Genetic diversity impacts of forest fires, forest harvesting, and alternative reforestation practices in black spruce (Picea mariana)

Abstract

Benchmarks were established for genetic diversity inherent in natural mature populations, and genetic diversity impacts of forest fires, clearcut harvesting and alternative natural and artificial silvicultural regeneration practices were determined in black spruce (Picea mariana). Allozymes of 32 loci were used to determine and compare genetic diversity and genetic relationships of adjacent or nearby four stand types: post-fire natural mature (FNM), post-fire natural young (FNR), post-harvest natural young (HNR) and post-harvest plantation (PLT), of black spruce at each of the four study sites located in two ecoregions in Manitoba: Ecoregion 90-Lac Seul Upland (Eastern) and Ecoregion 158 - Mid-Boreal Lowland (Northern). Both allelic- and genotypic-based genetic diversity parameters, as well as latent genetic potential, were determined. Black spruce populations showed typical moderate to high levels of allozyme genetic diversity. The mean genetic diversity parameters over the 16 black spruce populations sampled were as follows: percent loci polymorphic - 67%, mean number of alleles per locus - 2.52, effective number of alleles per locus - 1.70, observed heterozygosity - 0.222, expected heterozygosity - 0.308, mean number of observed genotypes per locus - 3.65, mean number of expected genotypes per locus - 5.03, genotype additivity (observed) - 116.8, genotype additivity (expected) - 161, genotype multiplicity (observed) - 6.16 x 10(15), genotype multiplicity (expected) - 2.06 x 10(19) and latent genetic potential - 26.12. The four stand types (FNM, FNR, HNR and PLT) had comparable and statistically similar genetic diversity levels at each of the four study sites as well as overall. No significant differences in black spruce genetic diversity levels were observed between the two ecoregions in Manitoba, as well as between the post-fire and post-harvest regenerated stands. No particular order of genetic relatedness among the four stand types was observed. Black spruce populations showed some sort of site-related differentiation in their genetic constitution. Allelic heterogeneity and genetic distances among populations within stand types and among four stand types suggest that the genetic diversity was maintained at the landscape level in black spruce. The results of our study demonstrate that forest fires and currently used clearcut harvesting, and alternative natural and artificial silvicultural regeneration practices, do not adversely affect genetic diversity in black spruce, and that the genetic diversity effects of clearcut harvesting are not significantly different from those due to forest fires in black spruce.

Diversity of microsatellite markers in the populations of Picea asperata originating from the mountains of China

“…Vettori et al [34] observed a similar situation when studying the geographic distribution of chloroplast variation in Italian populations of beech. In general, the population genetic structure of P. asperata seems to resemble that observed in P. strobes [3] and P. mariana [35]. Fig.…”

Comparison of pollen gene flow among four European beech (Fagus sylvatica L.) populations characterized by different management regimes

“…This usually determines a time lag before the consequences of disturbances, such as habitat fragmentation or exploitation, can be detected (Kramer et al, 2008). In fact, several studies did not find any reduction in genetic diversity or changes in the mating systems of wind-pollinated temperate species following silvicultural practices (for example, Rajora and Pluhar, 2003;Robledo-Arnuncio et al, 2004). However, evidence that silvicultural treatments may modify within-stand genetic structure exists (Rajora, 1999;Rajora et al, 2000).…”

Genetic diversity in young and mature cohorts of cultivated and wild populations of Picea asperata Mast (Pinaceae), a spruce endemic in western China

“…Genetic diversity within tree populations may confer superiority in individual fitness and a buffer against pressure from environmental change (Lambeth and McCullough 1997;Mosseler et al 2003;Rajora and Pluhar 2003;González-Martínez et al 2006). Maintenance of adequate genetic diversity in forest trees not only plays a decisive role in species persistence, but also has an important influence on the continuity of forest regeneration and succession (Newton et al 1999;Booth and Grime 2003;Navascués and Emerson 2007).…”