Seasonal variation in C:N:P stoichiometry, nonstructural carbohydrates, and carbon isotopes of two coniferous pioneer tree species in subtropical China

Yuanxi Liu; Jiandong Xiao; Jianli Sun; Zhijuan Zhao; Xin Deng; Junwen Wu; Deguo Zhang; Yun Bao

doi:10.3389/fpls.2023.1225436

Seasonal variation in C:N:P stoichiometry, nonstructural carbohydrates, and carbon isotopes of two coniferous pioneer tree species in subtropical China

Front Plant Sci. 2023 Nov 27:14:1225436. doi: 10.3389/fpls.2023.1225436. eCollection 2023.

Authors

Yuanxi Liu^#¹, Jiandong Xiao^#¹, Jianli Sun^#¹, Zhijuan Zhao^#¹, Xin Deng², Junwen Wu¹, Deguo Zhang³, Yun Bao²

Affiliations

¹ College of Forestry, Southwest Forestry University, Kunming, Yunnan, China.
² Yunnan Academy of Ecological and Environmental Sciences, Kunming, Yunnan, China.
³ College of art and design, Southwest Forestry University, Kunming, Yunnan, China.

^# Contributed equally.

Abstract

The characteristics of C:N:P stoichiometry, nonstructural carbohydrate (NSC) content, and C stable isotopes and their relationships affect plant responses to environmental changes and are critical to understanding the ecosystem carbon and water cycles. We investigated the water use strategies and physiological changes of two pioneer tree species (Pinus armandii and Pinus yunnanensis) in response to seasonal drought in subtropical China. The seasonal variation in needle δ¹³C values, C:N:P stoichiometry, and NSC contents of the two tree species were studied in 25-year-old plantation in central Yunnan Province. The needle δ¹³C values of both species were highest in summer. Soluble sugars, starch and NSC content of the two tree species decreased from spring to winter, while there was no significant difference in the seasonal variation of soluble sugars/starch in P. armandii needles, the maximum soluble sugars/starch in P. yunnanensis needles was in autumn. In addition, the C, N, and P contents of the needles and the C:N and C:P ratios of the two species showed different seasonal fluctuations, whereas the N:P ratio decreased with the season. The C:N:P stoichiometry and NSC content of the needles showed significant correlations, whereas the needle δ¹³C was weakly correlated with C:N:P stoichiometry and NSC content. Phenotypic plasticity analysis and principal component analysis revealed that the needle nutrient characteristics (NSC and P contents and N:P ratio) and needle δ¹³C values were critical indicators of physiological adaptation strategies of P. armandii and P. yunnanensis for coping with seasonal variation. These results increase our understanding of the water-use characteristics of the two pioneer tree species and the dynamic balance between the NSC, C, N, and P contents of the needles.

Keywords: needle carbon stable isotope; nonstructural carbohydrates; pioneer tree species; seasonal variation; stoichiometry; winter and spring drought.

Grants and funding

This study was co-supported by the National Natural Science Foundation of China (31960306), and Basic Research Program of Yunnan Province (2019FD074).