scholarly journals Boreal Forest Songbird Communities of the Liard Valley, Northwest Territories, Canada

The Condor ◽  
2003 ◽  
Vol 105 (1) ◽  
pp. 27-44 ◽  
Author(s):  
Craig S. Machtans ◽  
Paul B. Latour
Keyword(s):  
Boreal Forest ◽  
Northwest Territories ◽  
Boreal Forests ◽  
Bird Community ◽  
Deciduous Forests ◽  
Zonotrichia Albicollis ◽  
Catharus Ustulatus ◽  
Regional Patterns ◽  
Dendroica Coronata ◽  
Spizella Passerina

Abstract Songbird communities in the boreal forest of the Liard Valley, Northwest Territories, Canada, are described after three years of study. Point count stations (n = 195) were placed in six types of forest (mature deciduous, coniferous, and mixedwood; young forests; wooded bogs; clearcuts) in a 700-km2 area. Vegetation characteristics at each station were also measured. Eighty-five species of birds (59 passerine species) occurred in 11 647 detections. Mixedwood forests had the highest richness of songbirds (∼41 species per 800 individuals) of the six forest types, and contained approximately 30% more individuals than nearly pure coniferous or deciduous forests. Species richness and relative abundance was 10–50% lower than in comparable forests farther south and east, and the difference was most pronounced in deciduous forests. Communities were dominated by a few species, especially Tennessee Warbler (Vermivora peregrina), Magnolia Warbler (Dendroica magnolia), Swainson's Thrush (Catharus ustulatus), Yellow-rumped Warbler (Dendroica coronata) and Chipping Sparrow (Spizella passerina). White-throated Sparrow (Zonotrichia albicollis), a dominant species in boreal forests farther south, was notably scarce in all forests except clearcuts. Clearcuts and wooded bogs had the simplest communities, but had unique species assemblages. Canonical correspondence analysis showed that the bird community was well correlated with vegetation structure. The primary gradient in upland forests was from deciduous to coniferous forests (also young to old, respectively). The secondary gradient was from structurally simple to complex forests. These results allow comparisons with other boreal areas to understand regional patterns and help describe the bird community for conservation purposes. Comunidades de Aves Canoras de Bosques Boreales del Valle de Liard, Territorios del Noroeste, Canadá Resumen. Luego de tres años de estudio, se describen las comunidades de aves canoras de bosques boreales del Valle de Liard, Territorios del Noroeste, Canadá. Se ubicaron estaciones de conteo de punto (n = 195) en seis tipos de bosque (maduro caducifolio, conífero y de maderas mixtas; bosques jóvenes; pantanos arbolados; zonas taladas) en un área de 700 km2. Las características de la vegetación en cada estación también fueron medidas. Se registraron 85 especies de aves (59 especies de paserinas) en 11 647 detecciones. Los bosques mixtos presentaron la mayor riqueza de aves canoras (∼41 especies por 800 individuos) de los seis tipos de bosque, y contuvieron aproximadamente 30% individuos más que los bosques de coníferas y los caducifolios. La riqueza de especies y la abundancia relativa fue 10–50% menor que en bosques comparables más al sur y al este, y la diferencia fue más pronunciada en los bosques caducifolios. Las comunidades estuvieron dominadas por unas pocas especies, especialmente Vermivora peregrina, Dendroica magnolia, Catharus ustulatus, Dendroica coronata y Spizella passerina. Zonotrichia albicollis, una especie dominante en bosques boreales más al sur, fue notablemente escasa en todos los bosques, excepto en las zonas taladas. Las áreas taladas y los pantanos arbolados tuvieron las comunidades más simples, pero presentaron ensamblajes únicos. Análisis de correspondencia canónica mostraron que la comunidad de aves estuvo bien correlacionada con la estructura de la vegetación. El gradiente primario en bosques de zonas altas fue de bosque caducifolio a conífero (también de joven a viejo, respectivamente). El gradiente secundario fue de bosques estructuralmente simples a bosques complejos. Estos resultados permiten hacer comparaciones con otros bosques boreales para entender los patrones regionales y ayudar a describir las comunidades de aves con fines de conservación.

