Institute of Botany, Academy of Sciences of the Czech Republic, Pruhonice, Czech Republic.
PLoS One. 2012;7(3):e33065. doi: 10.1371/journal.pone.0033065. Epub 2012 Mar 16.
Understanding how past climate changes affected biodiversity is a key issue in contemporary ecology and conservation biology. These diversity changes are, however, difficult to reconstruct from paleoecological sources alone, because macrofossil and pollen records do not provide complete information about species assemblages. Ecologists therefore use information from modern analogues of past communities in order to get a better understanding of past diversity changes. Here we compare plant diversity, species traits and environment between late-glacial Abies, early-Holocene Quercus, and mid-Holocene warm-temperate Carpinus forest refugia on Jeju Island, Korea in order to provide insights into postglacial changes associated with their replacement. Based on detailed study of relict communities, we propose that the late-glacial open-canopy conifer forests in southern part of Korean Peninsula were rich in vascular plants, in particular of heliophilous herbs, whose dramatic decline was caused by the early Holocene invasion of dwarf bamboo into the understory of Quercus forests, followed by mid-Holocene expansion of strongly shading trees such as maple and hornbeam. This diversity loss was partly compensated in the Carpinus forests by an increase in shade-tolerant evergreen trees, shrubs and lianas. However, the pool of these species is much smaller than that of light-demanding herbs, and hence the total species richness is lower, both locally and in the whole area of the Carpinus and Quercus forests. The strongly shading tree species dominating in the hornbeam forests have higher leaf tissue N and P concentrations and smaller leaf dry matter content, which enhances litter decomposition and nutrient cycling and in turn favored the selection of highly competitive species in the shrub layer. This further reduced available light and caused almost complete disappearance of understory herbs, including dwarf bamboo.
了解过去的气候变化如何影响生物多样性是当代生态学和保护生物学的一个关键问题。然而，这些多样性变化仅从古生态学资料很难重建，因为宏观化石和花粉记录并不能提供关于物种组合的完整信息。因此，生态学家利用过去群落的现代类似物的信息，以便更好地了解过去的多样性变化。在这里，我们比较了韩国济州岛末次冰期的冷杉、早全新世的栎树和中全新世暖温带的山毛榉林避难所的植物多样性、物种特征和环境，以深入了解与它们更替相关的冰后期变化。通过对遗留群落的详细研究，我们提出朝鲜半岛南部的末次冰期开阔树冠针叶林富含维管植物，特别是喜阳性草本植物，它们的急剧减少是由早全新世矮竹入侵栎树林下层引起的，随后中全新世强烈遮荫的枫树和山毛榉树扩张。这种多样性的丧失在山毛榉林中部分得到了常绿乔木、灌木和藤本植物的增加的补偿。然而，这些物种的数量远小于喜光草本植物，因此无论是在山毛榉林和栎树林的局部地区还是整个地区，总物种丰富度都较低。在山毛榉林中占主导地位的强烈遮荫树种具有较高的叶片组织氮和磷浓度以及较小的叶片干物质含量，这促进了凋落物分解和养分循环，从而有利于灌木层中高竞争力物种的选择。这进一步减少了可用光，并导致包括矮竹在内的林下草本植物几乎完全消失。
