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Taiga Shield Ecozone+ Evidence for Key Findings Summary

Theme: Habitat, Wildlife and Ecosystem Processes

 

Intact landscapes and waterscapes

 
Theme Habitat, wildlife, and ecosystem processes

Intact landscapes and waterscapes was initially identified as a nationally recurring key finding and information was subsequently compiled and assessed for the Taiga Shield Ecozone+. In the final version of the national report,Footnote 3 information related to intact landscapes and waterscapes was incorporated into other key findings. This information is maintained as a separate key finding for the Taiga Shield Ecozone+.

Within the boundaries of the Taiga Shield Ecozone+, there is a relatively low level of human disturbance. Human settlements are thinly scattered, industrial development is comparatively low, and the road network is sparse. At the current rate of human activity, habitat changes are site-specific and local. However, their cumulative footprint is increasing and concerns are growing. For example, the Dene First Nations near Great Slave Lake report that caribou locations have shifted from the past and that the animals are avoiding areas inhabited by people.Footnote 54

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Species of special economic, cultural, or ecological interest

Key finding 17
Theme Habitat, wildlife, and ecosystem processes

National key finding
Many species of amphibians, fish, birds, and large mammals are of special economic, cultural, or ecological interest to Canadians. Some of these are declining in number and distribution, some are stable, and others are healthy or recovering.

Migratory tundra caribou

This section is based on the report on Northern caribou population trends in Canada,Footnote 12 a technical thematic report prepared for the 2010 Ecosystem Status and Trends Report. As per this report, Northern caribou include migratory tundra caribou of three sub-species: barren-ground caribou (Rangifer tarandus groenlandicus) which range east of the McKenzie River, Grant's caribou (R. t. granti), which range west of the Mackenzie River, and woodland caribou (forest-tundra population) (R. t. caribou) comprised of two large herds in Ungava and two small herds that calve along the south coast of Hudson Bay).

Migratory tundra caribou are a pivotal species ecologically, as well as for people, so their distribution is well monitored through aerial surveys or satellite telemetry. Caribou use the Taiga Shield mainly from fall to spring, although the areas they use vary from year to year. Migratory caribou numbers have generally declined since peak abundance in the mid-1990s – and some have declined severely in recent years. The declines may be part of natural cycles, perhaps augmented by cumulative effects from stressors including climate change, harvest pressures, and increasing human presence on parts of the ranges. Highs and lows in historic abundance since the 1800s have been reconstructed from the frequency of hoof scars on spruce roots for the Bathurst and George River herds.Footnote 109 Footnote 110

The following herds – all in decline in 2010 – use significant parts of the western Taiga Shield over their annual cycle (Figure 26): Bathurst (Figure 27), Beverly (Figure 28), and Qamanirjuaq (Figure 29). The Bluenose East herd increased from 2006 to 2010Footnote 12 but declined in 2013.Footnote111 The status of the Lorillard Herd is unknown and the Ahiak Herd is declining based on preliminary data. In the eastern Taiga Shield, the George River Herd (Figure 30) summers and winters in the ecozone+. The Leaf River Herd (Figure 31) uses the area in winter only. Both herds are in decline.

Figure 26: Distribution and status of migratory tundra caribou herds with ranges extending into the Taiga Shield Ecozone+
Map
Source: Gunn et al., 2011Footnote 12 Bluenose East Herd information updated with 2013 census information from Government of Northwest Territories Environment and Natural ResourcesFootnote111
Long description for Figure 26

This map presents the distribution and status (increasing or decreasing) of caribou herds in the Taiga Shield Ecozone+. Most of the caribou herds in the ecozone+ are decreasing in population size, including the Bathurst, Beverly, and George River herds. The Leaf River, Qamanirjuaq and Bluenose-east caribou herds also show evidence of decline, but are not well studied. The Ahiak herd also shows evidence of decline, based on preliminary data. The status of the Lorillard Caribou Herd is also unknown. The Cape Churchill Caribou Herd is considered stable.

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Figure 27. Bathurst Caribou Herd population estimates, 1977-2009.
Graph
Source: Gunn et al., 2011Footnote 12
Long description for Figure 27

This bar graph shows the following information:

Bathurst
YearBathurst

Calving-ground photo survey
Bathurst

Visual calving-ground survey
Bathurst

Standard error
1977-160,000-
1978-127,000-
1980140,000140,000-
1982174,000--
1984384,000-65,000
1986472,000-72,900
1990351,683-77,800
1996349,046-94,900
2003186,005-40,146
2006128,047-24,000
200931,900-6,270

The Bathurst Herd uses the Taiga Shield in fall and winter. The historical trend, based on Tlicho elders' recollections of enough caribou in fall hunting camps, was high numbers in 1940s, low in the 1950s and increasing during the 1970s and 1980s. Since 1998, the southern boundary of the winter range has contracted.

Figure 28. Beverly Caribou Herd population estimates, 1971-2008.
Graph
Source: Gunn et al., 2011Footnote 12
Long description for Figure 28

This bar graph presents the following information:

Beverly
YearBeverly

Calving-ground photo survey
Beverly

Visual calving-ground survey
Beverly

Standard error
1971-210,000-
1978-130,000-
1980-105,000-
1982164,338-72,332
1984263,691-80,652
1988189,561-70,961
199387,000-17,900
1994276,000-106,600

The Taiga Shield provides fall and winter range for the Beverly Herd. The herd's trends in abundance and vital rates were not monitored between 1994 and 2008. However, a 2002 systematic reconnaissance survey reported lower densities than in 1994. Four calving ground delineation surveys from 2006 to 2009 also found few cows and even fewer calves. This information suggests a declining population. However, population estimates were unable to be determined from this data and are not shown in Figure 28.

