Seidel Hannes, Menzel Annette
Professorship of Ecoclimatology, Department of Ecology and Ecosystem Management, TUM School of Life Sciences Weihenstephan, Technische Universität München Freising, Germany.
Professorship of Ecoclimatology, Department of Ecology and Ecosystem Management, TUM School of Life Sciences Weihenstephan, Technische Universität MünchenFreising, Germany; Institute for Advanced Study, Technische Universität MünchenGarching, Germany.
Front Plant Sci. 2016 Jul 7;7:1014. doi: 10.3389/fpls.2016.01014. eCollection 2016.
Seedling establishment is a critical part of the life cycle, thus seedling survival might be even more important for forest persistence under recent and future climate change. Scots pine forests have been disproportionally more affected by climate change triggered forest-dieback. Nevertheless, some Scots pine provenances might prove resilient to future drought events because of the species' large distributional range, genetic diversity, and adaptation potential. However, there is a lack of knowledge on provenance-specific survival under severe drought events and on how acclimation alters survival rates in Scots pine seedlings. We therefore conducted two drought-induced mortality experiments with potted Scots pine seedlings in a greenhouse. In the first experiment, 760 three-year-old seedlings from 12 different provenances of the south-western distribution range were subjected to the same treatment followed by the mortality experiment in 2014. In the second experiment, we addressed the question of whether acclimation to re-occurring drought stress events and to elevated temperature might decrease mortality rates. Thus, 139 four-year-old seedlings from France, Germany, and Poland were subjected to different temperature regimes (2012-2014) and drought treatments (2013-2014) before the mortality experiment in 2015. Provenances clearly differed in their hazard of drought-induced mortality, which was only partly related to the climate of their origin. Drought acclimation decreased the hazard of drought-induced mortality. Above-ground dry weight and height were the main determinants for the hazard of mortality, i.e., heavier and taller seedlings were more prone to mortality. Consequently, Scots pine seedlings exhibit a considerable provenance-specific acclimation potential against drought mortality and the selection of suitable provenances might thus facilitate seedling establishment and the persistence of Scots pine forest.
幼苗建立是生命周期中的关键部分，因此在当前和未来气候变化背景下，幼苗存活对于森林的持续存在可能更为重要。苏格兰松树林受到气候变化引发的森林衰退影响的程度尤其严重。然而，由于该物种分布范围广、遗传多样性高以及适应潜力大，一些苏格兰松种源可能对未来干旱事件具有韧性。然而，对于在严重干旱事件下特定种源的存活率以及驯化如何改变苏格兰松幼苗的存活率，我们还缺乏了解。因此，我们在温室中对盆栽苏格兰松幼苗进行了两项干旱诱导死亡率实验。在第一个实验中，来自西南分布范围12个不同种源的760株三年生幼苗接受相同处理，随后于2014年进行死亡率实验。在第二个实验中，我们探讨了对反复出现的干旱胁迫事件和升高温度的驯化是否可能降低死亡率这一问题。因此，在2015年进行死亡率实验之前，来自法国、德国和波兰的139株四年生幼苗接受了不同的温度处理（2012 - 2014年）和干旱处理（2013 - 2014年）。种源在干旱诱导死亡率的风险方面存在明显差异，这仅部分与它们起源地的气候相关。干旱驯化降低了干旱诱导死亡率的风险。地上干重和高度是死亡率风险的主要决定因素，即较重和较高的幼苗更容易死亡。因此，苏格兰松幼苗对干旱死亡率表现出相当大的种源特异性驯化潜力，选择合适的种源可能有助于幼苗建立和苏格兰松森林的持续存在。
