scholarly journals Detecting Local Drivers of Fire Cycle Heterogeneity in Boreal Forests: A Scale Issue

Forests ◽  
2016 ◽  
Vol 7 (12) ◽  
pp. 139 ◽  
Author(s):  
Annie Bélisle ◽  
Alain Leduc ◽  
Sylvie Gauthier ◽  
Mélanie Desrochers ◽  
Nicolas Mansuy ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Fire Cycle

How does increased fire frequency affect carbon loss from fire? A case study in the northern boreal forest

2011 ◽  
Vol 20 (7) ◽  
pp. 829 ◽  
Author(s):  
C. D. Brown ◽  
J. F. Johnstone
Keyword(s):  
Boreal Forests ◽  
Forest Canopy ◽  
Short Interval ◽  
Fire Frequency ◽  
Fire Return Interval ◽  
Fire Cycle ◽  
Return Interval ◽  
Canopy Soil ◽  
Carbon Stores ◽  
Stand Conditions

Fire frequency is expected to increase due to climate warming in many areas, particularly the boreal forests. An increase in fire frequency may have important effects on the global carbon cycle by decreasing the size of boreal carbon stores. Our objective was to quantify and compare the amount of carbon consumed during and the amount of carbon remaining following fire in black spruce (Picea mariana (Mill.) BSP) forests burned after long v. short intervals. We hypothesised that stands with a shortened fire return interval would have a higher carbon consumption than those experiencing a historically typical fire return interval. Using field measurements of forest canopy, soil organic horizons and adventitious roots, we reconstructed pre-fire stand conditions to estimate the biomass lost in each fire and the effects on post-fire residual carbon stores. We found evidence of a higher loss of carbon following two fire events that recurred after a short interval, resulting in a much greater total reduction in carbon relative to pre-fire or mature stand conditions. Consequently, carbon storage across disturbance intervals was dramatically reduced following short-interval burns. Recovery of these stores would require a subsequent lengthening of the fire cycle, which appears unlikely under future climate scenarios.

scholarly journals Landscape composition influences local pattern of fire size in the eastern Canadian boreal forest: role of weather and landscape mosaic on fire size distribution in mixedwood boreal forest using the Prescribed Fire Analysis System

2010 ◽  
Vol 19 (8) ◽  
pp. 1099 ◽  
Author(s):  
Christelle Hély ◽  
C. Marie-Josée Fortin ◽  
Kerry R. Anderson ◽  
Yves Bergeron
Keyword(s):  
Boreal Forest ◽  
Prescribed Fire ◽  
Boreal Forests ◽  
Weather Conditions ◽  
Landscape Composition ◽  
Burned Area ◽  
Fire Size ◽  
Fire Cycle ◽  
Area Burned ◽  
Analysis System

Wildfire simulations were carried out using the Prescribed Fire Analysis System (PFAS) to study the effect of landscape composition on fire sizes in eastern Canadian boreal forests. We used the Lake Duparquet forest as reference, plus 13 forest mosaic scenarios whose compositions reflected lengths of fire cycle. Three fire weather risks based on duff moisture were used. We performed 100 simulations per risk and mosaic, with topography and hydrology set constant for the reference. Results showed that both weather and landscape composition significantly influenced fire sizes. Weather related to fire propagation explained almost 79% of the variance, while landscape composition and weather conditions for ignition explained ∼14 and 2% respectively. In terms of landscape, burned area increased with increasing presence of shade-tolerant species, which are related to long fire cycles. Comparisons among the distributions of cumulated area burned from scenarios plus those from the Société de Protection des Forêts contre le Feu database archives showed that PFAS simulated realistic fire sizes using the 80–100% class of probable fire extent. Future analyses would best be performed on a larger region as the limited size of the study area could not capture fires larger than 11 000 ha, which represent 3% of fires but 65% of the total area burned at the provincial scale.