Figure 29. Qamanirjuaq Caribou Herd population estimates, 1976-2008.
Graph
Source: Gunn et al., 2011Footnote 12
Long description for Figure 29

This bar graph presents the following information:

Qamanirjuaq
YearQamanirjuaq

Calving-ground photo survey
Qamanirjuaq

Visual calving-ground survey
Qamanirjuaq

Standard error
1976-43,800-
1977-44,095-
1980-39,000-
1982-180,000-
1983230,000-59,000
1985272,000-142,000
1988221,000-72,000
1994495,665-105,426
2005---
2006---
2007---
2008348,661-44,861

The Taiga Shield is fall and winter range for the Qamanirjuaq Herd. Numbers were very low in the 1970s and increased until at least 1994. Nunavut completed a calving ground survey in 2008 and determined the herd had declined but that the trend was not statistically significant.Footnote 112

Figure 30. George River Caribou Herd population estimates.
Graph
Source: Gunn et al., 2011Footnote 12
Long description for Figure 30

This bar graph presents the following information:

George River
YearGeorge River

Calving-ground
photo survey
George River

Visual calving-ground survey
George River

Post calving
photo survey
George River

90% CI
1973-105,000--
1975-205,000--
1976-263,100--
1980-390,100--
1982-360,450--
1984644,000--161,644
1993775,891--103,969
2001--385,000108,000
2010--74,13112,602

The herd increased from the 1950s to the mid-1990s. Degradation of summer habitat may have facilitated the decline to 74,100 individuals in 2010.

Figure 31. Leaf River Caribou Herd population estimates 1975-2001.
Graph
Source: Gunn et al., 2011Footnote 12
Long description for Figure 31

This bar graph presents the following information:

Leaf River
YearLeaf River

Calving-ground
photo survey
Leaf River

Visual calving-ground survey
Leaf River

Post calving
photo survey
Leaf River

90% CI
1975-56,000--
1983-101,000-43,430
1986121,000--56,386
1991276,000--75,900
2001--628,000-

The Leaf River (Rivière-aux-Feuilles) Herd increased from 1975 to the last census in 2001. Observations of body condition and calf recruitment in 2007 and 2008 suggest the population has likely declined since 2001.

Boreal caribou

Woodland caribou, boreal population (i.e., boreal caribou) was listed as Threatened under the Species at Risk Act (SARA) in 2003.Footnote113 The classification of caribou used in this report follows the current Species at Risk Act (SARA) classification system. In 2011, COSEWIC adopted 12 designatable units for caribou in Canada that will be used in caribou assessments and subsequent listing decisions under SARA beginning in 2014. This section on boreal caribou is based on the 2011 Scientific Assessment to Inform the Identification of Critical HabitatFootnote114 and the 2012 Recovery Strategy for the Woodland Caribou (Rangifer tarandus caribou), boreal population in Canada.Footnote115 The information in this section has been updated since the release of the ESTR national thematic report, Woodland caribou, boreal population, trends in Canada.Footnote 13

Six boreal caribou local populations have ranges that are fully or partially in the Taiga Shield ecozone+. Very small portions of the range in the Northwest Territories and the range in Northern Saskatchewan, both with unavailable population trends, occur in the western Taiga Shield.Footnote 13 In the eastern Taiga Shield, four local populations extend across the south of the ecozone+. The Quebec local population is considered stable; the three local populations in Labrador are declining (Figure 32).

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Figure 32: Status of boreal caribou local populations in the Taiga Shield (east) Ecozone+.
Map
Source: updated from Callaghan et al., 2011,13 based on Environment Canada 2012Footnote115
Long description for Figure 32

This map presents the status of four caribou populations located in the Taiga Shield Ecozone+ in central Quebec and Labrador. The Quebec population is considered stable and the three in Labrador, Red Wine Mountain, Lac Joseph, and Mealy Mountain, are declining.

Broad-scale reduction of range and population declines of boreal caribou in Canada are associated with loss and degradation of mature coniferous forest habitat.Footnote 13 The most immediate effect of this reduction in mature forest is an increase in younger forest types that favour other ungulates such as moose (Alces alces) and white-tailed deer (Odocoileus virginianus). This change in turn results in more predators and increased predation on caribou.Footnote114 Footnote127 Although deer are rare, their abundances are increasing and the distributions of moose are changing in the Taiga Shield (see Major range shifts in species native to Canada on page 56).

Human disturbances (right of ways, for example), will also facilitate predator movement. This increases the risk of predation by increasing predator-caribou encounter rates.Footnote128 Boreal caribou are closely associated with late-successional coniferous forests and peatlandsFootnote129 that function as refugia, away from high densities of predators and their alternate prey.Footnote 120 Footnote 122 Footnote 124 Footnote 130 Footnote 131

The extent of hunting is poorly understood in most areas. Analyses of historical population trends, data from radio-collared animals, and current demographic information indicate that hunting remains an important component of adult female boreal caribou mortality and hence is a primary threat to some local populations.Footnote132 In Labrador, harvest by humans is the most significant threat to boreal caribou.Footnote 13 Hunting of boreal caribou by humans and predators, such as wolves, is facilitated by construction of roads and other linear features and by use of off-road vehicles that permit access to previously inaccessible areas.Footnote128

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Waterfowl

This section is based on Trends in breeding waterfowl in Canada,10 a technical thematic report prepared for the 2010 Ecosystem Status and Trends Report. Analyses of trends by ecozone+ in the waterfowl report included data up to 2006 and have not been updated here.
Scaup (Aythya spp.), American wigeon (Anas americana), and scoters (Melanitta spp.) are experiencing population declines in the western part of the Taiga Shield (Figure 33). Declining trends were also reported for neighbouring ecozones+ for most of these species, suggesting common factors are at work. Climate change may be driving at least some of these declines. Lesser scaup (A. affinis), white-winged scoters (M. deglandi) and American wigeon are relatively late nesters,Footnote 133 Footnote 134 Footnote 135 and DeVink et al. Footnote136 suggest that, if there is a dependence on photoperiod as a breeding cue, there may be a growing mismatch between timing of nesting and food availability. The availability of their invertebrate food source may be shifting with changing temperatures, resulting in decreased hen and duckling survival.

