scholarly journals Xylogenesis in black spruce subjected to rain exclusion in the field1This article is one of a selection of papers from the 7th International Conference on Disturbance Dynamics in Boreal Forests.

2012 ◽  
Vol 42 (7) ◽  
pp. 1306-1315 ◽  
Author(s):  
Evelyn Belien ◽  
Sergio Rossi ◽  
Hubert Morin ◽  
Annie Deslauriers
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Black Spruce ◽  
Water Status ◽  
Soil Horizon ◽  
Summer Drought ◽  
Normal Water ◽  
Short Time ◽  
And Control ◽  
Selection Of

The predicted climate warming and more frequent and longer droughts are expected to produce potentially severe water stresses in the boreal forest. The aim of this experiment was to study the effect of a summer drought on xylem phenology and anatomy of mature black spruce ( Picea mariana (Mill.) BSP) trees in their natural environment. The trees were excluded from rain during June–September 2010 by the installation of under-canopy roofs in four sites of the boreal forest of Quebec. Xylem phenology, stem radius variations, and physiological traits of treated and control trees were monitored at short time resolution. At the end of the growth season, cell characteristics were measured. The rain exclusion reduced the cell area of the xylem, but no significant change was observed in cell wall thickness, cell production, or phenology. Stem radius variations of the treated trees were lower but followed the same pattern as the control. After removal of the exclusion, trees and soil quickly recovered their normal water status. One summer of drought led to the formation of smaller tracheids but showed that black spruce is resistant to this rain exclusion treatment. This is likely due to the ability to collect water from sources other than the superficial soil horizon.

scholarly journals Splitting in Fire-Killed Trees in the Boreal Forest of Alberta

2003 ◽  
Vol 20 (4) ◽  
pp. 167-174
Author(s):  
Nobutaka Nakamura ◽  
Paul M. Woodard ◽  
Lars Bach
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Black Spruce ◽  
Lodgepole Pine ◽  
White Spruce ◽  
Balsam Fir ◽  
Crown Fire ◽  
In Fire ◽  
Solar Angle

Abstract Tree boles in the boreal forests of Alberta, Canada will split once killed by a stand-replacing crown fire. A total of 1,485 fire-killed trees were sampled, 1 yr after burning, in 23 plots in 14 widely separated stands within a 370,000 ha fire. Sampling occurred in the Upper and Lower Foothills natural subregions. The frequency of splitting varied by species but averaged 41% for all species. The order in the frequency of splitting was balsam fir, black spruce, white spruce and lodgepole pine. The type of splitting (straight, spiral, or multiple) varied by species, as did the position of the split on the tree bole. Aspect or solar angle was not statistically related to the type or occurrence of splitting.

Expert System for EPMA

1999 ◽  
Vol 5 (S2) ◽  
pp. 592-593
Author(s):  
C. Fournier ◽  
C. Merlet ◽  
P.F. Staub ◽  
O. Dugne
Keyword(s):  
Quantitative Analysis ◽  
Expert System ◽  
Reasonable Accuracy ◽  
Experimental Conditions ◽  
Sample Composition ◽  
Starting Point ◽  
Accuracy Of Results ◽  
Short Time ◽  
And Control ◽  
Selection Of

Analysis parameters for an electron microprobe are numerous, and the accuracy of the quantitative analysis is very sensitive to the selection of these experimental conditions. The expert system intends to optimize the choice of each analysis parameter as well as to automate the phases of a quantitative analysis on all kinds of materials. To summarise, the aim of the expert system is to simplify the procedures, improve the accuracy of results and control the analysis time. The figure 1 illustrates the various stages of the expert system.The starting point of the expert system is an interactive questionnaire concerning the sample,( ie, what is already known), and about the expectations on the analysis,( ie, the accuracy of the results and/or the duration of the analysis required by the operator). Then, the expert system performs a semi-quantitative analysis on the sample. Based on the acquisition of a wavelength qualitative spectrum, this method is a way to obtain the sample composition in a short time with the advantages of the WDS system, and with a reasonable accuracy.

The influence of wildfire boundary delineation on our understanding of burning patterns in the Alberta foothills1This article is one of a selection of papers from the 7th International Conference on Disturbance Dynamics in Boreal Forests.

