State of the Arctic Terrestrial Biodiversity Report: Findings

The Arctic Terrestrial Biodiversity Monitoring Plan (CBMP Terrestrial Plan) is an agreement by Arctic states and Permanent Participants (PPs) to compile, harmonize and compare results from Arctic terrestrial biodiversity monitoring efforts. This work is coordinated under the Circumpolar Biodiversity Monitoring Program (CBMP) of the Arctic Council’s Conservation of Arctic Flora and Fauna (CAFF) Working Group.

The CBMP is a network of scientists, Indigenous Knowledge and/or Local Knowledge holders, governmental bodies, Indigenous organizations, conservation groups, and practitioners, working to harmonize and integrate efforts to monitor the Arctic’s living resources.

Key elements of the terrestrial ecosystem, called Focal Ecosystem Components (FECs), were identified as important to monitor because they may indicate changes in the overall terrestrial environment. FECs were identified within vegetation, arthropods, birds, and mammals. Furthermore, several attributes of FECs, such as abundance, demographics, diversity, or phenology, were identified and further classified as essential or recommended for monitoring. The START focuses its reporting on essential attributes, as these data are more often available.

Spring tundra. Photo: Vladimir Yakovlev

Climate change is the overwhelming driver of change in terrestrial Arctic ecosystems, causing diverse, unpredictable, and significant impacts that are expected to intensify.

Increasing temperatures cause earlier onset, longer duration and increased plant growth, and changes in diversity, abundance, composition and structure of vegetation. Since 2001 there has been a significant increase in vegetation productivity across the Arctic, and an earlier start of the growing season in the sub and low Arctic.
Different climate scenarios predict that up to 80% of high-Arctic breeding waders may lose much of their current breeding areas in 50 years, potentially changing species interactions and migration patterns.
Higher spring temperatures and less snow cover increase nesting success for many geese.
Increasing temperatures influence development, distribution, and emergence of some caribou/reindeer and muskoxen pathogens that may negatively impact health.
Recovery from declines in some Arctic island populations of caribou/reindeer may be hampered by multiple threats, including decreases in sea ice connectivity between winter and summer ranges.
Earlier springs disrupt the timing of ecological cues that some species use to start key life events. Although evidence varies, mismatches are considered among the leading potential stressors of climate change.
- Earlier snow melt can lead to earlier arthropod emergence and peak activity, affecting key ecosystem services like pollination, and food availability for birds. Missing an advancing window of peak food abundance has reduced growth rates and body size of some wader species, while other species appear unaffected.
- Changes in spring snow cover can influence the timing and success of breeding waders. Some species have advanced their breeding, while others are unable to keep pace, all with unknown effects at the population level.
- Some caribou/reindeer populations have experienced reproductive failures associated with a mismatch in timing with their food.
Natural population cycles of some species are fluctuating beyond historical levels, with potential effects on predator-prey dynamics and other species interactions.
- Reduced snow cover can negatively impact lemming winter reproduction, and although no circumpolar trend has been detected, declining lemming populations reduce an important food source for many Arctic species and may increase the predation risk to ground-nesting birds.
- In Scandinavia, the rough-legged buzzard population has declined by almost 50% since the 1970s and has been partly decoupled from rodent cycles, and snowy owls have very low productivity in areas and years with low lemming population.
- Reductions in ptarmigan abundance reduce the breeding success of gyrfalcon in some areas.
- Some caribou/reindeer populations have hit historic lows, in part from a warming climate and industrial development, including habitat fragmentation, degradation and disturbance.

Changing frequency, intensity and timing of extreme and unusual weather events due to climate change are affecting some species, with unknown effects on populations.

Increasingly mild winters and ground-ice formation is causing damage to vegetation.
Increases in surface icing may result in increased winter mortality of springtails, important for decomposition and nutrient cycling.
Increased frequency of heavy rain events, and warm temperatures causing massive blackfly outbreaks, have killed Arctic peregrine falcon chicks.
Winter rain and midwinter thaws lead to impenetrable layers of hard snow and icing, making it difficult for species to access forage, leading to reduced movement, reproduction, and survival of lemmings, decreased caribou/reindeer calf survival and, in extreme cases, caribou/reindeer die-offs

Although some trends have been observed, natural variability in Arctic terrestrial environments and large information gaps make it difficult to assess and summarize global trends for Arctic terrestrial biodiversity.