Fires can overwinter in boreal forests of North America

2020 ◽  
Author(s):  
Rebecca Scholten ◽  
Sander Veraverbeke
Keyword(s):  
North America ◽  
Boreal Forest ◽  
Northwest Territories ◽  
Boreal Forests ◽  
Fire Spread ◽  
Burned Area ◽  
Organic Soils ◽  
Boreal Winter ◽  
Large Fire ◽  
Lightning Strikes

<div>The boreal forest stores 35 % of the world’s soil carbon reserves. Wildfires burn frequently in the boreal forest of North America and drive the boreal forest carbon balance. Previously, lightning strikes and human activities were identified as the sole ignition sources for wildfires in the boreal regions of North America. In recent years however, fire managers in Alaska, USA and Northwest Territories, Canada have started reporting the occurrence of overwintering fires. Overwintering fires are fires, that survive the cold and wet boreal winter by smouldering in deep, carbon-rich soils and re-emerge early in the subsequent spring, when fire weather favours fire spread.</div><div>Using the location and ignition dates of 42 overwintering fires reported by fire managers in Alaska and Northwest Territories between 2002 and 2017, we developed an algorithm to identify these new ignition sources. Our algorithm detected 8 out of 9 additional reported fires we used for validation, and further identified 15 unreported overwintering fires. Even though overwintering fires make up only 0.5 % of the burned area in total, they can amount to up to more than 10 % of the annual burned area after exceptionally large fire years.</div><div>We found that overwintering of fires is facilitated by deep burning into the organic soils. Overwintering fires occur more frequently after large fire years in combination with subsequent mild winters and springs leading to an early snowmelt.</div><div>In a warming climate, the boreal forest is burning more frequently and more intensely. As a consequence, the burned area and burn depth are predicted to increase. Our results suggest that overwintering fires are closely tied to these conditions and will therefore occur more often in the future.</div>

Maintenance of the Boreal Forest Rainbelts during Northern Summer

2006 ◽  
Vol 19 (8) ◽  
pp. 1437-1449 ◽  
Author(s):  
Jin-Ho Yoon ◽  
Tsing-Chang Chen
Keyword(s):  
Water Vapor ◽  
Boreal Forest ◽  
High Latitude ◽  
Boreal Forests ◽  
Storm Tracks ◽  
The Arctic ◽  
Eastern Canada ◽  
Regional Patterns ◽  
Vapor Flux ◽  
Northern Summer

Abstract It is not unreasonable to expect that boreal forests that exist along 60°N in the Eurasian and North American continents were created and are maintained by warm seasonal rainfall. As revealed from satellite observations and various precipitation sources, zonally elongated rainbelts appear along these forests. Previous studies show that a relationship may exist between the frontal zone along the Arctic seaboard and regional patterns of high-latitude precipitation. It was observed by this study that baroclinic zones associated with strong Arctic westerlies coincide with minor storm tracks and boreal forest rainbelts only in eastern Canada. In contrast, this coincidence does not occur in northern Europe, eastern Siberia, and the Alaska–Pacific coast, because boreal forest rainbelts in these regions are located farther south of strong Arctic westerlies and ahead of high-latitude troughs over central Eurasia, the Bering Sea, the Labrador Sea, and the Norwegian Sea. Therefore, instead of baroclinicity along strong Arctic westerlies, favorable environments for the formation of minor storm tracks are developed by positive vorticity advections ahead of these high-latitude troughs. The water vapor budget analyses performed with NCEP and Goddard Earth Observing System (GEOS-1) reanalyses show that the boreal forest rainbelts are essentially maintained by the convergence of water vapor flux associated with transient disturbances at high latitudes.

Song pitch – habitat relationships in white-throated sparrows: cracks in acoustic windows?

1988 ◽  
Vol 66 (11) ◽  
pp. 2578-2581 ◽  
Author(s):  
Joseph R. Waas
Keyword(s):  
Boreal Forest ◽  
Inverse Relationship ◽  
Habitat Type ◽  
Zonotrichia Albicollis ◽  
Acoustic Window ◽  
Wrong Reason ◽  
Foliage Density ◽  
The Right ◽  
Forest Habitats

I compared the hypothesis that birds singing from song posts above 1–2 m should sing in as low a pitch as possible regardless of habitat type, with the traditional "acoustic window" hypothesis which argues that selection favours an inverse relationship between song pitch and foliage density. Songs of white-throated sparrows, Zonotrichia albicollis, were obtained from four habitats which could be arranged in a gradient of foliage density. The pitch of these songs was found to be inversely related to the density of foliage in the habitat occupied, consistent with the acoustic window hypothesis. Significant pitch variation occurred not only between open and forest habitats, but also between mixed and boreal forest habitats. I distinguish between hypotheses that could explain support for the traditional hypothesis despite recent data suggesting that low pitched sound travels best regardless of habitat at song post heights used by white-throated sparrows (5–10 m). I conclude that the acoustic window model may make the right prediction for the wrong reason in white-throated sparrows. I emphasize the need to define and test the assumptions of models before the models themselves are accepted on the basis of support for their predictions.

