Demography of Floerkea Proserpinacoides, A Forest-Floor Annual: I. Density- Dependent Growth and Mortality

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Abstract
F. proserpinacoides is a spring ephemeral annual plant of mesic North American deciduous forests that typically grows at high density. This study tests the hypothesis that growth and mortality are commonly density-dependent under natural conditions. The state and the number of buds, branches, nodes, leaves and leaflets present on individual plants were recorded at intervals throughout the growing season. Survivorship curves of plants were of similar shape at different densities, but plants at high density died sooner than did those at low density. Birth rates of nodes and leaflets decreased sooner at progressively higher density. The result was a significantly density-dependent trend in the production per plant of these parts. The production of buds and branches was also significantly smaller at high density, but the phenologies of bud and branch production did not differ with density. The number of nodes produced per plant is the product of 3 sequential vegetative bud processes: bud production per plant, shoot production per bud, and node production per shoot. All three were negatively affected by density, but node production per shoot was influenced most. This, together with the high sensitivity of branch production to density, suggests that processes initiated later are those most affected by crowding. Bud behavior and branch structure varied significantly according to their node-position on the plant.