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 CO 2 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 complexitiesof succession in forest ecosystems in terms of adaptation and evolution in local pine populations under a rapid warming condition. In addition, increasing atmospheric CO 2 concentrations have a positive effect on tree growth. This effect can be detected with conventional dendrochronological methods.