Genetic variation and phenotypic plasticity play a role in determining the performance of a tree provenance at a planting site. This paper explores their relative importance in determining growth, phenology and tree form in a broad geographic sample of 42 British provenances of common ash (Fraxinus excelsior L.) grown at two contrasting trial sites. We found significant genetic differences for tree height, timing of leaf flushing and leaf senescence, and stem forking among the provenances. These followed a clear latitudinal and climatic cline, where the northern provenances were shorter, their leaves flushed later and senesced earlier than the southern provenances. Provenance explained a much larger proportion of the variance for spring phenology (63 per cent) than for autumn phenology (15 per cent). The effect of the planting site was contrasting between spring and autumn: spring phenology showed very little plasticity, while autumn phenology presented higher levels of phenotypic plasticity. This could indicate that for ash spring phenology is under stronger selective pressure. We found a correlation between tree height, leaf phenology and forking, with early flushing provenances tending to be taller and more forked, which could reflect repeated frost damage. The findings underline the complexity of predicting performance in novel environments and demonstrate that small gains in tree growth may be counteracted by detrimental effects on stem form, a key contributor to timber value, due to susceptibility to the contemporary environment.

中文翻译：

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普通灰 (Fraxinus excelsior L.) 叶片物候、生长和茎形的临床遗传变异和表型可塑性

遗传变异和表型可塑性在决定种植地点的树木来源的性能方面发挥作用。本文探讨了它们在确定在两个对比试验地点生长的 42 个英国普通灰 (Fraxinus excelsior L.) 种源的广泛地理样本中它们在确定生长、物候和树形方面的相对重要性。我们发现树高、叶片潮红和叶片衰老的时间以及种源之间的茎分叉存在显着的遗传差异。它们遵循明显的纬度和气候倾斜，北部种源较短，它们的叶子比南部种源晚冲洗和衰老。与秋季物候学（15%）相比，春季物候学（63%）的出处解释了更大比例的变异。种植地点的影响在春季和秋季之间形成对比：春季物候表现出非常小的可塑性，而秋季物候表现出更高水平的表型可塑性。这可能表明灰泉物候处于更强的选择压力下。我们发现树高、叶片物候和分叉之间存在相关性，早期冲洗的种源往往更高且分叉更多，这可能反映了反复的霜害。研究结果强调了在新环境中预测性能的复杂性，并表明由于对当代环境的敏感性，树木生长的小幅增长可能会被对木材价值的关键贡献者茎形态的不利影响所抵消。而秋季物候表现出更高水平的表型可塑性。这可能表明灰泉物候处于更强的选择压力下。我们发现树高、叶片物候和分叉之间存在相关性，早期冲洗的种源往往更高且分叉更多，这可能反映了反复的霜害。研究结果强调了在新环境中预测性能的复杂性，并表明由于对当代环境的敏感性，树木生长的小幅增长可能会被对木材价值的关键贡献者茎形态的不利影响所抵消。而秋季物候表现出更高水平的表型可塑性。这可能表明灰泉物候处于更强的选择压力下。我们发现树高、叶片物候和分叉之间存在相关性，早期冲洗的种源往往更高且分叉更多，这可能反映了反复的霜害。研究结果强调了在新环境中预测性能的复杂性，并表明由于对当代环境的敏感性，树木生长的小幅增长可能会被对木材价值的关键贡献者茎形态的不利影响所抵消。早期冲刷的种源往往更高，更分叉，这可能反映了反复的霜冻损害。研究结果强调了在新环境中预测性能的复杂性，并表明由于对当代环境的敏感性，树木生长的小幅增长可能会被对木材价值的关键贡献者茎形态的不利影响所抵消。早期冲刷的种源往往更高，更分叉，这可能反映了反复的霜冻损害。研究结果强调了在新环境中预测性能的复杂性，并表明由于对当代环境的敏感性，树木生长的小幅增长可能会被对木材价值的关键贡献者茎形态的不利影响所抵消。