Arctic Ecology E-Book
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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
The Arctic is often portrayed as being isolated, but the reality is that the connectivity with the rest of the planet is huge, be it through weather patterns, global ocean circulation, and large-scale migration patterns to name but a few. There is a huge amount of public interest in the ‘changing Arctic’, especially in terms of the rapid changes taking place in ecosystems and exploitation of resources. There can be no doubt that the Arctic is at the forefront of the international environmental science agenda, both from a scientific aspect, and also from a policy/environmental management perspective.
This book aims to stimulate a wide audience to think about the Arctic by highlighting the remarkable breadth of what it means to study its ecology. Arctic Ecology seeks to systematically introduce the diverse array of ecologies within the Arctic region. As the Arctic rapidly changes, understanding the fundamental ecology underpinning the Arctic is paramount to understanding the consequences of what such change will inevitably bring about.
Arctic Ecology is designed to provide graduate students of environmental science, ecology and climate change with a source where Arctic ecology is addressed specifically, with issues due to climate change clearly discussed. It will also be of use to policy-makers, researchers and international agencies who are focusing on ecological issues and effects of global climate change in the Arctic.
About the Editor
David N. Thomas is Professor of Arctic Ecosystem Research in the Faculty of Biological and Environmental Sciences, University of Helsinki. Previously he spent 24 years in the School of Ocean Sciences, Bangor University, Wales. He studies marine systems, with a particular emphasis on sea ice and land-coast interactions in the Arctic and Southern Oceans as well as the Baltic Sea. He also edited a related book: Sea Ice, 3rd Edition (2017), which is also published by Wiley-Blackwell.
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Table of Contents
Cover
Title Page
Copyright
Preface
References
List of Contributors
1 What Is the Arctic?
1.1 Setting the Scene
1.2 In Which Ways Is the Arctic Different?
1.3 How Was the Arctic Discovered?
1.4 How Large Is the Arctic?
1.5 What Is in the Arctic?
1.6 Climate and Weather
1.7 Ice and Snow
1.8 Permafrost, Polygons, Pingos, and Palsas
1.9 Animals, Plants, and Fungi
1.10 Arctic Ecosystems
1.11 Which Natural Resources and Ecosystem Services does the Arctic Offer?
1.12 Biotic Changes in the Arctic
References
2 Arctic Ecology – A Paleoenvironmental Perspective
2.1 Introduction
2.2 The Distant Past
2.3 Rings and Things: Examining Paleoenvironmental and Paleoclimatic Change Using Dendrochronology
2.4 Lake Sediments: Continuous Archives of Environmental Change
2.5 Paleolimnology and Arctic Climate Change
2.6 Concluding Remarks
References
3 Climate Change in the Arctic
3.1 Introduction to Arctic Climates – Datasets Available for Analyzing Climate Change
3.2 Atmospheric Aspects of Arctic Climate Change: Arctic Amplification and Global Warming, Changes in Air Temperature and Precipitation, and Changes in Atmospheric Circulation
3.3 Oceanic Aspects of Arctic Climate Change, Including Surface and Deep Ocean Circulation Changes
3.4 Climate Change Impacts on Arctic Sea Ice and Greenland Ice Sheet – The Unprecedented Recent Decline in Late Summer Sea-Ice Cover and Record Greenland Ice Sheet Surface Melt and Mass Loss
3.5 Feedbacks in the Arctic Climate System and Global Impacts – the Ice/Albedo Feedback and Ice Insulation Feedbacks – the “Warm Arctic, Cold Continents” Hypothesis
3.6 Concluding Remarks
References
4 Arctic Permafrost and Ecosystem Functioning
4.1 Permafrost and Ecosystems in the Arctic
4.2 Permafrost Shapes the Landscape
4.3 The Biology of Permafrost
4.4 Ecosystem Function – Carbon Cycling in Permafrost Environments
4.5 Concluding Remarks
References
5 Arctic Tundra
5.1 Distribution and Description of Arctic Tundra
5.2 Tundra Organisms: A Typical Food Web
5.3 Flora and Fauna: Diversity and Communities
5.4 Primary Production and Organic Matter Stocks in the Low and High Arctic
5.5 Primary Production and Organic Matter Stocks
5.6 Adaptations to the Arctic Tundra
5.7 Reproductive Strategies
5.8 Populations and Communities of the Tundra
5.9 Tundra Ecosystem Analysis
5.10 Expected Future Changes and Responses in Arctic Tundra
References
6 Ecology of Arctic Glaciers
6.1 Introduction
6.2 The Biodiversity and Food Webs of Glacial Habitats
6.3 Quantification of Microbial Processes in Glaciers and Export of Material to Adjacent Ecosystems
6.4 Anthropogenic Impacts
References
7 Ecology of Arctic Lakes and Ponds
7.1 Introduction
7.2 Physical and Chemical Characteristics of Arctic Lakes and Ponds
7.3 Biological Communities and Production
7.4 Global Climate Change and Arctic Lakes
References
8 Ecology of Arctic Streams and Rivers
8.1 Introduction
8.2 A Primer on Stream Ecology: General and Arctic Perspectives
8.3 Concluding Remarks
References
9 Ecology of Arctic Pelagic Communities
9.1 Introduction
9.2 The Arctic Marine Highways: The Transpolar Drift and the Interconnected Current Systems
9.3 Members and Key Players of Arctic Pelagic Communities
9.4 A Lipid-Driven Food Chain
9.5 Effects of Climate Change
References
10 Ecology of Arctic Sea Ice
10.1 Introduction to Sea Ice
10.2 Types of Habitats
10.3 Food Webs and Carbon Flow
10.4 Physical Environment
10.5 Colonization of Sea Ice and Winter Survival
10.6 Adaptations to and Relationships with Environmental Conditions
10.7 Climate Change and the Ice-Associated Ecosystem
References
11 Ecology of Arctic Shallow Subtidal and Intertidal Benthos
11.1 Introduction
11.2 The Physical Environment
11.3 Biomes
11.4 Disturbance Regimes and Succession
11.5 Trophic Interactions
11.6 Reproduction in Coastal Benthos
11.7 Effects of Global Climate Change on Shallow Arctic Benthos
References
12 Ecology of Arctic Shelf and Deep Ocean Benthos
12.1 Introduction
12.2 The Physical Environment
12.3 Biodiversity, Community Structure, and Functioning of Shelf and Deep Sea Benthos
12.4 Productivity and Food Webs of Shelf and Deep Sea Benthos
12.5 Impact of Global Climate Change on Shelf and Deep Sea Benthic Communities
References
13 Fat, Furry, Flexible, and Functionally Important: Characteristics of Mammals Living in the Arctic
13.1 Introduction
13.2 The Mammal Assemblage in the Arctic Today
13.3 Arctic Mammals and Adaptations to Life in the Arctic
13.4 The Role of Mammals in Arctic Ecosystems
13.5 The Future for Arctic Mammals in a Changing Climate
13.6 Concluding Remarks
References
14 Ecology of Arctic Birds
14.1 Introduction: The Bird Species and Their Feeding Ecology
14.2 Traveling to Breed
14.3 Long Distance Migrations
14.4 Reproduction
14.5 Survival
14.6 Population Change
14.7 Climate Change
14.8 Endangered Species
14.9 Concluding Remarks
References
15 Arctic Ecology, Indigenous Peoples and Environmental Governance
15.1 Introduction
15.2 The Impacts of Social and Environmental Change
15.3 Traditional Ecological Knowledge and Wildlife Management
15.4 Arctic Ecology and Community-Based Monitoring
15.5 Indigenous Peoples and Environmental Policy: The Case of the Inuit Circumpolar Council
15.6 Concluding Remarks
References
Index
End User License Agreement
List of Tables
Chapter 1
Table 1.1 Some Arctic explorers and expeditions up to 1900.
