scholarly journals Long-Term Steady-State Dry Boreal Forest in the Face of Disturbance

Ecosystems ◽  
2019 ◽  
Vol 23 (5) ◽  
pp. 1075-1092 ◽  
Author(s):  
Christopher Carcaillet ◽  
Mireille Desponts ◽  
Vincent Robin ◽  
Yves Bergeron
Keyword(s):  
Steady State ◽  
Boreal Forests ◽  
Pinus Banksiana ◽  
Fire History ◽  
Cenococcum Geophilum ◽  
Natural Fire ◽  
Aeolian Dunes ◽  
The Face ◽  
Original Vegetation ◽  
Soil Dryness

Abstract We used bioproxies from paleosoils buried within two aeolian dunes to test hypotheses concerning the origin of dry sandy boreal forests in Canada. These forests are dominated today by Pinus banksiana Lamb. One hypothesis is that too frequent Holocene stand-replacing fires would have transformed the original vegetation through extirpation of susceptible species to fire in water stress habitat. Alternatively, the ecosystem would have not changed since the dunes stabilized enough to support forest establishment. The vegetation composition and richness were determined by identification of charcoal and macroremains and radiocarbon dating for the chronology. Both sites revealed a similar history covering 6400 years. Half of the charcoal layers were less than 2500 years old in both sites, indicating that they had been subjected to the same fire history. Data indicated a stable plant composition and richness, although the percentage of Pinus decreased slightly over 4000 years (decreasing rate 1% per century). The fungus Cenococcum geophilum was consistently present, with a stochastic abundance. The vegetation grew under natural fire conditions and soil dryness since 6000 years. The ecosystem was probably not stressed by late-Holocene fires or climate changes, as the multi-millennial steady state reveals a resistant and resilient ecosystem.

scholarly journals The Delphi method as an alternative to standard committee meetings to identify ecological issues for forest ecosystem-based management: A case study

2016 ◽  
Vol 92 (04) ◽  
pp. 453-464 ◽  
Author(s):  
K. Waldron ◽  
J.-M Lussier ◽  
N. Thiffault ◽  
F. Bujold ◽  
J.-C. Ruel ◽  
...  
Keyword(s):  
Forest Ecosystem ◽  
Delphi Method ◽  
Boreal Forests ◽  
Expert Consultation ◽  
Committee Meeting ◽  
Eastern Canada ◽  
Face To Face ◽  
Time Investment ◽  
Second Growth ◽  
The Face

The face-to-face committee meeting is one of the most common expert consultation methods used in forest management. However, it is also laden with disadvantages, such as potential inequity in its consideration of participant opinion and the time involvement required. This led us to evaluate another expert consultation method, the Delphi method, namely by implementing it to identify ecological issues associated with second-growth boreal forests in eastern Canada. We compared this method to the committee meeting method with regard to the time investment required and the efficiency of the consultations. In all, 21 experts participated in three rounds of our implementation of the Delphi method. Subsequently, we administered an appreciation survey comparing the participants’ attitudes vis-à-vis the two methods. These comparisons showed that Delphi was less time-consuming compared to a committee meeting consultation of comparable scope. Participants also considered the Delphi method to be fair and impartial, as all opinions were considered, which is frequently not the case in committee meetings. That said, participants believed that committee meetings allowed for a greater understanding of others’ opinions. Overall, the application of the Delphi method was shown to be a promising way of determining forest ecosystem management issues.

scholarly journals Trade-Offs among Release Treatments in Jack Pine Plantations: Twenty-Five Year Responses

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 370
Author(s):  
Holly D. Deighton ◽  
Frederick Wayne Bell ◽  
Nelson Thiffault ◽  
Eric B. Searle ◽  
Mathew Leitch ◽  
...  
Keyword(s):  
Plant Diversity ◽  
Boreal Forests ◽  
Pinus Banksiana ◽  
Vegetation Management ◽  
Jack Pine ◽  
Forest Diversity ◽  
Trade Offs ◽  
Jack Pine Forests ◽  
Stand Yield ◽  
Forest Managers

