Response of radial growth to warming and CO2 enrichment in southern Northeast China: a case of Pinus tabulaeformis

The southern part of northeast China has experienced a marked warming and drying climate. We provide dendrochronological evidence for atmospheric CO2 fertilization and the impacts of warming on Chinese pine (Pinus tabulaeformis) growth. The results of this study show that increased temperature has a negative effect on pine growth during a major part of the growing season and a weakly positive effects on growth during the remaining portion of the year. The monthly temperatures explain ca. 20 % of the total variance in the annual radial growth of Chinese pine from 1901 to 2009. An increase of approximately 3–5 °C is the maximum that Chinese pine can tolerate in this region with an annual rainfall of 500–700 mm. Our results suggest a that there is a proportional response to warming only up to a maximum of 1 °C warming, and indicate the complexities of succession in forest ecosystems in terms of adaptation and evolution in local pine populations under a rapid warming condition. In addition, increasing atmospheric CO2 concentrations have a positive effect on tree growth. This effect can be detected with conventional dendrochronological methods