Table 1.2 Some examples of the different bases for defining the extension of ...
Table 1.3 Ecosystem types in the Arctic, in million km
2
.
Chapter 5
Table 5.1 Characteristics of the Low and High Arctic within North America. To...
Table 5.2 Primary production and organic matter stocks in major arctic ecosys...
Table 5.3 Microbial genome size within the Arctic compared with other habitat...
Table 5.4 The biomass (mg C m
−2
) of various trophic levels of the below...
Chapter 6
Table 6.1 Chlorophyll
a
, primary production and assimilation number (chlorophy...
Table 6.2 Maximum bacterial numbers and bacterial production in surface glaci...
Table 6.3 Respiration rates and bacterial production as a fraction of respira...
Chapter 7
Table 7.1 Some physicochemical and biological characteristics for different f...
Chapter 9
Table 9.1 List of zooplankton expatriate species advected into the Arctic Oce...
Chapter 11
Table 11.1 Arctic coastal top predators and their food preferences. This sele...
Table 11.2. Habitat, mean adult size, and caloric content of common benthic i...
Chapter 12
Table 12.1 Summary of physical descriptors for the Arctic continental shelf a...
Chapter 13
Table 13.1. Taxonomic groups of arctic small rodents belonging to the sub-fam...
List of Illustrations
Preface
Figure P.1 A view of the Arctic showing the Arctic Circle and human populati...
Chapter 1
Figure 1.1 Iceberg in spring. Devon Island.
Figure 1.2 Sea ice in spring. Kent Peninsula.
Figure 1.3 Wetland polygons. Chatanga.
Figure 1.4 Reindeer antlers. Northwestern Taymyr Peninsula.
Figure 1.5 Polar desert. Ellef Ringnes Island.
Figure 1.6 Mosses near the ice front. Melville Island.
Figure 1.7 A dead muskox creating a green patch on the nutrient-poor tundra....
Figure 1.8 Brent geese. Pechora Bay.
Figure 1.9 Polar bear during ice break-up. Cape Bathurst.
Figure 1.10 Mussel shells and seaweeds on the seashore, Kent Peninsula.
Figure 1.11 Nomads at Kamchatka in summer.
Figure 1.12 Reindeer sledge made only of wood. Western Yamal Peninsula.
Chapter 2
Figure 2.1 A large retrogressive thaw slump on the Peel Plateau near the bor...
Figure 2.2 One of many mummified tree-stumps preserved in a 45 million-year-...
Figure 2.3 Section of an ice core recovered from the Prince of Wales icefiel...
Figure 2.4 CO
2
concentrations (Lüthi et al. 2008) (black) and reconstructed ...
Figure 2.5 (a) Complacent ring width series that would be characteristic of ...
Figure 2.6 Collecting a sediment core. The removal of a 7.6 cm (3″) diameter...
Figure 2.7 Summary pollen and stomata diagram from a tundra lake in northern...
Figure 2.8 Highly magnified light micrograph of a freshwater diatom.
Figure 2.9 Schematic diagram showing ice and snow conditions on a High Arcti...
Figure 2.10 Habitat availability for diatoms and other biota can be closely ...
Figure 2.11 Representative diatom profiles (relative frequency diagrams) fro...
Figure 2.12 Image taken from a helicopter flying over the study area, showin...
Figure 2.13 Stratigraphic profile showing the changes in the relative abunda...
Figure 2.14 The whale-bone supports of a Thule Inuit overwintering site, as ...
Chapter 3
Figure 3.1 Mean (a) winter (December to February) and (b) summer (June to Au...
Figure 3.2 Arctic (land stations north of 60°N) and global mean annual land
Figure 3.3 Map of the Arctic Ocean showing major seas and two major schemati...
Figure 3.4 Seasonal changes in the Arctic Oscillation for (a) winter (DJF), ...
Figure 3.5 Time series of Northern Hemisphere sea-ice extent anomalies in Ma...
Figure 3.6 A time series of sea ice age in March from 1985 to 2018 (c) and m...
Figure 3.7 (a) Interpolated (TMB, light blue diamonds) or observed (dark blu...
Figure 3.8 Greenland near-surface (2 m) air temperature changes for (a) summ...
Figure 3.9 GrIS surface melt extent: (Top) Time series of daily simulated me...
Figure 3.10 Hypothesized steps linking Arctic amplification with extreme wea...
Figure 3.11 Monthly temperature anomalies for the Arctic domain (60–90°N) av...
Chapter 4
Figure 4.1 Permafrost distribution in the Arctic and beyond.
Figure 4.2 An example of a high arctic permafrost environment with active th...
Figure 4.3 A conceptual transect describing the distribution of permafrost a...
Figure 4.4 Thermokarst pond in Stordalen, subarctic Sweden, bordering a pals...
Figure 4.5 Ice wedge polygon shapes appearing (right) out of winter snow and...
Figure 4.6 Increasing active layer can result in unstable ground that create...
Figure 4.7 General carbon cycling in permafrost environments including some ...
Chapter 5
Figure 5.1 Extent of the High Arctic, Low Arctic, and Sub-Arctic vegetation ...
Figure 5.2 An example of a typical tundra food web. Solid arrows represent t...
Figure 5.3 Arctic landscapes and plant cover from the Low to the High Arctic...
Figure 5.4 Growth forms of arctic plants, mosses, and lichens (ACIA 2005). ©...
Figure 5.5 A transect of vegetation and soils along the Sagavanirktok River,...