2012 ◽  
Vol 42 (7) ◽  
pp. 1253-1263 ◽  
Author(s):  
David W. Andison
Keyword(s):  
Sensitivity Analysis ◽  
Boreal Forest ◽  
Boreal Forests ◽  
Research And Practice ◽  
International Conference ◽  
Pattern Metrics ◽  
Natural Region ◽  
Biological Responses ◽  
The Relationship ◽  
Selection Of

Under the auspices of ecosystem-based management, historical disturbance patterns are promoted as a means of providing benchmarks for ecosystem sustainability. The associated research in support of this strategy in the boreal forest has substantially increased our understanding of frequencies, sizes, shapes, and severities of wildfires. However, despite the fact that different spatial definitions of wildfires exist in both research and practice, we have not considered the significance or impact of those differences on observed patterns. This study addresses this gap by conducting a sensitivity analysis on the influence of 11 spatial definitions of a wildfire on six pattern metrics for 24 wildfires in the Foothills Natural Region of Alberta. The results suggest that all pattern metrics were sensitive to changes to wildfire delineation, but in particular the total amount of remnants, wildfire shape, and the relationship between pre-burn fuel types and the probability of burning. The results also suggest that simple mortality maps do not necessarily identify multiple disturbed patches within wildfires, an attribute undocumented by previous research. These pattern differences potentially correspond to some fundamental differences in perception of how and why wildfires burn and our understanding of the associated processes and biological responses.

Wildlife-mitigated precommercial thinning maintains the abundance of fruit shrubs in a boreal forest

2013 ◽  
Vol 43 (3) ◽  
pp. 306-310 ◽  
Author(s):  
Mélanie Major ◽  
André Desrochers
Keyword(s):  
Species Composition ◽  
Boreal Forest ◽  
Boreal Forests ◽  
Late Summer ◽  
Diameter Growth ◽  
Precommercial Thinning ◽  
Wildlife Species ◽  
Abundance And Distribution ◽  
And Control ◽  
The Impact

In boreal forests, fruits are an abundant resource in late summer and benefit many wildlife species. Fruits are mainly found in early successional stands, which are often subject to precommercial thinning designed to increase diameter growth of residual trees and manage stand species composition. Concerns about the consequences of precommercial thinning on wildlife have led to various methods of precommercial thinning with mitigation for wildlife. In summers 2007 and 2008, we examined the impact of wildlife-mitigated thinning on fruit shrub abundance and distribution at the Forêt Montmorency, Quebec. The abundance of fruit shrubs of all species except Amelanchier was similar in thinned and control stands but was highly variable among individual stands. Amelanchier shrubs appeared to benefit from thinning, especially 10 to 20 years after clearcutting. Fruit shrubs were highly clustered within early successional stands, but less so after thinning. We conclude that wildlife-mitigated precommercial thinning does not reduce access to fruits for birds and other frugivores and may even facilitate it in eastern Canadian boreal forests.

scholarly journals Wolverine, Gulo gulo, Home Range Size and Denning Habitat in Lowland Boreal Forest in Ontario

2010 ◽  
Vol 124 (2) ◽  
pp. 139 ◽  
Author(s):  
F. Neil Dawson ◽  
Audrey J. Magoun ◽  
Jeff Bowman ◽  
Justina C. Ray
Keyword(s):  
Home Range ◽  
Boreal Forest ◽  
Boreal Forests ◽  
Radio Telemetry ◽  
Habitat Type ◽  
Home Range Size ◽  
Home Ranges ◽  
Minimum Convex Polygon ◽  
Northwestern Ontario ◽  
Selection Of

We conducted the first radio-telemetry study of Wolverines in northwestern Ontario during the winter of 2003-2004 to determine whether home ranges and movements of Wolverines in lowland boreal forest were typical of this species in other ecosystems and to describe reproductive den sites in this habitat type. Seven Wolverines (3 M, 4 F) were radio-tagged and monitored for 31 to 269 (Mean ± SE = 153 ± 35) days using a combination of remotely monitored Argos satellite and conventional aerial telemetry. Male and female 95% minimum convex polygon (MCP) home ranges (±SE) during December to October were 2,563 (796) km2 and 428 (118) km2, respectively, for combined VHF and Argos locations. A lactating female had a 95% MCP home range of 262 km2. The den site for this female included large boulders and downed trees, similar to dens described for this species in montane ecosystems. Boulder complexes and downed trees may be critical features of wolverine dens in lowland boreal forests. Mean road densities (± SE) within 95% MCP and 50% MCP home ranges were 0.43 (0.13) and 0.33 (0.23) km/km2, respectively, and our results suggest that road densities may affect selection of home ranges by Wolverines. The Wolverine population was a resident, reproductive population. Erratum for table included.

