Vegetation Monitoring by the Southwest Alaska Network (SWAN): 2007-2024 — Data Package

Ground-based monitoring for the vegetation composition and structure vital sign for the Southwest Alaska Network (SWAN), focuses on documenting trends in the structure, composition, and demography of selected late-successional vegetation classes in response to environmental changes across three elevation bands (0-450 m; >450-900 m; >900 m) within the three largest parks: Katmai (KATM), Kenai Fjords (KEFJ), and Lake Clark (LACL). SWAN employed a Generalized Random-Tesselation Stratified (GRTS) sampling design, which involved a two-stage sampling scheme to ensure safety and accessibility while establishing permanent plots in selected vegetation classes. In order to focus on long-term changes rather than successional dynamics, the monitoring targeted specific vegetation classes that are common, late-seral, and sensitive to environmental changes, while avoiding early-successional classes. The selected vegetation associations included low elevation interior spruce forests, mid-elevation white spruce woodlands, low and dwarf shrub communities, and alpine dwarf shrub-fellfield communities, reflecting a gradient from warm coastal to colder alpine environments. Selected monitoring plots were revisited at approximately 5 year intervals, during which point intercept, nested quadrat frequency, tree censuses, and other structural and environmental measurements were performed.