[Nutrient and metabolic responses of the leaves of Cunninghamia lanceolata seedlings to warming and reduced precipitation in different season].

We examined the effects of warming (+5 ℃) and reduced natural precipitation (-50%) on nutrient status and physiological indices of Cunninghamia lanceolata seedlings during winter and summer in subtropical China. The results showed that seasonal changes in temperature and precipitation caused the seasonal differences in plant nutrient contents and metabolites levels. Contents of carbon, nitrogen, phosphorus, and potassium in leaves in winter were significantly higher than those in summer. In summer, reduced precipitation and warming had no significant effects on antioxidant enzyme activities in C. lanceolata leaves. In winter, superoxide dismutase and peroxidase activities in the leaves significantly decreased with reduced precipitation by 20.7% and 17.8%. Additionally, in winter, warming treatment significantly increased non-enzymatic ascorbic acid content by 132.5%. Carbon content decreased, whereas proline accumulation and nitrogen content increased under stress induced by combined warming and reduced precipitation in winter. However, carbon content increased by 3.3% under the treatment of simultaneous warming and reduced precipitation in summer. In addition, combined warming and reduced precipitation had no significant effects on the antioxidant system irrespective of the season. In conclusion, the adaptation mechanism of C. lanceolata to warming in summer might be different from that in winter. The changes in nutrient contents in C. lanceolata leaves were more sensitive to stress induced by combined warming and reduced precipitation. Nutrient demand and supply and seasonal changes in plant responses under climate change scenarios should be considered for better managing forest plantations and improving plant productivity.