Responses of radial growth of Pinus massoniana and Castanopsis eyrei to climate change at different elevations in south China

Rapid warming and increasing drought intensity are exposing forest ecosystems to increasing stress, challenging silvicultural decision-making. Tree growth-climate relationships may provide valuable information on tree species' adaptive potentials. However, it is not clear how subtropical trees will respond to climate change. Here, we present a dendrochronological study on Pinus massoniana and Castanopsis eyrei growing at two elevations (400 m and 890 m) at the northern Luoxiao Mountain in China to reveal their adaptability to climate change. Results show that long-term drought caused by rapid warming and reduced precipitation after 1997 led to a significant (p < 0.05) decline trend in radial growth of trees at all sites except low elevation P. massoniana. Temperatures in almost all seasons were significantly negatively correlated with the radial growth of C. eyrei. The radial growth of P. massoniana at high elevation was significantly positively correlated with relative humidity and negatively correlated with vapor pressure deficit. The relationship between relative humidity and radial growth of P. massoniana at high elevation showed an increasing trend with time, while P. massoniana at low elevation showed the opposite. At the two elevations, the relationships between the radial growth of C. eyrei and precipitation gradually increased, and the relationships with the temperature gradually weakened. The elevation- or hillslope-related hydrothermal redistribution caused the variations in species-specific growth-climate relationships. Our results suggested that large-scale planting of P. massoniana and C. eyrei in the subtropical area of south China is not effective for wood production or carbon sequestration, and both species- or elevation-related tree growth-climate relationships should be considered in forest management.