Skip booklet index and go to page content

Atlantic Maritime Ecozone evidence for key findings summary

Theme: Habitat, wildlife, and ecosystem processes

Key finding 16
Agricultural landscapes as habitat

Theme Habitat, wildlife, and ecosystem processes

National key finding
The potential capacity of agricultural landscapes to support wildlife in Canada has declined over the past 20 years, largely due to the intensification of agriculture and the loss of natural and semi-natural land cover.

Although some biodiversity is lost when land is converted to agriculture, agricultural lands still contribute significant biodiversity values as the varied habitats on agricultural landscapes provide some or all of the requirements for many wildlife species.Footnote183

Agricultural landsFootnotevi comprised close to 10% of the AME in 2006 and were characterized generally by small-scale farming. With the exception of a few areas of higher production (e.g., PEI, Annapolis–Minas Lowlands, Saint John River Valley), agricultural land made up a relatively small component of the broader landscape (Figure 40).Footnote184 Most agricultural areas were made up of a diversity of cover types that included a considerable amount of natural and semi-natural land. The relatively light agricultural footprint along with the presence of abundant, high-value habitat on agricultural land means that the influence of agriculture on habitat is much less here than in the major Canadian agricultural ecozones+.

Figure 40. Percentage of land defined as agricultural in the Atlantic Maritime ecozone+, 2006. Soil Landscapes of Canada polygons were the base unit used for this analysis.

map

Long Description for Figure 40

This heat map shows the percentage of land defined as agricultural in the Atlantic Maritme Ecozone+ for the year 2006. Overall, agricultural land made up a relatively small component of the broader landscape in 2006, comprising 10 percent or less in most areas. Higher percentages of agricultural land were found in the southern Quebec portion of the ecozone+ as well as on Prince Edward Island.

Soil Landscapes of Canada polygons were the base unit used for this analysis.
Source: Javorek and Grant, 2011184

From 1986 to 2006, the total agricultural land shrank by about 6% (from 22,000 to 20,800 km2). The share of “All Other Land” declined from approximately 49 to 47% of the total agricultural landscape. Tame Hay, the second most abundant cover type, expanded its share from 21 to 26%, while both Improved Pasture (9 to 5%) and Unimproved Pasture (9 to 6%) declined. The share of Other Crops expanded from 2 to 3%, mainly due to increased potato production on Prince Edward Island and in the Saint John River Valley (Figure 41).184

Figure 41. Total agriculture area, the amount of land per cover type (bar chart), and the relative percentage of each cover type (table) for the Atlantic Maritime ecozone+ in 1986, 1996, and 2006.

graph

Long Description for Figure 41

This figure is a stacked bar graph showing the following information:

Data for figure 41.
TypeAgricultural land
(hectares) - 1986
Agricultural land
(hectares) - 1996
Agricultural land
(hectares) - 2006
Oilseeds1037192,265
Pulses154185161
Soybeans2,2554,44714,017
Berries11,78423,64120,865
Improved Pasture196,264130,244108,401
All Other Land1,072,0791,063,783979,019
Summerfallow18,5433,2942,976
Unimproved Pasture194,269204,362127,699
Cereals162,100171,670167,272
Corn17,95420,37243,646
Tame Hay456,701489,075533,195
Other Crops51,57369,88667,282
Fruit Trees6,1654,9264,158
Vegetables8,7408,5035,547
Winter Cereals6,2926,1407,646

Source: Javorek and Grant, 2011184

Wildlife habitat capacity on agricultural land

A total of 292 species (215 birds, 52 mammals, 9 reptiles, and 16 amphibians) potentially use this agricultural landscape, with 88% associated with wetland, riparian, shelterbelts, woodland, old field, and idle land (All Other Land category). The All Other Land category was the dominant land cover type making up close to half of the total agricultural land base. The capacity of agricultural landscapes to provide habitat for wildlife was calculated for the years 1986, 2001, and 2006 using a model that ranked land cover types based on potential uses (e.g., breeding and reproduction, migration, wintering) and value (primary, secondary, or tertiary) for different species into ten categories (see legend in Figure 42).184 In 2006, average wildlife habitat capacity on agricultural land was rated as high despite a significant decline since 1986 (Figure 42). Between 1986 and 2006, habitat capacity decreased on 43% of agricultural land, increased on 28%, and was constant on 29% (Figure 43). Declining habitat capacity trends were associated with a number of areas reporting more intense agricultural activity. The significant decline resulted from a general expansion of the comparatively low habitat Cropland (32 to 36%) and a decline of cover types with higher value to wildlife.184 Despite this decline, average wildlife habitat capacity in the AME remained high.

