Sensitive Vegetation Communities
Resource Brief - March 2009
Background
High latitude plant communities are sensitive to climatic variation and physical disturbance and, as such, may serve as early indicators of environmental change on the landscape. These plant communities are strongly controlled by physical factors (e.g., hydrology, thermal regime) or may at the edge of their environmental tolerance. Nunataks and salt marshes are two ecosystem types targeted for monitoring by the SWAN.
Importance/Issues
Nunatak Communities
Figure 1. Nunatak on Double Glacier, Lake Clark NPP
Nunataks, or exposed mountain ridges surrounded by ice (Fig. 1), were included as a SWAN vital sign under sensitive plant communities. Nunataks are of interest due to their geographic isolation and because they may have supported plant populations that survived the Last Glacial Maximum, approximately 20,000 years ago. In addition to harboring regionally or globally rare species, nunataks are sensitive to subtle changes in climate. They may also play an important role in the re-establishment of plant and animal species in recently deglaciated areas.
Natural Resource Year in Review-2006: Understanding biological Diversity of nunataks in southwestern Alaska
Salt Marsh Communities
Figure 2. Sow and cub in a salt marsh at Silver Salmon Creek, Lake Clark NPP.
Sheltered salt marshes and tidal flats along the coastlines of Lake Clark and Katmai NPP provide critical feeding and resting habitat for brown bears, waterfowl, and shorebirds (Fig. 2). Ground- and surface water hydrology, salinity, sedimentation and erosion rates, and physical disturbance influence the distribution and abundance of plant communities in these systems. Information gained from monitoring may be integrated with that of other related vital signs (e.g., brown bears, marine birds, intertidal marine invertebrates) to support a broader understanding of change in the marine nearshore ecosystem.
Sampling Design and Objectives
Nunatak Communities
Monitoring objectives for nunatak communities are to estimate long-term changes in species richness, cover and diversity, and, where applicable, document changes in the cover of woody species (e.g., shrub encroachment). In 2005, the SWAN inventoried and established baseline monitoring on nunataks in Kenai Fjords and Lake Clark NPP {link to nunatak report and poster}. Sites =1.5 km from the ice margin and =25 ha in area were selected in a GIS. Baseline species cover and frequency were recorded in nested plots along transects at each site.
Salt Marsh Communities
Figure 3. SWAN staff collect species cover data in a coastal meadow, Lake Clark NPP, 2007
Protocol development for salt marshes will include SOPs for measuring storm surges in tidal guts, soil characteristics (salinity, pH), and vegetation attributes (species composition, richness, cover, diversity). In 2007, the SWAN field-tested a protocol for salt marshes on the coast of Lake Clark (Fig. 3), adapted from methods developed by Cape Cod National Seashore {link to site with CACO protocol}. Testing will continue in 2008 in Katmai NPP.
Current and Future Work Efforts
In 2005, eight permanent monitoring sites were established in LACL and KEFJ for monitoring changes in species composition and cover on nunataks.
The sites will be revisited every 2-3 years for the first ten years of monitoring, and at 5-10 year intervals thereafter. Funds permitting, additional sites may be added in the future. Historic survey and high-altitude aerial photography, late-season Landsat TM/ETM+ scenes, and IKONOs imagery will be used to track changes in snow and ice cover around nunataks. Where possible, ancillary climate data will be used to interpret short-term variation and longer-term change.
