Ecological impacts of wheat seeding after a Sierra Nevada wildfire*
Jon E. KeeleyU.S. Geological Survey, Western Ecological Research Center, Sequoia-Kings Canyon Field Station, Three Rivers, CA 93271-9651, USA, and Department of Organismic Biology, Ecology and Evolution, University of California, Los Angeles, CA 90095, USA. Telephone: +1 559 565 3170; fax: +1 559 565 3170; email: jon_keeley@usgs.gov
International Journal of Wildland Fire 13(1) 73-78 https://doi.org/10.1071/WF03035
Submitted: 20 March 2003 Accepted: 19 August 2003 Published: 8 April 2004
Abstract
The Highway Fire burned 1680 ha of mixed ponderosa pine–oak–chaparral in the newly created Giant Sequoia National Monument and the adjacent Sequoia National Forest of Fresno County, California in August 2001. The USDA Forest Service Burned Area Emergency Rehabilitation (BAER) program recommended that portions of the burned forest be seeded with a non-persistent variety of wheat at a density of 157 kg ha–1 (140 lb/ac). The present study compared the vascular plant diversity and cover in seeded and unseeded parts of this burn to evaluate the ecological impact of seeding an alien grass. In the first post-fire growing season, the natural regeneration of unseeded control sites averaged ~55% ground surface covered. Wheat seeding enhanced the ground cover, averaging 95% ground surface cover. Wheat was the dominant species on the seeded sites, comprising 67% of the total cover. Dominance–diversity curves were markedly affected by the seeding and indicated a disruption in the natural ecological structure of these communities. On seeded sites, wheat dominated and all other species were poorly represented whereas, on unseeded control sites, there was a more equitable distribution of species. Correlated with the wheat cover was a significant decrease in species richness at all scales examined. Total species richness was reduced from 152 species across all unseeded sites to 104 species on all seeded sites. Average species richness, at scales from 1 to 1000 m2, was 30–40% lower on seeded sites. Species most strongly inhibited were post-fire endemics whose lifecycle is restricted to immediate post-fire environments. Seeded sites had fewer alien species than unseeded sites; however, this may not have any lasting effect since other studies show the primary alien threat is not in the first post-fire year. Seeding was also associated with an order of magnitude drop in Pinus ponderosa seedling recruitment and, coupled with the massive thatch still remaining on the site, it is likely that recruitment will be inhibited in subsequent years.
Additional keywords: BAER; biodiversity; species area curves; erosion; forest fire; non-persistent wheat; sterile wheat.
Acknowledgements
I thank Elizabeth Martin and Trent Draper for field sampling and Kim Bollens for obtaining the BAER Report and other information on the post-fire seeding. Larry Bird, District Silviculturist for the USFS Hume Lake Ranger District, was very helpful in providing details on the seeding treatments and reports. Thanks for critiques of an earlier draft to Julio Betancourt, Jan Beyers, Kim Bollens, Mark Borchert, C.J. Fotheringham, Steve Schwartzbach, Nate Stephenson, and Philip van Mantgem. This work was supported by the Joint Fire Science Program project 01B-3–2-08 Pre-Fire Fuel Manipulation Impacts on Alien Plant Invasion of Wildlands.
Amaranthus MP, Trappe JM , Perry DA (1993) Soil moisture, native revegetation, and Pinus lambertiana seedling survival, growth, and mycorrhiza formation following wildfire and grass seeding. Restoration Ecology 1, 188–195.
Anderson WE , Brooks LE (1975) Reducing erosion hazard on a burned forest in Oregon by seeding. Journal of Range Management 28, 394–398.
Anonymous (2001) Burned-area report (Reference FSH 2509.13). Date of report 08/30/01. On file at the Hume Lake District Office (USDA Forest Service, Sequoia National Forest: Dunlap, CA)
Anonymous (2003) Highway Fire BAER Monitoring Report. Date of report 7 March 2003. On file at the Hume Lake District Office (USDA Forest Service, Sequoia National Forest: Dunlap, CA)
Barro SC , Conard SG (1987) Use of ryegrass seeding as an emergency revegetation measure in chaparral ecosystems. USDA Forest Service, Pacific Southwest Forest and Range Experiment Station General Technical Report PSW-102
Beyers JL, Wakeman CD, Wohlgemuth PM , Conard SG (1998) Effects of post-fire grass seeding on native vegetation in southern California chaparral. Proceedings 19th annual forest vegetation management conference wildfire rehabilitation (USDA Forest Service: Sacramento, CA)
Conard SG, Beyers JL , Wohlgemuth PM (1995) Impacts of post-fire grass seeding on chaparral systems—what do we know and where do we go from here? In
Conard SG, Regelbrugge JC , Wills RD (1991) Preliminary effects of ryegrass seeding on post-fire establishment of natural vegetation in two California ecosystems. Proceedings of the 11th conference on fire and forest meteorology (Society of American Foresters: Bethesda, MD)
Davis SD , Mooney HA (1986) Water use patterns of four co-occurring chaparral shrubs. Oecologia 70, 172–177.