Figure 42. The share of agricultural land in each habitat capacity category (left axis, stacked bars) and the average habitat capacity (right axis, points and line) for the Atlantic Maritime ecozone+ in 1986, 1996, and 2006.

graph

Long Description for Figure 42

This stacked percentage bar graph shows the following information:

Habitat capacity Categories

Very high 90->100
High  70-90
Moderate 50-70
Low 30-50
Very low  <20-30

Data for figure 42.
Scale198619962006
<200.000.000.00
20-300.000.000.00
30-400.022.402.98
40-503.904.114.78
50-606.219.3510.21
60-707.8310.089.50
70-8013.5311.5314.43
80-9033.9123.3528.88
90-10019.3722.7816.59
>10015.2216.4112.63

The average habitat capacity for the Atlantic Maritime Ecozone+  was 94.17 in 1986, 93.17 in 1996 and 88.75 in 2006.

Years with different letters indicate a statistically significant difference.
Source: Javorek and Grant, 2011184

Figure 43. Change in wildlife habitat capacity on agricultural lands in the Atlantic Maritime ecozone+, 1986–2006.

map

Long Description for Figure 43

This map shows the change in the wildlife capacity of agricultural lands in the Atlantic Maritime Ecozone+ between 1986 and 2006. Agricultural land in the ecozone+ is mapped and coloured by area to depict habitat capacity change that is either: constant, decreasing, increasing or not reported in the time frame. Between 1986 and 2006, habitat capacity decreased on 43% of agricultural land, increased on 28%, and was constant on 29%.

All Soil Landscapes of Canada (SLC) polygons with >5% agricultural land were included in the analysis.
Source: Javorek and Grant, 2011184

Soil erosion on cropland

Occupying only 4% of the total land area, croplandFootnotevii in the AME has some of the highest erosion risk on agricultural land in Canada due to intensive tillage and a climate that poses a high threat of water erosion of unprotected soils in some areas.Footnote185 However, the risk of soil erosion declined in the AME from 1981 to 2006. McConkey et al. 185 found that 36% of the cropland was classified as having unsustainable erosion risk in 2006 (Figure 44), down from 41% in 1981. In 2006, 18% of agricultural land was at moderate to very high erosion risk compared to 20% in 1981.

Figure 44. Soil erosion risk classes for cropland in the Atlantic Maritime ecozone+, 2006.

map

Long Description for Figure 44

This map shows the classification of erosion risk for cropland in the Atlantic Maritime Ecozone+ for the year 2006. The categories are: Very Low (<6 t/ha/yr), Low 6-11 t/ha/yr), Moderate (11-22 t/ha/yr), High (22-33 t/ha/yr), and Very High ( >33 t/ha/yr).  The map shows that 36% of cropland in the ecozone+ has an unsustainable soil erosion risk. The largest area of moderate erosion risk is on the east shore of the St. Lawrence River and the area of highest erosion risk, in the Very High risk class, is on the central-west coast of Nova Scotia.

All Soil Landscape of Canada polygons containing >5% cropland were included in the analysis and entire polygons are shown on the map.
Source: McConkey et al., 2011185

Birds of grassland and other open habitats

Grassland birds, which include birds of some agricultural habitats such as hayfield, pastures and rangeland, and birds of other open habitats, which include agricultural lands not included in the grassland category and abandoned fields, have declined significantly (Figure 45). Vesper sparrow (Pooecetes gramineus), bobolink (Dolichonyx oryzivorus), and eastern meadowlark (Sturnella magna) populations declined by over 75% since the 1970s. Many aerial-foraging insectivores, included in the other open habitat category, declined as a group.42

Figure 45. Annual indices of population change in bird assemblages for grassland habitat (left) and other open habitats (right) in the Atlantic Maritime ecozone+, 1968–2006.

graph

Long Description for Figure 45

This figure has two line graphs depicting the following information:

Data for figure 45.
Grassland habitat
- Year
Grassland habitat
- Abundance index
Open habitats
- Abundance index
196833.5762.54
196936.8375.42
197031.6761.82
197134.2977.33
197238.8172.89
197336.9073.50
197440.2468.19
197532.2643.36
197644.1357.94
197744.9558.10
197852.5776.85
197942.9257.88
198040.1869.19
198147.6770.59
198245.4969.63
198346.6970.50
198446.6860.24
198538.6873.05
198636.4469.72
198728.6664.01
198825.6164.96
198925.8058.44
199024.0249.85
199122.5646.08
199221.5540.85
199320.5537.35
199417.3334.16
199519.0331.83
199617.2833.86
199718.4433.52
199817.7727.76
199916.4427.93
200015.0728.96
200113.8625.95
200214.9421.97
200312.4520.81
200411.3521.03
200512.1717.17
200613.6019.20

Grassland habitats include native grasslands and some agricultural habitat such as hayfield, pastures and rangeland. Other open habitats include open country, including species of agricultural landscapes not considered in grassland. The index is an estimate of the average number of individual birds that would be counted on a randomly selected route by an average observer in a given year.

