ARS | Publication request: Artemisia tridenata seed bank densities following wildfires

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 10, 2008
Publication Date: December 9, 2008
Citation: Clements, C.D., Harmon, D.N., Young, J.A. 2008. Artemisia tridenata Seed Bank Densities Following Wildfires [abstract]. Wildfires and Invasive Plants in American Deserts, December 9-12, 2008, Reno, Nevada.

Technical Abstract: Big sagebrush (Artemisia spp.) is a critical shrub to such sagebrush obligate species as sage grouse, (Centocercus urophasianus), mule deer (Odocoileus hemionus), and pygmy rabbit (Brachylagus idahoensis). Big sagebrush do not sprout after wildfires and big sagebrush seed is generally short-lived and do not survive wildfires (Young and Evans 1989). In recent years land managers have brought to our attention that they have been informed that big sagebrush does build persistent seed banks and that these seed banks have the potential to re-establish big sagebrush back into burned habitats. Young and Evans (1989) also reported that they found no mountain big sagebrush (Artemisia tridentata ssp. vaseyana) or Basin big sagebrush (Artemisia tridentate ssp. tridentata) emerged from germination tests of 1,000 soil surface samples from burned habitats. We tested any possible seed bank potential of mountain big sagebrush and Wyoming big sagebrush (Artemisia tridentate ssp. wyomingensis) following wildfires at two separate sites in western Nevada. We established fifty-four 3m plots on the south as well as the north edge of the fire line for both locations. Plots were established at 1m, 10m, and 30m from the fire edge in the burned soil and soil bioassays were collected and returned to the greenhouse to undergo germination of seed bank densities. Bioassays were conducted in mid September following the August wildfires and again in late February after seed set. Adjacent 3m plots were also established and seeded at a rate of 45g/ha rate to record any differences in big sagebrush establishment when seeded versus not seeded. We found no evidence that Wyoming big sagebrush seeds survived the wildfire event in our bioassay efforts and no seedlings were recorded (from natural seed dispersal) at our 1m, 10m, and 30m plots that were unseeded. We did experience the recruitment of seedlings (1/plot) in 3 of the seeded plots. Our mountain big sagebrush site yielded evidence of an active seed bank following the wildfire. The south edge of the wildfire average 1.8, 6.7, and 1.8 seeds per plot in the 1m, 10m, and 30m plots, respectively. The north edge recorded an active seed bank in the 1m plot, averaging 1.8/plot. We also recorded the recruitment of sagebrush seedlings in 7 of the seeded plots, averaging 1.3/plot. Wyoming big sagebrush sites are more xeric and much more difficult when it comes to restoring these communities following devastating wildfires. Our data, along with much of the literature, recommends that Wyoming big sagebrush requires seeding or transplanting efforts in its restoration process. Mountain big sagebrush communities receive more favorable precipitation and thus the communities have a greater potential to re-establish on their own. The data that we have collected suggests that mountain big sagebrush has a greater potential of restoring itself due to this active seed bank than some of the past literature suggests, nonetheless, this restoration process varies by site and to get back to pre-burn densities may very well be longer than that of most resource managers entire career.