The globally observed trend of changing intensity of tropical cyclones over the past few decades emphasizes the need for a better understanding of the effects of such disturbance events in natural and inhabited areas. On the Korean Peninsula, typhoon intensity has increased over the past 100 years as evidenced by instrumental data recorded from 1904 until present. We examined how the increase in three weather characteristics (maximum hourly and daily precipitation, and maximum wind speed) during the typhoon activity affected old-growth oak forests. Quercus mongolica is a dominant species in the Korean mountains and the growth releases from 220 individuals from three sites along a latitudinal gradient (33-38°N) of decreasing typhoon activity were studied. Growth releases indicate tree-stand disturbance and improved light conditions for surviving trees. The trends in release events corresponded to spatiotemporal gradients in maximum wind speed and precipitation. A high positive correlation was found between the maximum values of typhoon characteristics and the proportion of trees showing release. A higher proportion of disturbed trees was found in the middle and southern parts of the Korean peninsula where typhoons are most intense. This shows that the releases are associated with typhoons and also indicates the differential impact of typhoons on the forests. Finally, we present a record of the changing proportion of trees showing release based on tree-rings for the period 1770-1979. The reconstruction revealed no trend during the period 1770-1879, while the rate of forest disturbances increased rapidly from 1880 to 1979. Our results suggest that if typhoon intensity rises, as is projected by some climatic models, the number of forest disturbance events will increase thus altering the disturbance regime and ecosystem processes.
Abstract Aim Species on islands are at high risk of extinction due to environmental changes, including global warming, land‐use alterations and invasions. At local scales, extinctions can be offset by strategies promoting in situ persistence. We explored how persistence‐related traits of plants—that is, linked to belowground resource conservation, growth, size and longevity—on edaphic islands respond to variation in insularity and the environment (soil and microclimate), including intraspecific variability, which is rarely considered in functional island biogeography. We hypothesised that plants facing strong insularity and harsh soil conditions are characterised by enhanced persistence abilities. Location Shallow‐soil temperate dry grasslands on granite outcrops, Central Europe. Methods We focussed on edaphic island specialist species belonging to different life histories, namely clonal and non‐clonal perennial plants. We used linear and linear mixed‐effect models to examine intra‐ and interspecific trait patterns versus variation in insularity, soil and microclimate. Results Insularity tended to promote smaller plants (non‐clonal species) and belowground resource‐conservative strategies (both clonal and non‐clonal species), increasing the likelihood of local persistence. Soil also contributed largely to explaining persistence‐related trait patterns: plants growing in harsh soil conditions tended to be resource conservative. Clonal species are distinguished by highly consistent responses to variation in insularity and soil conditions, whereas non‐clonal plants showed distinct species‐specific responses. Main conclusions Our findings have important implications for the conservation biogeography of edaphic island plant specialists. Clonal species may be susceptible to local extinction should insularity or soil conditions vary, for example, due to abrupt changes in the geographical setting (e.g. habitat loss) or local environmental factors (e.g. N‐deposition). Non‐clonal species may instead face environmental changes differently; some will go extinct, whereas others will survive, depending on the prevailing abiotic pressures. This seems to challenge previous views that predicted clonal species to be the winners and non‐clonal species the losers against local extinction.
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