Figure 5.6 Elevation effects at the centimeter level. (a) Aerial view of rec...
Figure 5.7 Moss and vascular plants (Huryn and Hobbie 2012). (a)
Sphagnum
mo...
Figure 5.8 Tundra plant net photosynthesis at Barrow, northern Alaska, as af...
Figure 5.9 Lichens (Huryn and Hobbie 2012). The lichen in the lower left is
Figure 5.10 Carbon (black) and nitrogen (gray) budgets of moist acidic tundr...
Figure 5.11 (a) The brown lemming.(b) The under-snow cropping of grasses...
Figure 5.12 The mortality rates incurred on the larvae of the moth
Sympistis
...
Figure 5.13 The belowground food web of the moist acidic tundra of the Low A...
Figure 5.14 Total aboveground
net primary productivity
(
NPP
) of various grow...
Figure 5.15 Tundra wildfires. (a) Small tundra fire in northern Alaska.(...
Chapter 6
Figure 6.1 Green (left) and red (middle) snow and gray ice (right) photograp...
Figure 6.2 Overview of a section of the Greenland Ice Sheet with dispersed c...
Figure 6.3 Parallel elongated ice shelf lakes on the Ward Hunt Ice Shelf (Ca...
Figure 6.4 The structure of the food web found in cryoconite hole sediment a...
Figure 6.5 Schematic representation of the main glacial habitats that are re...
Figure 6.6 Photos of the organisms found in cryoconite holes. These can be p...
Figure 6.7 NASA MODIS Terra image acquired 17 August 2010 showing the presen...
Chapter 7
Figure 7.1 A variety of lakes on a West–East gradient from Canada to Finland...
Figure 7.2 (a) Chlorophyll
a
and (b) primary productivity as a function of t...
Figure 7.3 Adult crustacean zooplankton abundance (bars) in oligotrophic (ch...
Figure 7.4 Life cycle of a calanoid copepod
Mixodiaptomus laciniatus
in an A...
Figure 7.5 Relationship between maximum length of Arctic Charr and (a) lake ...
Figure 7.6 A schematic illustration of the interconnections between the clas...
Figure 7.7 Boxplot (median, 10, 25, 75, and 90% fractiles) of a number of bi...
Figure 7.8 Abundance (number m
−2
, mean ±
SD
) of various benthic invert...
Chapter 8
Figure 8.1 Map of the Arctic Ocean Watershed showing major rivers and other ...
Figure 8.2 (a) Tundra stream (Blueberry Creek, Toolik Field Station, North S...
Figure 8.3 Aerial photo of a tundra stream on the North Slope of Alaska (Kup...
Figure 8.4 (a) Frost polygons in the vicinity of the airport at Deadhorse Al...
Figure 8.5 (a) Tundra stream showing main channel with numerous linear water...
Figure 8.6 Completely frozen stream channel (bedfast ice) during early winte...
Figure 8.7 Bedfast ice during the spring freshet (Atigun River, Toolik Field...
Figure 8.8 Floating ice debris in the Sagavanirktok River (North Slope, Alas...
Figure 8.9 (a) An imaginary lateral view of a generalized, 2-dimensional nut...
Figure 8.10 (a) Arctic grayling (
Thymallus arcticus
; Oksrukuyik Creek, North...
Figure 8.11 (a) Larva of non-biting midge (Diptera: Chironomidae:
Orthocladi
...
Figure 8.12 (a) Emergent larva of
Isocapnia integra
(Plecoptera: Capniidae) ...
Figure 8.13
Aufeis
formed by winter discharge from Cobblestone Spring (Colvi...
Figure 8.14 (a) Melt channel on thawing
aufeis
formed by Cobblestone Spring ...
Figure 8.15 During spring,
aufeis
may host communities of invertebrates on t...
Figure 8.16 Detail of the Mackenzie Delta during winter showing the main riv...
Chapter 9
Figure 9.1 Arctic pelagic ecosystem and its connection to the sympagic (ice-...
Figure 9.2 The physical characteristics of the central Arctic Ocean are very...
Figure 9.3 Conceptual understanding of the timing of ice algae and phytoplan...
Figure B9.1.1 Ice camp on Severnyi Poljus (=North Pole) drift ice stations S...
Figure 9.4 (a) Bathymetry and major current systems of the Arctic. (b) Highl...
Figure B9.2.1 Polynya formation and “ice factories” along the Siberian coast...
Figure B9.2.2 Drift ice zone north of Kong Karls Land, Svalbard: the ice is ...
Figure 9.5 The Arctic pelagic food web: The metazoan food web (upper) is int...
Figure 9.6 Conceptual depiction of the seasonal development of important abi...
Figure 9.7 Adult females of the three congener
Calanus
species and their mai...
Figure 9.8 Conceptual understanding of life cycles of the three
Calanus
spec...
Figure 9.9 Common zooplankton species from the Arctic. (a) Common small-size...
Figure 9.10 Macrozooplankton and fish species from the Arctic. (a) The cteno...
Figure 9.11 Lipids in the Arctic. (a)
Calanus glacialis
with lipid sac: the ...
Figure B9.5.1 Match and mismatch scenarios between timing of ice break-up, a...
Figure 9.12 Changes in the distribution of Arctic and boreal fish communitie...
Chapter 10
Figure 10.1 A diagrammatic representation of Arctic ice-associated communiti...
Figure 10.2 Ice core showing a bottom ice community with dominant pennate di...
Figure 10.3 Schematic food web diagram of diffuse interior (gray box) and bo...
Figure 10.4 Examples of sympagic meiofauna in Arctic sea ice: acoel worm of ...
Figure 10.5 Examples of some common Arctic under-ice metazoans: an autochtho...
Figure 10.6 Example vertical profiles of temperature, bulk salinity, brine v...
Figure 10.7 A diagrammatic representation of possible scavenging (a) and sie...
Figure 10.8 Horizontal section images of tank grown artificial ice without (...
Figure 10.9 Distribution of Arctic sea ice age for March (Week 11) 1985 (a) ...
Chapter 11
Figure 11.1 Arctic fast-ice thickness in three types of coastal environment ...
Figure 11.2 Estimated annual discharge (km
3
) of large Arctic rivers indicati...
Figure 11.3 A mass of lysianassid amphipods attacks a piece of seal skin on ...
Figure 11.4 An iceberg grounded on the seafloor with drop stones frozen into...
Figure 11.5 (a) Intertidal sand flat in a Svalbard fjord. Note scattered bou...
Figure 11.6 Benthic macrofauna inhabiting tidal flats of Svalbard. This prov...
