In Louisiana, Cameron, Jefferson, Orleans, Plaquemines, and St. Bernard parishes were excluded from he grid be cause of limited forest occurrence. More specialized retrievals may be obtained at cost. Total land area by county comes from U.S. Bureau of the Census files.
Crews visit a subsample of photopoints and adj ust forest and nonforest photo interpretation.
For forested plots, field crews collect additional information by plot, species, and tree stems, and office staff make additional computations from field-collected data. FIA surveys routinely report forest re sources by area, species, volume, and other attributes. 1992, Woudenberg and Farrenkopf. Lund et al. FIA crews gather field observations at approximately 1.5 mile intervals and have been doing so at approximately 10 year intervals since the 1970's.