Source: Downes et al., 201142using data from the Breeding Bird Survey43

Top of Page

Key finding 17
Species of special economic, cultural, or ecological interest

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.

Species of particular interest within the AME include the Atlantic (Gaspésie) population of woodland caribou and Atlantic salmon. Some landbirds that use the AME have declined , in some cases due to pressures elsewhere in their migratory ranges.

In the past 150 to 200 years, some of the largest mammals were extirpated from the AME. including wolf (Canis lupus), cougar (Felis concolor), and wolverine (Gulo gulo).135 Woodland caribou (Rangifer tarandus caribou) has been reduced to a single endangered population. The wolf’s ecological niche has largely been filled by the coyote (Canis latrans), and that of the caribou has been filled to some degree by the white-tailed deer (Odocoileus virginianus). Beaver (Castor canadensis) were nearly extirpated 200 years ago due to overharvest, but have since recovered.

Woodland caribou

The Atlantic-Gaspésie population of the woodland caribou is an isolated relict population that formerly ranged more broadly in the AME. Prior to European settlement, woodland caribou were commonly found throughout much of Nova Scotia and New Brunswick and were present on PEI.Footnote186 Extirpation from these three provinces was well underway by the 1830s. Caribou were extirpated from Nova Scotia by 1912,Footnote187 New Brunswick by the 1930s,16 and from PEI much earlier. Efforts to re-establish caribou on their historic ranges in Nova Scotia failed because of fatal infections with Parelaphostrongylus tenuis, a brain worm carried by the more recently established white-tailed deer.Footnote188

The current population is found only in and adjacent to Gaspésie National Park of Quebec.Footnote189 It is at risk from predation and habitat loss, and its low numbers and restricted range make it susceptible to chance catastrophic events.186 Trend data from 1983 to 2006 show an overall decline over this period, with a low population size of less than 100 individuals in 1999 (Figure 46).189 In 2002, COSEWIC re-assessed the population and elevated its status from Threatened to Endangered; it is also listed on Schedule 1 of Canada’s Species at Risk Act.

Figure 46. Trend in the estimated numbers of the Gaspésie woodland caribou population, 1983–2006.

graph

Long Description for Figure 46

This bar graph shows following information:

Data for figure 46.
YearEstimated number
of caribou
1983273
1984253
1985123
1986251
1987249
1988216
1989134
1990213
1991181
1992149
1993147
1994130
1995119
1996179
1997176
1998137
199996
2000126
2001113
2002156
2003143
2004160
2005204
2006200

The trend line of the graph indicates that the overall population declined from 273 in 1983 to 200 in 2006, although there was year-to-year variability around this trend. The smallest population size was 96 individuals in 1999.

Source: Gaspésie Woodland Caribou Recovery Team, 2007189 Ministry of Energy and Natural Resources

Other ungulates

Other large herbivores in the AME include moose (Alces alces) and white-tailed deer. Nova Scotia mainland moose have declined by 20% to about 1,000 individuals since 1970 due to human intrusion into its habitat, hunting, climate change, and disease.Footnote190 White-tailed deer are a recent arrival to the Maritimes and  have been expanding. They have benefited from human modifications of the forested landscape, as well as extirpations or reductions of many of their predators.136

Atlantic salmon

Atlantic salmon are broadly distributed in rivers throughout the AME. Populations are sensitive to a number of environmental factors including predation, fishing, and the availability of breeding habitat.Footnote191 As was mentioned in the  section (page 52), Atlantic salmon are also highly sensitive to acidity, and a high percentage of fish habitat has been lost in the region due to acid rain, with many runs in coastal Nova Scotia either extinct or heavily impacted.175 Construction of dams has had an impact on salmon populations, and industrial and municipal effluents, as well as run-off from intensive agriculture, degrade water quality and reduce suitable breeding habitat for salmon. Invasive predators such as muskellunge (Esox masquinongy), smallmouth bass, and rainbow trout (Oncorhynchus mykiss) reduce juvenile salmon survival.

