Breeding Biologies for Chaenactis Douglasii (Asteraceae) and Bee Community Fates in a Chronosequence of Past Wildfires
Pollinating Insects-- Biology, Management and Systematics Research
2013 Annual Report
1a.Objectives (from AD-416):
1) The breeding biology of the Great Basin wildflower Chaenactis douglasii will be characterized experimentally to inform prospective seed growers of this plant’s pollination needs when farming it to produce restoration seed.
2) The post-fire fates of native bee communities across the northern Great Basin will be sampled from a chronosequence of past wildfires. This knowledge is important for the reproductive success of large seedings of wildflowers meant to rehabilitate recently burned sage-steppe and juniper habitats.
1b.Approach (from AD-416):
1) The breeding biology of C. douglasii will be studied in a common garden by comparing achene and seed sets at caged flowers, openly visited flowers, and manually self- and cross-pollinated flowers in our common garden. Combined with flower production, we can then estimate seed production per plant by each treatment.
2) A chronosequence of accessible large Great Basin wildfires will be visited during spring bloom and the bee faunas of 1-2 target wildflower species will be quantitatively sampled in and outside of the fire perimeter. Bloom density, forb diversity, shrub density and densities of the dominant wildflowers will be characterized by standard plant community measures.
A large propane burner barrel was earlier designed, modified, tested and calibrated for delivering flame intensity and soil heating characteristics like that found in sage-steppe wildfires. At the Malheur Experiment Station, it was used on plots of 5 established native forb species representing contrasting forb growth forms. Barrel-sized plots were marked and their plants counted and measured. These were then burned at each of 4 incremental intensities (plus paired controls) and durations last August. This spring and summer, counts of forb survival and measured growth were completed. Some species (e.g. biscuitroot) were unaffected, some showed a clear mortality threshold, and yet others show a more linear response between fire intensity and survival. One species’ bloom appears to have been delayed and reduced on surviving plants. Growth form and growing season seem key to predicting perennial forb response to late-summer fire, and for some species, the intensity of burn as well. Monitoring activities include telephone calls, email communication, discussions at workshops and professional meetings.