Determining the location of a deceased mother tree and estimating forest regeneration variables by use of microsatellites and spatial genetic models

摘要

In this paper we first mathematically formulate spatial genetic models that rely on dispersal kernels, using the genetic inhomogeneous Poisson process. On the basis of mapped and genotyped data pertaining to adult and juvenile trees we are able to estimate three fundamental variables of population dynamics: individual female reproductive success, seed dispersal, and pollen flow. The model was applied to a secondary Fagus crenata stand in northern Japan, regenerated after shelterwood harvesting. Highly polymorphic microsatellite data revealed that most of the juveniles around one adult tree were not that tree’s progeny and that some minor alleles were clustered there. These data suggested that another mother tree had formerly been present in the vicinity, produced offspring there and died. Inferring its genotype and location, we applied the genetic inhomogeneous Poisson process. Results confirmed that we would have wrongly assessed the regeneration if we had been unaware of the existence of the dead mother. The average distances for seed dispersal and pollen flow were 18 and 193 m, respectively. The contribution of outside mothers, simultaneously assessed using the dispersal variables in the models, ranged from 10 to 50% depending on their positions relative to preserved adults. Individual female reproductive success varied as much as fiftyfold among the eight preserved adults. Our comprehensive approach, utilizing currently available genetic information, mathematical models, and previous forestry records, helped elucidation of the past forest-regeneration processes.