Arctic Ecozone+ highlights and key findings summary
Key Findings Summary Table
Key findings at a glance: national and Ecozone+ level
- Theme: Biomes
- Theme: Human/Ecosystem Interactions
- Theme: Habitat, Wildlife, and Ecosystem Processes
- Theme: Science/Policy Interface
These tables present the national key findings from Canadian Biodiversity: Ecosystem Status and Trends 2010 Footnote1 together with a summary of the corresponding trends in the Arctic Ecozone+. Topic numbers refer to the national key findings in Canadian Biodiversity: Ecosystem Status and Trends 2010. Topics that are greyed out were identified as key findings at a national level but were either not relevant or not assessed for this Ecozone+. All material for trends in the Arctic Ecozone+ was drawn directly from the Arctic Ecozone+ Status and Trends AssessmentFootnote2 except where additional references are included as footnotes.
|Themes and Topics||Key Findings: National||Key Findings: Arctic Ecozone+|
|1. Forests||At a national level, the extent of forests has changed little since 1990; at a regional level, loss of forest extent is significant in some places. The structure of some Canadian forests, including species composition, age classes, and size of intact patches of forest, has changed over longer time frames.||As the southern boundary of the Arctic Ecozone+ is the tree line, forest cover is restricted to the forest-tundra transition zone. The northern boundary of tree distribution is often temperature limited, and it is anticipated that the overall trend will be northward expansion of forest under a warming climate. Current trends are variable, with, for example, treeline expanding northward in coastal areas of northern Quebec and Labrador, but not in the interior. A combination of increased growth and cover by shrubs and infilling by tree species may replace tundra at its southern margins in the forest-tundra zone.|
|2. Grasslands||Native grasslands have been reduced to a fraction of their original extent. Although at a slower pace, declines continue in some areas. The health of many existing grasslands has also been compromised by a variety of stressors.||Not relevant|
|3. Wetlands||High loss of wetlands has occurred in southern Canada; loss and degradation continue due to a wide range of stressors. Some wetlands have been or are being restored.||Wetlands cover approximately 10% of the Arctic Ecozone+. They are more common in the Southern Arctic. A high proportion of Arctic wetlands are wet sedge, grass, and moss wetlands. In moist regions of the Ecozone+, thaw lakes and ponds have increased in amount and extent, evidently as a result of permafrost melting and precipitation increasing. However, in drier regions of the Northern Arctic and Arctic Cordillera, ponds have been reduced in extent and some have disappeared. Some ponds on Ellesmere Island that had been permanent water bodies for millennia dried up completely in the warm summers of 2005 and 2006. Surrounding moss and grass wetlands also dried, with the loss of seasonal standing water. More permanent ponds, as well as seasonal ponds and wetlands, can be expected to be lost through desiccation as the climate warms further. Ephemeral ponds and wetlands in the Arctic are important stopover sites for migratory birds and important nesting sites for shorebirds and geese on the coastal plain.|
|4. Lakes and rivers||Trends over the past 40 years influencing biodiversity in lakes and rivers include seasonal changes in magnitude of stream flows, increases in river and lake temperatures, decreases in lake levels, and habitat loss and fragmentation.||About three-quarters of Canada is drained by rivers discharging through the Arctic Ecozone+ to Arctic marine waters, accounting for almost half (48%) of the total discharge of Canadian rivers. Flow regimes and ecosystem conditions for major rivers crossing briefly through the Ecozone+ at the far northern end of their courses are influenced strongly by climatic conditions, terrain, and stressors to the south. With few hydrometric stations with long-term datasets, information on trends in river discharge is limited. Total annual discharge from the Ecozone+ to Arctic marine waters decreased from the mid-1960s to the early 2000s, but with strong regional variation: there was a strong decline in discharge to Hudson Bay and the Labrador Sea, but no significant trend for rivers draining directly to the Arctic Ocean. Analyses that include more recent data show a reversal of the earlier decline, including in Hudson Bay, with a significant increase in annual average flows since 1989. Based on remote sensing, total Ecozone+ lake area declined from 2000 to 2009, likely related to the longer ice-free periods leading to increased evapotranspiration. In contrast, lake area increased over the same period in areas where melting permafrost led to increased land flooding--with, for example, an increase of 3% in the Mackenzie Delta. The impacts of climate change on ecological processes in lakes and rivers are complex and include shorter periods of ice cover, warmer water, changing lake mixing regimes, and changes in the distribution of nutrients and oxygen. Climate warming has been linked to shifts in algal and invertebrate species assemblages, food availability for fish, and overall freshwater ecosystem productivity.|
