How the Arctic Network Parks Monitor Tundra Vegetation, Lichens and Soils

Arctic vegetation is very sensitive to a changing climate, and scientists with the National Park Service’s Arctic Network are watching them on the ground. Their resource brief explains why vegetation is worth monitoring across five remote Alaska parks and how the plots work.

Arctic tundra vegetation of herbs and low shrubs in fall color. NPS/Dave Swanson.

Five parks

The Arctic Network covers 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.

The five Arctic parks collectively called the Arctic Network. Map from the Park Service’s page.

Why plants matter

Vegetation is the basis of ecosystem productivity and wildlife habitat. In the Arctic it is very sensitive to climate change and to disturbance such as fire, grazing by herbivores and human activity. Research has documented an increase in shrubs and, to a lesser extent, trees over recent decades, probably related to climate change. Large shifts in vegetation structure cascade into herbivore use patterns, fire regimes and the chemistry of water bodies.

Besides shrubs and herbs, the Arctic has abundant lichens, which add biodiversity and provide wildlife forage. Lichens are sensitive to grazing by caribou and reindeer, to competition from other plants, to fire and to contaminants, and all of these could reduce lichen diversity and biomass in future.

How the monitoring works

The network uses plots that can be relocated exactly and measured again. All are in remote areas reached by airplane or helicopter. There are nearly 500 comprehensive vegetation plots across the network. In them, scientists measure cover and height by species for sedges, grasses, forbs, shrubs and trees, the cover of selected mosses and lichens, and tree diameters and growth rates from cores, and they describe soil and site characteristics.

Scientists measure plant cover using a laser pointer set at regular intervals along a tape measure. Buried magnets let them find the plot again. NPS/Dave Swanson.

The team has started re-measuring the plots and expects to visit them all every 10 to 15 years. In Bering Land Bridge National Preserve there are 16 fenced grazing exclosures, each with permanent plots inside and outside, where lichen cover and height are measured. Hundreds of lichen species inventory plots around the network can be revisited to detect major change.

These portable chain-link fences keep caribou and reindeer from grazing lichens in a small area, so scientists can judge their impact on the surroundings. NPS/Peter Neitlich.

Locations of permanent vegetation monitoring. Each has a lake or flat open area to land an airplane on, a good campsite, and between 10 and 30 plots reachable on foot.

What they want to learn

• Long-term changes in plant structure, meaning the height and density of plants by species.
• Long-term changes in lichen abundance and diversity and how they relate to grazing by caribou or reindeer.
• How weather and climate have affected tree growth at the northern limit of trees. Plots in poplar forests near that limit in the Noatak Valley offer a chance to study the effect of climate change on trees.

Monitoring plots in poplar forests near the northern limit of trees in the Noatak Valley, Noatak National Preserve. NPS/Dave Swanson.

What it is for

Monitoring will help managers understand habitat changes that affect decisions on wildlife and fire. The network also plans interpretive products to teach the public how climate change is affecting Arctic ecosystems.

Sources

• National Park Service, Arctic Network, “Terrestrial Vegetation and Soils Resource Brief for the Arctic Network”: https://www.nps.gov/articles/000/terrestrial-vegetation-and-soils-resource-brief-for-the-arctic-network.htm; rewritten in hubnx's own words.