Paré ◽  
Lakhdar Guérine
Keyword(s):  
Organic Matter ◽  
Boreal Forest ◽  
Black Spruce ◽  
Forest Productivity ◽  
Organic Layer ◽  
Layer Depth ◽  
Potential Productivity ◽  
Organic Matter Accumulation ◽  
Soil Organic Layer ◽  
Time Since Fire

In many northern forest ecosystems, soil organic matter accumulation can lead to paludification and forest productivity losses. Paludification rate is primarily influenced by topography and time elapsed since fire, two factors whose influence is often confounded and whose discrimination would help forest management. This study, which was conducted in the black spruce ( Picea mariana (Mill.) BSP) boreal forest of northwestern Quebec (Canada), aimed to (1) quantify the effect of slope and time since fire on paludification rates, (2) determine whether soil organic layer depth could be estimated by surface variables that can potentially be remotely sensed, and (3) relate the degree of paludification to tree productivity. In this study, soil organic layer depth was used as an estimator of the degree of paludification. Slope and postfire age strongly affected paludification dynamics. Young stands growing on steep slopes had thinner organic layers and lower organic matter accumulation rates compared with young stands growing on flat sites. Black spruce basal area and Sphagnum cover were strong predictors of organic layer depth, potentially allowing mapping of paludification degree across the landscape. Tree productivity was negatively related to organic layer depth (R2 = 0.57). The equations developed here can be used to quantify forest productivity decline in stands that are undergoing paludification, as well as potential productivity recovery given appropriate site preparation techniques.

Dynamics of moisture content in spruce–feather moss and spruce–Sphagnum organic layers during an extreme fire season and implications for future depths of burn in Clay Belt black spruce forests

2014 ◽  
Vol 23 (4) ◽  
pp. 490 ◽  
Author(s):  
Aurélie Terrier ◽  
William J. de Groot ◽  
Martin P. Girardin ◽  
Yves Bergeron
Keyword(s):  
Climate Change ◽  
Moisture Content ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Black Spruce ◽  
Weather Conditions ◽  
Fire Disturbance ◽  
Fire Season ◽  
Organic Layer ◽  
Feather Moss

High moisture levels and low frequency of wildfires have contributed to the accumulation of the organic layer in open black spruce (Picea mariana)–Sphagnum dominated stands of eastern boreal North America. The anticipated increase in drought frequency with climate change could lead to moisture losses and a transfer of the stored carbon back into the atmosphere due to increased fire disturbance and decomposition. Here we studied the dynamics of soil moisture content and weather conditions in spruce–feather moss and spruce–Sphagnum dominated stands of the boreal Clay Belt of eastern Canada during particularly dry conditions. A linear mixed model was developed to predict the moisture content of the organic material according to weather, depth and site conditions. This model was then used to calculate potential depth of burn and applied to climate model projections to determine the sensitivity of depth of burn to future fire hazards. Our results suggest that depth of burn varies only slightly in response to changes in weather conditions in spruce–Sphagnum stands. The reverse holds true in spruce–feather moss stands. In conclusion, our results suggest that spruce–Sphagnum stands in the boreal Clay Belt may be resistant to an increase in the depth of burn risk under climate change.

Managing for adaptive capacity: thinning improves food availability for wildlife and insect pollinators under climate change conditions

2013 ◽  
Vol 43 (5) ◽  
pp. 428-440 ◽  
Author(s):  
Andrew R. Neill ◽  
Klaus J. Puettmann
Keyword(s):  
Climate Change ◽  
Adaptive Capacity ◽  
Food Availability ◽  
Management Practices ◽  
Basal Area ◽  
Understory Vegetation ◽  
Wildlife Habitat ◽  
Ecosystem Functions ◽  
Fleshy Fruit ◽  
Species Groups

A trait-based approach was developed to assess impacts of management practices on the adaptive capacity of ecosystems using impacts of overstory density and thinning on understory vegetation components related to wildlife habitat. The relationship between overstory basal area and understory vegetation for species grouped by traits that reflect food availability for wildlife (i.e., the production of flowers, fleshy fruit, and palatable leaves) was characterized in thinned and unthinned stands at seven Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests in western Oregon 6 years following thinning. Lower overstory densities and thinnings were associated with a higher likelihood of selected ecosystem functions, specifically the provision of food for wildlife, as evident by higher cover of flowering, fleshy fruit and palatable leaf producing species. Within these functional groups, thinning increased cover of drought-, fire-, and heat-tolerant species, which suggests that these ecosystem functions are more likely to be maintained under climate change conditions. The responses of species groups appear to be driven by the sensitivity of species to resource availability and to physical disturbances associated with thinnings.

Recent dynamics of jack pine at its northern distribution limit in northern Quebec

1992 ◽  
Vol 70 (6) ◽  
pp. 1157-1167 ◽  
Author(s):  
Mireille Desponts ◽  
Serge Payette
Keyword(s):  
Boreal Forest ◽  
Age Structure ◽  
Fire History ◽  
Black Spruce ◽  
Regional Scale ◽  
Jack Pine ◽  
Organic Layer ◽  
Average Life Span ◽  
Fire Scar ◽  
Postfire Regeneration

