Original article

Genetic consequences of harvest in a mature second-growth stand of black walnut (Juglans nigra L.)

¹ Department of Forestry and Natural Resources, Hardwood Tree Improvement and Regeneration Center (HTIRC), Purdue University, 715 West State St, Pfendler Hall, West Lafayette, IN 47907-2061, USA
² Laboratory of Genetics, University of Wisconsin, Madison, WI, 53706-1580, USA
³ Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907-2033, USA
⁴ USDA Forest Service, Hardwood Tree Improvement and Regeneration Center (HTIRC), Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907-2061, USA

^* Corresponding author: rod@hartmannsplantcompany.com

Received: 6 August 2009
Accepted: 15 January 2010

Abstract

• This study investigated the short-term changes in neutral genetic variation that would occur if a mature, second-growth, black walnut (Juglans nigra L.) stand was harvested following either a diameter-limited or value-limited cutting regime.

• This research tested whether or not the neutral genetic variation within a natural stand of black walnut was disproportionately distributed within the larger or more valuable cohort of trees. To test this hypothesis a complete census of 278 trees from a black walnut stand in Indiana was genotyped using 12 highly polymorphic microsatellites.

• Two types of simulated harvests were performed: (1) diameter-limit cuts, where every tree above a given diameter was removed; and (2) selective harvests based on value, where subsets of the most valuable trees were removed. Allelic diversity of the remaining population after each simulated harvest was compared to a corresponding distribution of outcomes from 10000 random harvests of equal intensity.

• None of the simulated harvests resulted in a reduction of allelic diversity significantly greater than that expected under random harvest, indicating that the allelic diversity of the population was evenly distributed across the entire population.

• These results indicated that typical harvest scenarios do not per se lead to loss of allelic diversity among trees for this species.