Plant Diversity Changes during the Postglacial in East Asia: Insights from Forest Refugia on Halla Volcano, Jeju Island

Abstract

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.

Relationship between Survival Rate of Avian Artificial Nests and Forest Vegetation Structure along a Tropical Altitudinal Gradient on Mount Cameroon

“…Vegetation parameters such as coverage of herb layer, density of trees, as well as the degree of canopy openness, vary altitudinally between habitats (Doležal et al . , Russo et al . , Djuikouo et al .…”

Classification of Korean forests: patterns along geographic and environmental gradients

“…When considering the geographic distribution of mountain forest types dominated by conifers (types 1.1 and 1.2), we can reasonably assume that during the last glacial maximum there was conifer‐rich vegetation covering the upper parts of mountain ridges on the Korean Peninsula (Igarashi ; Ren & Zhang ; Kong ; Doležal et al. ). During the Holocene warming, plant species retreated to cooler conditions (Ren & Zhang ; Kong ) and the coniferous forests were immigrated with oceanic taxa from both southern and lowland refugia (Yi et al.…”

“…This phenomenon can be conceived in terms of recent refugia of the main post‐glacial forest types (Doležal et al. ).…”

Was Jeju Island a glacial refugium for East Asian warm‐temperate plants? Insights from the homosporous fern Selliguea hastata (Polypodiaceae)

“…Some authors have suggested Jeju Island to be a crossroad between different plant migration routes (mainly, one from the east—likely from Pacific Japan—and another from the south through land bridges in the ECS; e.g., Dolezal et al, 2012). Postglacial recolonization of mainland Korea from propagules coming from Taiwan (i.e., through this southern route) seems unlikely, as the “white” genetic cluster characterizing this large island is not present in any of the sampled mainland Korean populations (and the UPGMA phenogram also include the Taiwanese populations in a clearly separated cluster).…”