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Knowledge of forest recovery processes after severe disturbances, such as tropical cyclones, is essential for understanding the mechanisms maintaining forest diversity and ecosystem functioning. However, studies examining the impact of tropical cyclones on forest dynamics are still rare, especially in Northeast Asia. Here, we explore the complex responses of vegetation and soil chemistry to severe tropical cyclone disturbances in Hallasan National Park in South Korea. Vegetation and soil were examined five years before and five years after passages of tropical cyclones in 2012 in natural broadleaf and coniferous forests along an elevation gradient from 950 to 1770 m a.s.l., including the largest population of endemic Abies koreana. Tropical cyclones caused abundant tree mortality, resulting in a 46% decrease in stem basal area. Tropical cyclone disturbances triggered the spread of pioneer trees and shrubs and intense clonal propagation of graminoids, including dwarf bamboo, resulting in less diverse understory vegetation, especially in coniferous forests. In contrast, broadleaf forests at lower elevations experienced only minor disturbance. Opening of canopies after tropical cyclone disturbance led to the decrease in soil cations and doubling of available soil phosphorus stock, which likely contributed to the increased coverage of clonal graminoids, especially in coniferous forests (from 36 to 66%). Hence, increased competition of graminoids and reduction in seed fall and seedling recruitment prevented A. koreana regeneration. The subalpine forest dominated by A. koreana is forecasted to gradual loss due to the fact of temperature increases, intensified tropical cyclones and, particularly, due to the altered competition between dwarf bamboo and fir seedlings. [ABSTRACT FROM AUTHOR]

Aim To describe the main vegetation types of the Korean zonal forests and explore their relationship with the main environmental and geographic gradients. Location Korean Peninsula. Methods A data set of 3847 relevés of zonal (semi)natural forest stands, together with environmental factors recorded in the field or derived from interpolated climatic data was collected. Using the hierarchical ISOPAM method, the relevés were classified into main forest types and their species composition, diversity and distribution were described. Their differentiation along main environmental gradients was analysed with classification and regression trees. Results Eleven vegetation types of forests were distinguished and assigned to five vegetation classes: Quercetea mongolicae (representing the core of the Korean temperate forests), Vaccinio-Piceetea (subalpine coniferous forest), Fagetea crenatae (rare beech-dominated forest included within a sub-montane and sub-oceanic type of oak-dominated forest), Querco mongolicae- Betuletea davuricae (sub-continental drought- and fire-tolerant forest, differentiated along elevational gradient) and Camellietea japonicae (oceanic evergreen forest). At a higher hierarchical level, these 11 vegetation types were grouped into three clusters, which most probably reflect different vegetation development in the Late Pleistocene and Holocene. Within the three major vegetation clusters, each forest type occupies a distinct environment. The forest types are especially well separated along elevational and temperature gradients. The distribution of individual forest types is joinly driven by total amount of incoming energy and thermal extremes, both affecting water supply to plant communities. Conclusions All distinguished vegetation types can be assigned to the recent syntaxonomic classification system. However, three main vegetation clusters do not correspond to traditionally distinguished syntaxonomic units. Nevertheless, the forest types within these clusters share common species with similar ecology and, especially, migration histories during the late glacial and post-glacial periods. Therefore, we interpret these clusters as biogeographic patterns reflecting vegetation history rather than the current environmental conditions. [ABSTRACT FROM AUTHOR]

We investigated successional vegetation on river sediments along the Nakdong River in South Korea at the time when a river regulation project, named the Four River Project, was launched. We sampled differently aged stages of succession in 63 plots of 10 × 10 m in 2010 using species cover estimations. To explain the observed species composition, we considered the following environmental variables: successional age, distance from the estuary, altitude, elevation above the river water line, texture of the substrate (silt, sand and gravel content) and cover of forest around each site within a radius of 1 km. We used ordination techniques to relate plant community characteristics to environmental variables. We distinguished three main successional vegetation types based on their floristic composition, which included especially a variety of willow species. Besides the cover of forest and certain components of substrate texture, all the variables exhibited significant effects on species composition of the vegetation over the course of succession. The most important factors determining the seral vegetation were the altitudinal gradient and successional age. Environmental factors in the riverine landscape together form a complex riverine environment and determine the vegetation pattern. Unfortunately, this environment has been largely destroyed by the massive river regulation project, but our results indicate that, under certain conditions, the riverine vegetation has a potential to at least partly recover even after such a large-scale disturbance. [ABSTRACT FROM AUTHOR]