Tree growth response of Fokienia hodginsii to recent climate warming and drought in southwest China.

To date, few attempts have been made to assess the influence of climate change on forest ecosystems and on the relationship between tree growth and climate in humid areas of low latitudes. In this paper, we studied the response of tree growth and forest ecosystem to climate change by using Fokienia hodginsii tree-ring cores from the northern Yunnan-Guizhou Plateau, southwest of China. Tree growth correlates the highest (r = -0.64, p < 0.01) with mean temperature (July-September), but the coefficients were changing with time as revealed by a moving correlation analysis. Tree growth is significantly (p < 0.05) and positively correlated with January-April mean temperature from AD 1961-1987, while correlations with precipitation are insignificant. In contrast, from 1988 to 2014, tree growth correlated negatively with mean temperature of previous summer and positively with precipitation of previous August-September. This indicated that the limiting factors for tree growth have changed under different climate conditions. The meteorological data suggested that from 1961 to 1987 it was cold and wet in the study area and radial growth is limited by winter and spring temperatures. This restriction is weaker if the climate is appropriate in general. However, from 1988 to 2014, the combined effects of recent warming and decreasing precipitation have led to an increasing response of tree-ring width to drought. In addition, a large proportion of mature F. hodginsii mortality occurred from 2007 to 2013, which corresponds with a drastic reduction of radial growth (narrowest in recent 100 years). The recent drought, induced by decreasing precipitation and increasing temperature, may have passed the threshold which F. hodginsii could tolerate, causing tree growth reduction, tree growth-climate relationship change, as well as catastrophic tree mortality. All these changes may lead to further responses of the local ecosystem to climate change which should be highly regarded.