Eissenstat DM , Mitchell JE (1983) Effects of seeding grass and clover on growth and water potential of Douglas-fir seedlings. Forest Science 29, 166–179.
Elliott K , White A (1987) Competitive effects of various grasses and forbs on ponderosa pine seedlings. Forest Science 33, 356–366.
Fowells HA (1965) Silvics of forest trees of the United States. Agriculture Handbook No. 271 (USDA: Washington, D.C.)
Gautier CR (1983) Sedimentation in burned chaparral watersheds: is emergency revegetation justified? Water Resources Bulletin 19, 793–802.
Geier-Hayes K (1997) The impact of post-fire seeded grasses on native vegetative communities in central Idaho. Proceedings: Fire conference on fire effects on rare and endangered species and habitats (International Association of Wildland Fire: Fairfield, WA)
Griffin JR (1982) Pine seedlings, native ground cover, and Lolium multiflorum on the Marble-Cone burn, Santa Lucia Range, California. Madrono 29, 177–188.
Hedrick DW (1949). Reseeding burned chaparral lands. M.S. thesis (University of California: Berkeley)
(1993) The Jepson manual (University of California Press: Berkeley)
Keeler-Wolf T (1995) Post-fire emergency seeding and conservation in southern California shrublands. In
Keeley JE (1996) Post-fire vegetation recovery in the Santa Monica Mountains under two alternative management programs. Bulletin of the Southern California Academy of Science 95, 103–119.
Keeley JE (2002) Fire and invasives in Mediterranean climate ecosystems of California. In
Keeley JE, Carrington M , Trnka S (1995) Overview of management issues raised by the 1993 wildfires in southern California. In
Keeley JE , Fotheringham CJ (2000) Role of fire in regeneration from seed. In
Keeley JE, Lubin D , Fotheringham CJ (2004) Fire and grazing impacts on plant diversity and alien plant invasions in the southern Sierra Nevada. Ecological Applications. 13, 1355–1374.
Keeley SC, Keeley JE, Hutchinson SM , Johnson AW (1981) Post-fire succession of the herbaceous flora in southern California chaparral. Ecology 62, 1608–1621.
(2000) Invasive species in a changing world (Island Press: Covelo, CA)
Nadkarni NM , Odion DC (1986) Effects of seeding exotic Lolium multiflorum on native seedling regeneration following fire in a chaparral community. Proceedings of the chaparral ecosystems research conference (University of California: Davis)
Robichaud PR, Beyers JL , Neary DG (2000) Evaluating the effectiveness of post-fire rehabilitation treatments. USDA Forest Service, Rocky Mountain Research Station General Technical Report RMRS-GTR-63
Ruby EC (1989) Rationale for seeding grass on the Stanislaus complex burn. Proceedings of the symposium on fire and watershed management (Berkeley, CA)
Schlesinger WH (1997) Biogeochemistry: An analysis of global change 2nd edn. (Academic Press: New York)
Schultz AM, Baunchbauch JL , Biswell HH (1955) Relationship between grass density and brush seedling survival. Ecology 36, 226–238.
Schwilk DW, Keeley JE , Bond WJ (1997) The intermediate disturbance hypothesis does not explain fire and diversity pattern in fynbos. Plant Ecology 132, 77–84.
| Crossref | GoogleScholarGoogle Scholar |
Taskey RD, Curtis CL , Stone J (1989) Wildfire, ryegrass seeding, and watershed rehabilitation. Proceedings of the symposium on fire and watershed management (Berkeley, CA)
Wade GL (1989) Grass competition and establishment of native species from forest soil seed banks. Landscape and Urban Planning 17, 135–149.
| Crossref | GoogleScholarGoogle Scholar |
Whittaker RH (1965) Dominance and diversity in land plant communities. Science 147, 250–260.
Zedler PH, Gautier CR , McMaster GS (1983) Vegetation change in response to extreme events: the effect of a short interval between fires in California chaparral and coastal scrub. Ecology 64, 809–818.
* This paper was written and prepared by U.S. Government employees on official time, and therefore is in the public domain and not subject to copyright. The use of trade or firm names in this paper is for reader information and does not imply endorsement by the U.S. Department of Agriculture of any product or service.