Figure 33. Western Taiga Shield Ecozone+ population trends for bufflehead, scaup, American widgeon and scoter, 1970-2006.
Changes are significant (p<0.05) for species marked with an asterisk. Species: scaup, American wigeon, and scoters
Graph
Source: Fast et al. 2011Footnote 10
Long description for Figure 33

This graphic is composed of two graphs: a bar graph showing the following information:

Change in abundance, 1970 to 2006
SpeciesPercentage
bufflehead-2%
scaup*-63%
American wigeon*-54%
scoter*-41%

and a line graph showing the following information:

YearBreeding pairs
1970692,043
1971777,289
19721,422,897
1973946,024
1974696,938
1975944,467
1976828,456
1977790,675
1978745,274
1979750,516
1980790,896
1981730,862
1982594,214
1983654,698
1984731,253
1985629,319
1986564,267
1987424,462
1988446,308
1989479,752
1990321,850
1991429,336
1992233,236
1993371,036
1994354,962
1995411,637
1996269,117
1997270,598
1998377,277
1999482,308
2000301,344
2001249,438
2002301,018
2003520,291
2004392,460
2005251,142
2006216,782

Surveys since 1991 in the eastern Taiga Shield ecozone+ show considerable year-to-year variation, but the trends suggest stable population levels for ring-necked duck (Aythya collaris), scaup , American black duck (Anas rubripes), and green-winged teal (Anas carolinensis) (Figure 34).

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Figure 34: Number of breeding pairs of American black duck, green-winged teal, scaup (Aythya affinis and A. marila combined), and ring-necked duck in the Eastern Taiga Shield ecozone+, 1990-2006. There were no significant trends.
Graph
Source: Fast et al. 2011Footnote 10
Long description for Figure 34

This multiple line graph shows the following information:

Number of breeding pairs
YearAmerican Black DuckGreen-winged TealScaupRing-necked Duck
199012,4541,2209,0512,089
199110,2884,2691,8101,492
19927,9423,28200
19932,1660905298
19948,1322,1289052,387
199510,1393,8291,418358
19966,9043,4443,1082,159
19974,1192,4051,8641,267
19984,4701,9761,821694
19997,4993,7531,4781,606
20008,3812,6101,1231,297
20017,3404,01901,389
20028,4306,1983,809723
20035,4904,9101,7981,056
20047,5947,8861,1122,530
20054,5744,0191,9541,215
20064,6012,1425,377668

Landbirds

Because few data were available for landbirds breeding in the taiga, landbird information was combined for all taiga ecozones+.Footnote 14 Populations of some species are monitored on their wintering ranges in the United States and southern Canada through the Christmas Bird Count (CBC). North American trends are shown below (Table 6) for six landbird species with breeding ranges that included portions of the three taiga ecozones+. Canada has a high stewardship responsibility for all of these species because large portions of their western hemisphere breeding populations are in Canada.

Table 6: Trends in annual abundance of selected landbirds from the three taiga ecozones+, 1966-2005
SpeciesMain breeding
range
Population trend
(%/yr)
PCBCAI
1970s
CBCAI
1980s
CBCAI
1990s
CBCAI
2000s
CBCAI
Change
Rusty blackbird(Euphagus carolinus)Hudson Bay Lowlands,
taiga and boreal
-5.46%*1.50.70.40.3-78%
Boreal chickadee (Poecile hudsonicus)Taiga and boreal-1.73%*1.61.31.21.2-29%
Northern shrike (Lanius excubitor)Taiga-0.79%*1.11.01.00.8-29%
Pine grosbeak (Pinicola enucleator)Taiga and boreal-0.78%5.13.42.82.5-52%
Smith's longspur (Calcarius pictus)Taiga-0.32% -0.050.060.070.0857%
Lincoln's sparrow (Melospiza lincolnii)Taiga and boreal-0.08% -1.51.51.71.68%

Source: based on data from the Christmas Bird Count (courtesy of D. Niven, Audubon) as reported in Downes et al., 2011Footnote 14

Table 6 description

Shown are the annual rate of change and the average CBC abundance index by decade. Asterisks (*) indicate statistically significant trends (P<0.05).

Three of six species show statistically significant long-term declines. In particular, the rusty blackbird (Euphagus carolinus), a temperate migrant that winters in the United States, declined by 78% between the 1970s and the 2000s (Figure 35). This decline was supported by surveysFootnote137 from other parts of its range that showed an even steeper rate of decline for Canada overall. Circumstantial evidence suggests that declines have not been as dramatic in the north.Footnote138 The declines in boreal chickadee (Poecile hudsonicus) and pine grosbeak (Pinicola enucleator) were also supported by evidence of declines from surveys in other parts of their breeding ranges.Footnote 14

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Figure 35: Trend in annual abundance index for the rusty blackbird
The decline is statistically significant (p<0.05).
Graph
Source: based on data from the Christmas Bird Count (courtesy of D. Niven, Audubon) as reported in Downes et al., 2011Footnote 14
Long description for Figure 35

This line graph depicts the following information:

YearAbundance Index
19662.74
19672.42
19682.28
19692.19
19701.80
19712.12
19721.69
19731.68
19741.42
19751.40
19761.34
19771.26
19781.05
19790.93
19801.05
19810.86
19820.89
19830.89
19840.63
19850.72
19860.63
19870.63
19880.51
19890.59
19900.50
19910.44
19920.46
19930.40
19940.35
19950.40
19960.38
19970.32
19980.41
19990.35
20000.36
20010.28
20020.34
20030.34
20040.31
20050.31

Fish

Information about general fish health from Aboriginal Traditional Knowledge in the western portion of the Taiga Shield shows varying changes. The Dene report fewer fish in the Mackenzie River areaFootnote139 and near Great Slave Lake, while other reports say fish populations in Great Slave Lake are at least as good as in the past.Footnote 54 Footnote 84 Footnote 140 In the Hudson Bay region, there are reports that fish behaviour and health have changed, that migration patterns have altered, and that dams and changing water levels stop fish moving upstream and into lakes.Footnote 88

In the eastern portion of the Taiga Shield, hydroelectric development has had a dramatic impact on a number of river basins. Changes affecting fish are discussed under Dams and reservoirs on page 23.

