Long-term dynamics of shrub facilitation shape the mixing of evergreen and deciduous oaks in Mediterranean abandoned fields
Long-term dynamics of shrub facilitation shape the mixing of evergreen and deciduous oaks in Mediterranean abandoned fields
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DOI：
10.1111/1365-2745.13309
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发表时间：
2019-11-19
影响因子：
5.5
通讯作者：
Rey-Benayas, Jose M.
中科院分区：
文献类型：
--
作者：
Cruz-Alonso, Veronica;Villar-Salvador, Pedro;Rey-Benayas, Jose M.
恢复地中海森林后，外地放弃是一个缓慢的过程，即使没有繁殖体的限制。这主要是由于幼苗建立的压力条件。在这种情况下，灌木在促进树木补充方面发挥着关键作用，但这一过程在田地废弃后如何展开还不完全清楚。我们评估了促进的长期动态的护士灌木Retama sphaerocarpa在招聘两个生态对比橡树，万年青栎冬青和落叶栎fagarpae。30年后的领域放弃，我们在一个老领域建立的灌木和橡树，估计每年的招聘率和调查时间招聘模式。对于橡树，我们区分招聘在两个微观网站：开放地区或灌木。为了评估如何护理灌木调制环境压力，我们模拟橡树招聘作为气候变量的函数。对于万年青橡树，我们评估了这些影响在每个微网站。最后，我们估计了灌木和万年青栎幼林之间的年度相互作用指数作为气候条件的函数。每个物种在定殖过程中表现出不同的招聘脉冲。灌木的更新率最高，其次是万年青栎。橡树在灌木下的定居是相当可观的20年后，外地放弃，当灌木覆盖率达到2.2%，并集中在中型和大型灌木超过7年。灌木不仅加速万年青栎殖民化，但也减弱了招聘脉冲的波动。对于万年青栎，相互作用指数表明，在夏季干旱（降水量< 47 mm，热浪持续时间超过8天）的年份，促进优势，在夏季潮湿的年份，竞争优势。合成.橡树殖民地在地中海被遗弃的领域进展缓慢，只有二十年后放弃先锋灌木种群的规模和数量增长到一个水平，可以有效地触发促进和加速树木招聘。灌木抚育效应在不同栎属树种间不平衡，仅对万年青栎类有一定的促进作用，且在干旱年份更为普遍。我们的研究说明了建立灌木促进过程中的森林植被化和气候不同的年份和生态不同的物种之间的变化性质，这一过程。这些信息为评估和管理地中海森林恢复提供了见解。
Recovery of Mediterranean forests after field abandonment is a slow process, even without propagule limitations. This is mainly due to stressful conditions for seedling establishment. In this context, shrubs play a critical role in facilitating tree recruitment, but how this process unfolds after field abandonment is not entirely known. We evaluated the long-term dynamics of facilitation by the nurse shrub Retama sphaerocarpa in the recruitment of two ecologically contrasting oaks, the evergreen Quercus ilex and the deciduous Quercus faginea. Thirty years after field abandonment, we dated shrubs and oaks established in an old field to estimate the annual recruitment rates and investigate temporal recruitment patterns. For oaks, we differentiated recruitment at two microsites: open areas or under shrub. To assess how nurse shrubs modulated environmental stressors, we modelled oak recruitment as a function of climatic variables. For the evergreen oak, we assessed these effects within each microsite. Finally, we estimated the annual interaction index between shrubs and evergreen oak juveniles as a function of climatic conditions. Each species showed different recruitment pulses during colonization. Recruitment rate was the highest for the shrub, followed by the evergreen oak. Oak colonization under shrubs was appreciable 20 years after field abandonment, when shrub cover reached 2.2%, and concentrated under medium and large shrubs older than 7 years. Shrubs not only accelerated evergreen oak colonization but also attenuated the fluctuations of recruitment pulses. For the evergreen oak, the interaction index indicated facilitation dominance in years with more arid summers (precipitation < 47 mm and heat waves longer than 8 days) and competition in wetter summers. Synthesis. Oak colonization in Mediterranean abandoned fields progressed slowly, and only two decades after abandonment pioneer shrub population grew to a level in size and number that could effectively trigger facilitation and accelerate tree recruitment. The shrub nurse effect was unbalanced between oak species, only benefiting the evergreen oak, and it was more prevalent in arid years. Our study illustrates the build-up of shrub facilitation during forest recolonization and the varying nature of this process among climatically different years and ecologically distinct species. This information provides insights for assessing and managing Mediterranean forest recovery.