Disturbance and tree life history on the shifting mosaic landscape

An analytical model of disturbance and plant population dynamics is developed to explore the optimal life history for a plant within a "shifting mosaic' metapopulation. The population dynamics consist of short-lived recruitment events followed by longer intervals of thinning. Plants balance costs and benefits of delayed maturation time that result from cohort thinning, a correlation between maturation time and longevity, and the distribution of recruitment events in space and time. Two fundamentally different responses to disturbance are explored: 1) the plant is killed by the disturbance that allows for new recruitment and 2) the plant may survive many such disturbances. Species maximize either the probability of being reproductively mature at the time of the next recruitment opportunity or the total number of recruitment opportunities to occur during the period of reproductive maturity. The optimal maturation time for a gap species in temperate North American forests is 30-60 yr. One test involved fire regimes where 2 species having different responses to fire and life histories co-occur, Pinus resinosa and P. banksiana. The maturation times of these species both match the predicted optima for a species that survives fire (P. resinosa) vs. one that is killed by fire (P. banksiana). The "intermediate' disturbance frequency is predicted to be that which implies the optimum life history that coincides with the life histories of the greatest number of species. -from Author

Duke Scholars

Author James S. Clark Environmental Natural Science