Comparative study on the effects of climate change on radial growth of Pinus tabuliformis in near and outer suburbs of Beijing

  Objective  Climate change dominated by climate warming has had a profound impact on tree health and ecosystem stability. By studying the impact of climate change on the radial growth of Chinese pine (Pinus tabuliformis) natural forest in the outer suburbs and Chinese pine plantation in the near suburbs, this paper reveals the difference of radial growth sensitivity of natural ecosystem in the outer suburbs and mountain trees in the near suburbs.

  Method  The standard chronology and residual chronology of Chinese pine in the outer suburb forest and near suburb plantation were established, and their relationship with climate indicators was conducted. R software was applied to construct an optimum model for the response of tree ring index to climate indicators. The response of radial growth of Chinese pine to drought was also analyzed based on four resilience indexes.

  Result  Both sites showed climatic warming and drying trend, which was more significant in the suburban area. The results from both chronologies showed that the radial growth of Chinese pine in suburban area was more sensitive to climate indicators. The radial growth of Chinese pine at the outer suburban site was significantly and positively related to the minimum temperature in fall and winter, also the standardized precipitation evapotranspiration index (SPEI) in the last summer and fall. The radial growth of Chinese pine at the near suburban site was significantly and negatively correlated with the daily maximum ground temperature of summer in the last and current years, and was significantly and positively correlated with SPEI of summer and autumn in the last and current years. It was also significantly and positively correlated with the annual mean Palmer drought severity index (PDSI), and was more sensitive to changes in PDSI during severe drought events.

  Conclusion  There is a “lag effect” of the growth response to climate change at both the outer suburb forest site and near suburb plantation site. During the process of urbanization, the radial growth of Chinese pine is more sensitive to climate change, and more vulnerable to summer heat and drought stress. However, within the tolerance threshold, the Chinese pine plantation at near suburb site has the ability to recover from long-term drought events.