An example null distribution of allelic richness (A_r) for the simulated diameter-limit harvest of > 50 cm. The distribution was generated by performing 10000 random harvests of equal intensity each with an equal number of “harvested” trees chosen at random with respect to diameter. After each simulated harvest, allelic diversity was recalculated based on the genotypes of the residual black walnuts, and the observed value for the > 50 cm harvest was then compared to this null distribution to obtain its statistical significance (one-tail test). All other simulated diameter-limit and value-based harvests generated similarly-shaped distributions and comparable P values, so only this example distribution is shown. The shadowed part of the histogram represents the amount of allelic richness (A_r) of the residual trees after the > 50 cm harvest was conducted.