Vander Mijnsbrugge Kristine, Turcsán Arion, Maes Jorne, Duchêne Nils, Meeus Steven, Steppe Kathy, Steenackers Marijke
Department of Forest Genetic Resources, Research Institute for Nature and Forest Geraardsbergen, Belgium.
Department of Forest Genetic Resources, Research Institute for Nature and ForestGeraardsbergen, Belgium; Department of Biometrics and Agricultural Informatics, Corvinus University of BudapestBudapest, Hungary; Department of Forest Reproductive Material and Plantation Management, Institute of Silviculture and Forest Protection, West-Hungarian UniversitySopron, Hungary.
Front Plant Sci. 2016 Mar 31;7:419. doi: 10.3389/fpls.2016.00419. eCollection 2016.
Climate change predicts harsher summer droughts for mid-latitudes in Europe. To enhance our understanding of the putative impacts on forest regeneration, we studied the response of oak seedlings (Quercus petraea) to water deficit. Potted seedlings originating from three locally sourced provenances were subjected to two successive drought periods during the first growing season each followed by a plentiful re-watering. Here, we describe survival and phenological responses after the second drought treatment, applying general linear mixed modeling. From the 441 drought treated seedlings 189 subsisted with higher chances of survival among smaller plants and among single plants per pot compared to doubles. Remarkably, survival was independent of the provenance, although relatively more plants had died off in two provenances compared to the third one with mean plant height being higher in one provenance and standard deviation of plant height being higher in the other. Timing of leaf senescence was clearly delayed after the severe drought treatment followed by re-watering, with two seedlings per pot showing a lesser retardation compared to single plants. This delay can be interpreted as a compensation time in which plants recover before entering the subsequent developmental process of leaf senescence, although it renders seedlings more vulnerable to early autumn frosts because of the delayed hardening of the shoots. Onset of bud flush in the subsequent spring still showed a significant but small delay in the drought treated group, independent of the number of seedlings per pot, and can be considered as an after effect of the delayed senescence. In both phenological models significant differences among the three provenances were detected independent from the treatment. The only provenance that is believed to be local of origin, displayed the earliest leaf senescence and the latest flushing, suggesting an adaptation to the local maritime climate. This provenance also displayed the highest standard deviation of plant height, which can be interpreted as an adaptation to variable and unpredictable weather conditions, favoring smaller plants in drought-prone summers and higher plants in more normal growing seasons.
气候变化预示着欧洲中纬度地区夏季干旱将更加严峻。为了加深我们对其对森林更新可能产生影响的理解，我们研究了栎树苗（欧洲栓皮栎）对水分亏缺的响应。来自三个本地种源的盆栽幼苗在第一个生长季节经历了两个连续的干旱期，之后每次都进行充足的重新浇水。在此，我们应用广义线性混合模型描述第二次干旱处理后的存活情况和物候响应。在441株经过干旱处理的幼苗中，189株存活下来，与每盆双株苗相比，单株苗以及较小植株的存活几率更高。值得注意的是，存活率与种源无关，尽管与第三个种源相比，有两个种源的死亡植株相对较多，其中一个种源的平均株高较高，另一个种源的株高标准差较高。在严重干旱处理并重新浇水后，叶片衰老的时间明显延迟，与单株苗相比，每盆两株苗的延迟程度较小。这种延迟可以被解释为一个补偿期，在此期间植物在进入随后的叶片衰老发育过程之前进行恢复，尽管由于新梢硬化延迟，这使得幼苗更容易受到早秋霜冻的影响。在随后的春季，干旱处理组的芽萌动仍有显著但较小的延迟，与每盆幼苗数量无关，可以被视为衰老延迟的后遗症。在两个物候模型中，检测到三个种源之间存在显著差异，与处理无关。唯一被认为是本地起源的种源，表现出最早的叶片衰老和最晚的芽萌动，这表明它适应了当地的海洋性气候。这个种源的株高标准差也最高，这可以被解释为对多变和不可预测天气条件的一种适应，有利于在易干旱的夏季生长较小的植株，而在更正常的生长季节生长较高的植株。
