Forest & Nature Lab, Department of Environment, Faculty of Bioscience Engineering, Ghent University, Melle-Gontrode, Belgium.
Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Lomma, Sweden.
Plant Biol (Stuttg). 2022 Aug;24(5):745-757. doi: 10.1111/plb.13412. Epub 2022 Apr 4.
Quercus spp. are one of the most important tree genera in temperate deciduous forests in terms of biodiversity, economic and cultural perspectives. However, natural regeneration of oaks, depending on specific environmental conditions, is still not sufficiently understood. Oak regeneration dynamics are impacted by climate change, but these climate impacts will depend on local forest management and light and temperature conditions. Here, we studied germination, survival and seedling performance (i.e. aboveground biomass, height, root collar diameter and specific leaf area) of four oak species (Q. cerris, Q. ilex, Q. robur and Q. petraea). Acorns were sown across a wide latitudinal gradient, from Italy to Sweden, and across several microclimatic gradients located within and beyond the species' natural ranges. Microclimatic gradients were applied in terms of forest structure, distance to the forest edge and experimental warming. We found strong interactions between species and latitude, as well as between microclimate and latitude or species. The species thus reacted differently to local and regional changes in light and temperature ; in southern regions the temperate Q. robur and Q. petraea performed best in plots with a complex structure, whereas the Mediterranean Q. ilex and Q. cerris performed better in simply structured forests with a reduced microclimatic buffering capacity. The experimental warming treatment only enhanced height and aboveground biomass of Mediterranean species. Our results show that local microclimatic gradients play a key role in the initial stages of oak regeneration; however, one needs to consider the species-specific responses to forest structure and the macroclimatic context.
栎属（Quercus spp.）是温带落叶林中生物多样性、经济和文化方面最重要的树种之一。然而，栎属的自然更新取决于具体的环境条件，这一点仍然没有得到充分的理解。栎属的更新动态受到气候变化的影响，但这些气候影响将取决于当地的森林管理以及光照和温度条件。在这里，我们研究了四个栎属物种（Q. cerris、Q. ilex、Q. robur 和 Q. petraea）的萌发、存活和幼苗表现（即地上生物量、高度、根颈直径和比叶面积）。橡实被播种在从意大利到瑞典的广泛纬度范围内，以及在物种自然分布范围内和之外的几个微气候梯度上。微气候梯度是根据森林结构、到森林边缘的距离和实验增温来应用的。我们发现，物种和纬度之间，以及微气候和纬度或物种之间存在强烈的相互作用。因此，这些物种对光照和温度的当地和区域变化反应不同；在南部地区，温带的 Q. robur 和 Q. petraea 在结构复杂的地段表现最好，而地中海地区的 Q. ilex 和 Q. cerris 在微气候缓冲能力较弱的简单结构森林中表现更好。实验增温处理仅增强了地中海物种的高度和地上生物量。我们的结果表明，当地的微气候梯度在栎属更新的初始阶段起着关键作用；然而，人们需要考虑到物种对森林结构和大气候背景的特定反应。
