Analyzing Lichen Indicator Data in the Forest Inventory and Analysis Program

摘要

Lichens are one of several forest health indicators sampled every year for a subset of plots on the permanent grid established by the Forest Inventory and Analysis (FIA) Program of the U.S. Department of Agriculture Forest Service. This report reviews analysis procedures for standard FIA lichen indicator data. Analyses of lichen data contribute to state, regional, and national reports that evaluate spatial pattern and temporal trends in forest biodiversity, air quality, and climate. Data collection and management follow standard national protocols. A lichen species richness index (the number of species per FIA plot) is available for all areas soon after data collection. Air quality and climate indexes (for defined regional gradients and based on lichen species composition at plots) are developed from an FIA lichen gradient model. Critical steps in standard data analysis include screening plots to exclude biased data, selection of appropriate populations, then analysis, presentation, and interpretation of data. Analysis of ranked indexes is recommended as the default data option, to compensate for frequent failure of indexes to meet assumptions for parametric statistical tests. Analysis of variance is the recommended default tool for standard analysis of both spatial pattern and trends across time. Because plot density is low, dot maps are currently recommended for display. Lichen data from the Southeast Lichen Model Region illustrate all steps in standard analysis. Lichen indicator data can also contribute to analyses of regional issues that may include specialized or experimental analysis techniques. Further development of analysis approaches is needed in several areas, including calibration between lichen gradient models for adjacent regions and better mapping techniques.