5th Symposium on Fire and Forest Meteorology and the 2nd International Wildland Fire Ecology and Fire Management Congress

Monday, 17 November 2003
Reduction of lichen habitat by wildland fire on the Kanuti National Wildlife Refuge, Alaska
A. Morton, U.S. Fish and Wildlife Service, Anchorage, AK; and L. B. Saperstein
Members of two caribou (Rangifer tarandus granti) herds periodically winter in lichen habitat on the Kanuti National Wildlife Refuge (NWR) in north central Alaska, providing an important subsistence resource for residents of nearby villages. Fire is often considered detrimental to caribou because recovery of key forage lichens can take decades and research indicates that it is unlikely that caribou will utilize burned winter range for at least 50 years post-fire. Despite this lengthy recovery period, fire, lichens, and caribou have evolved together in boreal forest ecosystems and periodic disturbance may be necessary to prevent lichen stands from becoming degenerate. Approximately 53% of the 6,475 km2 refuge has burned since 1950. The most recent large fire events occurred between 1990 and 1992 when about 32% of the refuge burned, prompting concern from local residents that caribou would avoid the area.

The objective of this study was to compare pre- and post-fire Landsat TM satellite imagery to determine how much lichen habitat was burned by the 1990-1992 wildlland fires. A 1986 image was compared to a 1999 landcover map generated by Ducks Unlimited and the Bureau of Land Management. Within the burned area, the 1986 image was classified into non-lichen and lichen habitat classes ( 20% lichen cover) using a combination of supervised and unsupervised classification algorithms. Lichen grows slowly so it was assumed that, outside of fire events, the extent of lichen habitat did not change between 1986 and 1999. Thus, lichen habitat remaining in 1999 was added to the lichen mapped from the 1986 image in order to derive a pre-fire estimate for the entire refuge. A total of 267 km2 of lichen habitat burned in the 1990-1992 fires. Lichen habitat comprised 9.1% of the refuge in 1986 and 5.3% in 1999, mostly in the form of open needleleaf lichen (25-60% canopy closure) and woodland needleleaf lichen (10-25% canopy closure) classes. Open needleleaf lichen had been reduced by 1.3% and woodland needleleaf lichen had been reduced by 1.9%. Dwarf shrub lichen was reduced from 0.6% cover in 1986 to 0.1% in 1999 and pure lichen was reduced from 0.2% to 0.1%. Much of the remaining lichen habitat is in an area that has not burned for at least 50 years, according to a statewide fire history map. Refuge managers may want to consider changing this area from a limited suppression prescription in order to retain caribou winter range on the refuge.

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