Structure and resilience of fungal communities in Alaskan boreal forest soilsThis 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. 1288-1301 ◽  
Author(s):  
D. Lee Taylor ◽  
Ian C. Herriott ◽  
Kelsie E. Stone ◽  
Jack W. McFarland ◽  
Michael G. Booth ◽  
...  
Keyword(s):  
Mycorrhizal Fungi ◽  
Picea Glauca ◽  
Boreal Forests ◽  
Black Spruce ◽  
Cellulose Degradation ◽  
Niche Partitioning ◽  
Environmental Parameters ◽  
Fungal Species ◽  
Fungal Communities ◽  
Soil Horizon

This paper outlines molecular analyses of soil fungi within the Bonanza Creek Long Term Ecological Research program. We examined community structure in three studies in mixed upland, black spruce ( Picea mariana (Mill.) BSP), and white spruce ( Picea glauca (Moench) Voss) forests and examined taxa involved in cellulose degradation at one upland site. We found that soil horizon was the factor by which fungal communities were most strongly structured and that predictable turnover in upland fungal species occurred through succession. Communities from consecutive summers were not significantly different, indicating that interannual variation was small in relation to differences between forest types and soil horizons, yet the community at a seasonal study site underwent significant changes within a year. In each study, mycorrhizal fungi dominated the community. Fungi rather than bacteria appeared to dominate [13C]cellulose degradation, with strongest growth in taxa that were not dominant members of the untreated community, including members of the genus Sebacina . Overall, our results point to considerable interannual resilience juxtaposed with narrow niche partitioning and the capacity of individual taxa in these hyperdiverse communities to respond strongly to resource inputs and changes in other abiotic environmental parameters such as temperature. Our data double the cumulative total of fungal sequences in GenBank and together achieve a better picture of fungal communities here than for any other ecosystem on earth at this time.

Pre-fire forest conditions and fire severity as determinants of the quality of burned forests for deadwood-dependent species: the case of the black-backed woodpecker

2011 ◽  
Vol 41 (5) ◽  
pp. 994-1003 ◽  
Author(s):  
Antoine Nappi ◽  
Pierre Drapeau
Keyword(s):  
Boreal Forests ◽  
Black Spruce ◽  
Fire Severity ◽  
High Quality ◽  
Forest Patches ◽  
Nest Sites ◽  
Mature Stands ◽  
Forest Conditions ◽  
Selection Of

Burned forests represent high-quality habitats for many deadwood-dependent species. Yet, post-fire conditions may vary greatly within and among burns and thereby may affect habitat suitability for these species. We studied habitat selection of nesting black-backed woodpeckers ( Picoides arcticus Swainson) in recently burned spruce-dominated boreal forests. Our objectives were to (i) identify factors involved in snag selection for both nesting and foraging and (ii) examine selection of nest sites within the burned landscape. A total of 92 nests and 1612 foraging observations were used to investigate snag selection. Our results show that both pre-fire forest conditions and fire severity are important in determining the quality of burned forests for black-backed woodpeckers. This species selected large snags for both nesting (>20 cm DBH) and foraging (>15 cm DBH). Woodpeckers selected deciduous and degraded “pre-fire” snags for nesting whereas black spruce snags that had been created by fire and that were moderately burned were preferred for foraging. Nest sites were concentrated in burned mature stands and supported higher densities of large snags (e.g., >15 cm DBH). Our results suggest that burned forest patches of at least 20 ha and composed mainly of burned mature and old-growth forests should be maintained during post-fire harvesting. The decrease in the amount of late seral stands in managed forest landscapes raises concerns about the future availability of high-quality burned forests for this species.

scholarly journals Snag use by Foraging Black-Backed Woodpeckers (Picoides Arcticus) in a Recently Burned Eastern Boreal Forest

The Auk ◽  
2003 ◽  
Vol 120 (2) ◽  
pp. 505-511 ◽  
Author(s):  
Antoine Nappi ◽  
Pierre Drapeau ◽  
Jean-François Giroux ◽  
Jean-Pierre L. Savard
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Black Spruce ◽  
High Quality ◽  
Salvage Logging ◽  
Northeastern North America ◽  
Picoides Arcticus ◽  
One Year ◽  
The Relationship ◽  
Wood Boring

