Swedish Species Information Centre, Swedish University of Agricultural Sciences, P.O. Box 7007, Uppsala, 75007, Sweden.
Finish Environment Institute, Friendship Park Research Centre, Lentiirantie 342B, Kuhmo, 88900, Finland.
Ecology. 2017 Mar;98(3):741-750. doi: 10.1002/ecy.1686. Epub 2017 Feb 10.
Understanding the relative importance of different ecological processes on the metapopulation dynamics of species is the basis for accurately forecasting metapopulation size in fragmented landscapes. Successful local colonization depends on both species dispersal range and how local habitat conditions affect establishment success. Moreover, there is limited understanding of the effects of different spatiotemporal landscape properties on future metapopulation size. We investigate which factors drive the future metapopulation size of the epiphytic model lichen species Lobaria pulmonaria in a managed forest landscape. First, we test the importance of dispersal and local conditions on the colonization-extinction dynamics of the species using Bayesian state-space modelling of a large-scale data set collected over a 10-yr period. Second, we test the importance of dispersal and establishment limitation in explaining establishment probability and subsequent local population growth, based on a 10-yr propagule sowing experiment. Third, we test how future metapopulation size is affected by different metapopulation and spatiotemporal landscape dynamics, using simulations with the metapopulation models fitted to the empirical data. The colonization probability increased with tree inclination and connectivity, with a mean dispersal distance of 97 m (95% credible intervals, 5-530 m). Local extinctions were mainly deterministic set by tree mortality, but also by tree cutting by forestry. No experimental establishments took place on clearcuts, and in closed forest the establishment probability was higher on trees growing on moist than on dry-mesic soils. The subsequent local population growth rate increased with increasing bark roughness. The simulations showed that the restricted dispersal range estimated (compared to non-restricted dispersal range), and short tree rotation length (65 yr instead of 120) had approximately the same negative effects on future metapopulation size, while regeneration of trees creating a random tree pattern instead of an aggregated one had only some negative effect. However, using the colonization rate obtained with the experimentally added diaspores led to a considerable increase in metapopulation size, making the dispersal limitation of the species clear. The future metapopulation size is thus set by the number of host trees located in shady conditions, not isolated from occupied trees, and by the rotation length of these host trees.
理解不同生态过程对物种的集合种群动态的相对重要性是准确预测破碎景观中集合种群大小的基础。成功的局部定殖既取决于物种的扩散范围，也取决于当地生境条件对建立成功率的影响。此外，人们对不同时空景观属性对未来集合种群大小的影响知之甚少。我们调查了哪些因素驱动了管理森林景观中附生模式地衣物种肺衣 Lobaria pulmonaria 的未来集合种群大小。首先，我们使用贝叶斯状态空间模型对在 10 年期间收集的大规模数据集进行分析，以检验扩散和当地条件对物种的定居-灭绝动态的重要性。其次，我们基于 10 年的繁殖体播种实验，检验了扩散和建立限制在解释建立概率和随后的局部种群增长中的重要性。第三，我们使用拟合经验数据的集合种群模型进行模拟，检验了未来集合种群大小如何受到不同集合种群和时空景观动态的影响。随着树木倾斜度和连通性的增加，定植概率增加，平均扩散距离为 97m（95%置信区间，5-530m）。局部灭绝主要由树木死亡率决定，但也受林业砍伐决定。在皆伐地上没有实验性建立，在封闭森林中，生长在潮湿土壤上的树木比生长在干燥-中湿土壤上的树木建立概率更高。随后的局部种群增长率随着树皮粗糙度的增加而增加。模拟结果表明，与非限制扩散范围相比，估计的受限扩散范围（与非限制扩散范围相比）和较短的树木轮伐期（65 年而不是 120 年）对未来集合种群大小有大致相同的负面影响，而树木更新形成随机树木模式而不是聚集模式只有一些负面影响。然而，使用实验添加的孢子获得的定居率导致集合种群大小的显著增加，从而清楚地表明了该物种的扩散限制。因此，未来的集合种群大小由位于阴凉条件下、与已占据树木不隔离的宿主树木数量以及这些宿主树木的轮伐期决定。