There is considerable variation in the status and trends in Atlantic salmon from one part of the AME to another.Footnote192 The Inner and Outer Bay of Fundy populations of Atlantic salmon were designated as Endangered by COSEWIC in 2001 and 2010, respectively.Footnote193 All survey data from the inner Bay of Fundy indicate that river-specific populations have suffered extreme declines since the 1970s and this population faces extinction. Estimates of declines are as high as 99% over 11 years (three generations) and greater than 99.6 % over 30 years.193 In 2003, fewer than 100 adults were estimated to have returned to the 32 rivers known to have contained salmon.193 Historically, as many as 40,000 salmon likely returned to these rivers.193 Although there is some uncertainty , it appears that offshore mortality of adult salmon is the primary threat to the Inner Bay of Fundy population.193

Of 37 salmon rivers in the AME (18 in the Maritime provinces and 19 in Quebec) the five-year average population size increased in only three rivers, all on Cape Breton Island, from 1987 to 2005 (Figure 47).192. Abundance declined in all other rivers, with declines of over 95% in four rivers in the inner Bay of Fundy and a 99.8% decline in the St. Croix River in the outer Bay of Fundy. Trends in abundance vary throughout rivers in Quebec, though populations generally increased and declined in only two rivers.

The Miramichi River produces at least 20% of North American Atlantic salmon and more wild Atlantic salmon than any other North American river. The salmon in the Miramichi and Restigouche rivers are extremely important to overall Atlantic salmon populations because these two rivers contribute a disproportionate number of spawning fish to populations of maiden salmon that return to spawn in the rivers after spending two years at sea. Atlantic salmon abundance has declined in both rivers from 1987 to 2005 (Figure 47), although populations have shown some recovery since 2000.192

Figure 47. Changes in abundance of salmon populations for the Maritime provinces (top) and Quebec (bottom), 1987–2005.

graph

Long Description for Figure 47

This figure shows two graphs which depict the change in abundance of salmon populations in rivers in the Maritime Provinces and Quebec.  

Of the 18 salmon rivers in the Maritime provinces, the five-year average population size increased in only three rivers (Margaree, Baddeck and Middle) , all on Cape Breton Island, from 1987 to 2005. Atlantic salmon abundance has declined in the Restigouche, Miramichi, Philip, East Pictou, West Antigonish, North, LaHave and Saint John rivers from 1987 to 2005. Atlantic salmon abundance has declined by more than 95% in the East Sheet Harbour (-97.5), Stewiake (-97.4), Big Salmon (-97.4), Magaguadavic (-98.9) and St.Croix (-99.8) rivers. No data is given for the Nashwaak River.

Of the 19 salmon rivers in Quebec, the  five-year average population size increased in twelve rivers (Mitis, Cap Chat (279%), Dartmouth, York, Saint Jean, Malbaie (284%), Du Petit Pabos (1107%), Du Grand Pabos (1099%), Du Grand Pabos Ouest, Port Daniel Nord (371%), Bonaventure and Matapedia). Atlantic salmon abundance has declined in the Sainte Anne and Grand Rivière rivers. The five-year average population size remained relatively stable in the Mantane and Madeleine rivers.  No data is given for the Petite Cascapedia, Cascapedia and Nouvelle rivers.

Scale on x axis is Log(Npresent/Npast). Each point is the change in five-year average population size. Points outside the graph’s range are labelled with their value.
Source: modified from Gibson et al., 2006192

Numbers of Atlantic salmon in rivers in PEI also declined. The fish were thought to occur in about 70 rivers in PEI prior to European settlement. By 1960, this had declined to approximately 55 rivers, and a comprehensive study in 2000–2002 found salmon in just 33 rivers. In 2008, 11 more rivers no longer had salmon and populations in 7 others were very low.Footnote194

American eel

The American eel (Anguilla rostrata) is an example of a once abundant species that is now listed as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Since the 1970s, populations have declined by 99% in the upper St. Lawrence,Footnote195 and less extreme declines have been observed in both the lower St. Lawrence and Gulf of St. Lawrence.Footnote196, Footnote197 The long life span of American eels, combined with their vast distances of up to 4,500 km, make them vulnerable to a wide range of stressors, such as mortality in hydroelectric turbines, physical barriers such as dams, overharvesting, and habitat alteration. Climate change, resulting in changes to ocean currents that carry eel larvae from the spawning grounds, may also contribute to population declines. American eels once provided both subsistence and commercial fisheries in Canada.197

In the Atlantic Maritime Ecozone+, trends in American eel populations have been mixed. Electrofishing surveys have been conducted regularly in six major rivers with available time series of data ranging from 15 to 45 years. While four rivers in New Brunswick (Miramichi, Restigouche, Nashwaak, and Big Salmon rivers) saw above average abundance in the 2000s, abundance in two rivers in Nova Scotia has strongly declined, by about 75% in the St. Marys River from 1998 to 2009 and by 86% in the LaHave River from 2000 to 2009.196

