Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada.
PLoS One. 2012;7(8):e44303. doi: 10.1371/journal.pone.0044303. Epub 2012 Aug 30.
Aspen naturally grows in large, single-species, even-aged stands that regenerate clonally after fire disturbance. This offers an opportunity for an intensive clonal forestry system that closely emulates the natural life history of the species. In this paper, we assess the potential of genetic tree improvement and clonal deployment to enhance the productivity of aspen forests in Alberta. We further investigate geographic patterns of genetic variation in aspen and infer forest management strategies under uncertain future climates.
METHODOLOGY/PRINCIPAL FINDINGS: Genetic variation among 242 clones from Alberta was evaluated in 13 common garden trials after 5-8 growing seasons in the field. Broad-sense heritabilities for height and diameter at breast height (DBH) ranged from 0.36 to 0.64, allowing 5-15% genetic gains in height and 9-34% genetic gains in DBH. Geographic partitioning of genetic variance revealed predominant latitudinal genetic differentiation. We further observed that northward movement of clones almost always resulted in increased growth relative to local planting material, while southward movement had a strong opposite effect.
CONCLUSION/SIGNIFICANCE: Aspen forests are an important natural resource in western Canada that is used for pulp and oriented strandboard production, accounting for ~40% of the total forest harvest. Moderate to high broad-sense heritabilities in growth traits suggest good potential for a genetic tree improvement program with aspen. Significant productivity gains appear possible through clonal selection from existing trials. We propose two breeding regions for Alberta, and suggest that well-tested southern clones may be used in the northern breeding region, accounting for a general warming trend observed over the last several decades in Alberta.
白杨自然生长在大型、单一物种、同龄的林分中，在火灾干扰后会以克隆的方式再生。这为密集克隆林业系统提供了机会，该系统可以紧密模拟物种的自然生活史。在本文中，我们评估了遗传树木改良和克隆部署的潜力，以提高阿尔伯塔省白杨林的生产力。我们进一步研究了白杨的地理遗传变异模式，并推断了在不确定未来气候下的森林管理策略。
方法/主要发现：在野外生长 5-8 季后，在 13 个共同田间试验中评估了来自阿尔伯塔省的 242 个克隆的遗传变异。高度和胸径（DBH）的广义遗传力范围为 0.36 至 0.64，允许高度提高 5-15%，DBH 提高 9-34%。遗传方差的地理划分显示出主要的纬度遗传分化。我们还观察到，克隆向北移动几乎总是导致生长增加，而向南移动则有强烈的相反效果。
结论/意义：白杨林是加拿大西部的一种重要自然资源，用于纸浆和定向刨花板生产，占总森林采伐量的~40%。生长性状的中等至高度广义遗传力表明，白杨具有良好的遗传树木改良计划潜力。通过现有试验的克隆选择，可能会获得显著的生产力提高。我们为阿尔伯塔省提出了两个繁殖区，并建议使用经过充分测试的南部克隆在北部繁殖区使用，这反映了过去几十年在阿尔伯塔省观察到的普遍变暖趋势。
