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United States Department of Agriculture

Agricultural Research Service

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Research Project: Breeding Biologies for Chaenactis douglasii (ASTERACEAE) and Bee Community Fates in a Chronosequence of Past Wildfires

Location: Pollinating Insect-biology, Management, Systematics Research

2011 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.

3. Progress Report
We have completed sampling bee communities in paired burned and unburned plots across a 15-year chronosequence of wildfires in sage-steppe and juniper woodlands of the northern Great Basin. The newest 8 locations all represent bee faunas ¼- ½ mile or more in from the burn boundary, so likely resident faunas. As before, we then sampled faunas at comparable sites around the unburned margins. Following specimen curation and identification of these last samples (previous years’ now completed), we will be comparing abundances, taxonomic diversities of bees, and relating these to densities of shrubs and prevalent wildflowers. We have sampled 1500 bees and flora at 35 site pairs of large fires (>1000 acres). We are preparing maps for fires and samples in ArcGIS. Forb communities seem more plentiful and slightly more diverse in most of the fires than the control sites, as do their native bees. Fire certainly has not diminished bees or bloom where exotic grasses did not take over. We have also coordinated a comparison of our plotless diversity and density measure for wildflowers with the more laborious method of quadrats being used by USFS collaborators on the large Scooby wildfire reseeding. We also recovered an experiment for foraging range for a pollinator of one of our target wildflowers, having deployed acquired nests from last year with nesting blocks at different distances (up to a mile) from their floral host in the 80,000 acre Black Pine Mtn. fire. We obtained considerable nesting from up to ½ mile away, but an unexpected alternative floral host appeared too, so we need to examine pollen from provisions of the many nests that we recovered. Our objective here is guidance for land managers on the distances from fire perimeters that they can expect pollination service from twig and wood nesting bee species.

4. Accomplishments

Last Modified: 09/19/2017
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