Freshwater fish

Between 1979 and 2008, the number of freshwater and diadromous fish taxa classified as imperilled in the AME by the American Fisheries Society tripled from three to nine species (Figure 48), Table 11).  Rainbow smelt was added  as a result of improved status information while populations of striped bass and Atlantic salmon were added due to the inclusion of discrete regional populations as of 2008.Footnote198

Figure 48. Trend in numbers of imperilled freshwater and diadromous fish taxa in each status category for North American ecoregions in the Atlantic Maritime ecozone+, 1979, 1989, and 2008.

graph

Long Description for Figure 48

This bar graph shows the following information:

Data for figure 48.
StatusNumber of taxa
1979
Number of taxa
1989
Number of taxa
2008
Extinct001
Endangered214
Threathened013
Vulnerable121

‘Taxa’ is used instead of ‘species’ because the list was updated to include discrete regional populations and infraspecific taxa. Previous lists may have underestimated the imperiled taxa because they did not include all designable units, only taxonomically recognized species.
Definitions of status categories differ slightly from COSEWIC and are described in Jelks et al.198

Table 11. Identification and status of imperilled freshwater and diadromous fish taxa in the Atlantic Maritime Ecozone+, 1979, 1989, and 2008.Table note1
English common nameGenusSpecies197919892008
Shortnose sturgeonAcipenserbrevirostrumETE
Atlantic sturgeonAcipenseroxyrinchus oxyrinchusVVV
Striped bass (Bay of Fundy population)Moronesaxatilis  T
Striped bass (Southern Gulf of St. Lawrence population)Moronesaxatilis  T
Striped bass (St. Lawrence Estuary population)Moronesaxatilis  Xp
Rainbow smelt (Lake Utopia, New Brunswick dwarf population)Osmerusmordax VT
Atlantic whitefishCoregonushuntsmaniEEE
Atlantic salmon (Bay of Fundy population)Salmosalar  E
Atlantic salmon (Gulf of Maine population)Salmosalar  E

Table 11 - Notes

Table note 1

In this table: Xp = ‘possibly extinct’, E = ‘endangered’, T = ‘threatened’, V = ‘vulnerable’ as defined in Jelks et al.198
Source: adapted from Jelks et al., 2008198

Return to note1referrer

Landbirds

All landbird species assemblages, except forest birds, declined from the 1970s to the 2000s, with the greatest declines in birds of grassland (includes species of agricultural habitats such as hayfields, pastures, and rangelands) and other open habitats (Table 12, see also Figure 45 in Agricultural landscapes as habitat section on page 60).

Table 12. Trends in abundance of landbirds for the Atlantic Maritime Ecozone+, 1970s to 2000sTable note1
Species AssemblageTrend
(%/yr)
PBBS Abundance Index
1970s
BBS Abundance Index
1980s
BBS Abundance Index
1990s
BBS Abundance Index
2000s
BBS Abundance Index
Change
Forest-0.4% 221.6218.3208.1187.1-16%
Shrub/Successional-0.6%*160.2141.9137.1134.9-16%
Grassland-3.5%*39.938.219.513.3-67%
Other Open-3.5%*64.867.036.322.6-65%
Urban / Suburban-0.6%*179.7162.0157.3154.9-14%

Table 12 - Notes

Table note 1

In this table: P is the Statistical significance: * indicates P <0.05; n indicates 0.05<P<0.1; no value indicates not significant
Change” is the percent change in the average index of abundance between the first decade for which there are results (1970s) and the 2000s (2000-2006).
Source: Downes et al., 201142 using data from the Breeding Bird Survey43

Return to note1referrer

Top of Page

Key finding 18
Primary productivity

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.

The Normalized Difference Vegetation Index (NDVI), calculated from remote sensing data, is an indicator of the amount and vigour of green vegetation present on a landscape. Changes in NDVI are a proxy for changes in primary productivity. From 1985 to 2006, NDVI values increased for 33,408 km2 (16.5%) and decreased for 720 km2 (0.4%) of the AME.7 The largest areas with increasing NDVI values were mixed forest along the Gaspé Peninsula and on Cape Breton Island (Figure 49).

