Responses of soil temperature and soil water content to extreme snow event in a subtropical evergreen broad-leaved forest in Ailao Mountains,Yunnan,Southwest China
The frequency and intensity of extreme weather and the associated disturbances,such as extensive floods,droughts,and ice storms,have been increasing against the pronounced global warming. In recent years,southern China has suffered increasing frequency of severe ice storms. During early January 2015,a primary subtropical evergreen broadleaved forest in Southwest China experienced an extreme snow event that damaged the forest. Based on the automatically collected data from meteorological station,we analyzed the soil temperature and soil water content before and after this severe snow event. The results showed that extreme snow led to extensive canopy damage and formation of canopy gaps. There was obvious time lag in maximal soil temperature between the forest and the open areas at different depths. However,no palpable time lag was observed in 10 cm and 20 cm soil depths in the year when extreme snow occurred. Similarly, no time lag occurred in 10 cm soil one year after extreme snow event. Soil water content at different depths showed a peak in both the forest and open areas after extreme snow damage,and then soil moisture in the forest kept higher against normal years. The extreme snow damage had stronger influence on topsoil water content in rainy season than in dry season. The increases of soil temperature and soil water content caused by extreme snow event would accelerate soil respiration, which may reduce the strength of carbon sink in the forest.