An 11,000-year vegetation and climate record from a subalpine peatland in the Luoxiao Mountains, subtropical Southeast China

Abstract

The evolution of broadleaved forests and their responses to climate changes in subtropical Southeast China remain largely unclear, partly because of the controversies regarding the history of climate (i.e., temperature and monsoonal precipitation) changes during the Holocene. In this study, we integrated pollen and other proxies (including loss on ignition, humification degree, and stable carbon isotope) from a subalpine peatland in the Luoxiao Mountains, to reveal the predominant patterns of vegetation and climate dynamics in mountainous Southeast China. Vegetation at the study site was dominated by Quercus-evergreen and Fagus with relatively flourishing herbs during the early Holocene. A transformation from mixed evergreen–deciduous broadleaved forests to evergreen broadleaved forests occurred between 8200 and 1850 cal. yr BP. The lag of the transformation in response to monsoonal rainfall changes in mountainous regions during the early Holocene can be attributed to thermal limitation. Since 1850 cal. yr BP, broadleaved pollen substantially declined with the expansion of Poaceae and pines, likely reflecting the impact of intensive anthropogenic activities. The expansion of evergreen broadleaved forests from different sites revealed a gradual warming in Southeast China during the Holocene. Additionally, monsoon precipitation in the study area underwent substantial changes, showing a pattern of wetting, sustained humid conditions, subsequent drying, and wetting. Overall, temperature and precipitation during the Holocene were decoupled at the study site, as supported by widely distributed records in mountainous subtropical Southeast China. This may be attributed to the influence of different driving factors on temperature and precipitation.