|5. Coastal||Coastal ecosystems, such as estuaries, salt marshes, and mud flats, are believed to be healthy in less-developed coastal areas, although there are exceptions. In developed areas, extent and quality of coastal ecosystems are declining as a result of habitat modification, erosion, and sea-level rise.||Coastal biomes are assessed in the ESTR marine Ecozone+ reports.|
|6. Marine||Observed changes in marine biodiversity over the past 50 years have been driven by a combination of physical factors and human activities, such as oceanographic and climate variability and overexploitation. While certain marine mammals have recovered from past overharvesting, many commercial fisheries have not.||Marine ecozones+ are assessed in other ESTR reports.|
|TundraFootnotea||Ecozone+-specific key finding||Polar barrens (less than 50% vegetation) and polar tundra (over 50% tundra vegetation) together cover 80% of the Ecozone+. Reflecting the widespread warming trend across the Ecozone+, the area of land with climatic conditions known to support tundra over the long term declined 20% since 1982. Tundra plant communities are changing across the biome in ways that are consistent with responses to experimental warming. Data from 1980 to 2010 for Canadian study sites were combined for analysis with results from other ground-based tundra monitoring sites across the circumpolar Arctic. Main trends include increases in average height of vegetation, more shrubs, and less bare ground. Experimental tundra plots (warmed 1 to 2°C by small, open greenhouses) provide an indication of the response of tundra to continued climate change. These responses include increases in shrubs, loss of species diversity, increased height of most vascular plants, and decreases in mosses, lichens, and bare ground cover.|
|7. Ice across biomes||Declining extent and thickness of sea ice, warming and thawing of permafrost, accelerating loss of glacier mass, and shortening of lake-ice seasons are detected across Canada’s biomes. Impacts, apparent now in some areas and likely to spread, include effects on species and food webs.||All forms of ice in Arctic biomes have shown rapid decline over the past 30 years, particularly over the past decade. |
Permafrost is warming and the depth of ground that thaws annually is increasing at monitoring sites across the Ecozone+ (measured over varying periods, extending back to the 1980s). Loss of permafrost is leading to broad-scale changes, including changes in vegetation structure and communities, as well as positive feedbacks that increase rates of warming (such as reduced albedo affecting regional air temperatures, and changes in the carbon balance of the Arctic landscape contributing to the greenhouse effect and thereby accelerating global climate warming). Sea ice extent throughout the year decreased significantly from 1979 to 2013, as measured by remote sensing. Increased summer ice melting has led to a loss of multi-year ice and ice is melting earlier in the spring. These changes in sea ice affect not only marine ecosystems and ice-dependent species such as polar bears, they also affect coastal regional climate and vegetation, and some species of terrestrial wildlife. There has been a general melting trend for Canadian Arctic Island glaciers and ice caps since the late 19th century, with the trend slowing down for a period in the mid-20th century, and with accelerated ice loss in the past 25 years. The glacier mass loss for Arctic Canada from 2003 to 2009 was about 28% of the global glacier mass loss, excluding Antarctica and Greenland, and it accounted for about 29% of global sea level rise over this period. Increasing amounts of land are exposed as the glaciers melt, and this will lead to some increase in the area of tundra vegetation coverage.
There is little information on trends in lake ice. Based on remote sensing data, the length of the annual ice-free period for seven lakes in the Arctic increased significantly from 1985 to 2004.
