Recolonization of Substrates Burned in the 1988 Yellowstone Park Fires by Cryptogams (Lichens, Mosses, Fungi)

Abstract

The fires of 1988 in Yellowstone National Park burned 1.1 million acres (1719.4 square miles) within the park boundaries, about 44.5% of the park. Six per cent of the area burned was meadow­grassland and 94% was forests. Most of the forested areas that burned were dominated by lodgepole pine (Pinus contorta Dougl. ex Loud), with smaller tracts of Douglas fir (Pseudotsuga menziesii (Mirbel) Franco)), Engelmann spruce (Picea engelmannii Parry) and whitebark pine (Pinus albicaulis Engelm.). The burns were mosaic in nature, leaving different sizes of areas severely burned, moderately burned and unburned, and adjacent patches of mostly ground fires, mostly canopy fires, both ground and canopy fires or unburned stands (Rothermel et al., 1994). Many park projects have documented recovery of vascular plants, especially lodgepole pine and the understory perennials (Anderson & Romme, 1991; Baskin, 1999; Foster, et al, 1999; Reed, et al ,1999; Tomback, et al, 2001; Turner et al, 1994, 1997). The conclusions were that lodgepole pine has regenerated itself, as expected, from seed sources in adjacent unburned patches. Herbaceous and shrubby understory regeneration has depended primarily on the plants that were present at the study sites before the fires, with regrowth from surviving underground parts as well as from nearby seed sources. This study investigates the initial return of non-vascular vegetation, lichens and mosses, all of which were presumably destroyed when their substrates were burned. None of the other Yellowstone studies included cryptogam observations. Studies concentrating on recolonizing cryptogamic crusts, including mosses, algae and lichens, on dryland soil after fires, have occurred in Utah (Johansen, et al, 1984) and Australia (Eldridge & Bradstock, 1994). Algae tended to return before lichens and mosses, especially during wet years, and after five years the lichens and mosses were recovering but not yet to pre-burn cover. Researchers have found that, on limestone, two lichen species colonized after four years. Thomas, et al. (1994) found that Ceratodon purpureus appeared to be insensitive to pH differences of burned peat surfaces and readily colonized ashed surfaces within one year after fire; Polytrichum piliferum was dominant after three years.