Data from: Environmental drivers of mast-seeding in Mediterranean oak species: does leaf habit matter?

Understanding the proximate factors that govern the widespread mast-seeding process is a question of considerable interest that remains poorly understood. The identity and effect of these factors may vary among coexisting species that differ in leaf habit, potentially resulting in temporally asynchronous patterns of seed production. In this study we aim to identify the proximate causes of mast-seeding using two oak species with contrasting leaf habit that coexist in southern Spain, the deciduous Quercus canariensis and the evergreen Q. suber. Simultaneously, we review the literature on environmental drivers of mast-seeding in Mediterranean oaks, distinguishing between evergreen and deciduous species. Our results indicate that Mediterranean oaks are primarily sensitive to weather, mast-seeding being strongly correlated with water availability and air temperature, mainly in the spring and summer. The two study oak species were affected by weather in quite different ways, most likely because of different abiotic requirements as well as contrasting functional strategies of resource use and biomass allocation. Specifically, annual seed production in Q. canariensis was more severely limited by drought than in Q. suber, but responded positively to warmer spring temperatures. Q. canariensis showed a large interannual variability, whereas Q. suber exhibited much more constant seed production. These two species also exhibited a very low level of synchrony in their temporal patterns of seed crop size, most likely due to phenological differences in the processes of flowering and seed maturation. Synthesis. Our results indicate that weather plays a crucial role as a proximate driver of mast-seeding in Mediterranean oaks. We hypothesize that the current abundance of co-occurring species that differ in leaf habit could be altered under future climate change scenarios. The decline of seed production with drier conditions will be potentially greater in deciduous species, particularly those inhabiting wetter sites. Alternatively, the expected warmer temperatures could negatively affect evergreen species as a consequence of their more conservative strategy of biomass allocation. Our findings suggest that understanding how species with different functional or phenological attributes adjust their reproductive abilities to weather may enable us to infer the effects of ongoing environmental changes on population recruitment and dynamics.

阐明调控广泛存在的种子大年现象（mast-seeding）的近因因子，是一个备受关注但至今仍未得到充分解析的科学问题。这些因子的作用特性与效应，会因共存物种的叶习性差异而有所不同，进而可能导致种子生产的时间异步格局。本研究以西班牙南部共存的两种叶习性迥异的栎属物种为研究对象：落叶的加那利栎（Quercus canariensis）与常绿的栓皮栎（Q. suber），旨在解析种子大年现象的近因。与此同时，本研究还综述了地中海栎属植物种子大年现象的环境驱动因子相关文献，并区分了常绿与落叶栎类的差异。研究结果表明，地中海栎类主要受气象条件调控，种子大年现象与水分可利用性及气温显著相关，且该关联主要出现在春夏季。两种受试栎类受气象条件的影响模式差异显著，这极可能源于其非生物需求的不同，以及资源利用与生物量分配的功能策略差异。具体而言，相较于栓皮栎，加那利栎的年度种子生产受干旱的抑制作用更强，但春季气温升高对其种子生产有正向促进效应。加那利栎的种子生产表现出较强的年际波动，而栓皮栎的种子生产则更为稳定。两种栎类的种子产量时间格局同步性极低，这大概率与二者开花与种子成熟过程的物候差异有关。综合分析：本研究结果证实，气象条件是调控地中海栎类种子大年现象的关键近因驱动因子。我们提出假说：在未来气候变化情景下，当前共存的叶习性各异的栎类物种的种群丰度可能发生改变。干旱加剧将对落叶栎类的种子生产造成更显著的抑制，尤其是栖息于湿润生境的落叶栎类。反之，未来气温升高可能会对常绿栎类产生负面影响，这源于其更为保守的生物量分配策略。本研究结果提示，阐明不同功能或物候属性的物种如何根据气象条件调控其繁殖能力，将有助于我们预测当前持续的环境变化对种群补充与种群动态的影响。