Riparian ecotones have been proven to be some of the most diverse, dynamic, and complex biophysical ecotones on the planet. A number of relict rare species are found to be concentrated in riparian forests of central China. The performance, distribution and adaptation of these species, along with their environmental interpretation, are challenging yet fascinating themes in ecology and vegetation science. Given the highly variable and dynamic nature of riparian ecosystems, trees may adopt more opportunistic strategies to deal with their environment, and interrelationships may be different in long versus short time windows if the relevant species is sufficiently sensitive to short-term environment changes. Cercidiphyllum japonicum is a rare endemic species of East Asia flora and a common component in riparian forests. Due to its long life-span and crossdatable annual rings, it can serve as an appropriate dendroclimatic material to dissect riparian ecological processes.

Scientists at Wuhan Botanical Garden conducted a dendroclimatic survey of C. japonicum in the Shennongjia area of central China at the core of its geographic range, with special reference to the temporal variability of radial growth–climate relationships. Their results showed that Ring width of C. japonicum was only weakly associated with precipitation, implying an excess of regional precipitation, the influence of river hydrology on local water supply, and/or less dependence of specific root habit on precipitation (facultative phreatophyte). Previous December and current summer temperatures consistently had a positive impact on radial growth of C. japonicum, while impacts of other monthly/seasonal climate variables vary temporally and are only occasionally significant. Alternative examination of monthly versus seasonal climatic summaries in radial growth–climate correlations demonstrated that individual climatic variables might work in some cumulative fashion. It appeared that observation timing and length influence patterns of radial growth–climate relationships for C. japonicum. Single versus evolutionary time interval (56 versus 32 years) analysis revealed that relationships between radial growth and monthly/seasonal climate are temporally unstable and suggests an opportunistic response of C. japonicum growth to climate variability and complex interactions in the riparian ecotones.

The study entitled "A dendroclimatic investigation of radial growth-climate relationship for the riparian species Cercidiphyllum japonicum in the Shennongjia area, central China" has been published in Trees. This research was funded by National Natural Sciences Foundation of China.

Abstract: http://www.springerlink.com/content/f8207067wu35018r/