Fire Rehabilitation Using Native and Introduced Species: A Landscape Trial

Abstract

Following the 1999 Railroad Fire in Tintic Valley, Utah, we initiated a large-scale fire rehabilitation study comparing a predominately introduced species seed mix used by the US Department of Interior-Bureau of Land Management (BLM), a mix of native and introduced species provided by the US Department of Agriculture-Agricultural Research Service (ARS), and 2 native seed mixes (high and low diversity). Mixes were seeded with a rangeland drill on the big sagebrush (Artemisia tridentata var. wyomingensis [Beetle A. Young] Welsh) study area whereas the pinyon-juniper (Pinus edulis Engelm.-Juniperus osteosperma [Torr.] Little) woodland study area was aerially seeded followed by 1-way chaining. On drill-seeded plots and by the third year after seeding the native high-diversity mix (16.4 kg pure live seed [PLS] ha-1) had the highest seeded species cover (11.5%) and density (14 plants m-2). Both the BLM (9.3 kg PLS ha-1) and ARS (9.1 kg PLS ha-1) seed mixes had higher seeded species cover (BLM = 8.5%, ARS = 8.2%) and density (BLM = 8.4 and ARS = 7.2 plants m-2) than plots seeded to the low-diversity native mix (8 kg PLS ha-1, cover = 3.8%, density = 3.6 plants m-2). Indian ricegrass (Achnatherum hymenoides [Roemer and J. A. Schultes] Barkworth ‘Nezpar’) in the native high-diversity mix was especially successful on the sandy soils of the drill site, whereas seeds of other species may have been buried too deep for optimum emergence. Aerially-seeded and chained plots had similar and successful seeded species frequency, cover, and density (third-year average = 10.6% cover, 17.2 plants m-2) among all species mixes. All seeded plots had lower cover of annual species than unseeded plots, indicating that revegetation is necessary to reduce weed invasion following catastrophic wildfire in big sagebrush communities lacking residual perennial understory vegetation.