Figure 11.7 Depth distribution of soft-sediment macrofauna around Qeqertarsu...
Figure 11.8 (a) Hard-bottom habitat showing large anemones, pink coralline a...
Figure 11.9 Graph showing a highly significant inverse correlation (coeffici...
Figure B11.2.1 Progression of physical and biological changes in an ice scou...
Figure 11.10 Underwater pool of hypoxic brine concentrated in an ice-scour d...
Figure 11.11 A benthic community dominated by the amphipod
Ampelisca macroce
...
Figure 11.12 Effects of glacial sedimentation on soft-bottom benthos accordi...
Figure 11.13 Modeled changes in food-web structure, and the production (prod...
Figure 11.14 Annual carbon budget for Young Sound (NE Greenland): Shallow-wa...
Figure 11.15 Benthos on the Canadian Beaufort coast adapted to ice scour dis...
Figure B11.3.1 (a) Relationships between indicators of kelp performance (dep...
Figure 11.16 The “island biogeography effect” in coastal species richness. O...
Chapter 12
Figure 12.1 Bathymetric map of the Arctic Ocean showing shelves and deep bas...
Figure 12.2 (a) Generic Arctic food web schematic for the Pacific Arctic....
Figure 12.3 Distribution of total organic carbon in surface sediments, 1974–...
Figure 12.4 Distribution of surface sediment silt and clay (sediment size ≥5...
Figure 12.5 Examples of benthic organisms. Crustacea, Amphipoda: (a)
Anonyx
...
Figure 12.6 Examples of benthic organisms. Mollusca, Bivalvia: (a)
Hiatella
...
Figure 12.7 Examples of benthic organisms. Sipuncula: (a)
Golfingia margarit
...
Figure 12.8 Macrozoobenthic species number on different Arctic shelf seas. B...
Figure 12.9 Faunal taxonomic richness across multiple decades in the Pacific...
Figure 12.10 (a) Iceland scallop (
Chlamys islandica
).http://www.iopan.gd...
Figure 12.11 Schematic figure illustrating sea-ice algae and phytoplankton p...
Figure 12.12 Distribution of sediment community oxygen consumption (mmol O
2
...
Figure 12.13 Distribution of macroinfaunal station biomass (g C m
−2
) a...
Figure 12.14 Effects on total oxygen demand of sediment cores during shipboa...
Figure 12.15 Schematic benthic food webs on the Arctic shelf, in Marginal Ic...
Figure 12.16 (a) Map of northern Bering Sea with location of five St. Lawren...
Figure 12.17 Contraction northward in spatial distribution of dominant amphi...
Chapter 13
Figure 13.1 Population dynamics of collared lemming (
Dicrostonyx groenlandic
...
Figure 13.2 Intra-guild predation: A red fox (
Vulpes vulpes
) killing an Arct...
Figure 13.3 Commercial whaling, here at Svalbard in 1910, reduced the whale ...
Figure 13.4 Polar bears may roam over vast areas but may also spend a consid...
Figure 13.5 A simplified view of the mammal food web interactions in the arc...
Figure 13.6 In winter, Arctic foxes may feed extensively on muskox carcasses...
Figure 13.7 Loss of reproductive output (production of cubs or fledglings) i...
Figure 13.8 Quantification of the relocation of plant biomass and nutrients ...
Figure 13.9 An example of how arctic mammals can contribute to transport of ...
Figure 13.10 Ground icing resulting from rain-on-snow events (b) may cause m...
Figure 13.11 Temporal mismatch between reindeer forage and calving may have ...
Chapter 14
Figure 14.1 Maximum New World avian species (a) and avian family (b) richnes...
Figure 14.2 Relationship between female body size and range of normal clutch...
Figure 14.3 Relationship between female body size and annual adult female su...
Figure 14.4 Relationship between annual survival and production of young per...
Guide
Cover Page
Table of Contents
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Arctic Ecology
Edited by
David N. ThomasUniversity of HelsinkiHelsinki, Finland
This edition first published 2021© 2021 John Wiley & Sons Ltd
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Library of Congress Cataloging-in-Publication Data
Names: Thomas, David N. (David Neville), 1962–editor.
Title: Arctic ecology / edited by David Neville Thomas, University of Helsinki, Helsinki Finland
Description: Hoboken, NJ : Wiley-Blackwell, 2021. | Includes index.
Identifiers: LCCN 2020026614 (print) | LCCN 2020026615 (ebook) | ISBN 9781118846544 (cloth) | ISBN 9781118846575 (adobe pdf) | ISBN 9781118846551 (epub)
Subjects: LCSH: Ecology–Arctic regions.
Classification: LCC QH84.1 .A745 2021 (print) | LCC QH84.1 (ebook) | DDC 577.0911/3–dc23
LC record available at https://lccn.loc.gov/2020026614
LC ebook record available at https://lccn.loc.gov/2020026615
Cover Design: Wiley
Cover Image: © Dennis Fischer Photography/Getty Images
Preface
Sitting down to write this brief introduction is overshadowed by recent reports of a record highest temperature of 38 °C within the Arctic Circle. Undeniably the Arctic is warming at an alarming rate and we can foresee climate and environmental records in the whole region being routinely broken in even the short term. This book was never intended to be a book about the effects of global climate change on Arctic ecology, although we have included two fundamental chapters covering climate change in the Arctic (Chapters 2 and 3). This is not because that issue is not important, in fact it is arguably the region where change is amplified to the greatest extent. However, many statements we make about climate change effects will quickly be out of date and there are more easily and regulated updated resources than a book like this (cf. Box et al. 2019; IPCC 2019; Overland et al. 2019). Instead our aim was to produce a book that seeks to systematically introduce the diverse array of ecologies within the Arctic region, highlighting some influences of global climate change where appropriate.
The Arctic is often portrayed as being isolated, but the reality is that the connectivity with the rest of the planet is huge, be it through weather patterns, global ocean circulation, and large-scale migration patterns to name but a few. A more immediate connectivity is evident in Figure P.1. From 2008 this illustration well reflects the connectivity in terms of human populations associated with the perimeter of the Arctic Circle. It does not leave much to the imagination as to how this will change over the next decades.
This project was conceived in October 2012 and gelled during 2013. The need for this book was obvious then, but over the intervening seven to eight years its pertinence has grown immensely. Our aim, as in 2012, is that the book stimulates a wide audience to think about the Arctic by highlighting the remarkable breadth of what it means to study its ecology. The Arctic is rapidly changing and by the time a second edition of this book is published, it will be a very different place than it is today. Understanding the fundamental ecology underpinning the Arctic is paramount to understanding the consequences of what such change will inevitably bring about.
