Initial response of understorey vegetation to fire severity and salvage‐logging in the southern boreal forest of Québec

This study aimed to characterize the vertical distribution of longhorned beetle larvae in burned trees of the eastern Canadian boreal forest. Black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.) and jack pine (Pinus banksiana Lamb.) trees burned at three severity levels were cut, and 30 cm boles were collected from the ground up to a height of 9.45 m. Boles were debarked and dissected to collect insect larvae. Results show that the three most abundant longhorned beetle species were vertically segregated among burned jack pine and black spruce trees, but the section having the highest timber value was heavily infested by woodborer larvae. Larval density distribution of Monochamus scutellatus scutellatus (Say) and of Acmaeops proteus proteus (Kirby) could be linked with bark thickness, which also depends on fire severity. Lightly burned stands of black spruce were the most heavily infested and should be salvaged only if they are easily accessible and can thus be rapidly harvested and processed at the mill. More severely burned stands should be salvaged later as they will be less affected by woodborers, as should jack pine, which is lightly infested compared with black spruce. The ecological role of stumps should be further investigated because they could still have an ecological value after salvage logging as Arhopalus foveicollis (Haldeman) uses them specifically.

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Short-term impact of post-fire salvage logging on regeneration, hazardous fuel accumulation, and understorey development in ponderosa pine forests of the Black Hills, SD, USA

International Journal of Wildland Fire ◽

10.1071/wf08004 ◽

2009 ◽

Vol 18 (4) ◽

pp. 451 ◽

Cited By ~ 29

Author(s):

Tara L. Keyser ◽

Frederick W. Smith ◽

Wayne D. Shepperd

Keyword(s):

Ponderosa Pine ◽

Tree Mortality ◽

Woody Debris ◽

Fire Severity ◽

Plant Cover ◽

Black Hills ◽

Understorey Vegetation ◽

Salvage Logging ◽

Ponderosa Pine Forests ◽

Fuel Accumulation

We examined the impacts of post-fire salvage logging on regeneration, fuel accumulation, and understorey vegetation and assessed whether the effects of salvage logging differed between stands burned under moderate and high fire severity following the 2000 Jasper Fire in the Black Hills. In unsalvaged sites, fire-related tree mortality created a large standing pool of available fuel, resulting in a rapid increase in surface fuel loads. After 5 years, fine woody debris (FWD) and coarse woody debris (CWD) increased ~1380% and 980% in unsalvaged sites, resulting in FWD and CWD loads of 13 and 25 Mg ha–1, respectively. In contrast, salvage logging limited the rate of accumulation of FWD to ~110% over the same time period and total accumulation of CWD to 16 Mg ha–1. In moderate-severity sites, regeneration was 75% lower in salvaged sites owing to low seed-tree retention, suggesting a re-evaluation of salvage guidelines during future operations in the Black Hills. The likelihood of timely regeneration in high-severity sites, regardless of salvage treatment, is low. We found no discernible effect of salvage logging on understorey development 5 years after fire. Logging caused neither a reduction in total plant cover nor an increase in the abundance of exotic species.

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Effects of Soil Abiotic and Biotic Factors on Tree Seedling Regeneration Following a Boreal Forest Wildfire

Ecosystems ◽

10.1007/s10021-021-00666-0 ◽

2021 ◽

Author(s):

Theresa S. Ibáñez ◽

David A. Wardle ◽

Michael J. Gundale ◽

Marie-Charlotte Nilsson

Keyword(s):

Boreal Forest ◽

Betula Pendula ◽

Fire Severity ◽

Tree Regeneration ◽

Soil Biota ◽

Fire Disturbance ◽

Burn Severity ◽

Soil Conditions ◽

Tree Seedling ◽

Seedling Regeneration

AbstractWildfire disturbance is important for tree regeneration in boreal ecosystems. A considerable amount of literature has been published on how wildfires affect boreal forest regeneration. However, we lack understanding about how soil-mediated effects of fire disturbance on seedlings occur via soil abiotic properties versus soil biota. We collected soil from stands with three different severities of burning (high, low and unburned) and conducted two greenhouse experiments to explore how seedlings of tree species (Betula pendula, Pinus sylvestris and Picea abies) performed in live soils and in sterilized soil inoculated by live soil from each of the three burning severities. Seedlings grown in live soil grew best in unburned soil. When sterilized soils were reinoculated with live soil, seedlings of P. abies and P. sylvestris grew better in soil from low burn severity stands than soil from either high severity or unburned stands, demonstrating that fire disturbance may favor post-fire regeneration of conifers in part due to the presence of soil biota that persists when fire severity is low or recovers quickly post-fire. Betula pendula did not respond to soil biota and was instead driven by changes in abiotic soil properties following fire. Our study provides strong evidence that high fire severity creates soil conditions that are adverse for seedling regeneration, but that low burn severity promotes soil biota that stimulates growth and potential regeneration of conifers. It also shows that species-specific responses to abiotic and biotic soil characteristics are altered by variation in fire severity. This has important implications for tree regeneration because it points to the role of plant–soil–microbial feedbacks in promoting successful establishment, and potentially successional trajectories and species dominance in boreal forests in the future as fire regimes become increasingly severe through climate change.

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Post-fire survival and flushing in three Sierra Nevada conifers with high initial crown scorch

International Journal of Wildland Fire ◽

10.1071/wf08129 ◽

2009 ◽

Vol 18 (7) ◽

pp. 857 ◽

Cited By ~ 8

Author(s):

Chad T. Hanson ◽

Malcolm P. North

Keyword(s):

Sierra Nevada ◽

Pinus Ponderosa ◽

Fire Severity ◽

Conifer Species ◽

Mature Trees ◽

Salvage Logging ◽

Abies Magnifica ◽

Crown Scorch ◽

Tree Survival ◽

Large Trees

With growing debate over the impacts of post-fire salvage logging in conifer forests of the western USA, managers need accurate assessments of tree survival when significant proportions of the crown have been scorched. The accuracy of fire severity measurements will be affected if trees that initially appear to be fire-killed prove to be viable after longer observation. Our goal was to quantify the extent to which three common Sierra Nevada conifer species may ‘flush’ (produce new foliage in the year following a fire from scorched portions of the crown) and survive after fire, and to identify tree or burn characteristics associated with survival. We found that, among ponderosa pines (Pinus ponderosa Dougl. ex. Laws) and Jeffrey pines (Pinus jeffreyi Grev. & Balf) with 100% initial crown scorch (no green foliage following the fire), the majority of mature trees flushed, and survived. Red fir (Abies magnifica A. Murr.) with high crown scorch (mean = 90%) also flushed, and most large trees survived. Our results indicate that, if flushing is not taken into account, fire severity assessments will tend to overestimate mortality and post-fire salvage could remove many large trees that appear dead but are not.

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