How Do Mediterranean Pine Trees Respond to Drought and Precipitation Events along an Elevation Gradient?
How Do Mediterranean Pine Trees Respond to Drought and Precipitation Events along an Elevation Gradient?
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DOI：
10.3390/f11070758
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发表时间：
2020-07
期刊：
影响因子：
2.9
通讯作者：
S. Szymczak;M. Häusser;É. Garel;S. Santoni;F. Huneau;Isabel Knerr;K. Trachte;J. Bendix;A. Bräuning
中科院分区：
文献类型：
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作者：
S. Szymczak;M. Häusser;É. Garel;S. Santoni;F. Huneau;Isabel Knerr;K. Trachte;J. Bendix;A. Bräuning
干旱是限制树木生长和植物活力的主要因素。在地中海地区，干旱胁迫的持续时间和强度随海拔和地点条件的不同而有很大差异。我们使用电子测树仪来分析两种本地松树对干旱和降水事件的响应。这5个研究中心位于地中海科西嘉岛（法国）的海拔梯度沿着。在原始测树仪测量中的正树干增量被分成径向树干生长和树干膨胀/收缩，以确定树木对气候信号的响应的哪一部分可以归因于生长。在两年内确定了至少5毫米的降水事件和至少连续7天没有降水的干旱期。茎围变化的季节性动态是高度可变的五个研究地点。在高海拔地区，季节性树木生长表现出寒冷环境的特征，而低海拔地区表现出干旱易发地区的双峰生长模式。对降水事件的反应是一致的，发生在降水事件开始后的前六个小时内。大部分茎围的增加是由径向生长引起的，而不是由于吸水引起的茎膨胀。生长诱导的茎周长增加发生在三个网站，即使在干旱时期，这可能是由于储存的水储备在树木或土壤。在土壤持水量低的地点的树木是最容易受到干旱时期。
Drought is a major factor limiting tree growth and plant vitality. In the Mediterranean region, the length and intensity of drought stress strongly varies with altitude and site conditions. We used electronic dendrometers to analyze the response of two native pine species to drought and precipitation events. The five study sites were located along an elevation gradient on the Mediterranean island of Corsica (France). Positive stem increment in the raw dendrometer measurements was separated into radial stem growth and stem swelling/shrinkage in order to determine which part of the trees’ response to climate signals can be attributed to growth. Precipitation events of at least 5 mm and dry periods of at least seven consecutive days without precipitation were determined over a period of two years. Seasonal dynamics of stem circumference changes were highly variable among the five study sites. At higher elevations, seasonal tree growth showed patterns characteristic for cold environments, while low-elevation sites showed bimodal growth patterns characteristic of drought prone areas. The response to precipitation events was uniform and occurred within the first six hours after the beginning of a precipitation event. The majority of stem circumference increases were caused by radial growth, not by stem swelling due to water uptake. Growth-induced stem circumference increase occurred at three of the five sites even during dry periods, which could be attributed to stored water reserves within the trees or the soils. Trees at sites with soils of low water-holding capacity were most vulnerable to dry periods.