Seasonal Fluctuation of Non-Structural Carbohydrates in Different Organs of Four Tree Species in Subtropical Forests

Non-structural carbohydrates (NSC) are important carbon pools in trees, and previous studies have mainly focused on the concentration of NSC in tree organs such as leaves, branches, trunk, and root, separately. However, the seasonality of the concentration of NSC in different organs among tree species in the subtropical forests is less known. In this study, we measured the seasonal dynamics of the concentration of NSC in four tree species (Nothotsuga longibracteata W. C. Cheng, Pinus kwangtungensis Chun ex Tsiang, Schima superba Gardn. et Champ, and Betula alnoides Buch.-Ham. Ex D.Don) in subtropical forests at organ levels including canopy, trunk, and root. The results showed that the concentration of NSC in conifer species was higher than that in broadleaf species. Also, the average concentration and range of the concentration of NSC were higher in the canopy than in other organs. The concentration of NSC decreased at the beginning of the growing season and increased at the end of the growing season for all species. Specifically, the concentration of NSC in tree species was significantly higher in the dry season than that in the wet season. Our results revealed the seasonal dynamics of NSC in different organs, which is beneficial to a better understanding of the growth strategies of different tree species in subtropical regions.