Vascular plants

Aboriginal peoples report many local changes in vegetation, for example:

  • Anaktalak Bay area of Nunutsiavut (south of Nain), 2007: an increase in the growth and abundance of some plants, such as berries, that are good for food.Footnote 85
  • Wemindji, James Bay, 2005: terrestrial vegetation is replacing aquatic vegetation, and willows and other shrubs cover previously bare ground. Both changes have impacts on geese. In areas that previously grew berries, trees now grow.Footnote 57
  • Near Great Slave Lake, 2002: pin cherries, trees that commonly grow on disturbed ground, appeared after a new road was built.Footnote 99

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Major range shifts in species native to Canada

Range extensions to the Taiga Shield ecozone+ from ecozones+ to the south have been noted in some areas since the 1960s. Newly arrived species include: white-tailed deer in the NWTFootnote141 and Alberta,Footnote142 coyote (Canis latrans) in the NWTFootnote143 and Labrador, Footnote144 wood bison (Bison bison athabascae),Footnote143 and magpies (Pica pica).Footnote145

Several range shifts have been directly associated with human activities.143 White-tailed deer, coyote, and wood bison likely followed the Yellowknife highway corridor northward into the Taiga Shield.Footnote146 Elders report that when bison populations were high in the Slave River Lowlands (Taiga Plains ecozone+), there was some westward spillover into the Taiga Shield, but because habitat patches were small, the animals would not stay.146 Some species, such as coyote and magpie rarely venture beyond the Yellowknife city limits.Footnote145, Footnote146 Climate change is expected to make larger areas more hospitable to new arrivals and these and other species may spread further.Footnote 147 Footnote 148

Photo: James Sangris with a white-tailed deer doe harvested at Wool Bay, Great Slave Lake, western
Photo: James Sangris with a white-tailed deer
Taiga Shield, October 2007. © GNWT-D. Cluff

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Range changes are often noticed first by local residents and hunters and observations of unusual animal sightings are an important way to track species distribution changes.Footnote142 Some examples of range change information based on local knowledge: Range expansion or vagrancies from the north into the western Taiga Shield have been noted for grizzly bear (Ursus arctos) and muskoxen (Ovibos moschatus).Footnote142, Footnote145 The Dene First Nation reported an increase in moose and bears along the tree line in the Artillery Lake area.Footnote140 Along the Labrador coast Inuit have observed moose (around Anaktalak Bay) and consider that they are moving northward because of climate change.Footnote 85 The communities of eastern James Bay have observed a decrease in moose and moose habitat and a decline in moose body condition.Footnote 86 Footnote 149

Primary productivity

Key finding 18
Theme Habitat, wildlife, and ecosystem processes

National key finding
Primary productivity has increased on more than 20% of the vegetated land area of Canada over the past 20 years, as well as in some freshwater systems. The magnitude and timing of primary productivity are changing throughout the marine system.

This section is based on analyses and interpretations in Monitoring biodiversity remotely: a selection of trends measured from satellite observations of Canada.Footnote 16 Additional material has been added on the relationship between primary productivity and forest fires.

Over 36% of the land area of the Taiga Shield ecozone+ showed a significant increase in NDVI (an index related to primary productivity, derived from remote sensing) from 1986-2006 (Figure 36). Less than 1% of the land showed a decreasing trend. The increase in this ecozone+, one of the highest in Canada,Footnote 16 was strongest in the east, especially south of Ungava Bay (an area dominated by tundra vegetation), and also in southern Labrador (conifer forest and shrubland). The NDVI in the area between these two "hotspots" also exhibited a positive but less pronounced trend. NDVI increased in large parts of the northern portion of the western Taiga Shield. This area, characterized by the most productive soil in the western Taiga Shield,Footnote 22 is predominantly covered with conifer forests, but shrub and tundra vegetation are also well represented.

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Figure 36: Trend in Normalized Difference Vegetation Index (NDVI), Taiga Shield ecozone+, 1985-2006
Trends are in annual peak NDVI, measured as the average of the 3 highest values from 10-day composite images taken during July and August of each year. Spatial resolution is 1 km, averaged to 3 km for analysis. Only points with statistically significant changes (p<0.05) are shown.
Map
Source: NDVI trend analysis by Pouliot et al., 2009;Footnote150 ecozone+ analysis by Ahern et al., 2011Footnote 16
Long description for Figure 36

This map presents significant differences in annual peak Normalized Difference Vegetation Index (NDVI) for the eastern and western parts of the Taiga Shield Ecozone+. These data are presented as units of area that have increased or decreased in NDVI between 1985 and 2006. Across the ecozone+, 36% of the land area experienced a significant increase in NDVI, and more of the land area experiencing increases was in the eastern Taiga Shield. Increased NDVI in the western Taiga Shield was more prevalent in the northwest part of the ecozone+, and the large majority of land with decreased NDVI (<1% of total area) were in the western part of the ecozone+.

Pouliot et al. (2009)Footnote150 found that burns can have positive, negative, and zero NDVI trends, depending on the age of the burn. For example, an analysis of burned and unburned sites in the boreal forest of central CanadaFootnote151 found significant increases in NDVI at all sites with fires since 1984 and at 50% of unburned sites. Fire cannot, however, account for all the substantive increase in NDVI in the Taiga Shield – a comparison of the NDVI trend map with the map of large fires since the 1980s (Figure 37) shows that the main areas of increased NDVI are not areas that have recently burned. The areas in the western Taiga Shield showing negative NDVI trends may be recently burned black spruce-lichen woodland occupying poor soils. On better soils, lichen does not compete well with vascular understory plants. After fire in spruce-lichen woodland, soil surfaces may remain blackened for many years as black spruce and lichen are very slow to recover.Footnote 145 Footnote 146

Figure 37: Locations of large fires by decade, 1980s to 2000s
Map
Source: Krezek-Hanes et al., 2011Footnote 8
Long description for Figure 37

This map shows the locations of fires in the Taiga Shield Ecozone+, by decade. The eastern part of the Taiga shield experienced large burns in the 1980s in the area near James Bay, and fewer fires in later decades. In the western Taiga Shield, the fires were prevalent in the 1980s and 1990s, and concentrated in the central-southern part of the ecozone+. Fires in the 2000s are distributed more sparsely across the ecozone+.