We assessed 27 indicators of plant diversity, stand yield and individual crop tree responses 25 years post-treatment to determine long-term trade-offs among conifer release treatments in boreal and sub-boreal forests. This research addresses the lack of longer-term data needed by forest managers to implement more integrated vegetation management programs, supporting more informed decisions about release treatment choice. Four treatments (untreated control, motor-manual brushsaw, single aerial spray, and complete competition removal) were established at two jack pine (Pinus banksiana Lamb.) sites in Ontario, Canada. Our results suggest that plant diversity and productivity in boreal jack pine forests are significantly influenced by vegetation management treatments. Overall, release treatments did not cause a loss of diversity but benefitted stand-scale yield and individual crop tree growth, with maximum benefits occurring in more intensive release treatments. However, none of the treatments maximized all 27 indicators studied; thus, forest managers are faced with trade-offs when choosing treatments. Research on longer term effects, ideally through at least one rotation, is essential to fully understand outcomes of different vegetation management on forest diversity, stand yield, and individual crop tree responses.

scholarly journals Assessing the Translucence and Color-Change Methods for Estimating Sapwood Depth in Three Boreal Species

Forests ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 686 ◽  
Author(s):  
M. Quiñonez-Piñón ◽  
Caterina Valeo
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Wood Anatomy ◽  
Color Change ◽  
Microscopic Analysis ◽  
Forest Monitoring ◽  
Statistical Comparison ◽  
The Face ◽  
Species Specific

The translucence and color change in wood methods, which are commonly used to differentiate sapwood from heartwood in tree cores, are compared against the microscopic analysis of wood anatomy method for determining sapwood depth. The translucence method was tested on collected wood cores of White Spruce (Picea glauca (Moench) Voss) and Jack Pine (Pinus banksiana Lamb.). The color change in wood method was tested on Trembling Aspen (Populus tremuloides Michx.). For every statistical comparison, sapwood depth values obtained with the translucence or color-change methods were significantly different from those obtained using the microscopic analysis. Using the sapwood depth values obtained with microscopy as a reference, the bias associated with the translucence or color-change methods used on Picea glauca, Pinus banksiana and Populus tremuloides constantly under- or overestimated sapwood depths within −0.3 cm to 1.6 cm; −4.9 cm to 0.5 cm; and 0 to 1.8 cm, respectively. The different ranges of over- and underestimation arise from species-specific anatomical characteristics. Estimates for the errors in sapwood depth, when the depth is measured using either the translucence or color-change methods, are presented. These relationships and research outcomes will lead to more efficient forest monitoring and improved estimates of forest water balance, which in turn will lead to improved forest management in the face of climate change.

Steady-state response of quadriplegic subjects to inspiratory resistive load

1986 ◽  
Vol 60 (5) ◽  
pp. 1482-1492 ◽  
Author(s):  
V. Im Hof ◽  
H. Dubo ◽  
V. Daniels ◽  
M. Younes
Keyword(s):  
Steady State ◽  
Chest Wall ◽  
Muscle Spindles ◽  
Normal Subjects ◽  
Afferent Feedback ◽  
Resistive Load ◽  
State Response ◽  
The Face ◽  
Inspiratory Resistance

Normal subjects preserve tidal volume (VT) in the face of added inspiratory resistance by increasing maximal amplitude and duration of the rising phase of respiratory driving pressure (DP) and by changing the shape of this phase to one that is more concave to the time axis. To explore the possible role of chest wall afferents in mediating these responses, we determined averaged DP in eight quadriplegic subjects during steady-state unloaded breathing and while breathing through an inspiratory resistance (8.5 cmH2O X 1(-1) X s). As with normal subjects, quadriplegics preserved VT (loaded VT = 106% control) by utilizing all three mechanisms. However, prolongation of the inspiratory duration derived from the DP waveform (+22% vs. +42%) and shape response were significantly less in the quadriplegic subjects. Shape response was completely absent in subjects with C4 lesions. The results provide strong evidence that respiratory muscle spindles are responsible for shape response and that changes in afferent feedback from the chest wall play an important role in mediating inspiratory prolongation.