A final comment is that although we have tried to synthesize current understanding, for many habitats within the Arctic we are still only beginning to understand some key processes and mechanisms. It is hoped that this book will spur the imagination of many readers to go on to dedicate their efforts so that some of the conclusions outlined here are confirmed, or even disproven, and the many knowledge gaps filled.
David N. Thomas
Anglesey, July 2020
Figure P.1 A view of the Arctic showing the Arctic Circle and human population density in red and large oil fields in black.
Source: Hugo Ahlenius, UNEP/GRID-Arendal. https://www.grida.no/resources/7143.
References
Box, J.E., Colgan, W.T., Christensen, T.R. et al. (2019). Key indicators of Arctic climate change: 1971–2017.
Environmental Research Letters
14 (4): 045010.
https://doi.org/10.1088/1748-9326/aafc1b
.
IPCC (2019). Special Report on the Ocean and Cryosphere in a Changing Climate.
https://www.ipcc.ch/srocc/
(accessed 26 June 2020).
Overland, J., Dunlea, E., Box, J.E. et al. (2019). The urgency of Arctic change.
Polar Science
21: 6–13.
https://doi.org/10.1016/j.polar.2018.11.008
.
List of Contributors
Jon Aars
Norwegian Polar Instiute
Tromsø
Norway
Alexandre M. Anesio
Department of Environmental Science
Aarhus University
Roskilde
Denmark
Jørgen Berge
Department of Arctic and Marine Biology
UiT The Arctic University of Norway
Tromsø
Norway
Joseph Bowden
Atlantic Forestry Centre
Natural Resources Canada
Corner Brook
Canada
Torben R. Christensen
Department of Bioscience
Aarhus University
Roskilde
Denmark
Kirsten S. Christoffersen
Department of Biology
University of Copenhagen
Copenhagen
Denmark
Kathleen E. Conlan
Zoology Section
Canadian Museum of Nature
Ottawa
Canada
Malin Daase
Department of Arctic and Marine Biology
UiT The Arctic University of Norway
Tromsø
Norway
Kjell Danell
Department of Wildlife, Fish, and Environmental Studies
Swedish University of Agricultural Sciences
Umeå
Sweden
Stig Falk-Petersen
Akvaplan-niva
Tromsø
Norway
Anthony D. Fox
Department of Bioscience
Aarhus University
Rønde
Denmark
Olivier Gilg
Laboratoire Chrono-environnement
Université de Bourgogne Franche-Comté
Besançon
France
Jacqueline M. Grebmeier
Chesapeake Biological Laboratory
University of Maryland Center for Environmental Science
Solomons
USA
Richard J. Hall
School of Geographical Sciences
University of Bristol
Bristol
UK
Edward Hanna
School of Geography & Lincoln Centre for Water and Planetary Health
University of Lincoln
Lincoln
UK
John Hobbie
The Ecosystems Center
Marine Biological Laboratory
Woods Hole
USA
Toke T. Høye
Department of Bioscience and Arctic Research Centre
Aarhus University
Rønde
Denmark
Alexander D. Huryn
Department of Biological Sciences
University of Alabama
Tuscaloosa
USA
Rolf A. Ims
Department of Arctic and Marine Biology
University of Tromsø
Tromsø
Norway
Erik Jeppesen
Department of Bioscience
Aarhus University
Silkeborg
Denmark
Monika Kędra
Institute of Oceanology
Polish Academy of Sciences
Sopot
Poland
Torben L. Lauridsen
Department of Bioscience
Aarhus University
Silkeborg
Denmark
Johanna Laybourn-Parry
School of Geographical Sciences
University of Bristol
Bristol
UK
Klaus M. Meiners
Department of Agriculture, Water, and the Environment, and Australian Antarctic Program Partnership (AAPP)
University of Tasmania
Hobart
Australia
C.J. Mundy
Department of Environment and Geography
University of Manitoba
Winnipeg
Canada
Joseph E. Nolan
European Polar Board
The Hague
The Netherlands
Mark Nuttall
Department of Anthropology
University of Alberta
Edmonton
Canada
James E. Overland
NOAA/Pacific Marine Environmental Laboratory
Seattle
USA
Michael Pisaric
Department of Geography and Tourism Studies
Brock University
St. Catharines
Canada
Milla Rautio
Département des Sciences Fondamentales
Université du Québec à Chicoutimi
Canada
Paul E. Renaud
Akvaplan-niva
Tromsø
Norway
The University Centre in Svalbard
Longyearbyen
Svalbard
Norway
Niels M. Schmidt
Department of Bioscience
Aarhus University
Roskilde
Denmark
Gaius Shaver
The Ecosystems Center
Marine Biological Laboratory
Woods Hole
USA
John P. Smol
Department of Biology
Queen’s University
Kingston
Canada
Janne E. Søreide
Department of Arctic Biology
The University Centre in Svalbard
Longyearbyen
Svalbard
Norway
David N. Thomas
Faculty of Biological and Environmental Sciences
University of Helsinki
Helsinki
Finland
Jan Marcin Węsławski
Department of Marine Ecology
Institute of Oceanology
Polish Academy of Sciences
Sopot
Poland
1 What Is the Arctic?
Kjell Danell
Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, SE 901 83, Umeå, Sweden
1.1 Setting the Scene
The aim of this chapter is to “set the scene” for the rest of the book. The “actors” are climate, glaciers, lakes, streams, rivers, sea ice, pelagic, benthic, plants, soil, birds, and mammals. In which ways is the Arctic different? How was it discovered and explored? How large is it? What is found there? What is the Arctic providing in terms of natural resources and ecosystem services? And finally, what are the biotic changes due to various major drivers including global climate change?
The name Arctic derives from the Greek word Arktikós, meaning the land of the North. It relates to Arktos, the Great Bear, which is the star constellation close to the Pole Star (CAFF 2013). For a long time, the Arctic has fascinated people and such intrigue extends back some three millennia according to notes and drawings in early Chinese culture. Since then the Arctic has been mapped and its landscape, biota and native people discovered and documented. Visions, bold ideas and the search for natural resources stimulated much of this endeavor. It took hundreds of years to get a reliable picture of this “unknown and mysterious” far-away land. Many of the “mysteries” are now resolved, but the immense beauty is still there, and it is safe to say that many exciting things and phenomena remain to be discovered by coming generations of Arctic explorers.
Today many of these northern realms are possible to reach within a few hours. Anyone with internet and access to global maps can “explore” even the most remote corners of the Arctic in an armchair. In addition, modern field and laboratory techniques have given us more powerful tools for certain advanced research than have ever before existed. This chapter will give a brief overview of the Arctic: Although trying to avoid generalities, some cannot be escaped – remember Aldous Huxley's (1894–1963) statement in Brave New World (1932) “Generalities are intellectually necessary evils.”
