Instruments were set up in six burned areas of Yellowstone National Park that were 7, 13, 25, 57, 90, and 260± years old, and analyses were made to measure the variation in physical factors, soil characteristics, plant cover, and animal communities . The 7, 13, and 25 year old burns were found to represent open habitats. The 57 year old burned area presented a closed canopy forest with a still extensive ground cover. In the 90 year old burn the undergrowth was still sparse and in the 260 year burn, it was negligible in most areas.
Costain, W. Brenton
"Biotic Succession in Lodgepole Pine Communities of Fire Origin in Yellowstone National Park,"
Jackson Hole Research Station Annual Report: Vol. 1967
, Article 15.
Available at: http://repository.uwyo.edu/jhrs_reports/vol1967/iss1/15