Arctic Biodiversity Trends 2010

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Arctic Biodiversity Trends 2010

Ecosystems

Arctic sea ice is a unique ecosystem providing habitat to many ice-associated species, including micro-organisms, fish, birds, and marine mammals. Although Arctic sea ice has decreased substantially in extent and thickness in recent years, the response of individual species to changes in sea ice depends on its ability to adapt and its natural history, as well as the scale of environmental change. Information to assess the status and trends of ice-associated species is very limited, and in some cases the relationship between sea ice and species is not entirely understood. Continued sea ice loss due to climate change is expected to lead to changes in the sea-ice ecosystem towards a pelagic, sub-Arctic ecosystem over a larger area. Increased production in open water may increase prey concentrations for some species, such as bowhead whales; however, with less ice there will be less ice algae, affecting bottom-feeding marine species. Continued warming and continued reductions in sea ice will likely result in the northward expansion of sub-Arctic species, with the associated potential for increase in disease, predation, and competition for food. Arctic sea-ice ecosystem Indicator #10 PAGE 58

Indicator #11 PAGE 62

Greening of the Arctic

Climate change is impacting terrestrial Arctic ecosystems, with evidence showing that Arctic vegetation has undergone significant shifts in recent decades. There is an increase in productivity over much of the Arctic, as well as an increase in the length of the growing season. The northward movement of the treeline is encroaching on the southern margin of the tundra and could result in significant losses of tundra habitat by 2100. Climate warming is also likely to change the composition of plant communities. While the number of plant species inhabiting the Arctic may actually increase over the long term, the diversity of plants unique to the Arctic will probably decrease in abundance.

Indicator #12 PAGE 65

Changes in the timing of reproduction in plants and animals have been reported from the Arctic. There is some evidence indicating that the timing of reproduction – including the flowering of plants, emergence of insects, and egg-laying in birds – is occurring earlier in response to warming conditions and earlier snowmelt. Longer growing seasons may be an advantage to some species in terms of reproduction and growth. There is, however, a serious risk of disruptions in food webs when there is a “trophic mismatch”, where the breeding of some species (e.g., caribou or birds) no longer matches up with the timing of the most abundant and nutritious food (e.g., new plant growth or insects). Reproductive phenology in terrestrial ecosystems