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Summers in Alaska’s Arctic Network parks started about 11 days earlier in 2020, on average, than in 2000. This National Park Service resource brief reports what 20 years of monitoring show about the “landscape dynamics” of five parks: Bering Land Bridge National Preserve, Cape Krusenstern National Monument, Noatak National Preserve, Kobuk Valley National Park and Gates of the Arctic National Park and Preserve.
Muskox photographed by a remote automated camera at the Mt. Noak climate monitoring station in Cape Krusenstern National Monument on 5 September 2020, near the end of the growing season, when only a few plants, like the green patch near the muskox, were still green.
The five Arctic Network parks, in all of which landscape dynamics are monitored.
What the monitoring shows
| Measure | Finding |
|---|---|
| Season timing | The start and end of the growing and snow-free seasons vary by about a month from year to year, but the 20-year trend is toward longer summers |
| Lakes and ponds | Area has fluctuated without major gains or losses over much of the network, but parts of Bering Land Bridge and Kobuk Valley lost a significant amount of surface water, mostly where lakes drained suddenly through bank breaches in ice-rich permafrost |
| Vegetation | Stable over most of the area, but tall shrubs are expanding and thickening in some places, concentrated in tundra with the warmest summers |
On the northern coastal plain of Bering Land Bridge, lake and pond area fell from about 8.5% of the land surface in 2000 to under 7% by 2019, mostly through rapid drainage.
Both the end of the continuous snow season and the start of the green season vary a lot from year to year, but now come earlier than 20 years ago.
Lake and pond area on the northern coastal plain of Bering Land Bridge National Preserve.
A lake in Bering Land Bridge National Preserve that drained suddenly in 2018. NPS/Dave Swanson.
Why it matters
The length and warmth of the growing season set how much plant matter grows, the energy supply for everything else and crucial for wildlife. Big vegetation changes will likely help some species and hurt others. Ponds and lakes, important habitat, form and drain naturally, and climate change may speed that up. Landscape changes affect most other natural resources and could shape decisions on wildlife, fire, cultural resources and visitors.
How it is monitored
- Satellites. For over 20 years they have measured reflected sunlight, from which a greenness index gives growing season length and peak greenness, and when snow cover comes and goes.
- Remote cameras. Cameras at five NPS climate stations photograph the same scene daily, showing the snow-free season and plant flowering and leaf-out, and checking the satellite readings.
- Aerial photographs. Detailed photographs on a 20-km grid across the network show shrub cover, tree cover and small ponds from thawing permafrost. The plan is to repeat them every 10 years.
- Lake maps. Satellite images from 2000 onward map lakes and ponds and find ones that drained or dried up.
Aerial photographs show ice-wedge polygons (angular lines), small lakes and dark green shrub patches. NPS/Matt Nolan.
Sources
- National Park Service, “Terrestrial Landscape Dynamics Resource Brief for the Arctic Network” (https://www.nps.gov/articles/000/terrestrial-landscape-dynamics-resource-brief-for-the-arctic-network.htm); rewritten in hubnx's own words.
En estas publicacionesBering Land Bridge National PreserveGates Of The Arctic National Park & PreserveCape Krusenstern National MonumentNoatak National PreserveKobuk Valley National Park
Licencia: CC0 1.0 (dominio público) · Adaptado de www.nps.gov
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