Enhanced growth of Juniperus thurifera under a warmer climate is explained by a positive carbon gain under cold and drought
Enhanced growth of Juniperus thurifera under a warmer climate is explained by a positive carbon gain under cold and drought
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DOI：
10.1093/treephys/tps011
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发表时间：
2012-03-01
期刊：
影响因子：
4
通讯作者：
Valladares, Fernando
中科院分区：
文献类型：
--
作者：
Gimeno, Teresa E.;Julio Camarero, J.;Valladares, Fernando
刺柏(Juniperus thurifera L.)是地中海盆地西部特有的一种针叶树种，在那里它承受着冬季低温和夏季干旱的严重气候胁迫。鉴于该地区气候变暖引起的干旱胁迫增加的趋势，以及该物种对气候的敏感性，我们预计气候变化将对该物种在其占主导地位的恶劣环境中的生长和生态生理表现产生负面影响。为了评估这一点，我们在西班牙中部的三个地点使用树状年代学、光合作用和水分利用效率测量了雄性、雌性和青少年的长期和短期径向生长。对气候进行了监测，并完成了历史记录。研究区域的年平均气温每十年上升0.2摄氏度，主要变暖趋势对应于春季(每十年上升0.2摄氏度)和夏季(每十年上升0.3摄氏度)。径向生长和最大光合作用高峰出现在春秋两季。正的光合作用速率全年保持不变，尽管冬季和夏季的速率有所下降。前一年秋季的湿润条件和年轮形成当年的温暖春季和夏季高降水促进了径向生长。夏季的云层增加了增长，而多云的冬季导致碳增量受损，从长期来看增长放缓。我们认为，在严酷的条件下(冬季低温和夏季干旱月份)保持碳增量和塑料木质化是苏里费尔藻能从气候条件变化中获利的基础，例如更早的春季到来和不稳定的夏季降雨。我们的结果强调，气候变化对地中海树木生长和持久性的影响不仅是大小的，而且是物种特有的。
Juniperus thurifera L. is an endemic conifer of the western Mediterranean Basin where it is subjected to a severe climatic stress characterized by low winter temperatures and summer drought. Given the trend of increased warming-induced drought stress in this area and the climatic sensitivity of this species, we expect a negative impact of climate change on growth and ecophysiological performance of J. thurifera in the harsh environments where it dominates. To evaluate this, we measured long- and short-term radial growth using dendrochronology, photosynthesis and water-use efficiency in males, females and juveniles in three sites in Central Spain. Climate was monitored and completed with historical records. Mean annual temperature has increased +0.2 degrees C per decade in the study area, and the main warming trends corresponded to spring (+0.2 degrees C per decade) and summer (+0.3 degrees C per decade). Radial growth and maximum photosynthesis peaked in spring and autumn. Positive photosynthetic rates were maintained all year long, albeit at reduced rates in winter and summer. Radial growth was enhanced by wet conditions in the previous autumn and by warm springs and high precipitation in summer of the year of tree-ring formation. Cloud cover during the summer increased growth, while cloudy winters led to impaired carbon gain and reduced growth in the long term. We argue that maintenance of carbon gain under harsh conditions (low winter temperatures and dry summer months) and plastic xylogenesis underlie J. thurifera's ability to profit from changing climatic conditions such as earlier spring onset and erratic summer rainfall. Our results highlight that not only the magnitude but also the sign of the impact of climate change on growth and persistence of Mediterranean trees is species specific.