PARENT SESSION
Contributed Oral Session 87: Rare, Threatened, and Endangered Species: Flora; Habitat
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 522 A, Level 5, Palais des congrès de Montréal
Golden paintbrush (Castilleja levisecta) common garden studies: selecting seed sources and reintroduction sites to support recovery of an endangered PNW prairie species.
Lawrence, Beth *,1, Kaye, Thomas1, 2, 1 Oregon State University, Corvallis, OR, USA2 Institute for Applied Ecology, Corvallis, OR, USA
ABSTRACT- The origin of source material used to establish new plant populations is a contentious issue in conservation biology. Several factors are likely to influence the success of introduced populations, including ecological similarity between source and introduced populations, genetic diversity and size of source populations, and site conditions at the introduction site. Habitat similarity between source and introduced populations may be crucial because of ecotypic differentiation and local selective pressures. Genetic diversity and size of the source population may also affect the success of reintroductions, as these parameters may be correlated with plant performance. Castilleja levisecta is a threatened species with only eleven populations remaining within its historic range, and establishment of new populations is a top priority for its recovery. In order to facilitate C. levisecta reintroduction in the Willamette Valley, OR, we initiated common garden experiments to evaluate the success of different source populations under field conditions similar to those in potential reintroduction sites. Ten common gardens, each comprised of individuals grown from seed collected from six source populations, were planted in prairie habitat during two planting events in 2004. Average stem growth during the first growing season varied significantly by source population (F5,1157 = 9.7, p< .001) and common garden site (F9,1157 = 49.1, p< .001). Nonparametric multiple regression analyses indicate that the percent cover of non-native plants at common garden sites greatly reduced the size of C. levisecta transplants after accounting for the genetic diversity and size of the source population, and the ecological distance between source population and common garden site. Our preliminary results do not support the hypothesis that habitat similarity between seed source and reintroduction site affect plant success, nor do genetic diversity or source population size. Pending the results of further observations, we recommend using reintroduction sites in Oregon that have a low abundance of invasive plants and selecting seed from source populations that grow well in the Willamette Valley.
Key words: common garden, reintroduction, Castilleja levisecta, plant performance