Population dynamics of <i>Aster pyrenaeus</i> Desf., a threatened species of temperate forest edges: A view of meso- and micro-scales

The effect of forest edges on population viability is one of the most unexplored aspects of plant conservation, and questions arise as to the most adequate management model for preserving species in these habitats. Here, we investigate the population dynamics of a high-priority species (<i>Aster pyrenaeus</i>) related to temperate forest edges in northern Spain. One isolated population was monitored during a 6-year period to analyse its response to habitat configuration at different scales. The effect of the sun-shade gradient was tested at the micro-scale using vegetation cover classes, and stochastic simulations were conducted at the meso-scale using spatially explicit models. At the micro-scale, monitored individuals were preferably located in sunny and semi-shady habitats, where population growth was greater. Species presence at the meso-scale was restricted to mixed shady vegetation, showing a null extinction risk in all the tested scenarios but a high probability of decline under past land use. The studied population seems to have persisted on historical remnants with habitat heterogeneity, supporting the hypothesis that the species has its proper ecological niche in grassland–forest edges. We conclude that the conservation management of plant populations dependent on forest edges should consider the maintenance of heterogeneous habitats.森林边缘对种群生存力的影响是植物保护领域最未被充分探索的方向之一，针对此类生境中的物种保护，最适宜的管理模式仍存在诸多待解问题。本研究针对西班牙北部与温带森林边缘相关的高优先级物种西班牙紫菀（Aster pyrenaeus）的种群动态展开调查。研究人员对一处孤立种群开展了为期6年的监测，以分析其在不同尺度下对生境配置的响应。在微观尺度上，研究团队借助植被覆盖等级检验了阳生-阴生梯度的效应；在中观尺度上，则通过空间显式模型开展了随机模拟。微观尺度的监测结果显示，被监测个体更偏好分布于阳生和半阴生生境，此类生境的种群增长速率更高。中观尺度下，该物种仅局限于混合阴生植被生境中；所有测试情景下其灭绝风险均为零，但在过往土地利用模式下，种群衰退的概率较高。本次研究的种群似乎依托具有生境异质性的历史遗留生境得以存续，这支持了该物种的核心生态位恰处于草原-森林边缘的假说。综上，依赖森林边缘的植物种群保护管理应将维持生境异质性纳入考量范畴。