Microbial Processes in the Alaskan Boreal Forest

2006 ◽  
Author(s):  
Joshua P. Schimel ◽  
F. Stuart Chapin III
Keyword(s):  
Boreal Forest ◽  
Tree Growth ◽  
Boreal Forests ◽  
Growing Season ◽  
Microbial Processes ◽  
Soil Processes ◽  
Forest Stands ◽  
Soil System ◽  
Fire Cycle ◽  
Successional Stages

Forest ecosystems typically occur in moderate environments where growing season rainfall is adequate to support tree growth and where nongrowing season conditions are not too extreme. The Alaskan boreal forests, however, occur at the limit of the forest biome, in an environment that is climatically extreme, with strong physical gradients. The seasonal variation in temperature is among the greatest on earth, with winter temperatures as low as –50ºC and summer growing season temperatures that can reach +30ºC (Chapter 4). The growing season is short, the climate is semi-arid, and growing season rainfall is limited. Forests exist in the region because evapotranspiration is also limited. Steep south-facing slopes can be too dry to support tree growth (Chapter 6). In contrast, in flat, low-lying areas, low evapotranspiration combined with permafrost produces wetlands despite the low rainfall. Regular drought makes the forest highly susceptible to fires. At large scales (many square kilometers), the boreal forest experiences regular, extensive fires that destroy whole stands, resetting succession (Chapter 17). This regular fire cycle produces a patchwork mosaic of forest stands in different successional stages across the landscape (Dyrness et al. 1986, Kasischke and Stocks 2000; Chapter 7). In large rivers (e.g., the Tanana), the cutting and filling of meander loops washes away some forest stands while depositing new silt bars for colonization and succession (Zasada 1986). At the landscape scale, the biogeochemical cycles in the boreal forest are therefore dominated by landscape structure (e.g., dry uplands vs. wet lowlands) and by disturbance (particularly fire). At smaller scales, however, the strong feedbacks between plant and soil processes control much of the functioning of individual forest stands, and possibly the rate of transition among successional stages. In this chapter, we discuss how microbial processes in the boreal forest produce unusual patterns of nutrient cycling that drive the overall functioning of boreal forest stands. Figure 14.1 illustrates the linkages between plant and microbial communities that dominate the functioning of the boreal forest soil system. In the feedbacks between plant and soil processes, plants drive the loop largely through inputs of organic materials.

Syntaxonomy of mid-successional stages of secondary forests of the central elevated part of the Southern Urals

2012 ◽  
pp. 109-134
Author(s):  
P. S. Shirokikh ◽  
A. M. Kunafin ◽  
V. B. Martynenko
Keyword(s):  
Boreal Forests ◽  
Floristic Composition ◽  
Southern Urals ◽  
Secondary Forests ◽  
Natural Forests ◽  
The Southern Urals ◽  
Active Growth ◽  
Tree Layer ◽  
Shade Tolerant Species ◽  
Successional Stages

The secondary birch and aspen forests of middle stages of succession of the central elevated part of the Southern Urals are studied. 4 subassociations, 1 community, and 7 variants in the alliances of Aconito-Piceion and Piceion excelsae are allocated. It is shown that the floristic composition of aspen and birch secondary forests in the age of 60—80 years is almost identical to the natural forests. However, a slight increase the coenotical role of light-requiring species of grasslands and hemiboreal forests in the secondary communities of the class Brachypodio-Betuletea was noticed as well as some reduction of role the shade-tolerant species of nemoral complex and species of boreal forests of the class Vaccinio-Piceetea. Dominant tree layer under the canopy of secondary series is marked by an active growth of natural tree species.

Enhanced Seasonal Exchange of CO2 by Northern Ecosystems Since 1960

Science ◽  
2013 ◽  
Vol 341 (6150) ◽  
pp. 1085-1089 ◽  
Author(s):  
H. D. Graven ◽  
R. F. Keeling ◽  
S. C. Piper ◽  
P. K. Patra ◽  
B. B. Stephens ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Atmospheric Carbon Dioxide ◽  
Ecosystem Models ◽  
The North ◽  
Ecological Changes ◽  
Term Change ◽  
Major Shift ◽  
Underlying Mechanisms ◽  
Global Carbon

Seasonal variations of atmospheric carbon dioxide (CO2) in the Northern Hemisphere have increased since the 1950s, but sparse observations have prevented a clear assessment of the patterns of long-term change and the underlying mechanisms. We compare recent aircraft-based observations of CO2 above the North Pacific and Arctic Oceans to earlier data from 1958 to 1961 and find that the seasonal amplitude at altitudes of 3 to 6 km increased by 50% for 45° to 90°N but by less than 25% for 10° to 45°N. An increase of 30 to 60% in the seasonal exchange of CO2 by northern extratropical land ecosystems, focused on boreal forests, is implicated, substantially more than simulated by current land ecosystem models. The observations appear to signal large ecological changes in northern forests and a major shift in the global carbon cycle.

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