Global Ecology Unit CSIC-CEAB-CREAF, Centre de Recerca Ecològica i Aplicacions Forestals, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Plant Biol (Stuttg). 2011 Mar;13(2):252-7. doi: 10.1111/j.1438-8677.2010.00358.x.
Current climate projections predict drier and warmer conditions in the Mediterranean basin over the next century. While advanced spring growth due to warming has been described in the literature, few data are available on the effects of drought on phenology. Hence, the phenology and growth of two Mediterranean shrubs, Erica multiflora and Globularia alypum, was studied in a rainfall exclusion field experiment to simulate spring drought in a natural shrubland. We estimated the onset of growth in spring by monitoring the appearance of new stems, and the end of growth in summer by following the elongation of stems. Drought treatment caused earlier onset of the spring growing season in E. multiflora, whereas no advance was observed in G. alypum. However, growth cessation was not affected in E. multiflora. Drought reduced the growth of both shrubs, as reflected in less stem elongation. The results show that a drier climate might affect not only growth but also spring phenology of some Mediterranean species. We suggest that a reduction in the cooling effect of transpiration may have analogous effects to warming and might advance the start of growth in E. multiflora, a species whose phenology has been described as warming-sensitive. The lengthening of the growing season resulting from advanced growth did not imply higher productivity, as growth was restricted by drought.
目前的气候预测预计在下个世纪地中海盆地的条件将更加干燥和温暖。尽管文献中已经描述了由于变暖导致的早春生长，但关于干旱对物候的影响的数据很少。因此，在一个模拟自然灌丛中春季干旱的降雨排除野外实验中，研究了两种地中海灌木——多花艾和Globularia alypum 的物候和生长。我们通过监测新茎的出现来估计春季生长的开始，通过观察茎的伸长来估计夏季生长的结束。干旱处理导致多花艾的春季生长季节更早开始，而Globularia alypum 则没有提前。然而，生长停止在多花艾中不受影响。干旱减少了两种灌木的生长，表现在茎伸长较少。研究结果表明，更干燥的气候可能不仅会影响生长，还会影响某些地中海物种的春季物候。我们认为，蒸腾冷却效应的减少可能会产生类似于变暖的类似影响，并可能提前开始生长，多花艾的物候已经被描述为对变暖敏感。由于干旱限制了生长，生长提前导致的生长季节延长并不意味着更高的生产力。