- Footnote a
This key finding is not numbered because it does not correspond to a key finding in the national report
Theme: Human/Ecosystem Interactions
|Themes and Topics||Key Findings: National||Key Findings: Arctic Ecozone+|
|8. Protected areas||Both the extent and representativeness of the protected areas network have increased in recent years. In many places, the area protected is well above the United Nations 10% target. It is below the target in highly developed areas and the oceans.||In 2009, almost 11.3% of the Arctic Ecozone+ was protected, an increase from just over 7.4% in 1992. Almost all of this land was protected as IUCN categories I–III. As of May 2009, the Arctic Archipelago had the highest proportion of protected areas, at 24.0% in 10 protected areas, followed by the Southern Arctic with 15.9% protected through 21 protected areas. The Northern Arctic had 6.7% of its land protected through 22 protected areas. Much of the growth of protected areas in the Arctic has been related to the settlement of land claims.|
|9. Stewardship||Stewardship activity in Canada is increasing, both in number and types of initiatives and in participation rates. The overall effectiveness of these activities in conserving and improving biodiversity and ecosystem health has not been fully assessed.||Stewardship activity related to conserving ecosystems in the Arctic Ecozone+ is important at community, regional, circumpolar, and global scales. Within the Ecozone+, stewardship initiatives are often carried out within the framework of natural resource management systems that have strong community-level involvement. Fish, wildlife, and habitat are co-managed or managed with strong participation of the Inuit through resource management boards established pursuant to land claims agreements. These boards make use of both science and Aboriginal traditional knowledge to inform decision-making and are supported by hunters’ and trappers' associations and other community-level organizations. At the circumpolar scale, the Arctic Council, an intergovernmental organization of the eight circumpolar nations, provides a forum for collaboration and oversight of many international initiatives related to ecological science, conservation of ecosystems, and sustainable development in the Arctic. International Arctic indigenous organizations are Permanent Participants in the Council. Responsibility for one of the most important stewardship activities for the Arctic--reduction in the rate of greenhouse gas emissions--is shared globally.|
|10. Invasive non-native species||Invasive non-native species are a significant stressor on ecosystem functions, processes, and structure in terrestrial, freshwater, and marine environments. This impact is increasing as numbers of invasive non-native species continue to rise and their distributions continue to expand.||Few invasive species are known from the Arctic compared to other ecozones+ but the impacts of these to biodiversity can still be severe, given that most native plant species have specialized northern niches.Footnote3 Risk of introduction of invasive plants will increase with climate warming and changes in patterns of human use, particularly increased shipping, energy development, mineral exploration, and associated shore-based developments, such as ports, roads, and pipelines.Footnote4|
|11. Contaminants||Concentrations of legacy contaminants in terrestrial, freshwater, and marine systems have generally declined over the past 10 to 40 years. Concentrations of many emerging contaminants are increasing in wildlife; mercury is increasing in some wildlife in some areas.||Contamination of Arctic wildlife has been a concern since the 1970s, especially in relation to potential health effects for Arctic indigenous peoples. Three classes of contaminants of particular concern in the Arctic are: legacy contaminants (persistent organic pollutants such as DDT, PCBs, and toxaphene), newer toxic contaminants, such as brominated flame retardants, and mercury. Trends in the Arctic are consistent with the national key finding trends. Contaminant levels in Arctic fish and wildlife are considered to be below levels that would result in widespread effects on the health of fish and wildlife, with some possible exceptions, including for some polar bear populations.|
|12. Nutrient loading and algal blooms||Inputs of nutrients to both freshwater and marine systems, particularly in urban and agriculture-dominated landscapes, have led to algal blooms that may be a nuisance and/or may be harmful. Nutrient inputs have been increasing in some places and decreasing in others.||Not relevant|
|13. Acid deposition||Thresholds related to ecological impact of acid deposition, including acid rain, are exceeded in some areas, acidifying emissions are increasing in some areas, and biological recovery has not kept pace with emission reductions in other areas.||Despite the presence of potential acidifying pollutants in the atmosphere, there is little indication of soil or surface water acidification in the Arctic Ecozone+ to date.Footnote5, Footnote6 Most Arctic soils have low sensitivity to acid deposition, with the exception of some areas of the Northwest Territories, Yukon Territory, and Baffin Island, where soils and bedrock have low potential to reduce the acidity of atmospheric deposition.7Footnote7 Of lakes sampled in Arctic Canada, the only extremely acid-sensitive lakes found so far occur on Baffin Island and the central mainland straddling the border of Nunavut and the Northwest Territories.|