Figure 49. Change in the Normalized Difference Vegetation Index for the Atlantic Maritime ecozone+, 1985–2006.

map

Long Description for Figure 49

This map shows areas of increase and decrease in the annual peak Normalized Difference Vegetation Index (NDVI) for the Atlantic Maritime Ecozone+ between 1985 and 2006.  Of areas showing change over this period, the vast majority had increasing trends. Areas with decreasing trends were small and scattered.  The map shows that, from 1985 to 2006, NDVI values increased for 33,408 km2 (16.5%) and decreased for 720 km2 (0.4%) of the ecozone+. The largest areas with increasing values were mixed forest along the Gaspé Peninsula and on Cape Breton Island.

Trends are in annual peak NDVI, measured as the average of the three 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.
Source: adapted from Pouliot et al, 2009199 by Ahern et al., 20117

Changes in NDVI can be attributed to climate change, land cover change, and land use or other management changes.7 Increasing trends in parts of the AME may be associated with commercial logging that has increased the proportion of broadleaf trees, but more detailed studies would be needed to confirm this hypothesis. Because of the high proportion of deciduous and mixed deciduous forests in this ecozone+, NDVI values were in a higher range, close to the saturation point, making subtle changes difficult to detect.Footnote199 Footnote200 Footnote201 In addition, the result of NDVI analyses in southeastern Canada (including the AME) are sensitive to the period being analyzed. Earlier time periods (such as 1982 to 1999) are more likely to show extensive increasing trendsFootnote202 Footnote203 Footnote204 Footnote205  while analyses of more recent periods (such as 1985 to 2006, as analyzed here) show less extensive positive trends or even some areas of negative trends.199 Footnote206 Footnote207 More detailed land cover and vegetation productivity studies would be necessary to fully understand these trends.

Top of Page

Key finding 19
Natural disturbance

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.

Natural disturbances include extreme weather events, fire, and insect outbreaks. Although fire was important within the AME historically, severe weather events and insect outbreaks are the dominant disturbance types today due, in part, to effective fire suppression. Spruce budworm is the most influential forest insect.

Extreme weather events

Since the AME borders the Atlantic Ocean, it is especially vulnerable to hurricanes and other tropical storms tracking up North America’s Eastern Seaboard. The winds and tidal events associated with these storms can also lead to storm surges and flooding.

Tropical storms and hurricanes

The frequency and severity of tropical storms and hurricanes has increased over the past three decades.Footnote208, Footnote209 Footnote210 Footnote211 The average number of tropical cyclones--that is, hurricanes, tropical storms, and tropical depresssions--per year was 8.7 from 1900 to 1999, 9.9 from 1950 to 1999, and rose to 11.8 from 1991 to 2000, the highest 10-year average on record (Figure 50).211 Other recent studies showed that the duration of tropical-storm events in the Atlantic region has increased by about 60% since 1949 and the annual peak-wind speed increased by about 50%.103 Since 1975, the total dissipation of power (an index of a hurricane’s potential destructiveness) has doubled.Footnote212

Figure 50. Trends in the average number of tropical cyclones in the Atlantic Basin, 1900–1999, 1950–1999, and 1991–2000

graph

Long Description for Figure 50

This figure is a line graph showing the frequency and severity of tropical storms and hurricanes in the Atlantic Basin for the time periods 1900–1999, 1950–1999, and 1991–2000.  The graphs show that the frequency and severity of tropical storms and hurricanes has increased over the past three decades. The average number of tropical cyclones per year was 8.7 from 1900 to 1999, 9.9 from 1950 to 1999, and rose to 11.8 from 1991 to 2000, the highest 10-year average on record.

Source: Environment Canada, 200211

Storm surges and flooding

Storm surges and flooding are often associated with hurricanes and tropical storms and result from increased marine-wave action and heavy rainfall. They can have significant impacts on coastal ecosystems, including soil erosion and vegetation loss (see also Coastal section on page 29). Susceptibility to storm surges varies widely in the AME: some areas are likely to be more severely affected than others, depending on the nature of the coastline and degree of exposure (Figure 51).

Figure 51. Storm surge maxima return level on the Atlantic coast of Canada based on the 40-year hindcast.

map

Long Description for Figure 51

This heat map shows the susceptibility of coastal areas in the Atlantic Maritime Ecozone+ to storm surges. The map shows that susceptibility to storm surges varied widely in the ecozone+: some areas are likely to be more severely affected than others, depending on the nature of the coastline and degree of exposure. Areas predicted to be most susceptible were the northeast coast of Nova Scotia and New Brunswick and the south coast of Prince Edward Island, as well as the shores of the St. Lawrence River.

