Seasonal dynamics of non-structural carbohydrate content in branch of <i>Quercus variabilis</i> growing in east Qinling Mountain range

Abstract

Aims Measure of non-structural carbohydrate (NSC) reserves indicates tree carbon surplus or shortage stored. Branches connect NSC sources (leaves) and NSC sinks (stemwood, root) of woody plants. Therefore, the seasonal dynamics of NSC concentration in branches will be of important implications for understanding and modeling plant carbon allocation. Methods We conducted a field survey monitoring branch NSC concentrations of Chinese cork oak (Quercus variabilis). We also synchronously observed the leaf phenology of the trees in uneven-aged secondary oak forests at its upper and lower distribution limits (650 m to 970 m) in east Qinling Mountain ranges. Sampling intervals were set semimonthly/monthly during the leaf unfolding period (March to May), and monthly/bimonthly during the tree's full growing season (June to November) from May 2016 to May 2017.