|14. Climate change||Rising temperatures across Canada, along with changes in other climatic variables over the past 50 years, have had both direct and indirect impacts on biodiversity in terrestrial, freshwater, and marine systems.||Summer and fall temperatures increased significantly across the Ecozone+ over the past 50 years, with increases at all seasons recorded for many climate stations. There were no significant cooling trends at any station in any season. Annual precipitation increased across the Ecozone+, with the most significant change being in winter and with little to no change in summer. Across the Ecozone+, snow cover duration decreased both in the fall and in the spring over the 50 year period. Annual maximum snow depth also decreased. In Canada, as at the global scale, the climate is warming faster in the Arctic than at lower latitudes. With this amplification of climate change, the direct and indirect impacts on ecosystems are of particular prominence in this Ecozone+. Rapid loss of snow and ice across biomes, in particular, is leading to major changes in ecosystem structure and function.|
|15. Ecosystem services||Canada is well endowed with a natural environment that provides ecosystem services upon which our quality of life depends. In some areas where stressors have impaired ecosystem function, the cost of maintaining ecosystem services is high and deterioration in quantity, quality, and access to ecosystem services is evident.||Arctic ecosystems provide important provisioning, cultural, and regulating services. They produce food, fuel, and fibre essential to traditional Arctic cultures and economies, as well as commercial hunting, gathering, and small-scale fishing industries. Arctic fish and wildlife further support recreational and sport fishing and hunting. Cultural services include the significance of fish and wildlife to Inuit culture and tourism. Regulating services include carbon sequestration and climate regulation, increasingly impaired by climate warming and positive feedbacks caused by changes in albedo from diminished snow and ice cover. |
Studies since the 1970s show the continuing reliance of Inuit and Inuvialuit on traditional (country) foods as a significant source of calories and nutrients and as a central cultural feature. A snapshot of subsistence use is provided by an extensive 2001 survey from Labrador to the Western Arctic: over 60% of Inuit and Inuvialuit are active fishers, while about 50% hunt caribou, moose or sheep (with caribou being particularly important). Trapping participation rates were much lower, at or below 10 to 20% depending on region. Participation rates in subsistence activities were higher for people outside of major population centres.
Theme: Habitat, Wildlife and Ecosystem Processes
|Themes and Topics||Key Findings: National||Key Findings: Arctic Ecozone+|
|16. Agricultural landscapes as habitat||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.||Not relevant|
|17. Species of special economic, cultural, or ecological interest||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.||Polar bears: In 2013, the Canadian population of polar bears was estimated at approximately 16,200 individuals. Although the total size of the global population is unknown, it is likely over half of the world’s polar bears live in Canada. Status and trends vary among subpopulations. As of 2013, two sub-populations were considered to be increasing or likely increasing, 6 were stable, and 4 were declining or likely declining. Data was insufficient to provide a trend for one sub-population. Polar bears, adapted to hunting seals from the ice, cannot persist without seasonal sea ice and rapidly declining sea ice poses the most serious threat to the species. Earlier sea-ice break-up around western Hudson Bay has led to poorer physical condition and poorer reproductive performance of polar bears. Other threats include overharvest, disturbance and loss of habitat due to increased human activity, and contaminants, including mercury and persistent organic pollutants. |
Caribou: Over the last 50 years, Peary caribou have declined from about 44,000 to 11,000 to 12,000. Trend analyses are limited by the infrequency of surveys and lack of older surveys. Factors influencing caribou abundance include weather, harvest, and predation. Periodic severe winters trigger large-scale mortality and reduction in productivity.
Based on surveys of herds, migratory tundra (barren-ground) caribou numbers across the Arctic generally increased from low abundance around 1975 to peak abundance around 1995, followed by a decline with some indication of a recent levelling off or reversal of the decline. However, status and trends for individual herds vary. Current trends are likely a reflection of natural cycles in caribou abundance accentuated by the cumulative effects of increasing human presence on the caribou ranges, possibly interacting with climate change impacts.
Muskoxen: As of 2012, Canada had about 115,000 muskoxen, which is about three-quarters of the world total. Muskoxen were hunted to near extinction on the Arctic mainland and on some Arctic islands by the early 1900s. They have since recovered through natural population increases and range extension, aided by a period of no harvesting from 1924 to 1969, followed by regulated harvest as populations expanded.