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Natural disturbance

Key finding 19
Theme: Habitat, wildlife, and ecosystem processes

National key finding
The dynamics of natural disturbance regimes, such as fire and native insect outbreaks, are changing and this is reshaping the landscape. The direction and degree of change vary.

Fire, weather extremes, and diseases shape and modify the flora and fauna of the Taiga Shield Ecozone+. Disturbances such as forest fires tend to be small and frequent or large and rare, and so the calculation of trends of disturbances requires longer temporal datasets. Other than data on forest fires, relatively little specific information has been compiled for the Taiga Shield.

Fire trends

This section is based on analyses and interpretations in Trends in large fires in Canada, 1959-2007.Footnote 8 and Monitoring biodiversity remotely: a selection of trends measured from satellite observations of Canada.Footnote 16

The fire regime in the Taiga Shield is characterized by large, severe fires.Footnote 152 Footnote 153 Footnote 154 Trees and other plants in the Taiga Shield evolved in a fire environment and a changing fire regime will impact the distribution of species and plant communities. For example, fire plays a stronger role than climate in determining the northern limit of jack pine (Pinus banksiana).Footnote155

The area burned in the Taiga Shield (Figure 38) increased from the 1960s until the 1990s, a trend attributed to changes in detection methods and warmer temperatures.Footnote 156 Footnote 157 The decline since the 1990s is similar to the pattern shown for the Taiga Plains ecozone+, and the magnitude of the decline is the same as changes between previous decades. The decline may be related to large atmospheric oscillations.Footnote 8

Figure 38: Trend in total area burned per decade in the Taiga Shield ecozone+, 1960s-2000s
The value for the 2000s decade was pro-rated over 10 years based on the 2000-2007 average.
Graph
Source: Krezek-Hanes et al., 2011Footnote 8
Long description for Figure 38

This bar graph illustrates the following information:

DecadeTotal area burned (km2)
1960s6,003
1970s36,338
1980s46,575
1990s69,305
2000s34,283

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The average duration of the active fire season, about 75 days, has not changed significantly over the period of record (Figure 39).Footnote 8 Fires occur most commonly between June and August, peaking in July, but there was a significant increase in May fires from the 1960s to the 1990s. Few May fires were recorded, however, and the record is relatively short. There are no comparable records, for example, for fires in the warm, dry decade of the 1940s, which may have experienced fires in May. Fires in the eastern portion of the Taiga Shield generally occurred earlier than fires in the west.Footnote158

Figure 39: The proportion of large fires that occur in each month of the fire season by decade.
This fire trend is based on the number of large fires (over 200 ha in size). Monthly numbers are the percentage of the total number of fires that occurred during the month.
clustered bar chart
Source: Krezek-Hanes et al., 2011Footnote8
Long description for Figure 39

This clustered bar chart shows the following information:

DecadePercent
May
Percent
June
Percent
July
Percent
August
Percent
September
Days
Average Duration
1960s0355411147
1970s1285713185
1980s2185227284
1990s2323926191

Lightning causes, on average, 92% of large fires in the Taiga Shield. The proportion of fires caused by lightning has increased over the last 40 years due to a decrease in human-caused fires. The absolute number of fires caused by lightning also increased over the same time period, although this increase was not statistically significant.Footnote 8

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Insect outbreaks

There is little information on insect outbreaks specific to the Taiga Shield. In the eastern Taiga Shield, insect disturbance seems to play a less important role than in the drier northwestern part of the continent.Footnote159

The spruce bark beetle (Dendroctonus rufipennis), the main pest affecting white spruce at the north of its distribution, appears to occur sporadically in the eastern Taiga Shield. A large section of lowland forest along Napaktok Bay, Labrador experienced severe tree mortality from 1989 to 1991, likely caused by an outbreak of spruce bark beetles.Footnote 27 Tree-ring analyses in the Kuujjuarapik region of James Bay found low levels of spruce bark beetle activity, but without regional outbreaks, extending back about 400 years (the age of the trees).Footnote159 At one of the three study sites, an outbreak resulted in extensive tree mortality in the late 20th century.

Outbreaks of the spruce bark beetle may become more significant in the Taiga Shield in the future as summer and winter temperatures increase. Outbreaks are normally associated with forest disturbances such as windthrow, fire, or land clearing. A severe, recent outbreak in the Boreal Cordillera ecozone+, however has been attributed to an increase in drying out of spruce trees in the summer (making the trees more vulnerable to bark beetle attack) and to increased beetle reproductive success in the warmer summers along with decreased beetle mortality in the milder winters.Footnote160

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Food webs

Key finding 20
Theme: Habitat, wildlife, and ecosystem processes

National key finding
Fundamental changes in relationships among species have been observed in marine, freshwater, and terrestrial environments. The loss or reduction of important components of food webs has greatly altered some ecosystems.

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Population cycles

Detecting changes in ecosystems dominated by seasonality and climate variability generally requires long-term monitoring, which is rare in this ecozone+. The low level of species diversity means that both predators and herbivores are vulnerable to fluctuations in the abundance of their food supplies, accentuating the natural pulses in the ecosystem. Most mammals in the Taiga Shield have cyclic dynamics. The principal exceptions are large-bodied mammals, such as moose and muskoxen. The latter are at the edge of their range in the Taiga Shield, but are increasing in the ecozone+.Footnote145

Variations in high densities of snowshoe hare populations have been linked with variations in fire frequencies across their range in North America. Fires create abundant early succession plants that are eaten by hares in winter.Footnote161 The highest densities of snowshoe hares in peak years have been measured where fire frequencies are the highest, including in the western Taiga shield.Footnote162

An increasing body of evidence identifies climate variables, especially snow and winter temperatures, as drivers in cyclic dynamics. For example, a decreasing amplitude of cyclic dynamics and collapse of cycles are reported for voles, grouse, and the larch budmoth (Zeiraphera diniana) in northern Fennoscandia, coinciding with climatic change.Footnote163 The variability in the amplitude of small mammal cycles in the Taiga Shield (Figure 40), however, means that detecting trends requires a longer series of data than is currently available.

