Ecological life history of the facultative woodland biennial Arabis laevigata variety laevigata (Brassicaceae): survivorship

(1.2)THOMAS C. BLOOM, (1)JERRY M. BASKLN, AND (1.3)CAROL C. BASKIN ('School Of Biological Sciences, University of Kentucky, Lexington, Kentucky 40506- 0225, (2)1209 Glade Street, College Station, TX 77840, and 'Department of A gronomy, University of Kentucky, Lexington, KY 40546-0091). Ecological life history of the facultative woodland biennial Arabis laevigata variety laev igata (Brassicaceae): survivorship. J. Torrey Bet. Sec. 128:000-000. 2001. - Survivorship was studied over an 8.5-year period in a population of the f acultative biennial Arabis laevigata var, laevigata in a rocky deciduous wo odland (Scott's: Grove) in northcentral Kentucky, where most individuals of this species are associated with rook outcrops. Of the 2,269 seedlings mar ked in 1986 and 814 in 1987, only 101 (4.5%) and 35 (4.3%), respectively, s urvived 1 year, and only 24 (0.78%) of the 3,083 plants bolted before they died. In a separate study, only about 63% of the plants that bolted produce d seeds. Thus, only about 15 (0.49%) of the 3,083 plants marked as seedling s in 1986 and 1987 actually reproduced. Cohorts: exhibited a Deevey Type II I survivorship curve. Small plants had a greater probability of dying than large ones. Survival was higher in microsites ton and near rock outcrops) w ith a thin, patchy leaf litter than in those with a moderate leaf cover; pl ants were not found in sites with a thick and persistent litter cover. Rose tte herbivory also was a cause of mortality. Plants at Scott's Grove may fl ower in their second, third, fourth, fifth, or even a later year of life. S urvivorship of A. laevigata in its woodland rock outcrop habitat is similar to that of facultative biennials of various other habitat types.