Birds: Data on Arctic birds are lacking or sparse for many species, and it is often difficult to determine the causes of trends where data are available. Many Arctic-nesting shorebird and landbird species are declining on a continental basis, as are some sea ducks (e.g., king eiders, common eiders). Other Arctic bird groups, such as geese and swans, have mainly stable populations or have increased (due to changes in agricultural practices on their southern wintering grounds) over the past few decades. Arctic-nesting birds winter in many parts of the world where they may be vulnerable to stressors including loss of food supplies and habitat, pollution, disturbance, and overharvesting during winter and during migration. In the Arctic, they are vulnerable to changes in their habitat and food supplies and, in some cases, to overharvest.
|18. Primary productivity||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.||Primary productivity is low in the Arctic compared with other ecozones+. Evidence is accumulating that the Arctic is getting greener and that the productivity of Arctic ecosystems is increasing. From 1985 to 2006, primary productivity, as measured by the Normalized Difference Vegetation Index (NDVI), increased over 12.2% of Arctic Ecozone+ land area and decreased over only 0.1% of area. Areas with strong increases in NDVI were all in the tundra landcover class (over 50% cover of tundra vegetation), including areas located on Banks Island, Melville Island, Bowman Bay on Baffin Island, the northwestern Hudson Bay shore, and on the northern Labrador Peninsula, particularly in the lower elevations bordering Ungava Bay. The proportion of lands with increasing NDVI trends was highest in the Southern Arctic. Increases in plant productivity are due to increases in peak productivity and in growing season length. Long-term studies on Ellesmere and Bylot islands show that there have been large increases in biomass (net production) in Canadian High Arctic tundra over the past 20-plus years in response to climate change. Based on lake sediment core data, primary production has also increased rapidly in six Baffin Island lakes since the late 19th century, following a period of stable levels of primary production for millennia, leading to changes in algal species assemblages. Similar results have been found in other Canadian Arctic lake sediment studies.|
|19. Natural disturbance||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.||Permafrost disturbance and thawing due to higher temperatures has increased the frequency and magnitude of slope failures and converted areas of tundra to thermokarst ponds. In addition to changing the nature of the landscape for vegetation and wildlife, slope failures can expose previously frozen carbon to oxidation and alter biogeochemistry in lakes, leading to shifts in nutrient, light, and phytoplankton relationships. Fire is not a significant natural disturbance. Between 1960 and 2007, only five large fires (over 2 km2) were documented for Arctic tundra. When they occur, tundra fires remove vegetation cover, deepen the active layer, and can release large amounts of carbon into the atmosphere. Increases in tundra fires will likely the trend to warmer summers, and the temperature-related increases in shrub vegetation, as has occurred in recent years in northern Alaska. Severe weather events that influence the timing, amount, or quality of snow can have major ecological impacts on ungulates, small mammals, and vegetation. Heavy snow and icing, for example, is known to reduce forage availability for ungulates and small mammals, increasing the risk of mortality or reproductive failure. Trends in severe weather events are not known.|
|20. Food webs||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.||Arctic food webs are relatively intact, with a diverse group of predators, including foxes, wolves, and grizzly bears, wolverines, weasels, and raptors. Predator-prey dynamics depend on heavily in most areas on lemmings and other small rodents, with alternative prey, such as geese and shorebirds, utilized by some predators in low abundance years. Compared with boreal ecosystems, large predators are not abundant in the Arctic tundra and predation impacts on ungulates are usually low unless the ungulates are at low densities. Wolves and tundra grizzly bears depend on caribou as prey, although the regulatory role of predation for caribou population dynamics is uncertain.|
Theme: Science/Policy Interface
|Themes and Topics||Key Findings: National||Key Findings: Arctic Ecozone+|