Figure 40: Snowshoe hare density at three sites in the western Taiga Shield, 1988-2008
Data were missing for 1997 and 1998; according to local knowledge numbers were increasing rapidly during these years.
Graph
Source: Data provided by S. Carrière, Government of the Northwest Territories. Photo © iStock.com
Long description for Figure 40

This line graph shows the estimated density of snowshoe hares in the Taiga shield in the Northwest Territories between 1988 and 2008. Density at the Yellowknife and Yukon River is variable, and experienced a low of <1 hare/ha in 1994, but was very high (>5 hares/ha) in 1999 (data were not available for 1997-98). A major drop in hare density occurred between 1999 and 2003, with a trend for gradual increase into the late 2000s. The Gordon Lake and Tibbitt Lake sites were less variable, with fairly consistent levels of <1 hare/ha, though these data were only available from 2000 to 2008.

Migratory species

The Taiga Shield ecozone+ has a high proportion of migratory species. Most species that glean insects from foliage or hunt on the wing, including bats, migrate to southern ecozones+ in winter. Twenty-nine bird species use the boreal forest as a stopover during migration.Footnote164 The Taiga Shield is also the seasonal destination for migrants from more northern ecozones+, from ptarmigan (Lagopus sp.) to barren ground caribou.

There is much uncertainty about the implications and cascades of effects related to changes in population dynamics of migratory species. For example, many species of migratory insectivorous birds are declining, some due to changes in their winter ranges. How these declines are linked to the population dynamics of their insect prey and how they might influence insect outbreaks and tree health in the Taiga Shield are unknown, though these chains of effects have been demonstrated in other regions.Footnote 165 Footnote 166

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Footnotes

Footnote 3

Federal, Provincial and Territorial Governments of Canada. 2010. Canadian biodiversity: ecosystem status and trends 2010. Canadian Councils of Resource Ministers. Ottawa, ON. vi + 142 p.

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Reference 8

Krezek-Hanes, C.C., Ahern, F., Cantin, A. and Flannigan, M.D. 2011. Trends in large fires in Canada, 1959-2007. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 6. Canadian Councils of Resource Ministers. Ottawa, ON. v + 48 p.

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Reference 10

Fast, M., Collins, B. and Gendron, M. 2011. Trends in breeding waterfowl in Canada. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 8. Canadian Councils of Resource Ministers. Ottawa, ON. v + 37 p.

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Reference 12

Gunn, A., Russell, D. and Eamer, J. 2011. Northern caribou population trends in Canada. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 10. Canadian Councils of Resource Ministers. Ottawa, ON. iv + 71 p.

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Reference 13

Callaghan, C., Virc, S. and Duffe, J. 2011. Woodland caribou, boreal population, trends in Canada. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 11. Canadian Councils of Resource Ministers. Ottawa, ON. iv + 36 p.

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Reference 14

Downes, C., Blancher, P. and Collins, B. 2011. Landbird trends in Canada, 1968-2006. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 12. Canadian Councils of Resource Ministers. Ottawa, ON. x + 94 p.

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Reference 16

Ahern, F., Frisk, J., Latifovic, R. and Pouliot, D. 2011. Monitoring ecosystems remotely: a selection of trends measured from satellite observations of Canada. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 17. Canadian Councils of Resource Ministers. Ottawa, ON.

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Footnote 22

Timoney, K.P. 1995. Tree and tundra cover anomalies in the Subarctic forest-tundra of northwestern Canada. Arctic48:13-21.

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Footnote 27

Payette, S. 2007. Contrasted dynamics of northern Labrador tree lines caused by climate change and migrational lag. Ecology88:770-780.

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Footnote 54

Lutsel K'e Dene First Nation, Parlee, B., Basil, M. and Casaway, N. 2001. Final report: Traditional Ecological Knowledge in the Kaché Tué study region. Lutsel K'e Dene First Nation. 87 p.

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Footnote 57

Bussières, V. 2005. Towards a culturally-appropriate locally-managed protected area for the James Bay Cree community of Wemindji, northern Québec. Thesis (Master of Public Policy and Public Administration). Concordia University, Department of Geography, Planning and Environment. Montréal, QC. 125 p.

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Footnote 84

Lutsel K'e Dene Community Members, Krieger, M., Catholique, H., Drygeese, D., Casaway, N., Lantz, A., Desjarlais, P., Boucher, E., Michel, P., Catholique, S., Lockhart, J. and Catholique, L. 2005. Ni hat'ni - watching the land: results of 2003-2005 monitoring activities in the traditional territory of the Lutsel K'e Denesoline - final report. Lutsel K'e Dene First Nation. 109 p.

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Footnote 85

Davies, H. 2007. Inuit observations of environmental change and effects of change in Anaktalak Bay, Labrador. Thesis (Master of Environmental Studies). Queen's University, School of Environmental Studies. Kingston, ON. 156 p.

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Footnote 86

McDonald, M., Arragutainaq, L. and Novalinga, Z. (compilers). 1997. Voices from the bay: Traditional Ecological Knowledge of Inuit and Cree in the Hudson Bay bioregion. Canadian Arctic Resources Committee and Environmental Committee of the Municipality of Sanikiluaq. Ottawa, ON. xiii + 98 p.

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Footnote 88

Municipality of Sanikiluaq and Nunavuummi Tasiujarjuamiuguqatigiit Katutjiqatigiingit (NTK). 2008. Community Environmental Monitoring Systems (CEMS) workshop summary report, January 17, 2008-January 21, 2008. Update of Voices from the Bay. Municipality of Sanikiluaq. Sanikiluaq, NU. 41 p.