1.2 In Which Ways Is the Arctic Different?
The Arctic is situated at high latitudes and includes land, ice, rivers, lakes, and seas above the boreal forest and ends at the North Pole. The Arctic is to a large extent covered by ice and snow. Generally, it is a cold region of the planet with four distinct seasons. However, the Saami people, with a culture strongly connected to reindeer herding, divide the year into eight functional seasons. Winters and summers are cold, but the summer can be 30–50 °C warmer than the winter. For much of the Arctic there is a continuous winter night at mid-winter, but at mid-summer the sun shines both day and night. In spring, the bright light demands sunglasses. Many artists have stressed how different the light is in the Arctic compared with what is found elsewhere. The Arctic is generally silent except during a few weeks in spring and fall when the migrating birds arrive and leave.
In the Arctic ice dominates as icebergs, glaciers, ice sheets, ice-covered lakes, rivers, seas, and oceans as well as the frozen subsoil, the permafrost (Figure 1.1). The land is without trees and is generally divided into two major vegetation zones, polar desert and tundra. There are peculiar geometric patterns on the ground as well as heap-like structures with an ice core. Winds and waters transport nutrients, pollutants, living plants, and animals from the south and so the Arctic is not isolated in the way that the Antarctic is. Human communities and settlements are small and most of the Arctic is not populated but if it is, only sparsely.
The Arctic is changing now but always has been. The most dramatic time was when the Arctic was formed by rotation and migration of tectonic plates. During the ice ages it was totally covered by ice and snow. Between these cold periods there were warmer times with steppes and forests inhabited by mammoths, tigers, and rhinoceros. Today there is intense discussion about how serious the changes we have noted in modern times really are, and sometimes some of this controversy depends upon what is studied, where and for which time period. However, beyond this, there are without doubt many alarming observations of significant deviations from normal, and which demand our attention and action. Science and gathering traditional knowledge help us to understand what is going on, and perhaps may help us mitigate serious unwanted changes.
Figure 1.1 Iceberg in spring. Devon Island.
Source: Photo: Kjell Danell.
Table 1.1 Some Arctic explorers and expeditions up to 1900.
Years
Travelers
Area
c. 330
BCE
Pytheas of Massilia
The waters north of Scotland
c. 879
CE
Floki Vilgerdarson
Iceland
983
Erik the Red
Greenland
1000
Leif Eriksson
Newfoundland
1000–1200
Novgorodians
White Sea
1594–1597
Willem Barents
Spitzbergen, Novaya Zemla
1615–1616
William Baffin and Robert Bylot
Hudson Bay, Baffin Bay
1725–1734
Vitus Bering
Kamchatka
1825–1827
John Franklin
Coronation Gulf – Prudhoe Bay
1845
John Franklin
Northwest Passage
1878–1879
Adolf Nordenskiöld
Northeast Passage
1888
Fridtjof Nansen
Greenland
1893–1895
Fridtjof Nansen
Arctic Ocean
1.3 How Was the Arctic Discovered?
The Arctic was discovered tens of thousands of years ago by small groups of humans who migrated to it. During the last centuries many Arctic expeditions carved their names into the Arctic history (Table 1.1). The first true discoverers of a given area are often difficult or impossible to determine (Levere 1993; Liljequist 1993).
The Greek, Hippocrates (c. 460–370 BCE) never visited the Arctic, but he drew a map of the northern land where the Hyperboreans lived. They were too far away to be reached by anyone. Another Greek, the sailor Pytheas (c. 380–310 BCE), was the first Arctic explorer as far as we know. Around 325 BCE he sailed to search for tin, which was used for the production of bronze and he found it in Cornwall, and during the voyage he was told about the mysterious northern land of Thule. Pytheas sailed north and after a week he reached a frozen sea. He reported polar bears and what could have been the Aurora Borealis and the midnight sun. Unfortunately, the exact route he sailed is not known.
The Vikings were early Arctic explorers of North America, Iceland, Greenland, and eastern areas too. The Pomors, Russian settlers and traders at the White Sea, started exploration of the Northeast Passage as early as the eleventh century. In 1553, Russians founded the Pechenga Monastery on the northern Kola Peninsula, from which the Barents Region, Spitzbergen, and Novaya Zemlja were explored. A settlement on Yamal Penisula was established in the early sixteenth century and Russians reached the trans-Ural as well as northern Siberia. It is not possible to describe the exploration of all Arctic lands here, but there are many fascinating stories to read (e.g. John Franklin's travel on the Northwest Passages in 1845 and Salomon August Andrée's polar expedition by balloon in 1896–1897).
Table 1.2 Some examples of the different bases for defining the extension of Arctic.
1) Arctic Circle, 66.3°N
2) Mean summer temperature of no more than 10 °C
3) Permafrost
4) Lakes and sea ice-covered
5) Absence of trees
6) Vegetation zones
7) National borders
8) Practical solutions
In 1878 the Finnish–Swedish explorer Adolf Erik Nordenskiöld (1832–1901) managed to sail through the Northeast Passage with his ship Vega. The Northwest Passage was also traversed in 1906 by the Norwegian Roald Amundsen (1872–1928) on the herring boat Gjøa. The first undisputed sighting of the Pole was made in 1926 from the airship Norge by Roald Amundsen and others.
More recently of significant importance for the exploration of the Arctic has been the International Polar Years. During the first one, 1882–1883, 12 meteorological stations were established. Fifty years thereafter, the Second International Polar Year took place and among other activities, 94 arctic meteorological stations were set in place. The Fourth International Polar Year, 2007–2008, involved more than 10 000 scientists from more than 60 countries engaged in over 170 research projects (Allison et al. 2007).
1.4 How Large Is the Arctic?
Because of the many different definitions of the Arctic (Table 1.2) various figures for its size are given. Commonly, around 10 million km2 for the land between the closed boreal forest and the Arctic Ocean is used (The Millennium Ecosystem Assessment 2005). The Arctic Ocean is larger, 14 million km2. However, some of the map projections mislead us and make the Arctic seem much larger on the map. This is especially true when the drawings do not take into account that the distances between the latitudes get smaller toward the north. The circumference of the Equator is around 40 000 km and the 70°N parallel is only about 13 750 km (Nuttall and Callaghan 2000).
1.5 What Is in the Arctic?
1.5.1 Arctic Haze and Ice Fog
During winter, the Arctic receives air masses with pollution from mid-latitudes due to emissions from the burning of fossil fuel and industrial processes; this is called Arctic haze. Ice fog is more local and occurs around −30 °C and during situations with significant temperature inversions. Water vapor from for example trucks and heating systems condense into droplets which supercool or freeze (Nuttall and Callaghan 2000; AMAP 2003, 2011a).