The stock and age of pyrogenic carbon in boreal forest soils of the Mackenzie Basin, Northern Canada

2021 ◽  
Author(s):  
Marcus Schiedung ◽  
Philippa Ascough ◽  
Severin-Luca Bellè ◽  
Samuel Abiven
Keyword(s):  
Boreal Forest ◽  
Forest Soils ◽  
Boreal Forests ◽  
Radiocarbon Dating ◽  
Bulk Soil ◽  
Northern Canada ◽  
Pyrogenic Carbon ◽  
Discontinuous Permafrost ◽  
Soc Stocks ◽  
Mackenzie River

<p>Wildfires occur regularly in the boreal forests of Northern Canada and an increasing frequency and intensity due to the global climate change is projected. A by-product of these forest fires is pyrogenic carbon (PyC) as a residue of incomplete combustion. The quantity and age of PyC in boreal forest soils, however, are largely unknown although boreal soils contribute to a large extent to the global soil organic carbon (SOC) stocks. The Mackenzie River is a major export pathway for PyC between terrestrial and marine environments, with exported PyC ages on geological timescales. This indicates that soil may play an important role as an intermediate pool prior to the PyC export. We sampled eleven forest soils (with nine replicates) in the Canadian Taiga Plains and Shield within the Mackenzie River basin. Our sample sites were located in regions with soils under continuous permafrost in the Inuvik region (northern sites) and under sporadic and discontinuous permafrost in the South Slave Lake regions (southern sites). All sites were unaffected by fire for at least four decades. We used the hydrogen pyrolysis (HyPy) method to separate the PyC<sub>HyPy</sub> from the non-fire-derived SOC in the upper 0-15 cm to determine PyC<sub>HyPy</sub> stocks and performed radiocarbon dating upon both bulk soil and isolated PyC<sub>HyPy</sub>. The total SOC stocks were lower in the soil from the southern sites with on average 26 ± 20 Mg ha<sup>-1</sup> (10-153 Mg ha<sup>-1</sup>) compared to 57 ± 29 Mg ha<sup>-1</sup> (16-188 Mg ha<sup>-1</sup>) in the northern sites. The radiocarbon dating revealed much older PyC<sub>HyPy</sub> compared to the bulk soil SOC radiocarbon age, supporting the persistent nature of PyC and stabilization in soils. The PyC<sub>HyPy </sub>found in the soil of the southern sites, however, was much younger with ages in the range of 495-3 275 radiocarbon years BP than in the northern sites with ages on the range of 2 083-10 407 radiocarbon years BP. The larger SOC stocks and higher ages of PyC<sub>HyPy</sub> in the soils of the northern sites indicate the importance of permafrost conditions for the whole carbon cycle of boreal forests soils.</p>

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.

Multi-objective forestry increases the production of ecosystem services

2020 ◽  
Author(s):  
Olalla Díaz-Yáñez ◽  
Timo Pukkala ◽  
Petteri Packalen ◽  
Manfred J Lexer ◽  
Heli Peltola
Keyword(s):  
Ecosystem Services ◽  
Boreal Forest ◽  
Boreal Forests ◽  
Carbon Balance ◽  
Net Present Value ◽  
Simulation And Optimization ◽  
Multi Objective ◽  
Clear Cut ◽  
Trade Offs ◽  
Continuous Cover Forestry

Abstract Boreal forests produce multiple ecosystem services for the society. Their trade-offs determine whether they should be produced simultaneously or whether it is preferable to assign separate areas to different ecosystem services. We use simulation and optimization to analyse the correlations, trade-offs and production levels of several ecosystem services in single- and multi-objective forestry over 100 years in a boreal forest landscape. The case study area covers 3600 ha of boreal forest, consisting of 3365 stands. The ecosystem services and their indicators (in parentheses) considered are carbon sequestration (forestry carbon balance), biodiversity (amount of deadwood and broadleaf volume), economic profitability of forestry (net present value of timber production) and timber supply to forest industry (volume of harvested timber). The treatment alternatives simulated for each of the stands include both even-aged rotation forestry (thinning from above with clear cut) and continuous cover forestry regimes (thinning from above with no clear cut). First, we develop 200 Pareto optimal plans by maximizing multi-attribute utility functions using random weights for the ecosystem service indicators. Second, we compare the average level of ecosystem services in single- and multi-objective forestry. Based on our findings, forestry carbon balance and the amount of deadwood correlate positively with each other, and both of them correlate negatively with harvested timber volume and economic profitability of forestry. Despite this, the simultaneous maximization of multiple objectives increased the overall production levels of several ecosystem services, which suggests that the management of boreal forests should be multi-objective to sustain the simultaneous provision of timber and other ecosystem services.

