Response of non-structural carbohydrates in the roots of Larix gmelinii to climate warming and provenance variation.

We employed a common garden experiment to simulate climate warming, based on which we investigated the responses of non-structural carbohydrates (NSC), soluble sugars (SS), starch (ST) concentrations and the SS/ST in fine, medium, and coarse roots of 11 provenances of Larix gmelinii at the end of the growing season. The results showed that climate warming significantly decreased NSC concentration, SS concentration and SS/ST by 8.0%-10.6%, 16.4%-24.5% and 25.3%-30.8%, respectively, across all root types. ST concentration in the fine and middle roots significantly increased by 9.9%-15.3%, and ST concentration in the coarse roots varied insignificantly. As root diameter increased, the decrease in SS concentration showed an increasing trend, while the increase in ST concentration showed a decreasing trend. The warming-induced changes in NSC concentration, SS concentration, and SS/ST across different root diameter classes after climate warming, namely the warming effect, were significantly and positively correlated with aridity index (AI) of the seed collection sites. In contrast, the warming effect on ST was significantly and negatively correlated with AI. L. gmelinii adapted to climate warming by regulating NSC concentration and the proportions of its components in roots of different diameter classes, and this capacity varied among provenances. The effects of root diameter class and provenance should be considered when investigating the responses of root NSC to climate warming.