Phenodynamics of production and chemical pools in mayapple and flowering dogwood

Phenology has been described as the observation of life phases of plants and animals in their environment throughout the year. Because of seasonality influences, the period during which an event occurs can be predicted provided basic environmental information is available. Phenological considerations relative to productivity and nutrient storage studies are valuable because previous studies with harvests at the end of the growth period only yielded an estimate of net production. Phenological observations are provided for 133 species found on the U.S. Department of Energy's Oak Ridge Reservation. These data provide insight as to the arrival of spring, definition of the growing season, and the initiation of fall dormancy. A model (Y = 20.74 + 0.61X - 0.00055X²) was developed to predict date of first flower based on temperature summation techniques. Phenological events represent mineral inputs into elemental storage pools and subsequently contribute to the mineral cycle within the ecosystem. Detailed studies of the influences of seasonality on production and nutrient storage are provided for mayapple and dogwood. Mayapple represents a population whose phenology responds in almost total synchrony in the manifestation of life stage events. Mayapple populations are very compact, such that plant density (Y) can be estimated from the population area (X) with the model, log₁₀Y - 1.12 + 0.85 (log₁₀X). Dogwood was selected because of its importance to the understory canopy, and its landscape and horticultural value. Increases in biomass are noted with the progression of life stage events, reaching maximum productivity at the reproductive phase for mayapple. Element pools are presented for K, Ca, Mg, P, C, N, and S among mayapples. The importance of these reserves probably serve as short-term storage with a rapid turnover available to fall emerging plants or accumulated in the decomposing litter layer. Dogwood, on the other hand, represents a long-term storage of elements because of its long turnover rate among the woody components. Aboveground biomass (Y) can be estimated from diameter breast height measurements (X) using the model, Y = -3.32 + 2.092X, whereas the belowground biomass (Y) can be determined from the diameter at the base of the tree (X) using the model, Y = -0.75 + 0.34X. Leaves accumulate Ca and may function as a primary reservoir for this element in some forest stands. Among dogwoods the influence of seasonality is observed in biomass production and chemical pools related to phonological development. Nutrient pools determined for dogwood include K, Ca, Mg, and P.