Jernegan, Marissa , Coons, Janice , Rolfsmeier, Steven .
Influence of Associated Species, Soil and Seed Biology on Disjunct Distribution of Physaria ludoviciana (silvery bladderpod; Brassicaceae).
Physaria ludoviciana (Nuttall) O’Kane and Al-Shehbaz (silvery bladderpod; Brassicaceae) is an endangered plant of Illinois and Minnesota sand prairies but occurs commonly in western states in scattered pockets. The populations occur in adverse conditions isolated from each other. It is unclear why these populations are so disjunct. The goal was to investigate parameters which might influence why P. ludoviciana is disjunct with specific objectives: 1) to compare associated species and soils in parallel areas with and without P. ludoviciana, and 2) to evaluate how seed biology (production, afterripening, and establishment into seedlings) influences the ability of P. ludoviciana to establish in new areas. Parallel sites with or without P. ludoviciana were surveyed in Illinois, Minnesota, and Nebraska in June 2007. At each site, associated plant species were surveyed, and soil cores were collected and analyzed. Seed production was estimated by counting inflorescence structures. Afterripening was evaluated by germinating seeds in Petri dishes with moistened filter paper at 2 month intervals after fruit collection. Seedling establishment was estimated by counts during surveys. Sites with and without P. ludoviciana had 82 and 81 species respectively, including 47 species in common. Significant differences in species were found between states but not between sites where P. ludoviciana was present or absent. Soils at all sites were sand and/or loam, with pH of 8 at sites with P. ludoviciana and pH of 7 at sites without P. ludoviciana. Illinois had the greatest estimated seeds per plant (479), and Minnesota had the lowest (127). Seeds exhibited afterripening as germination was lowest in trials that began 8 days after harvest, but increased in later trials. Illinois had the greatest density of seedlings (122), and Minnesota had the lowest (0). Knowledge gained provides important information about this species to aid management of these disjunct populations.
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1 - Eastern Illinois University, Department of Biological Sciences, 600 Lincoln Ave, Charleston, Illinois, 61920-3099, USA
2 - Eastern Illinois University, Biological Sciences, 600 Lincoln Avenue, Charleston, Illinois, 61920, USA
3 - High Plains Herbarium, Chadron State College, Chadron, NE, 69337
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 4:15 PM