Effective fire suppression in boreal forests

2005 ◽  
Vol 35 (4) ◽  
pp. 772-786 ◽  
Author(s):  
S G Cumming
Keyword(s):  
Boreal Forests ◽  
Regression Models ◽  
Fire History ◽  
Fire Suppression ◽  
Fire Regimes ◽  
Operational Effectiveness ◽  
Logistic Regression Models ◽  
Area Burned ◽  
Large Fires ◽  
Northeastern Alberta

Fire suppression is (functionally) effective insofar as it reduces area burned. In North American boreal forests, fire regimes and historical records are such that this effect cannot be detected or estimated directly. I present an indirect approach, proceeding from the practice of initial attack (IA), which is intended to limit the proportion of "large" fires. I analysed IA's (operational) effectiveness by a controlled retrospective study of fire-history data for an approximately 86 000 km2 region of boreal forest in northeastern Alberta, Canada, from 1968 to 1998 (31 years). Over this interval, various improvements to IA practice, including a 1983 change in management strategy, created a natural experiment. I tested the results with multiple logistic regression models of the annual probabilities of a fire becoming larger than 3 and 200 ha. Annual fire counts (Nt) were a surrogate for fire weather and peak daily counts within years (arrival load). Measured by odds ratios, mean IA effectiveness against 3- and 200-ha fires increased in 1983 by factors of 2.02 (95% CI = 1.70–2.40) and 2.41 (95% CI = 1.69–3.45), respectively. Prior to 1983, the functional response to Nt was consistent with saturation of IA capacity at high arrival loads. From 1983–1998, effectiveness was independent of Nt. I introduce the proportional reduction in area burned (impact) as a measure of functional effectiveness and state conditions under which it can be estimated from the regression models. Over 1983–1998, if suppressed and actual fires were comparable, relative IA impact ([Formula: see text]) was 0.58 (95% CI = 0.34–0.74) and area burned was reduced by 457 500 ha. If fires larger than 1 × 105, 1 × 104, or 1 × 103 ha are assumed to be unpreventable, [Formula: see text] declines to 0.46, 025, or 0.08, respectively, but there is no evidence this is the case.

Mapping fuels in Yosemite National Park

2013 ◽  
Vol 43 (1) ◽  
pp. 7-17 ◽  
Author(s):  
Seth H. Peterson ◽  
Janet Franklin ◽  
Dar A. Roberts ◽  
Jan W. van Wagtendonk
Keyword(s):  
Random Forests ◽  
National Park ◽  
Fire History ◽  
Fire Regime ◽  
Fire Suppression ◽  
Remotely Sensed ◽  
Yosemite National Park ◽  
Natural Fire ◽  
Fuel Loads ◽  
Fuel Models

Decades of fire suppression have led to unnaturally large accumulations of fuel in some forest communities in the western United States, including those found in lower and midelevation forests in Yosemite National Park in California. We employed the Random Forests decision tree algorithm to predict fuel models as well as 1-h live and 1-, 10-, and 100-h dead fuel loads using a suite of climatic, topographic, remotely sensed, and burn history predictor variables. Climate variables and elevation consistently were most useful for predicting all types of fuels, but remotely sensed variables increased the kappa accuracy metric by 5%–12% age points in each case, demonstrating the utility of using disparate data sources in a topographically diverse region dominated by closed-canopy vegetation. Fire history information (time-since-fire) generally only increased kappa by 1% age point, and only for the largest fuel classes. The Random Forests models were applied to the spatial predictor layers to produce maps of fuel models and fuel loads, and these showed that fuel loads are highest in the low-elevation forests that have been most affected by fire suppression impacting the natural fire regime.

scholarly journals A note on dynamical compensation and its relation to parameter identifiability

2017 ◽  
Author(s):  
Omer Karin ◽  
Uri Alon ◽  
Eduardo Sontag
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
The Other ◽  
Apparent Discrepancy ◽  
Parameter Identifiability ◽  
Other Hand ◽  
The Face ◽  
System Variables

