Forest Inventory and Analysis National Program

Lichen Communities

Methods

A detailed chapter of lichen community field methods is available in PDF format or online in the national FIA Methods Handbook (see field guides section, phase 3 measurements). We present below a brief summary of methods. 
 
 

Field procedures were designed to be conducted by non-lichenologists for practical reasons of staffing field crews. Data is collected in the field by FIA field crews each summer. Prior to the field season, each crew participates in a 3 day intensive training in lichen communities methods. Only crews who pass the certification test at the end of training are allowed to collect lichen data. To be certified, crews must attain the required measurement quality objective (MQO) of collecting 65% of an expert's species capture on the same plot. 

The method has two parts that are performed simultaneously. (1) In each standard 0.38 ha FIA plot (see methods chapter for plot design and field methods) the field crew searches for macrolichens on woody plants and collects a sample of each lichen believed to be distinct species. Tree and shrub bases below 0.5 m are excluded from sampling. Lichens on fallen branches and other lichen litter may be included. Given the large plot area, fallen branches typically provide an excellent sample of the canopy lichens. The collection represents the species diversity of macrolichens in the plot as fully as possible, with a maximum time limit of 2 hours. (2) The field crew estimates the abundance of each species using a four-step scale: 1 = rare (< 3 individuals in plot); 2 = uncommon (4-10 individuals in plot); 3 = common (> 10 individuals in plot but less than half of the boles and branches have that species present); and 4 = abundant (more than half of boles and branches in the plot have the subject species present). As plots are finished, specimens are sent to specialists for identification. Note that the field crew need not accurately assign species names to the lichens, but must be able to distinguish among species, and be able to estimate abundances accurately. 

Quality Assurance (QA)

Reliability and Repeatability

FIA lichen communities methods have been studied intensively for reliability and repeatability. The ultimate measurement quality objective (MQO) for a plot lichen sample is for repeated measurements of the same plot on the same year to produce climate and air quality scores that are within 10% of one another. In a study of multiple crews and experts (McCune et al., 1997) on the same plots, it was determined that:

1. there was a tight clustering (<10% difference) of both expert and crew gradient scores even though the number of species found by experts and crews differed greatly
   
2. scores from multiple observers on the same plots clustered tightly (<10% difference) along both climate and air quality gradients
   
3. so long as crews collected at least 65% of the species obtained by experts on the same plot, plot scores on air quality and climate gradients achieve desired MQO's