The northernmost jack pine (Pinus banksiana Lamb.) populations in northern Quebec are located at the boreal forest–forest tundra boundary, along the Grande rivière de la Baleine, where they colonize the sandy terraces affected by recurrent fires. The recent fire history in the study area, as deduced from fire scar and age structure data, spans a 216-year period from 1773 to 1988. Forest fires occurred on the sites at intervals averaging 40 to 80 years. The analysis of 19 coniferous stands (jack pine and black spruce (Picea mariana (Mill.) Bsp)) indicated that forest communities younger than 67 years old were open jack pine – Cladina mitis or jack pine – black spruce – C. mitis woodlands, while the oldest stands, more than 132 years old, were dominated by jack pine, black spruce, and Cladina stellaris. Stands less than 67-years-old had an age structure almost normally distributed and regeneration often occurred within less than 30 years after fire in both species, while most stands older than 132 years had a multiaged structure. In sites with a prolonged fire-free interval, jack pine was overgrown by black spruce. Spruce woodlands have developed on sites where the organic layer was relatively thick and continuous and they are the end result of the postfire successional process. However, at several sites both conifer species showed an ability to regenerate in prolonged absence of fire disturbance, particularly in open sites with exposed mineral substrates. At the regional scale, fire frequency during the last 200 years has been high enough to prevent pine exclusion at its range limit. The key requirement for the long-term maintenance of jack pine populations is that fires return at intervals shorter than the average life-span of individual trees. It is concluded that the northernmost jack pine populations are able to maintain and regenerate under present fire conditions. Key words: fire, subarctic, jack pine, postfire regeneration, boreal forest.

Does Soil Organic Layer Thickness Affect Climate–Growth Relationships in the Black Spruce Boreal Ecosystem?

Ecosystems ◽  
2010 ◽  
Vol 13 (4) ◽  
pp. 556-574 ◽  
Author(s):  
Igor Drobyshev ◽  
Martin Simard ◽  
Yves Bergeron ◽  
Annika Hofgaard
Keyword(s):  
Layer Thickness ◽  
Black Spruce ◽  
Organic Layer ◽  
Soil Organic Layer ◽  
Boreal Ecosystem

Sphagnum mosses limit total carbon consumption during fire in Alaskan black spruce forests

2008 ◽  
Vol 38 (8) ◽  
pp. 2328-2336 ◽  
Author(s):  
Gordon Shetler ◽  
Merritt R. Turetsky ◽  
Evan Kane ◽  
Eric Kasischke
Keyword(s):  
Organic Matter ◽  
Forest Floor ◽  
Black Spruce ◽  
High Water ◽  
Total Carbon ◽  
Organic Layer ◽  
Sphagnum Mosses ◽  
Spruce Forests ◽  
Feather Moss ◽  
Soil Organic Layer

The high water retention of hummock-forming Sphagnum species minimizes soil moisture fluctuations and might protect forest floor organic matter from burning during wildfire. We hypothesized that Sphagnum cover reduces overall forest floor organic matter consumption during wildfire compared with other ground-layer vegetation. We characterized variability in soil organic layer depth and organic matter stocks in two pairs of burned and unburned black spruce ( Picea mariana (Mill.) BSP) stands in interior Alaska. In the unburned stands, microsites dominated by Sphagnum had more than twice as much soil organic matter·m–2 as microsites dominated by feather moss and (or) lichens. Whereas 20% of soil organic matter was consumed during fire in microsites dominated by Sphagnum, 45% was consumed in microsites dominated by the feather moss and (or) lichens. Across 79 recently burned black spruce stands, unburned moss abundance (primarily remnant Sphagnum hummocks), landscape position (backslope, flat upland, flat lowland classes), and the interaction among these variables explained 60% of postfire organic soil depths. We suggest that “Sphagnum sheep” could serve as a useful visual indicator of variability in postfire soil carbon stocks in boreal black spruce forests. Sphagnum mosses are important ecosystem engineers not only for their influence on decomposition rates, but also for their effect on fuel consumption and fire patterning.

scholarly journals Soil characteristics mediate the distribution and response of boreal trees to climatic variability

2014 ◽  
Vol 44 (5) ◽  
pp. 487-498 ◽  
Author(s):  
Sylvie Gewehr ◽  
Igor Drobyshev ◽  
Frank Berninger ◽  
Yves Bergeron
Keyword(s):  
Populus Tremuloides ◽  
Black Spruce ◽  
Climatic Variability ◽  
Basal Area ◽  
Organic Layer ◽  
Dormant Period ◽  
Study Region ◽  
Growing Period ◽  
Soil Organic Layer ◽  
The Relationship

We studied the effects of the soil organic layer (SOL) accumulation on growth and distribution of black spruce (Picea mariana (Mill.) BSP) and trembling aspen (Populus tremuloides Michx.) within the Quebec Clay Belt. At the landscape scale, spruce was present over a much larger gradient in SOL thickness (∼1 to 100 cm) than aspen (∼1 to 30 cm). For trees between 60 and 100 years old, SOL thickness had no effect on the basal area increment (BAI) of spruce but showed a strong and negative correlation with BAI in aspen. Radial growth of black spruce was favored by higher precipitation in June of the previous growing season, higher temperatures in early winter and in spring, and by low temperatures in summer. SOL thickness had statistically significant but moderate effects on the climate–growth relationships in spruce, apparently affecting root insulation during the dormant period and water availability during the growing period. In aspen, current-year June temperature was the most important factor positively correlated with growth. The SOL thickness affected the relationship between the aspen growth and (i) January temperature and (ii) June–August monthly drought code. We predict that the response of black spruce to climate change should be rather uniform across the study region, while the response of aspen is likely to be strongly mediated by SOL thickness.

Sign in / Sign up

Export Citation Format

Share Document