1.5.2 Aurora Borealis
The Arctic as well as the Antarctic have “windows” to space. The atmosphere of the sun and our atmosphere are brought into contact by the earth's magnetic field (Nuttall and Callaghan 2000). In the Arctic, the Aurora Borealis is most common in the zone 20°–25° from the Magnetic Pole, which is not exactly the same as the geographic North Pole. An explanation for the phenomenon is that high energy electrons and protons are accelerated down the magnetic field lines to collide at 70–200 km height with our neutral atmosphere and release numerous electrons and ionizing atoms and molecules. When these are transformed back to their ground states, various colors of light are emitted and we see the Aurora.
Under extreme conditions in the atmosphere there are many optical and acoustic phenomena due to microscopic ice crystals suspended in the air which change how light and sound travel. Under such conditions, conversations between humans can sometimes be heard up to three kilometers away. Further, snow, ice, and layers of air with different characteristics produce illusions. Together, these conditions form a base which may account for many “Arctic mysteries.”
1.6 Climate and Weather
The climate is what happens over a longer time period, for example 30 years. Weather is the short-term variations and is what we experience when outside during a day. The climate and weather of the Arctic are extreme, and the limited sunlight makes these environments inhospitable for most plants, animals, and humans. The snow-free seasons are short and range from one to three months. The warmest month, often July, has a mean temperature below 10–12 °C in many places. Winters are cold and temperatures can go down to −60 °C or more in continental parts. The difference in temperature between the coldest and the warmest months is at extremes 80 °C or more (CAFF 2013).
In the Arctic there are two main types of climate, maritime and continental. There are large variations in time and space. The Arctic is part of the global circulation patterns of the atmosphere and oceans. The drivers are the sun and the difference in temperature between the Equator and the poles. Large amounts of solar energy are received in the equatorial regions and much of it is transported by air masses and oceans north- and southwards. From the poles, energy goes back to space. On the other hand, cold water current and air masses from the poles go to warmer regions (The Millennium Ecosystem Assessment 2005). “Arctic” temperature conditions can occur at relatively low latitudes (e.g. at 52°N in eastern Canada), but on the other hand forestry and agriculture is practiced north of the Arctic Circle in Fennoscandia.
1.7 Ice and Snow
There are many types of ice and snow on land and water in the Arctic. The land ice sheets cover 50 000–100 000 km2 and can be up to several thousand meters thick. The ice can flow in all directions from the center. Within the Arctic, the Greenland Ice Sheet is the largest and represents about 15% of the total area of all glaciers in the world. Its mean thickness is around 1500 m with a maximum of 3200 m. It has been estimated that the age of the base is over 100 000 years old. This is the reason for drilling in this unique frozen archive to collect information on past events. Glaciers are smaller ice masses, often less than 8000 km2.
The average cover of sea ice varies between 6.5 × 106 km2 in September and 15.5 × 106 km2 in March (Figure 1.2). It controls the exchange of energy and mass between the atmosphere and ocean (Chapter 10; AMAP 2011b; Laybourn-Parry et al. 2012; Thomas 2017).
1.8 Permafrost, Polygons, Pingos, and Palsas
There is continuous permafrost in the Arctic, and it is present under all land and even below the continental shelves. Permafrost is a substrate which has been at or below 0 °C for at least two years in a row (The Millennium Ecosystem Assessment 2005).
Figure 1.2 Sea ice in spring. Kent Peninsula.
Source: Photo: Kjell Danell.
The annual freezing and thawing processes result in repeated expansions and contractions of soils. During freeze–thawing from the top, the larger particles move upwards and the finer ones move down. This sorting may produce circles and polygons, often of very striking orthogonal or hexagonal patterns on the ground (Figure 1.3). Such processes also form more distinct landform, for example boulder fields, pingos, and palsas. A pingo is a continuous frost mound which can be several tens of meters in height, has a massive ice core and is covered with soil and vegetation. A palsa is similar and occurs in peaty, permafrost-dominated material. Its height ranges from 0.5 to 10 m and it has a width of over 2 m.
Most of the Arctic permafrost is found on Greenland; 80% of Alaska and about 50% of Russia and Canada are covered. There is little information on the thickness of permafrost, but it reaches 400–1000 m. The thickness decreases southwards in parallel with an increase in the depth of the active layer, which ranges from 0.3 m in the High Arctic to over 2 m in the southern parts. The top three meters of permafrost soils contain more than twice the amount of carbon as the atmosphere (CAFF 2013), so thawing permafrost may further influence global warming.
1.9 Animals, Plants, and Fungi
The Arctic biota contains more than 21 000 species of mammals, birds, fish, invertebrates, plants, and fungi with lichens included. In addition, there are numerous known and unknown endoparasites and microbes. Some of the Arctic species have become icons, e.g. Arctic fox, caribou/reindeer, muskox, narwhal, walrus, ivory gull, and snowy owl (Figure 1.4; Blix 2005; Pielou 2012; CAFF 2013; Crawford 2014).
Figure 1.3 Wetland polygons. Chatanga.
Source: Photo: Kjell Danell.
Mammals: About 70 terrestrial and 35 marine species are found in the Arctic, which represents 1 and 27%, respectively, of the global species pool of approximately 4000 species; in all 2%. Out of the totals, 19 terrestrial and 11 marine mammalian species are predominantly Arctic (CAFF 2013). The species richness is generally higher in the Low Arctic than in the High Arctic. The highest numbers of species are found in areas which were not glaciated during the last ice age, for example Beringia. For the marine mammals, species richness is highest in the Atlantic and Pacific sectors.
Examples of human translocations of mammals are bison, muskox, and muskrat. Human-induced global extinctions include Steller's sea cow and populations of Atlantic gray whale and Northeast Atlantic northern right whale. Local extinctions have occurred in many places, but some such as walrus, beluga whale, and large terrestrial predators are now recovering from heavy hunting. Significant northern range expansions during the last decades are shown by moose, snowshoe hare, and red fox. An endangered mammalian species, according to the International Union for Conservation of Nature (IUCN) criteria, is the Pribilof Island shrew (CAFF 2013).
