Torres-Ruiz José M, Cochard Hervé, Fonseca Elsa, Badel Eric, Gazarini Luiz, Vaz Margarida
BIOGECO, INRA, University of Bordeaux, 33615 Pessac, France.
INRA, UCA, PIAF, 63000 Clermont-Ferrand, France.
Tree Physiol. 2017 Jun 1;37(6):755-766. doi: 10.1093/treephys/tpx013.
A significant increase in drought events frequency is predicted for the next decades induced by climate change, potentially affecting plant species mortality rates and distributions worldwide. The main trigger of plant mortality is xylem hydraulic failure due to embolism and induced by the low pressures at which water is transported through xylem. As the Mediterranean basin will be severely affected by climate change, the aim of this study was to provide novel information about drought resistance and tolerance of one of its most widely distributed and common genera as a case study: the genus Cistus. Different functional and anatomical traits were evaluated in four co-occurring Cistus species in the Mediterranean Montado ecosystem. Soil water availability for each species was also assessed to evaluate if they show different ecological niches within the area. Results showed physiological and xylem anatomical differences between the four co-occurring species, as well as in the soil water availability of the sites they occupy. Despite the significant differences in embolism resistance across species, no trade-off between hydraulic safety and efficiency was observed. Interestingly, species with narrower vessels showed lower resistance to embolism than those with higher proportions of large conduits. No correlation, however, was observed between resistance to embolism and wood density. The four species showed different water-use and drought-tolerance strategies, occupying different ecological niches that would make them cope differently with drought. These results will allow us to improve the predictions about the expected changes in vegetation dynamics in this area due to ongoing climate change.
预计在未来几十年，气候变化将导致干旱事件频率显著增加，这可能会影响全球植物物种的死亡率和分布。植物死亡的主要诱因是木质部水力失效，这种失效是由栓塞引起的，而栓塞又是在水分通过木质部运输时的低压条件下诱发的。由于地中海盆地将受到气候变化的严重影响，本研究的目的是提供关于该地区分布最广且常见的属之一——岩蔷薇属的抗旱性和耐受性的新信息，以此作为一个案例研究。对地中海蒙塔多生态系统中四种共生的岩蔷薇属植物的不同功能和解剖特征进行了评估。还评估了每个物种的土壤水分可利用性，以评估它们在该地区是否表现出不同生态位。结果表明，这四种共生物种在生理和木质部解剖结构上存在差异，它们所占据地点的土壤水分可利用性也有所不同。尽管不同物种间在抗栓塞能力上存在显著差异，但未观察到水力安全性和效率之间的权衡。有趣的是，导管较窄的物种比大导管比例较高的物种对栓塞的抵抗力更低。然而，未观察到抗栓塞能力与木材密度之间存在相关性。这四个物种表现出不同的水分利用和耐旱策略，占据不同的生态位，这将使它们在应对干旱时表现各异。这些结果将有助于我们改进对该地区由于持续气候变化而导致的植被动态预期变化的预测。