AbstractWe recently identified a motif for dynamical compensation (DC) – a property where a system maintains the dynamics and steady-state of a regulated variable robust in the face of fluctuations in key parameters. Such parameters are therefore unidentifiable from measurements of the regulated variable at steady-state. On the other hand, since the models showing dynamical compensation are typically non-redundant, their parameters are identifiable from experimental data. We clarify this apparent discrepancy by requiring that the parameters of DC circuits be identifiable both away from steady-state and when measuring other system variables. We use this observation to provide a definition for DC in terms of parameter identifiability and discuss its relevance for the examples provided in Karin et al.

scholarly journals Vegetation dynamics and Fire History in Färnebofjärden National Park, Central Sweden

The Holocene ◽  
2020 ◽  
Vol 31 (1) ◽  
pp. 28-37
Author(s):  
Gina E Hannon ◽  
Karen Halsall ◽  
Chiara Molinari ◽  
Erin Stoll ◽  
Diana Lilley ◽  
...  
Keyword(s):  
Iron Age ◽  
National Park ◽  
Fire History ◽  
Plant Macrofossils ◽  
Natural Fire ◽  
Disturbance Factor ◽  
Long Time ◽  
History Of ◽  
Flooding Events

Palaeoecological studies can identify past trends in vegetation communities and processes over long time scales. Pollen, plant macrofossils and charcoal analyses are used to reconstruct vegetation over the last 6400 years and provide information about former human impact and disturbance regimes in Färnebofjärden National Park, Central Sweden. Three specific conservation planning topics were addressed: (1) the changing ratio of conifers to broadleaved trees; (2) the origin and history of the river meadows and the biodiverse Populus tremula meadows; (3) the role of fire in the maintenance of biological values. Early diverse mixed broadleaved forest assemblages with pine were followed by significant declines of the more thermophilic forest elements prior to the expansion of spruce in the Iron Age. The rise to dominance of spruce was a ‘natural’ process that has been exaggerated by anthropogenic disturbance to artificially high levels today. The initial river meadow communities were facilitated by fire and frequent flooding events, but subsequent dynamics have more definitely been supported by human activities. Rural abandonment during the last 100 years has led to woody successions. Fire has been a continual disturbance factor with an influence on conservation issues such as Picea abies dominance and the maintenance of diverse, non-forest communities. Present occurrence of fire is unusually low, but natural fire frequencies are increasing in the region.

Reconstruction of fire history (1680–2003) in Gaspesian mixedwood boreal forests of eastern Canada

2007 ◽  
Vol 244 (1-3) ◽  
pp. 41-49 ◽  
Author(s):  
Ève Lauzon ◽  
Daniel Kneeshaw ◽  
Yves Bergeron
Keyword(s):  
Boreal Forests ◽  
Fire History ◽  
Eastern Canada

Response of boreal plant communities to variations in previous fire-free interval

2006 ◽  
Vol 15 (4) ◽  
pp. 497 ◽  
Author(s):  
Jill F. Johnstone
Keyword(s):  
Plant Community ◽  
Plant Communities ◽  
Populus Tremuloides ◽  
Boreal Forests ◽  
Fire History ◽  
Yukon Territory ◽  
Deciduous Species ◽  
Community Patterns ◽  
Free Interval ◽  
Species Cover

The present study used overlapping burn scars from natural wildfires to examine the effects of changes in the fire-free interval on early successional plant communities in boreal forests of central Yukon Territory, Canada. Data on plant community composition and residual organic material were collected in the first decade of post-fire regeneration in two study areas with recent fire overlap. Sites with a shorter fire-free interval had reduced loads of deadwood and shallower organic layers after the most recent fire. Multivariate analysis of species cover indicated that sites in and out of the burn overlap zones also supported distinct plant communities. Differences in the plant communities were associated with a greater abundance of woody deciduous species, such as Populus tremuloides, Salix spp., and Shepherdia canadensis, at sites that had recently re-burned. Sites that burned after a longer interval had higher moss cover and greater abundance of Picea mariana, Calamagrostis canadensis, and Ribes glandulosum in one study area, and Epilobium angustifolium in the second area. Ordinations of species cover indicated that plant community patterns were most strongly associated with gradients related to fire history and topography. In general, shorter fire-free intervals reduced pools of residual plant material and favored dominance of resprouting, woody deciduous species.

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