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.探明调控广泛发生的结种大年（mast-seeding）过程的近因因素，是一个广受关注但至今仍未被充分阐明的科学议题。这些因素的具体类型与效应，可能在叶习性各异的共存物种间存在差异，进而可能导致种子产量呈现时间异步的格局。本研究以西班牙南部共存的两种叶习性截然不同的栎属物种——落叶的加那利栎（Quercus canariensis）与常绿的栓皮栎（Q. suber）为研究对象，旨在探明结种大年的近因成因。与此同时，我们系统梳理了关于地中海栎类结种大年环境驱动因子的相关文献，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，结种大年现象与水分可获得性及气温显著相关，且该关联主要出现在春夏季。两种研究栎属物种对气象条件的响应模式存在显著差异，这大概率源于其非生物需求的差异，以及资源利用与生物量分配方面截然不同的功能策略。具体而言，与栓皮栎相比，加那利栎的年度种子产量受干旱的抑制作用更强，但会因春季气温升高而呈现增产响应。加那利栎的种子产量具有较强的年际变异性，而栓皮栎的种子产量则相对稳定。二者的种子产量时间格局也呈现极低的同步性，这极有可能源于开花与种子成熟过程中的物候差异。综上，本研究结果证实，气象条件是调控地中海栎类结种大年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，叶习性各异的共存物种的现有种群丰度可能会发生改变。在干旱化加剧的情境下，落叶栎类（尤其是栖息于湿润生境的物种）的种子产量降幅可能更为显著。反之，未来预期的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。本研究结果表明，明晰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，有助于我们推断当前持续发生的环境变化对种群补充与种群动态的影响。