Hindcasting is a method of developing a model by testing it to see whether it accurately predicts past observations. The coloured bar indicates the 40-year positive surge return levels in metres. The most extreme surge events are expected to occur in the coastal regions highlighted by the warmest colours.
Source: Bernier et al., 2006Footnote213

There were no comprehensive trend data on storm surges for the whole AME, however, a case study of storm surges in Charlottetown, PEI, indicate an increased severity and frequency in storm surge events between the 1940s and 1980s with surges over 90 cm becoming increasingly frequent (Figure 52). Since ice appears to have a damping effect on storm surge severity, storm surges and wave erosion may become more severe in a warmer climate, with reduced ice in the Gulf of St. Lawrence (see Ice across biomes section on page 37).107

Figure 52. Average number of storm surges per year above the threshold, by decade, at Charlottetown, PEI, 1940s–1990s.

graph

Long Description for Figure 52

This bar graph shows the following information:

Data for figure 52. - Charlettetown - Average number of events
Height Category
(cm)
1940-491950-591960-691970-791980-891990-99
>=607.98.289.986.4
>=7044.34.94.84.63.1
>=801.92.32.32.32.61.3
>=900.61.51.11.41.80.8
>=1000.20.50.80.61.20.4
>=110 0.30.40.10.60.3
>=120  0.30.10.10.2
>=130  0.2  0.2
>=140  0.1  0.1
>=150      

Source: adapted from Environment Canada in Forbes et al., 2006107

Fire

Wildfires historically played an important role in forest dynamics in the AME, although at a much smaller scale than many other parts of Canada.214 Footnote215 Records from the 17th and 18th centuries suggest that lightning strikes regularly burned large areas of forest.Footnote216 Today, fires are more numerous but smaller. The increased number of fires is due to the prevalence of human-caused fires. On average, between the 1960s and 2000s, 86% of fires were human-ignited.215 However, the extent of area burned has been reduced through early detection and active fire suppression.

Since the 1950s, large forest fires (those greater than 2 km2) have not been a common or significant natural disturbance. From 1959 to 2007, an average of only 34 km2 (0.02% of the AME) burned annually (Figure 53). Years with no large fires were common. Area burned was low due to fire prevention, early detection, and rapid suppression. Overall, total area burned was lower in the 1960s and 1970s, higher in the 1980s and 1990s, and lower again in the 2000s.215

Figure 53. Total annual area burned by large fires (>2 km2 in size) from 1959 to 2007 (left) and distribution of large fires from the 1980s to present in the Atlantic Maritime ecozone+.

graph/map

Long Description for Figure 53

This figure has a bar graph of the annual area in square kilometres burned in the Atlantic Maritime Ecozone+ by forest fires and a map of the location of forest fires from 1959 to 2007.  The graph shows the following information:

Data for figure 53.
YearArea burned (km2)
1959237.35
1960299.40
196120.02
19620.00
196321.58
19643.66
196513.06
19660.00
19670.00
196841.07
19695.57
197010.12
19710.00
19720.00
19730.00
19740.00
19753.86
19760.00
19770.00
19789.08
19790.00
198026.31
19810.00
198253.39
19835.90
19840.00
198517.01
1986374.17
198721.79
198816.32
19890.00
199071.79
199134.77
199248.03
19933.04
19940.00
1995296.00
19967.00
19977.00
1998 
199953.00
200059.00
200124.00
20021.00
20031.00
20048.00
20055.00
20063.00
20074.00

On map, red is 1980s, purple is 1990s. Fires from 2000s (up to 2007 included) are too small to show.

Source: Krezek-Hanes et al., 2010;215 data from 1959–1994 from the large fire database (Stocks et al., 2003)Footnote217 and data from 1995–2007 from remote sensing.

For some forests in the AME, fire has historically played an important role in the stand dynamics of forests, impacting tree species composition, age-class distribution, and patterns of succession.Footnote214 Footnote218 For example, in Nova Scotia, fire maintained forest diversity in pure Jack pine (Pinus banksiana) stands in Cumberland County and black spruce/white pine stands in the St. Mary’s River area. Over time, fire suppression is expected to reduce forest diversity in these areas.Footnote219

In some ecosystems, repeated fire disturbance is important because it limits tree growth. Loss of soil fertility and hardpan formation in the soil profile caused by fires, combined with the allelopathic effect of heath-like vegetation on coniferous species, can create open woodland ecosystems with stunted trees, as in the barrens of southwest Nova Scotia. Natural fires have helped to maintain the Annapolis Valley heathlands.134

Large-scale native insect outbreaks

Insect outbreaks are among the most frequent natural disturbances in the AME and the most common natural pathway for forest regeneration. Like fires, insect outbreaks also strongly influence a forest’s successional dynamics (growth, in-growth, and mortality).Footnote220 However, unlike fires, insect outbreaks usually result in individual tree or small-patch replacement, rather than the loss of large stands.16

