Genetic consequences of selection cutting on sugar maple (Acer saccharum Marshall)

Abstract

Selection cutting is a treatment that emulates tree‐by‐tree replacement for forests with uneven‐age structures. It creates small openings in large areas and often generates a more homogenous forest structure (fewer large leaving trees and defective trees) that differs from old‐growth forest. In this study, we evaluated whether this type of harvesting has an impact on genetic diversity of sugar maple (Acer saccharum Marshall). Genetic diversity among seedlings, saplings, and mature trees was compared between selection cut and old‐growth forest stands in Québec, Canada. We found higher observed heterozygosity and a lower inbreeding coefficient in mature trees than in younger regeneration cohorts of both forest types. We detected a recent bottleneck in all stands undergoing selection cutting. Other genetic indices of diversity (allelic richness, observed and expected heterozygosity, and rare alleles) were similar between forest types. We concluded that the effect of selection cutting on the genetic diversity of sugar maple was recent and no evidence of genetic erosion was detectable in Québec stands after one harvest. However, the cumulative effect of recurring applications of selection cutting in bottlenecked stands could lead to fixation of deleterious alleles, and this highlights the need for adopting better forest management practices.

Influence of northern limit range on genetic diversity and structure in a widespread North American tree, sugar maple (Acer saccharumMarshall)

“…Graignic et al. () reported the same difference between younger regeneration cohorts (seedlings and saplings) and mature trees. Foré et al.…”

“…() ( H E = 0.822), by Graignic et al. () ( H E = 0.689), and other species such as Acer mono Maxim. ( H E = 0.80, range: 0.70–0.85; Kikuchi, Shibata, Tanaka, Yoshimaru, & Niiyama, ; Takayama, Sun, & Stuessy, ) and Acer campestre L. ( H E = 0.602, range: 0.509–0.699; Chybicki, Waldon‐Rudzionek, & Meyza, ; Table ).…”

“…() revealed a high level of genetic diversity in sugar maple populations (see Table ). Only two studies using microsatellite markers on natural population of sugar maple (Graignic et al., ; Khodwekar, Staton, Coggeshall, Carlson, & Gailing, ) were available for comparison with our results. Our results were in the range reported by Khodwekar et al.…”

“…The eighteen microsatellite markers developed by Graignic et al (2013) revealed a high level of genetic diversity in sugar maple populations (see Table 1). Only two studies using microsatellite markers on natural population of sugar maple (Graignic et al, 2016;Khodwekar, Staton, Coggeshall, Carlson, & Gailing, 2015) were available for comparison with our results. Our results were in the range reported by Khodwekar et al (2015) (H E = 0.822), by Graignic et al (2016) (H E = 0.689), and other species such as Acer mono Maxim.…”

“…Replication of the edges makes it possible to determine whether the spatial distribution of genetic diversity in sugar maple populations reflects lasting signatures of postglacial range expansion ("range shift following the last glacial maximum"; Hampe & Petit, 2005), or if they are characteristic of peripheral populations per se (central-marginal hypothesis; Eckert et al, 2008). Graignic, Tremblay, and Bergeron (2016) previously reported the presence of higher genetic diversity and a lower inbreeding coefficient in mature trees than in younger regeneration cohorts in three natural sugar maple populations. Mature tree and sapling cohorts were sampled to explore whether the distribution of genetic diversity was different between cohorts in a larger area.…”