Submitted to: Society for Ecological Restoration Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/10/2007
Publication Date: 9/25/2007
Citation: Roche, C., Sheley, R.L., Korfhage, R. 2007. The healing hand of time: native species replace introduced grass cultivars seeded following wildfire [abstract]. Society for Ecological Restoration Northwest Section. P11.
Technical Abstract: Seeding of non-native species following wildfires to prevent erosion has become a controversial practice for several reasons: it risks inhibiting tree regeneration, introducing noxious weeds, and permanently replacing native species. The paper reports the fate of non-native seeded grasses 31 years after a post-fire seeding in a grand fir forest on the east side of the north Cascade Mountains, Washington. In that region, catastrophic wildfires in Abies grandis/Calamagrostis rubescens associations characteristically result in a flush of lodgepole pine (Pinus contorta) regeneration that creates a dense tree monoculture. In the study, seven long-lived perennial grass cultivars were broadcast seeded to prevent erosion, limit tree regeneration, and increase forage production for wildlife and livestock. Half of the plots were fertilized with nitrogen during the first three years. Tree regeneration, cover of native and non-native species, and above-ground biomass were evaluated in 1971, 1975, 1980, 1989, and 2001. The seeded species quickly established dominant cover with levels of biomass production two to three times the level of unfertilized native species. Density of tree regeneration was inversely correlated with perennial grass cover during the first 10 years. Then the seeded grasses gradually disappeared. In 15 to 20 years after the fire, native species regained dominance and after 30 years, the last remnants of the non-native cultivars were gone, long before the tree canopy closed. A monoculture of lodgepole pine dominated the unseeded areas in contrast to a diverse mixture of native graminoids, forbs, shrubs and trees in the seeded areas. This study showed that non-native grasses seeded after wildfires do not always persist and can serve as a transition to a diverse seral community.