Instituto Universitario Centro de Estudios Ambientales del Mediterráneo (CEAM-UMH), Charles R. Darwin 14, Parc Tecnològic, 46980, Paterna, Valencia, Spain.
Oecologia. 2012 Jul;169(3):723-31. doi: 10.1007/s00442-011-2244-1. Epub 2012 Jan 15.
In dry areas such as Mediterranean ecosystems, fluctuations in seed production are typically explained by resource (water) availability. However, acorn production in cork oak (Quercus suber) populations shows a very low relationship to weather. Because cork oak trees produce acorns with different maturation patterns (annual and biennial), we hypothesized that acorn production in coexisting individuals with a different dominant acorn maturation type should respond differently to climatic factors and that disaggregating the trees according to their acorn-maturation pattern should provide a more proximal relation to weather factors. We assessed acorn production variability in fragmented cork oak populations of the eastern Iberian Peninsula by counting the total number of acorns in 155 trees during an 8-year period. An initial assessment of acorn production variability in relation to weather parameters yielded very low explained variance (7%). However, after the trees were grouped according to their dominant acorn maturation pattern, weather parameters were found to account for 44% of the variability in acorn crops, with trees with annual acorns exhibiting mast fruiting in years with reduced spring frost and shorter summer droughts and trees with biennial acorns showing the opposite pattern. Thus, conditions that negatively affect annual production could be beneficial for biennial production (and vice versa). The results highlight the importance of the resource-matching hypothesis for explaining acorn production in Quercus suber and suggest that different seed maturation types within a population may allow the species to deal with highly variable weather conditions. They also emphasize the importance of understanding acorn maturation patterns for interpreting masting cycles.
在干旱地区，如地中海生态系统，种子产量的波动通常归因于资源（水）的可利用性。然而，栓皮栎（Quercus suber）种群的橡实产量与天气的关系非常低。由于栓皮栎树产生具有不同成熟模式（一年生和二年生）的橡实，我们假设具有不同主导橡实成熟类型的共存个体的橡实产量应该对气候因素有不同的反应，并且根据它们的橡实成熟模式对树木进行分类应该与天气因素有更直接的关系。我们通过在 8 年期间对 155 棵树的总橡实数量进行计数，评估了伊比利亚半岛东部 fragmented cork oak 种群的橡实产量变异性。对橡实产量与天气参数之间关系的初步评估产生了非常低的可解释方差（7%）。然而，在根据主导橡实成熟模式对树木进行分组后，发现天气参数可以解释橡实作物变异性的 44%，具有一年生橡实的树木在春季霜期减少和夏季干旱缩短的年份表现出mast fruiting，而具有二年生橡实的树木则表现出相反的模式。因此，对一年生产量产生负面影响的条件可能对二年生产量有利（反之亦然）。研究结果强调了资源匹配假说对解释栓皮栎橡实产量的重要性，并表明种群内不同的种子成熟类型可能使该物种能够应对高度变化的天气条件。它们还强调了理解橡实成熟模式对解释 mast 周期的重要性。
