History of forest disturbance recorded by old trees in Xishan Mountain,Beijing
Aims Old trees not only record the climate and environment change information,but also witness the history of social changes.Understanding the history of growth change and disturbance of old trees is useful to accurately assess the health of old trees in the context of global warming and to develop conservation plans.Methods We used tree-ring methods to analyze the disturbance history of the old trees(Pinus tabuliformis)in the Xishan Mountain of Beijing.Important findings There were six major growth suppression(1831-1837,1855-1868,1882-1891,1920-1930,1960-1970 and 1980-1986)and five release events(1820-1830,1869-1881,1909-1918,1947-1959 and 2004-2010).The response analysis of tree growth to climate factors and the historical data showed that drought events and subsequent climatic improvement were the main reasons for growth suppression and release events.Further studies showed that the average growth rate of diameter at breast height of old trees was 2.70 mm·a-1 before 1840,and then the growth rate of diameter at breast height gradually decreased.After 1980,there was an obvious growth suppression,and the annual average growth rate decreased to 0.38 mm·a-1.A stronger negative correlation between tree growth and temperature emerged after 1965,and a significant positive correlation emerged for Palmer Drought Severity Index(PDSI).These results suggest that the warming and drying trend in Beijing in recent years may further negatively affect old trees in the urban area.These results are helpful for further understanding the regularity of forest disturbance in the Beijing area during historical period,and are of great significance for accurately assessing the healthy status of elderly trees in the context of climate change.
tree-ringdisturbance historyclimate changeold tree
NETL
NSTL
万方数据