|21. Biodiversity monitoring, research, information management, and reporting||Long-term, standardized, spatially complete, and readily accessible monitoring information, complemented by ecosystem research, provides the most useful findings for policy-relevant assessments of status and trends. The lack of this type of information in many areas has hindered development of this assessment.||The Arctic Ecozone+ covers a vast, sparsely populated area, made up of three distinct ecozones under the Canadian classification system, making adequate and representative monitoring, research, and provision of information challenging. Monitoring programs that were of particular value in assessing ecosystem status and trends in the Arctic Ecozone+ include those that integrate monitoring and research at sites (notably Bylot Island) and monitoring through networks that use consistent monitoring protocols and take an ecosystem approach through integrating monitoring and research of specific ecosystem features with monitoring and research into drivers, processes, and stressors (notably the networks monitoring tundra vegetation and caribou). However, these ecologically framed sites and networks are rare. Much of status and trends reporting needs to be patched together from specific, often short-term monitoring programs undertaken for purposes such as harvest regulation, assessment of development impacts, or as part of short-term academic research projects. Monitoring stations for parameters essential to tracking and understanding trends in drivers and processes, including climate, permafrost, and river flows, are limited and often grouped in few locations and with short and interrupted or discontinued records. Nonetheless, there are good monitoring data sets within the Ecozone+, augmented by large-scale views from remote sensing. Canadian implementation of biome monitoring plans developed through the Arctic Council’s Circumpolar Biodiversity Monitoring Program will lead to major benefits to future status and trend assessment.|
|22. Rapid change and thresholds||Growing understanding of rapid and unexpected changes, interactions, and thresholds, especially in relation to climate change, points to a need for policy that responds and adapts quickly to signals of environmental change in order to avert major and irreversible biodiversity losses.||For the Arctic Ecozone+, climate change is of primary concern in relation to interactions and rapid changes and thresholds. Rapid changes observed and projected to continue in ice and snow in particular lead to rapid ecological change. For example, reduction in duration and extent of sea ice leads to rapid loss of essential habitat for polar bears, currently detected as loss of body condition in some populations. Permafrost is undergoing a widespread warming--when shallow permafrost temperatures cross the melting point threshold, rapid, landscape-scale changes occur, including thaw slumps and flooding, with consequent impacts on land cover and aquatic habitats. When warm summers increase the rate of evaporation from shallow ponds and lakes beyond a threshold, these productive water bodies are lost, as is observed in the High Arctic. Rapid changes to wildlife population health and abundance result from changes in winter conditions--for example, increased number of freeze-thaw events leads to ice layers that can result in starvation or reproductive failure. Other unexpected changes for which there are some warning signs appearing in the Ecozone+ include mismatches in timing of environmental conditions and species needs when, for example, spring comes earlier and hatching dates of birds are no longer synchronous with times of abundant food for the nestlings. These types of often poorly understood cascading ecological changes are likely to become of increasing importance as climate change progresses in the Canadian Arctic--pointing to the need for detection mechanisms and capacity for rapid response.|
- Footnote 1
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.
- Footnote 2
Eamer, J., Gunn, A. and Harding, L. In Prep. 2013. Arctic Ecozone+ Status and Trends Assessment. Technical Background Reports: Ecosystem Status and Trends Report for Canada. Canadian Councils of Resource Ministers.
- Footnote 3
CAFF. 2010. Arctic biodiversity trends 2010 - selected indicators of change. Conservation of Arctic Flora and Fauna International Secretariat. Akureyri, Iceland. 121 p.
- Footnote 4
CAFF. 2013. Arctic biodiversity assessment: status and trends in Arctic biodiversity. Conservation of Arctic Flora and Fauna. Akureyri, Iceland.
- Footnote 5
5. AMAP. 1998. Acidifying pollutants, Arctic haze, and acidification in the Arctic. In AMAP assessment report: Arctic pollution issues. Arctic Monitoring and Assessment Programme. Oslo, Norway. Chapter 9. pp. 621-659.
- Footnote 6
AMAP. 2006. AMAP assessment 2006: acidifying pollutants, arctic haze, and acidification in the Arctic. Arctic Monitoring and Assessment Programme. Oslo, Norway. xii + 112 p.
- Footnote 7
Environment Canada. 1988. Acid rain: a national sensitivity assessment. Environmental Fact Sheet No. 88-1. Inland Waters and Lands Directorate. Ottawa, ON. 6 p. (+ map).
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