Abstract We studied snag use for foraging by Black-backed Woodpeckers (Picoides arcticus) one year after a fire in an eastern black spruce (Picea mariana) boreal forest in Quebec, Canada. We searched for signs of foraging (bark flaking and excavation holes) by Black-backed Woodpeckers on 6,536 snags sampled in 56 plots located in portions of the burned forest that had not been salvage logged. A logistic regression model was developed based on the presence or absence of foraging signs. Results showed that Black-backed Woodpeckers used larger snags that were less deteriorated by fire (qualified as high-quality snags). Direct field observations of individuals foraging on 119 snags also indicated that used snags corresponded to those of high predicted quality. Finally, we assessed the relationship between food availability and snag characteristics by measuring the density of wood-boring beetle larvae holes on 30 snags of different size and deterioration classes. High-quality snags contained higher prey densities (wood-boring beetle holes) than smaller and more deteriorated snags. We recommend that forest blocks characterized by large and less deteriorated trees be preserved from salvage logging in recently burned boreal forests in northeastern North America.

Timing of growth reductions in black spruce stem and branches during the 1970s spruce budworm outbreak1This article is one of a selection of papers from the 7th International Conference on Disturbance Dynamics in Boreal Forests.

2012 ◽  
Vol 42 (7) ◽  
pp. 1220-1227 ◽  
Author(s):  
Cornelia Krause ◽  
Boris Luszczynski ◽  
Hubert Morin ◽  
Sergio Rossi ◽  
Pierre-Y. Plourde
Keyword(s):  
Picea Mariana ◽  
Boreal Forests ◽  
Radial Growth ◽  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
First Year ◽  
Growth Reduction ◽  
Lower Stem ◽  
Selection Of

Spruce budworm ( Choristoneura fumiferana (Clemens)) defoliation is known to regularly produce radial growth decrease in black spruce ( Picea mariana (Mill.) Britton, Sterns & Poggenb.) in the boreal forest of Quebec. Some studies have already shown that the first year of defoliation does not induce growth losses in the stem but could occur in other tree parts. We therefore examined the timing and duration of the growth reduction caused by the last outbreak in black spruce by also considering the branches. More than 79% of branches and 65% of stems exhibited a >40% growth decrease.The reduction was first registered in the upper part of the stem before being detected lower in the stem in 87% of the trees. Probabilities of growth reduction in the upper part of the stem were highest in 1976 and 1977. In the lower stem, the probabilities were highest in 1978. An interesting finding was that in 69% of the studied stands, the probability of growth reduction started earlier (1–2 years) in the branches than in the stem at 1.3 m. Branch analysis should be considered whenever questions arise in regard to the evolution of spruce budworm defoliation as well as the timing of observed growth reduction in black spruce.

Increasing nitrogen availability and soil temperature: effects on xylem phenology and anatomy of mature black spruce1This article is one of a selection of papers from the 7th International Conference on Disturbance Dynamics in Boreal Forests.

2012 ◽  
Vol 42 (7) ◽  
pp. 1277-1288 ◽  
Author(s):  
Carlo Lupi ◽  
Hubert Morin ◽  
Annie Deslauriers ◽  
Sergio Rossi ◽  
Daniel Houle
Keyword(s):  
Boreal Forest ◽  
Soil Temperature ◽  
Boreal Forests ◽  
Nitrogen Availability ◽  
Black Spruce ◽  
Anthropogenic Activities ◽  
N Availability ◽  
N Addition ◽  
Short Term Experiment ◽  
The Impact

Since plant growth in the boreal forest is often considered to be limited by low temperatures and low N availability and these variables are projected to increase due to climate warming and increased anthropogenic activities, it is important to understand whether and to what extent these disturbances may affect the growth of boreal trees. In this study, the hypotheses that wood phenology and anatomy were affected by increased soil temperatures and N depositions have been tested in two mature black spruce ( Picea mariana (Mill.) BSP) stands at different altitudes in Quebec, Canada. For 3 years, soil temperature was increased by 4 °C during the first part of the growing season and precipitations containing three times the current N concentration were added in the field by frequent canopy applications. Soil warming resulted in earlier onsets of xylogenesis and interacted with N addition producing longer durations of xylogenesis for the treated trees. The effect of warming was especially marked in the phenology of roots, while wood production, in terms of number of tracheids, was not affected by the treatment. Xylem anatomy and soil and needle chemistry showed no effect of the treatments, except for an increase of cell wall thickness in earlywood of treated trees. This short-term experiment with black spruce suggested that previous fertilization studies that used large and unrealistic rates of N addition may have overestimated the impact of N depositions on boreal forest productivity.

Sign in / Sign up

Export Citation Format

Share Document