Spruce budworm

Spruce budworm, which is native to North American boreal and mixedwood forests, is the most influential forest insect in the AME.16 Footnote221 Outbreaks occur somewhat synchronously over extensive areas,Footnote222 but the duration of outbreaks varies regionally. Typically, periods of high defoliation last 5 to 25 years221 Footnote223 Recurring spruce budworm outbreaks play an important role in shaping forest ecosystems. They influence the residual forest stand’s species composition, age-class distribution, successional dynamics, and forest condition.20 223 Footnote,224 Footnote225 In addition, because spruce budworm and other insect outbreaks occur frequently and cover large areas, they affect the forest’s carbon flux.224

There is no consensus on whether frequency and severity of outbreaks is changing. Some studies have found that the frequency of budworm outbreaks has increased,221, 222, Footnote226 while others have not found trends, especially when longer time scales were considered. For example, Boulanger and Arseneault223 found that the outbreak frequency in eastern Quebec was stable from 1500 to 2000, with a return-interval of between 30 and 48 years (Figure 54).

Figure 54. Intervals of spruce budworm outbreaks in eastern Quebec identified during previous reconstructions based on tree-ring chronologies, 1500–2000.

graph

Long Description for Figure 54

This timeline graphic shows the length of and intervals between spruce budworm outbreaks in eastern Quebec between the year 1500 and 2000. The time line depicts an outbreak frequency in eastern Quebec that was stable from 1500 to 2000, with a return-interval of between 30 and 48 years.

Source: adapted from Boulanger and Arseneault, 2004223

Some studies suggest that the severity of attacks increased during the 20th century.Footnote227 Footnote228 In contrast, severity of attacks decreased in New Brunswick from 1949 to 2007 (Figure 55).137 This decline could have resulted from insecticide applications to combat spruce budworm outbreaks. Between 1972 and 1993, aerial insecticide was applied in New Brunswick on close to 50% of the moderately and severely infested areas, which reduced defoliation significantly.221

Figure 55. Trend in (A) spruce budworm defoliation in New Brunswick, 1949–2007, and (B) the area treated with pesticides, 1952–2007.

graph

Long Description for Figure 55

This figure is comprised of two line graphs showing the area of extent of moderate to severe defoliation from spruce budworm in New Brunswick annually from 1949 to 2007 and the total area treated with pesticides annually from 1952 to 2007.The graphs show that the severity of attacks decreased in New Brunswick from 1949 to 2007 and particularly in the areas treated with pesticide.

Source: modified from Carter et al., 2008137
Detectable changes to the severity and frequency of insect outbreaks across the range of the eastern spruce budworm were attributed to changes in forest harvest practices, reduced frequency of fire due largely to fire suppression, increased insecticide spraying, and less reliability in outbreak records reconstructed from historic periods.16 134 223

Top of Page

Key finding 20
Food webs

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.

There was limited information on changes in trophic dynamics and population cycles in the AME. The loss or reduction of top mammalian predators can result in substantial changes to food webs. Historically, wolves were the largest mammalian predator but they were extirpated from New Brunswick and Nova Scotia sometime between 1870 and 1921.Footnote229 American martens (Martes americana) were extirpated from southern Quebec and PEI, and black bear (Ursus americanus) and lynx (Lynx canadensis) were also extirpated from PEI.

At the same time, coyotes expanded their ranges into the AME (Figure 56) and replaced wolves as the top predator. Across eastern North America, including the AME, coyotes have exerted a strong “top-down effect” on forest ecosystems;Footnote230 they directly reduced the abundance of prey which indirectly reduced the abundance of smaller carnivores such as red foxes (Vulpes vulpes).Footnote231 By reducing the abundance of smaller carnivores, coyotes also indirectly increased the number of birds, creating a positive relationship between coyotes and scrub-bird populations.

Figure 56. Chronology of colonization of a portion of the Atlantic Maritime ecozone+ by the eastern coyote from the 1960s to the 1980s.

map

Long Description for Figure 56

This map shows the movement of the eastern coyote into the Atlantic Maritime Ecozone+ between the 1960s and the 1980s.  The colonization of this species moved from east to west starting with the colonization of the Quebec and eastern New Brunswick portion of the Ecozone+ in the 1960s followed by a movement westward through New Brunswick and into northern Nova Scotia by the mid- to late 1970s. By 1980, the eastern coyote had colonized the entirety of Nova Scotia including Cape Breton Island and, by 1983, was also on Prince Edward Island.

Source: Moore and Parker, 1992Footnote232

Top of Page