Biodiversity & Ecology

English

Abstract: The FIADB Vegetation Diversity and Structure (VEG) Indicator (GIVD ID NA-US-007) is a suite of measurements including an inventory of vascular plants on an extensive systematic network of forest plots across the United States. This network is a subset of the standard forest inventory plots established by the U.S. Forest Service Forest Inventory and Analysis program. The VEG indicator provides data to assess trends in forest vascular plant species richness and composition, the relative abundance and spatial distribution of those species, and overall physical structure created by the plant species present. Permanent plots are established when at least one subplot in the plot configuration contains at least a portion of accessible forest. Only accessible forested land on the subplots is assessed; measurements are not taken on non-forested or inaccessible portions of the plot. The configuration of each permanent FIA ground plot consists of four 7.3 m-radius circular subplots arranged in a clustered formation. In addition, three 1 m2 quadrats are established per subplot at 4.56 m along transects running at 30°, 150° and 270° from subplot centre. To help standardise the sampling effort in the many different forest types across the country, a time limit is imposed for subplot species searches (time spent searching for additional species). Estimates with (variances) can be produced for a population or domain of interest within the population. Although this is a sparse network of plots, species composition data can be cross-walked to locally developed forest classifications and provide community and species distribution metrics on permanent plots to track regional and national trends. Data and documentation are available via public access web site.