Phenological responses to extreme droughts in a Mediterranean forest
Phenological responses to extreme droughts in a Mediterranean forest
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DOI：
10.1111/j.1365-2486.2010.02348.x
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发表时间：
2011-02
影响因子：
11.6
通讯作者：
L. Misson;D. Degueldre;C. Collin;R. Rodríguez;A. Rocheteau;J. Ourcival;S. Rambal
中科院分区：
文献类型：
--
作者：
L. Misson;D. Degueldre;C. Collin;R. Rodríguez;A. Rocheteau;J. Ourcival;S. Rambal
由于气候变化，预计地中海地区将经历更频繁、更持久和更严重的干旱。我们使用可伸缩的避雨棚来研究极端干旱对栎属冬青叶、花和果实发育的影响。 2008 年，秋季林地中 97% 的降雨量被排除在外，占当年降雨量 1127 毫米的 50%。 2009年，87%的降雨量被排除在春季，占全年降雨量749毫米的58%。避雨棚既不影响入射辐射，也不影响气温。排除秋季降雨并没有显着影响叶子、花朵或果实的发育。春季降雨的排除导致叶水势在叶和花发育的关键阶段出现更大和更持续的下降。因此，只有一半的样本树 (6) 达到了枝条伸长阶段，从而产生功能性成熟的叶子 (物候期 4)，其中一棵树在发芽 (物候期 3) 时放弃了叶子发育，另外两棵树则在芽膨大阶段 (物候期 2) 放弃了叶子发育。对照地块的所有树木都经过了物候期 4，其中大多数达到了完整的叶子发育。极端干旱对花朵发育的影响因性别而异。春季排除对雄花没有影响，但六棵树中只有一棵完成雌性果实成熟，而对照地块中有四棵树完成了雌性果实成熟。雄性和雌性干旱影响之间的差异可能归因于雄花发育发生在叶水势最低时期之前，以及雄花的资源分配需求较低。我们的实验方法提供的信息可能是评估气候变化导致的干旱加剧对地中海最主要树种的影响的关键一步，并有助于全面了解水资源减少在变化条件下对森林动态的生态后果。
Mediterranean regions are projected to experience more frequent, prolonged and severe drought as a consequence of climate change. We used a retractable rainfall shelter, to investigate the impact of extreme droughts on the development of Quercus ilex leaves, flowers and fruit. In 2008, 97% of rainfall was excluded from a forest plot during the autumn, representing 50% of the 1127 mm of rain that fell during the year. In 2009, 87% of rainfall was excluded during the spring, representing 58% of the 749 mm that fell during the year. The rainfall shelter did not impact neither incident radiation nor air temperature. Autumn rainfall exclusion did not significantly affect leaf, flowers or fruit development. Spring rainfall exclusion resulted in larger and more sustained depression of leaf water potential during the key phases of foliar and floral development. Consequently, only half of the sampled trees (6) reached the shoot lengthening stage which leads to functionally mature leaves (phenophase 4), with one abandoning leaf development at budburst (phenophase 3) and the other two at the bud swelling stage (phenophase 2). All trees of the control plot passed phenophase 4, with most reaching complete leaf development. The impact of extreme droughts on flower development differed between the sexes. The spring exclusion had no effect on male flower, but only one of six trees completed female fruit maturation, compared with four in the control plot. The difference between the male and female drought impacts is likely attributable to the occurrence of male floral development before the period of lowest leaf water potential, and to the lower resource allocation requirements of male flowers. The information provided by our experimental approach may constitute a crucial step to evaluate the impact of increasing drought due to climate change on the most dominant Mediterranean tree species and to help drawing a full picture of the ecological consequences of the decline in water resource on forest dynamics under changing conditions.