Growth and survival patterns of Cardiocrinum cordatum var. glehnii (Liliaceae) based on a 13-year monitoring study: Life history characteristics of a monocarpic perennial herb

Abstract

Based on 13 years of monitoring, the fates of individuals and contributions of size and age to demography through the life-history from seedling to flower were investigated in a monocarpic perennial herb, Cardiocrinum cordatum (Thunb.) Makino var. glehnii (F. Schmidt) H. Hara. Of 6155 seedlings, 5264 (85.5%) and 852 (13.8%) plants died at the seedling and one-leaf stage during the 13 years, respectively. Twelve individuals (0.40%) at the three- to seven-leaf stage reproduced after vegetative growth for 7–11 years, and all of them always showed constant positive growth patterns. Significant differences of sizes were detected between surviving and non-surviving individuals in earlier years at the one- and two-leaf stages. Logistic regression models showed that the survival and stage-increase probabilities increased until 5-years-old but decreased over 6-years-old, suggesting the significance of aging effects. At the four-leaf stage, the flowering probability increased with size, while it increased with leaf-stage but not size at greater stages. Individual growth models then suggested that many plants grew moderately: not only slow-growing but also rapidly-growing individuals tended to die within 7 years. Our study clarified three aspects of the life-history of C. cordatum: longevity of about a decade, constantly positive growth to flowering, and aging effects on growth and survival.