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Lutsel K'e Dene Elders, Ellis, S., Catholique, B., Desjarlais, S., Catholique, B., Catholique, H., Basil, M., Casaway, N., Catholique, S. and Lockhart, J. 2002. Traditional knowledge in the Kache Tué study region: phase three - towards a comprehensive environmental monitoring program in the Kakinÿne region - final report. Lutsel K'e Dene First Nation. 86 p.

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Footnote 109

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Payette, S., Boudreau, S., Morneau, C. and Pitre, N. 2004. Long-term interactions between migratory caribou, wildfires and Nunavik hunters inferred from tree rings. Ambio 33:482-486.

Footnote 110

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Zalatan, R., Gunn, A. and Henry, G.H.R. 2006. Long-term abundance patterns of barren-ground caribou using trampling scars on roots of Picea mariana in the Northwest Territories, Canada. Arctic, Antarctic, and Alpine Research 38:624-630.

Footnote 111

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Environment and Natural Resources. 2014. Bluenose East Herd [en ligne]. Government of Northwest Territories. (consulté le 5 Jan. 2014).

Footnote 112

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Campbell, M. 2008. Personal communication. Department of Environment, Government of Nunavut.

Footnote 113

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COSEWIC. 2002. COSEWIC assessment and update status report on the woodland caribou Rangifer tarandus caribou in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, ON. xi + 98 p.

Footnote 114

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Environment Canada. 2011. Scientific assessment to inform the identification of critical habitat for woodland caribou (Rangifer tarandus caribou), boreal population, in Canada: 2011 update. Environment Canada. Ottawa, ON. xiv + 103 p.

Footnote 115

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Environment Canada. 2012. Recovery strategy for the woodland caribou (Rangifer tarandus caribou), boreal population, in Canada. Species at Risk Act Recover Strategy Series. Environment Canada. Ottawa, ON. xi + 138 p.

Footnote 122

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Rettie, W.J. and Messier, F. 1998. Dynamics of woodland caribou populations at the southern limit of their range in Saskatchewan. Canadian Journal of Zoology 76:251-259.

Footnote 124

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Racey, G.D. and Armstrong, T. 2000. Woodland caribou range occupancy in northwestern Ontario: past and present. Rangifer 12:173-184.

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Vors, L.S., Schaefer, J.A., Pond, B.A., Rodgers, A.R. and Patterson, B.R. 2007. Woodland caribou extirpation and anthropogenic landscape disturbance in Ontario. Journal of Wildlife Management 71:1249-1256.

Footnote 128

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Whittington, J., Hebblewhite, M., DeCesare, N.J., Neufeld, L., Bradley, M., Wilmshurst, J. and Musiani, M. 2011. Caribou encounters with wolves increase near roads and trails: a time-to-event approach. Journal of Applied Ecology 48:1535-1542.

Footnote 131

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Bergerud, A.T. 1985. Antipredator strategies of caribou: dispersion along shorelines. Canadian Journal of Zoology 63:1324-1329.

Footnote 132

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Schmelzer, I., Brazil, J., Chubbs, T., French, S., Hearn, B., Jeffery, R., LeDrew, L., Martin, H., McNeill, A., Nuna, R., Otto, R., Phillips, F., Mitchell, G., Pittman, G., Simon, N. and Yetman, G. 2004. Recovery strategy for three woodland caribou herds (Rangifer tarandus caribou; boreal population) in Labrador. Department of Environment and Conservation, Government of Newfoundland and Labrador. Corner Brook, NL. 51 p.

Footnote 133

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Austin, J.E., Custer, C.M. and Afton, A.D. 1998. Lesser scaup (Aythya affinis). In The birds of North America online. Edited by Poole, A. Cornell Lab of Ornithology. Ithaca, NY. http://bna.birds.cornell.edu/bna/species/338.

Footnote 134

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Mowbray, T.B. 1999. American wigeon (Anas americana). In The birds of North America online. Edited by Poole, A. Cornell Lab of Ornithology. Ithaca, NY. http://bna.birds.cornell.edu/bna/species/401.

Footnote 135

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Brown, P.W. and Fredrickson, L.H. 1997. White-winged scoter (Melanitta fusca). In The birds of North America online. Edited by Poole, A. Cornell Lab of Ornithology. Ithaca, NY. http://bna.birds.cornell.edu/bna/species/274.

Footnote 136

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De Vink, J.M.A., Clark, R.G., Slattery, S.M. and Trauger, D.L. 2008. Are late-spring boreal lesser scaup (Aythya affinis) in poor body condition? Auk 125:297-298.

Footnote 137

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Breeding Bird Survey. 2008. North American Breeding Bird Survey [online]. U.S. Geological Survey, Patuxent Wildlife Research Center. http://www.pwrc.usgs.gov/bbs (accessed 23 October, 2009).

Footnote 138

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Machtans, C.S., Van Wilgenburg, S.L., Armer, L.A. and Hobson, K.A. 2007. Retrospective comparison of the occurrence and abundance of rusty blackbird in the Mackenzie Valley, Northwest Territories. Avian Conservation and Ecology/Écologie et conservation des oiseaux 2:1-14.

Footnote 139

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Cobb, D., Berkes, M.K. and Berkes, F. 2005. Ecosystem-based management and marine environmental quality in northern Canada. In Breaking ice: renewable resource and ocean management in the Canadian North. Edited by Berkes, F., Huebert, R., Fast, H., Manseau, M. and Diduck, A. University of Calgary Press. Calgary, AB. pp. 71-93.

Footnote 140

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Parlee, B., Manseau, M. and Lutsel K'e Dene First Nation. 2005. Understanding and communicating about ecological change: Denesoline indicators of ecosystem health. In Breaking ice: renewable resource and ocean management in the Canadian North. Edited by Berkes, F., Huebert, R., Fast, H., Manseau, M. and Diduck, A. University of Calgary Press. Calgary, AB. pp. 165-182.