scholarly journals Resilience of the boreal forest in response to Holocene fire-frequency changes assessed by pollen diversity and population dynamics

2010 ◽  
Vol 19 (8) ◽  
pp. 1026 ◽  
Author(s):  
Christopher Carcaillet ◽  
Pierre J. H. Richard ◽  
Yves Bergeron ◽  
Bianca Fréchette ◽  
Adam A. Ali
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Frequency Control ◽  
Regional Scale ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Frequency Changes ◽  
Fire Intervals ◽  
In Fire

The hypothesis that changes in fire frequency control the long-term dynamics of boreal forests is tested on the basis of paleodata. Sites with different wildfire histories at the regional scale should exhibit different vegetation trajectories. Mean fire intervals and vegetation reconstructions are based respectively on sedimentary charcoal and pollen from two small lakes, one in the Mixedwood boreal forests and the second in the Coniferous boreal forests. The pollen-inferred vegetation exhibits different trajectories of boreal forest dynamics after afforestation, whereas mean fire intervals have no significant or a delayed impact on the pollen data, either in terms of diversity or trajectories. These boreal forests appear resilient to changes in fire regimes, although subtle modifications can be highlighted. Vegetation compositions have converged during the last 1200 years with the decrease in mean fire intervals, owing to an increasing abundance of boreal species at the southern site (Mixedwood), whereas changes are less pronounced at the northern site (Coniferous). Although wildfire is a natural property of boreal ecosystems, this study does not support the hypothesis that changes in mean fire intervals are the key process controlling long-term vegetation transformation. Fluctuations in mean fire intervals alone do not explain the historical and current distribution of vegetation, but they may have accelerated the climatic process of borealisation, likely resulting from orbital forcing.

Effects of compaction on aeration and morphology of boreal forest soils in Alberta, Canada

2009 ◽  
Vol 89 (1) ◽  
pp. 45-56 ◽  
Author(s):  
A D Startsev ◽  
D H McNabb
Keyword(s):  
Boreal Forest ◽  
Forest Soils ◽  
Soil Compaction ◽  
Boreal Forests ◽  
Warm Season ◽  
Soil Morphology ◽  
Undisturbed Soil ◽  
Protective Measures ◽  
Soil Aeration ◽  
Poor Soil

Poor soil aeration is a factor limiting the productivity of boreal forests in western Canada. Soil compaction reduces air-filled porosity, which is hypothesized to further restrict soil aeration. Soil morphology at nine clearcut sites in west-central Alberta that had been significantly compacted by ground-based harvesting equipment and soil in an adjacent non-trafficked control were related to air-filled porosity and redox regimes. A warm-season air-filled porosity of about 0.1 m3 m-3 separated soils having adequate or restricted aeration, and was confirmed by redox < 200 mV. The values applied to both the undisturbed and compacted soil. Ratios of Feo:Fed and acid-soluble Fe:Mn in concretions were only associated with hydromorphism of undisturbed soil. Compaction reduced soil aeration for 3–4 yr after harvesting, and changed morphology of moderately well-drained soil to imperfectly drained soil at two of four sites; faster removal of water because of slope or vegetation probably prevented changes at the other two sites. Morphology of better and poorer drained soils was not altered by compaction because they either remain adequately aerated or aeration was naturally restricted. Sites with moderately well-drained soils are most at risk of detrimental soil compaction and in need of protective measures to maintain their productivity in these forests. Key words: Soil morphology, drainage class, air-filled porosity, soil aeration, redox potential, boreal forest soils, compaction

scholarly journals Modeling the effects of organic nitrogen uptake by plants on the carbon cycling of boreal forest and tundra ecosystems

