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LTEM: Monitoring Vegetation Communities
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Dr. Andrea Woodward, USGS, FRESC, OFS
 Vegetation community structure is the integrated physical manifestation of abiotic (e.g., climate, soil) and biotic (e.g., herbivory, habitat availability) relationships in an ecosystem. They link the biotic and abiotic realms through their central role in the carbon, nitrogen, hydrologic and mineral cycles, primary production and habitat provision. Consequently, ecosystem types or categories are often delineated by the vegetation communities that characterize them (e.g., tall-grass prairie, temperate rainforest). Therefore, change in vegetation community structure at greater than the local scale signals a noteworthy change in ecosystem structure and function. We can name specific threats to vegetation (e.g., exotic plants and animals, climate change, changes to atmospheric chemistry) but we cannot anticipate all of the future threats, exactly what the consequences of the threats will be, at what threat level vegetation change will be noticeable, and how multiple threats will interact.  Because vegetation community composition, structure and demography integrate environmental conditions, including multiple stresses, we expect them to be effective indicators of ecosystem integrity. Vegetation change is the ‘bioassay’ in some unmanaged terrestrial situations, analogous to human health in urban areas, that defines unacceptable levels of threat. National Parks, which are mandated to protect ecosystem structure and function, are interested in monitoring vegetation communities to determine whether they are complying with their mandate.
This project is a pilot study to determine the power of components of vegetation communities, including vascular and non-vascular plants, to detect desirable levels of change with a feasible number of samples. Recommendation for a plot design and sample frame for monitoring vegetation communities in national parks is the ultimate goal. The effect of intra-annual phenologic variability on inter-annual sample variability is also being studied.
 Three years of pilot data have been collected from six vegetation plots representing wet and dry environmental extremes in Olympic National Park. The data have been analyzed for power, but some follow-up analysis is still needed.
Shelley, A., T. Cardoso, and Jean-Yves Courbois. 2002. Detecting Changes in Vegetation and Wildlife Populations, Task1/Objective 1 Report.
Shelley, A., T. Cardoso, and Jean-Yves Courbois. 2002. Detecting Changes in Vegetation and Wildlife Populations: Simulation Study.
Thanks go to field crew members Charlene Burge, Steve Hahn, Karen Hutten, Pace Leake, Pilar Monteban, Lisa Nesbitt, Krista Rome, Jason Waling, James Walton, and Kelli Weed. Justin Yeager helped with data summary.
Andrea Woodward
Phone: 206-526-6282 x332
E-mail: andrea_woodward@usgs.gov
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