Footnote 141

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Veitch, A.M. 2001. An unusual record of a white-tailed deer (Odocoileus virginianus) in the Northwest Territories. Canadian Field-Naturalist 15:172-175.

Footnote 142

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Latham, A.D.M., Latham, M.C., Nicole, A.M. and Boutin, S. 2011. Invading white-tailed deer change wolf-caribou dynamics in northeastern Alberta. Journal of Wildlife Management 75:204-212.

Footnote 143

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Hansell, R.I.C., Chant, D.A. and Weintrau, J. 1971. Changes in the northern limit of spruce at Dubawnt Lake, Northwest Territories. Arctic 24:233-234.

Footnote 144

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Chubbs, T.E. and Phillips, F.R. 2005. Evidence of range expansion of eastern coyotes, Canis latrans, in Labrador. Canadian Field-Naturalist 119:381-384.

Footnote 145

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Ecosystem Classification Group. 2008. Ecological regions of the Northwest Territories: Taiga Shield. Northwest Territories Department of Environment and Natural Resources. Yellowknife, NT. viii + 146 p.

Footnote 146

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Chowns, T.J. 2012. Personal communication. Written submission in review of the draft report.

Footnote 147

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Environment and Natural Resources. 2012. State of the Environment Report, Indicator 15.5. Change in wildlife distribution. [online]. Government of the Northwest Territories. (accessed January, 2013).

Footnote 148

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Environment and Natural Resources. 2008. NWT climate change impacts and adaptation report. Government of Northwest Territories. Yellowknife. 31 p.

Footnote 149

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Huntington, H.P., Fox, S., Berkes, F. and Krupnik, I. 2005. The changing Arctic: indigenous perspectives. In Arctic Climate Impact Assessment. Edited by Symon, C., Arris, L. and Heal, B. Cambridge University Press. New York, NY. Chapter 3. pp. 61-98.

Footnote 150

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Pouliot, D., Latifovic, R. and Olthof, I. 2009. Trends in vegetation NDVI from 1 km Advanced Very High Resolution Radiometer (AVHRR) data over Canada for the period 1985-2006. International Journal of Remote Sensing 30:149-168.

Footnote 151

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Alcaraz-Segura, D., Chuvieco, E., Epstein, H.E., Kasischke, E.S. and Trishchenko, A. 2010. Debating the greening vs. browning of the North American boreal forest: differences between satellite datasets. Global Change Biology 16:760-770.

Footnote 152

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Burton, P.J., Parisien, M.-A., Hicke, J.A., Hall, R.J. and Freeburn, J.T. 2008. Large fires as agents of ecological diversity in the North American boreal forest. International Journal of Wildland Fire 17:754-767.

Footnote 153

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Parisien, M.A., Peters, V.S., Wang, Y., Little, J.M., Bosch, E.M. and Stocks, B.J. 2006. Spatial patterns of forest fires in Canada, 1980-1999. International Journal of Wildland Fire 15:361-374.

Footnote 154

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Stocks, B.J., Mason, J.A., Todd, J.B., Bosch, E.M., Wotton, B.M., Amiro, B.D., Flannigan, M.D., Hirsch, K.G., Logan, K.A., Martell, D.L. and Skinner, W.R. 2003. Large forest fires in Canada, 1959-1997. Journal of Geophysical Research 108:8149-8161.

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Asselin, H., Payette, S., Fortin, M.-J. and Vallée, S. 2003. The northern limit of Pinus banksiana Lamb. in Canada: explaining the difference between eastern and western distributions. Journal of Biogeography 30:1709-1718.

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Gillett, N.P., Weaver, A.J., Zwiers, F.W. and Flannigan, M.D. 2004. Detecting the effect of climate change on Canadian forest fires. Geophysical Research Letters 31:L18211-.

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Podur, J., Martell, D.L. and Knight, K. 2002. Statistical quality control analysis of forest fire activity in Canada. Canadian Journal of Forest Research/Revue canadienne de recherche forestière 32:195-205.

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Kasischke, E.S. and Turetsky, M.R. 2006. Recent changes in the fire regime across the North American boreal region - spatial and temporal patterns of burning across Canada and Alaska. Geophysical Research Letters 33:1-5.

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Caccianiga, M., Payette, S. and Filion, L. 2008. Biotic disturbance in expanding Subarctic forests along the eastern coast of Hudson Bay. New Phytologist 178:823-834.

Footnote 160

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Forest Managment Branch. 2010 Forest health report. Government of Yukon, Energy, Mines and Resources.

Footnote 161

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Ferron, J. and St-Laurent, M.-H. 2008. Forest-fire regime: the missing link to understand snowshoe hare population fluctuations? In Lagomorph biology: evolution, ecology, and conservation. Edited by Alves, P.C., Ferrand, N. and Hacklander, K. Springer-Verlag. Berlin and Heidelberg, Germany. pp. 141-152.

Footnote 162

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Bryant, J.P., Clausen, T.P., Swihart, R.K., Landhäusser, S.M., Stevens, M.T., Hawkins, C.D.B., Carrière, S., Kirilenko, A.P., Veitch, A.M., Popko, R.A., Cleland, D.T., Williams, J.H., Jakubas, W.J., Carlson, M.R., Bodony, K.L., Cebrian, M., Paragi, T.F., Picone, P.M., Moore, J.E., Packee, E.C. and Malone, T. Fire drives transcontinental variation in tree birch defense against browsing by snowshoe hares. American Naturalist 174:13-23.

Footnote 163

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Ims, R.A., Henden, J.A. and Killengreen, S.T. 2008. Collapsing population cycles. Trends in Ecology & Evolution 23:79-86.

Footnote 164

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Blancher, P. and Wells, J. 2005. The boreal forest region: North America's bird nursery. Canadian Boreal Initiative and Boreal Songbird Initiative. Ottawa, ON and Seattle, WA. 9 p. + appendix.