Rapid response of forest dynamics to strong seismic events in Jiuzhaigou Nature Reserve, eastern Tibetan Plateau over the last ∼ 1650 years

Abstract

Understanding the ecological effects of strong earthquakes and post-seismic vegetation dynamics in mountainous areas is essential for mitigating post-earthquake disasters. Here, a detailed palynological and radiocarbon-dating study was carried out on the tufa sediments from Huohuahai Lake, Jiuzhaigou National Nature Reserve, China. Rapid transitions in palynological assemblages, from high contents of shrubs and herbs to Quercus, Betula and Pinus tree pollen, have repeatedly occurred over the past ∼1650 years. These short-term variations, combined with historical seismic records, probably record post-seismic (open forest) and inter-seismic (mixed forest) periods. Strong earthquakes caused damage to forests and induced hydrological changes, resulting in low pollen concentrations and increases in shrubs and herbs after such events. Subsequently, mixed coniferous broad-leaved forest gradually developed during inter-seismic periods. A particularly large earthquake occurred in ∼520 CE near Jiuzhaigou, and the vegetation recovery time from this was up to ∼214 years; this recovery time could also have been influenced by the sudden cooling and gradual drying climate and/or a previous strong earthquake. Our findings confirm the high seismic risk in the Min Shan uplift zone and the important driving force of tectonic activity on forest succession in mountainous areas.