Klemow, Kenneth M. and D. J. Raynal. 1981. THE DEMOGRAPHY OF THE FACULATATIVE BIENNIAL PICRIS HIERACIOIDES (COMPOSITAE) IN A STRESSFUL ENVIRONMENT. Contributed paper: Ecological Society of America meeting. Abstract: Bulletin of the Ecological Society of America 62:149.
Facultative biennial plants may respond to competitive stress by delaying reproduction far several years. The demographic response of such species growing under physically stressful conditions (low soil moisture and nutrient availability, high soil surface temperatures) has received little attention. In this study, a population of the facultative biennial Picris hieracioides L. growing within an abandoned limestone quarry near Syracuse, NY was investigated. For five consecutive years, individuals were mapped and measured in permanent quadrats on two adjacent sites: one drought-prone, infertile, and sparsely vegetated, and the other with higher soil moisture, fertility, and vegetation cover. Mortality of sparse-site Picris seedlings was heavy, especially during the winters following the fall emergence flush. In contrast, dense-site seedlings displayed much better survival and establishment. Proportionally, more established sparse-site plants flowered and their time to maturity was less than their dense-site counterparts. These data suggest that this abiotically stressful habitat induces severe seedling mortality in Picris, not the reproductive delay often associated with competitive stress.