Terrestrial vegetation monitoring protocol for the Arctic Alaska Network: Establishment, sampling, and analysis of permanent monitoring plots

Swanson, David; Neitlich, Peter

Vegetation was selected as a “vital sign” for long-term monitoring in the Arctic Inventory and Monitoring Network (ARCN) of the National Park Service. Vegetation in ARCN is dominated by arctic tundra and is vulnerable to alteration as a result of climate change, herbivores, disturbance processes such as fire, and airborne pollutants. This protocol presents methods for field-based sampling of vegetation monitoring plots; remote sensing is also used to monitor vegetation in ARCN but is covered under a separate vital sign “Terrestrial Landscape Patterns and Dynamics”. The present protocol emphasizes monitoring of vegetation composition and structure (vascular and non-vascular) and lichen community composition. Our objective is to detect major changes in vegetation that occur at decadal time intervals. Lichens are of particular interest in ARCN because of their significant biomass and diversity, importance as forage, vulnerability to contaminants, and suitability for monitoring designs with long intervals between sampling. Vegetation plot monitoring in ARCN includes four major projects. 1) Vegetation composition and structure is monitored at a set of 24 “nodes”, which are study areas chosen to be accessible and representative of major ARCN ecosystems. Sampling at the nodes consists of 11 to 29 plots, located using a stratified systematic design. Most of these plots were established in 2011-2013. Plant cover and height by species are measured by point intercept transects, and trees are inventoried on a fixed-area plot. 2) Lichen community composition is monitored at an ARCN-wide set of plots, most of which were established using a stratified random design across the Western Arctic Parklands (WEAR) in the period 2000-2007 and Gates of the Arctic National Park and Preserve (GAAR) in 2012. These plots are sampled by a modification of the nationwide U.S. Forest Service Forest Inventory and Analysis (FIA) lichen monitoring protocol, which involves producing a comprehensive species list with the abundance of each taxon estimated as one of six classes. 3) Lichen and vascular plant cover and species composition along the Red Dog Mine haul road in Cape Krusenstern National Monument. These plots were established in 2006 using a stratified random design to monitor the effects of contaminants (primarily due to dust containing heavy metals) on vegetation. Sampling consists of cover by point intercept transects and composition on 4 by 8 m plots. 4) Lichen and vascular plant cover and species composition in ungulate exclosures, established in Bering Land Bridge National Preserve in 2012. A set of eighteen, 9 by 9 m exclosures, designed mainly to exclude caribou and reindeer, were constructed at subjectively chosen representative sites with potential for moderate to high lichen cover. Sample plots identical to those in project (3) above were placed inside and outside the exclosures to separate the effects of herbivores from other causes of vegetation change. The sampling interval for all four projects will be 10 to 15 years. Long sampling intervals are appropriate in ARCN in view of the significant expense involved in fieldwork, the slow rates of change, and absence of inter-annual variation in lichens and evergreen woody plants.

Terrestrial vegetation monitoring protocol for the Arctic Alaska Network: Establishment, sampling, and analysis of permanent monitoring plots

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