Department of Biology, Conservation Ecology, University of Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.
Faculty of Biology, University of Warsaw, Białowieża Geobotanical Station, PL-17-230 Białowieża, Poland.
Proc Biol Sci. 2022 May 25;289(1975):20220391. doi: 10.1098/rspb.2022.0391.
Forest degradation changes the structural heterogeneity of forests and species communities, with potential consequences for ecosystem functions including seed dispersal by frugivorous animals. While the quantity of seed dispersal may be robust towards forest degradation, changes in the effectiveness of seed dispersal through qualitative changes are poorly understood. Here, we carried out extensive field sampling on the structure of forest microhabitats, seed deposition sites and plant recruitment along three characteristics of forest microhabitats (canopy cover, ground vegetation and deadwood) in Europe's last lowland primeval forest (Białowieża, Poland). We then applied niche modelling to study forest degradation effects on multi-dimensional seed deposition by frugivores and recruitment of fleshy-fruited plants. Forest degradation was shown to (i) reduce the niche volume of forest microhabitat characteristics by half, (ii) homogenize the spatial seed deposition within and among frugivore species, and (iii) limit the regeneration of plants via changes in seed deposition and recruitment. Our study shows that the loss of frugivores in degraded forests is accompanied by a reduction in the complementarity and quality of seed dispersal by remaining frugivores. By contrast, structure-rich habitats, such as old-growth forests, safeguard the diversity of species interactions, forming the basis for high-quality ecosystem functions.
森林退化改变了森林的结构异质性和物种群落，可能对包括果实类动物传播种子在内的生态系统功能产生潜在影响。虽然种子传播的数量可能对森林退化具有很强的弹性，但通过定性变化来改变种子传播的有效性还知之甚少。在这里，我们在欧洲最后一片低地原始森林（波兰比亚沃维耶扎）中，对森林微生境结构、种子沉积地点和植物繁殖进行了广泛的野外采样，这些采样涉及森林微生境的三个特征（树冠覆盖、地面植被和枯木）。然后，我们应用生态位模型研究森林退化对果实类动物多维种子沉积和肉质果实植物繁殖的影响。研究表明，森林退化（i）使森林微生境特征的生态位体积减少一半，（ii）使果实类动物物种内和物种间的空间种子沉积均匀化，（iii）通过改变种子沉积和繁殖来限制植物的再生。我们的研究表明，在退化森林中，果实类动物的减少伴随着剩余果实类动物传播种子的互补性和质量的降低。相比之下，结构丰富的栖息地，如原始森林，保护了物种相互作用的多样性，为高质量的生态系统功能奠定了基础。
