Evaluating Suitability of Prairies for Golden Paintbrush – South Puget

The suitability of South Puget Sound prairie sites for supporting golden paintbrush plants
was assessed by outplanting paintbrush plugs in the field and observing growth and
survival. A total of 5478 plants, coming from 5 different sources, were installed in 6
prairies in fall, 2007. Plants were inspected in spring, 2008, and rated on several
characteristics of vigor. Associated species were recorded within outplanting plots, and in
similar plots associated with extant paintbrush plants at Rocky Prairie. We also examined
soil characteristics associated with microsites at Glacial Heritage and Mima Mounds
where outplantings survived and/or successfully reproduced. Overall, first-year survival
of paintbrush plants ranged from 77-92%, and flowering ranged from 4-11%. Plugs
grown from seed gathered at the Naas site had the highest flowering rate (average=22%).
Based on both survival and flowering, Glacial Heritage and Mima Mounds ranked
highest among the 6 sites. Where portions of sites had been recently burned, paintbrush
generally performed better. Soils associated with successful outplantings in 2002-2005
had higher mean levels of magnesium, calcium, potassium, sodium, cation exchange
capacity (CEC) and pH than soil gathered near plots that had no surviving paintbrush
plants. These results should only be regarded as preliminary, since they are based on only
a single growing season. However, they provide an indication that all the sites offer some
likelihood as suitable locations for restoring paintbrush populations, and that burning and
perhaps nutrient manipulations further enhance site suitability.