2013 ◽  
Vol 10 (12) ◽  
pp. 7943-7955 ◽  
Author(s):  
Q. Zhu ◽  
Q. Zhuang
Keyword(s):  
Boreal Forest ◽  
Carbon Cycling ◽  
Nitrogen Uptake ◽  
Plant Uptake ◽  
Boreal Forests ◽  
Organic Nitrogen ◽  
Tundra Ecosystem ◽  
Ecosystem Production ◽  
Tundra Ecosystems ◽  
Organic Nitrogen Uptake

Abstract. Boreal forest and tundra are the major ecosystems in the northern high latitudes in which a large amount of carbon is stored. These ecosystems are nitrogen-limited due to slow mineralization rate of the soil organic nitrogen. Recently, abundant field studies have found that organic nitrogen is another important nitrogen supply for boreal forest and tundra ecosystems. In this study, we incorporated a mechanism that allowed boreal plants to uptake small molecular amino acids into a process-based biogeochemical model, the Terrestrial Ecosystem Model (TEM), to evaluate the impact of organic nitrogen uptake on ecosystem carbon cycling. The new version of the model was evaluated for both boreal forest and tundra sites. We found that the modeled organic nitrogen uptake accounted for 36–87% of total nitrogen uptake by plants in tundra ecosystems and 26–50% for boreal forests, suggesting that tundra ecosystem might have more relied on the organic form of nitrogen than boreal forests. The simulated monthly gross ecosystem production (GPP) and net ecosystem production (NEP) tended to be larger with the new version of the model since the plant uptake of organic nitrogen alleviated the soil nitrogen limitation especially during the growing season. The sensitivity study indicated that the most important factors controlling the plant uptake of organic nitrogen was the soil amino acid diffusion coefficient (De) in our model, suggesting that the organic nitrogen uptake by plants is likely to be regulated by the edaphic characteristics of diffusion. The model uncertainty due to uncertain parameters associated with organic nitrogen uptake of the tundra ecosystem was larger than the boreal forest ecosystems. This study suggests that considering the organic nitrogen uptake by plants is important to carbon modeling of boreal forest and tundra ecosystems.

scholarly journals Arctic ground squirrel population collapse in the boreal forests of the Southern Yukon

2015 ◽  
Vol 42 (2) ◽  
pp. 176 ◽  
Author(s):  
Jeffery R. Werner ◽  
Charles J. Krebs ◽  
Scott A. Donker ◽  
Rudy Boonstra ◽  
Michael J. Sheriff
Keyword(s):  
Boreal Forest ◽  
Ground Squirrel ◽  
Boreal Forests ◽  
Ground Squirrels ◽  
The Arctic ◽  
Arctic Ground Squirrel ◽  
Forest Zone ◽  
Winter Climate ◽  
Population Collapse ◽  
Predator Pit

Context The arctic ground squirrel (Urocitellus parryii) comprised 17% of the biomass of herbivores in the Yukon boreal forest during the summer months from 1987 to 1996 and was responsible for 23% of the energy flow at the herbivore level. By 2000, ground squirrel populations in this region collapsed to nearly zero and have remained there. Aims We summarise the population monitoring (since 1975) and recent experimental work that has been done on this key herbivore in the Kluane area of the southern Yukon to test one mechanistic hypothesis as the possible explanation for this population collapse and subsequent lack of recovery: predation. Methods Ground squirrels are the preferred summer prey of bird and mammal predators when snowshoe hare (Lepus americanus) populations are declining. We used translocations into formerly occupied habitat and radiotelemetry to determine movements and causes of death from 2009 to 2014. We surveyed 158 sites between 2008 and 2013 to measure the disappearance of colonies in alpine and forest habitats over 25 000 km2. Key results Ground squirrels from 2000 to 2013 comprised a small fraction of the herbivore biomass in the boreal forest zone, down from 17% earlier. Most forest populations (~95%) are currently extinct, whereas just over half (65%) of low-elevation meadow populations are locally extinct. One hypothesis is that ground squirrels in the forest have been driven into a predator pit from which they cannot recover. They remain abundant in alpine tundra (93% occupancy rate) and around airport runways and human habitations (97% occupancy), but there is no apparent dispersal from alpine areas down into the boreal forest. Conclusion The predator pit hypothesis is a likely explanation for the initial collapse and sustained decline in population size from 2000 to 2013. Recent attenuation of the hare cycle and milder winter climate have allowed shrubs to expand throughout the forest, thereby reducing visibility and increasing predation risk. This conclusion will be tested in further research using reintroductions to formerly occupied sites. Implication If the loss of this herbivore from the boreal forest is not reversed, predator pressure on the other major herbivores of the montane forest zone is likely to change significantly.

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