Data for most FECs was often deficient, with uneven geographic coverage and incomplete time series. Therefore, it was possible to report on only about half of FEC attributes identified as essential or recommended by the CBMP Terrestrial Plan, and some FECs went unreported.
Changes in Arctic terrestrial environments are fundamentally diverse with some species’ populations increasing in some areas and decreasing in others. Summarizing these changes at the circumpolar scale can hide dramatic changes at the local level.
Given highly variable environments, drivers need to be investigated and interpreted in ecosystem or habitat specific contexts.

Red knot. Photo: Danita Delimont/Shutterstock.com

Species from southern ecosystems are moving into the Arctic and are expected to push Arctic species northwards, create an “Arctic squeeze,” and change species’ interactions

There has been increased growth and encroachment of shrubs and trees in parts of the low Arctic, expansion of woody plants into the tundra, and increased grass cover, while moss and lichen cover has decreased.
Outbreaks of fast-moving defoliating insects are expected to increase as species shift northward. Some birds species are moving northwards, for example, snowy owls are breeding further north in western Siberia, peregrine falcons have possibly expanded their range in high Arctic Greenland and the shorteared owl has expanded into the eastern Canadian high Arctic. In 2017, Lapland longspurs were found breeding over 650 kilometres further north of their previous-known range in east Greenland. In sub-Arctic Scandinavia, some bird ranges advanced 21 kilometres northward between 1970-2000.
Range extension of boreal mammals such as the red fox, moose, American beaver, snowshoe hare and voles into the Arctic introduces new competitors and predators with unclear effects on Arctic species.
Increased range overlap between muskoxen and grizzly bears in northeastern Alaska has resulted in new predator-prey dynamics.
Pathogens from southern latitudes are a concern for the health, distribution and dynamics of Arctic species.

Changes in culturally important food resources have implications on the food security and cultures of Indigenous Peoples and Arctic residents.

Indigenous Knowledge indicates increasing variability in year-to-year berry abundance, which may be particularly pronounced for plants with specialist pollinators.
In recent years, unprecedented outbreaks of defoliating insects have caused severe declines in berry yields for some Indigenous communities.
Most Arctic goose populations that stage or winter in North America and western Europe have increased but many goose populations that breed in the Russian Arctic and stage or winter in central and eastern Asia are declining. These changes are largely the result of influences outside the Arctic.
Some caribou/reindeer populations of importance to Indigenous communities have dramatically declined, with some experiencing changes in distribution, range, and fragmentation. For example, the Bathurst population declined by 98% between 1986 and 2015, with post-calving and autumn range declines, and a change in winter habitat from the boreal forest to the tundra, which reduced spring migration distance by 50%.
Lack of data makes it difficult to understand the extent and magnitude of change in many food resources.

Berries. Photo: longtaildog/Shutterstock.com

The range and complexity of drivers affecting Arctic terrestrial biodiversity signals the need for comprehensive, integrated, ecosystem-based monitoring programs, coupled with targeted research projects to help decipher causal patterns of change.

Integrated monitoring of abiotic and biotic interactions is critical for the ability to understand changes in Arctic terrestrial biodiversity and must permeate current and future monitoring and reporting.
Arctic biodiversity is under pressure from a variety of drivers acting alone and in combination. There is currently no scientific method or standardized approach for determining the cumulative effects of stressors, but various modelling frameworks look promising.
Knowledge about causalities in the ecosystem, spatial data on important areas for species and ecosystems, and data on the distribution and intensity of human activities are essential to establish a more adaptive and ecosystem-based approach to management.
Indigenous Knowledge encompasses entire annual cycles, extended time periods, evaluation processes, and methodologies. This long-term holistic perspective can provide important insights.