CEFE, Université de Montpellier, CNRS, EPHE, IRD, 1919 route de Mende, Montpellier Cedex 5, 34293, France.
New Phytol. 2021 Jul;231(2):631-645. doi: 10.1111/nph.17412. Epub 2021 May 17.
Climate change might impact tree fecundity by altering the relative influences of meteorological and physiological drivers, and by modifying resource investment in reproduction. Using a 13-yr monitoring of Quercus ilex reproduction in a rainfall exclusion experiment, we analysed the interactive effects of long-term increased aridity and other environmental drivers on the inter-annual variation of fecundity (male flower biomass, number of initiated and mature fruits). Summer-autumn water stress was the main driver of fruit abortion during fruit growth. Rainfall exclusion treatment strongly reduced the number of initiated and mature fruits, even in masting years, and did not increase fruit tolerance to severe drought. Conversely, the relative contribution of the meteorological and physiological drivers, and the inter-annual variability of fruit production were not modified by rainfall exclusion. Rather than inducing an acclimation of tree fecundity to water limitation, increased aridity impacted it negatively through both lower fruit initiation due to changes in resource allocation, and more severe water and resource limitations during fruit growth. Long-term increased aridity affected tree reproduction beyond what is expected from the current response to inter-annual drought variations, suggesting that natural regeneration of holm oak forest could be jeopardised in the future.
气候变化可能通过改变气象和生理驱动因素的相对影响，以及通过改变生殖资源的投资，从而影响树木的繁殖力。本研究通过对栎属树木繁殖的 13 年监测，在一个降雨量排除实验中，分析了长期干旱加剧以及其他环境驱动因素对繁殖力（雄花生物量、启动和成熟果实数量）年际变化的相互作用。夏秋季水分胁迫是果实生长过程中果实败育的主要驱动因素。降雨量排除处理强烈减少了启动和成熟果实的数量，即使在大年，也没有增加果实对严重干旱的耐受性。相反，降雨量排除并没有改变气象和生理驱动因素的相对贡献，以及果实产量的年际变异性。增加的干旱并没有通过改变资源分配导致果实启动减少，以及在果实生长过程中出现更严重的水分和资源限制，从而对树木的繁殖力产生适应性影响。长期干旱加剧影响了树木的繁殖，超出了当前对年际干旱变化的响应预期，这表明未来可能会危及栎属森林的自然更新。