Birds: About 200 bird species occur regularly in the Arctic, which is about 2% of the global total but only a handful of these birds stay year-round. Approximately one fourth of the total bird species are marine. Focusing on the Arctic, we can regard about 80 as freshwater and terrestrial birds, and about 25 as marine birds. The majority of the Arctic species are waterfowl, shorebirds, and seabirds. The Arctic is now the home for 30% of the world's shorebird species and two thirds of the global numbers of geese (CAFF 2013). Highest species richness is found in the Bering Strait region. In general, Arctic birds are more long-lived and often more specialized feeders than birds in other areas. Most Arctic seabirds nest in colonies, often in spectacular numbers. There are nine avian raptor species and two owls which are often partly dependent upon the abundance of lemmings and voles for good reproduction (Chapter 14). The great auk is extinct, the Eskimo curlew is probably extinct, and the spoon-billed sandpiper is close to extinction. Threatened species are the lesser white-fronted goose, red-breasted goose, bristle-thighed curlew, and Siberian crane (CAFF 2013).
Figure 1.4 Reindeer antlers. Northwestern Taymyr Peninsula.
Source: Photo: Kjell Danell.
Amphibians and reptiles: Only five amphibians and one reptile, a lizard, are found in the low Arctic. All species are considered to be stable.
Fish: There are about 250 marine and 127 anadromous and freshwater fishes in the Arctic. Together they constitute about 1% of the global fish pool with no difference between the groups. Of the first mentioned group there are about 80 species classified as mainly Arctic and of the second group about 60. The highest species richness is found in the Arctic gateways to the Atlantic and Pacific Oceans. There are no clear examples of extinct Arctic fish species. The IUCN status of the Arctic fish fauna has not yet been evaluated (CAFF 2013). Many fish species have been translocated, especially salmonids.
Terrestrial and freshwater invertebrates: There are upwards of 4750 species of terrestrial and freshwater invertebrates in the Arctic, but many additional species certainly remain to be described. The most species-rich groups are amoebae, rotifers, water bears, water fleas and copepods, ostracods, enchytraeid worms, eelworms, spiders, springtails, mites, and insects. For example, springtails are more common in the Arctic than expected and insects are less common. Endemism varies greatly between groups. For example, it is 31% for one group of mites and 0% for stoneflies (CAFF 2013). A group of insects which summer travelers cannot avoid are the mosquitos.
Marine invertebrates: About 5000 species of marine invertebrates are found in the Arctic, microbes excluded. Several areas are under-sampled, so estimates are uncertain. Around 90% of the fauna known today are benthic and compared with other marine areas in the world, the Arctic has an intermediate species richness. There are few endemic species. One of the invasive species is the red king crab from the Barents Sea (CAFF 2013).
Plants: Of the vascular plants about 2200 species are Arctic, about 1% of the global number. About 5% of the Arctic flora is constituted of non-native species, endemic species account for about 5% (CAFF 2013). No native species are known to have gone extinct due to human activities. The number of bryophytes is around 900; 6% of the global total. For terrestrial and freshwater algae more than 1700 species are reported, estimates for marine algae are of more than 2300 species.
Fungi: The total number of fungi in the Arctic is about 4300; 2030 macrofungi and 1750 lichens. This corresponds to about 4% for the total number of fungi in the world and c. 10% of the global lichen pool. Most species seem to occur throughout the Arctic and there are few species classified as endemic (CAFF 2013).
1.10 Arctic Ecosystems
The Arctic is situated around a mainly ice-covered ocean, the Arctic Ocean. It is connected to the Atlantic by a wide passage, and a narrow opening to the Pacific Ocean by the Bering Strait (Sakshaug et al. 2009). On one side of the Arctic Ocean, there is the northern part of Eurasia with a long and relatively straight shoreline with few peninsulas and islands. On the other side, there is North America with a more fragmented shoreline. One fifth of the world's total coastline, about 177 000 km, is found in the Arctic (CAFF 2013). The Arctic represents a wide variety of landscapes with mountains, glaciers, plains, rivers, lakes, wetlands, and polar deserts (Figure 1.5). Different seascapes occur from the shallow coastal areas to the deep ocean reaching a depth of about 5 km.
Here, we divide the Arctic ecosystem into terrestrial, freshwater, and marine ecosystems. There are productive and species-rich habitats between these major ecosystems, e.g. tidal flats. However, we should always keep in mind that the Arctic is an integrated ecosystem. During the Quaternary Period, the Arctic ecosystem was profoundly molded by climate during more than 20 cycles of glacial advances and retreats in parallel with changes in sea-ice cover (CAFF 2013). Still, it is a young ecosystem.
1.10.1 Terrestrial Ecosystems
The Arctic land covers about 5% of the global land surface (CAFF 2013). The main landforms are mountains and plains or plateaus. At coasts dominated by mountains we can find dramatic fjord landscapes. Sharp mountain peaks characterize young mountain ranges such as the Canadian Rockies, while the older Urals have more rounded peaks. Active volcanos are mainly located in Beringia and Iceland. The plains/plateaus are covered by deposits of glacial, alluvial, and marine origin.
Figure 1.5 Polar desert. Ellef Ringnes Island.
Source: Photo: Kjell Danell.
Table 1.3 Ecosystem types in the Arctic, in million km2.
Source: Hassan et al. (2005, p. 720).
Ecosystem types
Total
Canada
USA
Greenland
Eurasia
Ice
2.50
0.25
0.10
1.95
0.20
Barrens
3.01
1.90
0.11
0.12
0.88
Tundra
5.06
1.14
0.80
0.07
3.05
Ice covers a minor part of the Arctic (Table 1.3 and Figure 1.6). Barrens are partly free from vegetation in contrast to the tundra. The tundra is the largest natural wetland of the world and covers almost half of all the Arctic land (The Millennium Ecosystem Assessment 2005).
The tundra vegetation type is not unique for the Arctic because it also occurs in the upper boreal zone as well as in alpine areas (CAFF 2013). The high latitude tundra is found in the High Arctic, Low Arctic, and Sub-Arctic where they are inhabited by somewhat different functional groups of plants. For most Arctic plant taxa, the species richness is low. This is explained by the relatively young age of the ecosystem (around three million years), low solar energy influx, extreme climatic variability and decreasing biome area with increasing latitude (CAFF 2013). Many of the northern species have a circumpolar distribution and occur in a wide range of habitats. Particularly the temperature is responsible for the composition of the biota. All this leads to a rather uniform biota in the Arctic, which becomes more diverse closer to the tree line. The topographic variation between lowlands and mountain adds more biodiversity to the landscape (Nuttall and Callaghan 2000). In the rather uniform landscapes, we can notice greener patches when the composition of nutrients, water, and light are optimal. On a much smaller scale, such green patches occur around things such as a carcass of a muskox (Figure 1.7).
Figure 1.6 Mosses near the ice front. Melville Island.
Source: Photo: Kjell Danell.
