Life Cycle Characteristics of Aster Pilosus in Early Succesional Habitats

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Abstract
Aster pilosus is a perennial common in early successional fields. In much of the eastern United States, it becomes prominent in 2nd—yr and 3rd—yr old—fields. Its survivorship, growth and flowering are influenced greatly by competition with summer annuals. Spring—germinated individuals are flexible with respect to age of 1st reproduction; they flower during the fall or delay flowering for a year under resource— and especially nutrient—limiting conditions. Fall—germinated plants form rosettes that overwinter and bolt the following spring. Most Aster individuals are iteroiparous and remain established in the field for several years. Flowering, which is dependent on size rather than age, is apparently controlled photoperiodically only after a threshold of growth has been attained. Bolted individuals which are 2 yr old have a much higher seed output than reproducing plants in 1st—yr communities, although reproductive effort is the same. Germination is most favorable under high levels of irradiance, red light, and moderately high concentrations of NO2—, conditions associated with disturbance. Photosynthetic response changes ontogenetically, and productivity is maximized under changing light conditions of the developing plant community. High rates of photosynthesis under water limitation and over a broad range of temperature indicate the tolerance of Aster to the variable environmental conditions of early successional habitats. Aster is an early midsuccessional plant that keys is on disturbance. It does not compete well with 1st—yr annuals in growth from seed. However, the perennial habitat provides it with a competitive advantage over the annuals in subsequent years. Although early reproduction may be sacrificed by Aster under resource—limited conditions, investment of energy in overwintering rosettes guarantees continued establishment in the site and future opportunities for reproduction by seed.