Differential ecological stoichiometry of leaf and fine root litter decomposition under ozone stress

doi:10.17521/cjpe.2025.0229

Abstract

Abstract:

Aims Elevated atmospheric ozone (O₃) concentrations significantly affect plant nutrient allocation, thereby regulating litter decomposition. However, the stoichiometric responses of leaf and fine root litters to O₃ stress remain unclear. This study aimed to investigate how elevated O₃ influenced the dynamics and regulatory mechanisms of carbon (C), nitrogen (N), and phosphorus (P) stoichiometry during the decomposition of leaf and fine root litter.

Methods A 12-month decomposition experiment was conducted using Koelreuteria paniculata and Camellia sinensis at the O₃-FACE platform in Yanqing, Beijing. We applied two treatments i.e., ambient air (NF) and elevated O₃ (NF60, ambient air + 60 nmol·mol^-1 O₃). At four decomposition stages (0, 1, 3, and 12 month), we measured litter C, N, and P concentrations and stoichiometric ratios (C:N, C:P, N:P).

Important findings Elevated O₃ concentration significantly altered the initial stoichiometric structure and residual characteristics of the litter. Under NF60, the initial C:N ratio of K. paniculata leaves increased by 7.6%, while N:P decreased by 17.7%, leading to a 10.3% increase in mass remaining after 12 months. In C. sinensis fine root litter, phosphorus (P) concentration increased by 11.1% and the C:P ratio decreased by 14.5%, showing organ- and species-specific stoichiometric shifts. Litter mass remaining (%) was significantly correlated with C:N, C:P, and N:P ratios. During decomposition, the N:P ratio of leaf litter increased significantly in both species (K. paniculata: 43.6%-68.0%; C. sinensis: 52.9%-59.3%), indicating enhanced P limitation in the later stages. Consistent with the microbial growth rate hypothesis, fine root litter also exhibited organ-specific increases in N:P, but the magnitude and treatment effects depended on species. O₃ altered litter stoichiometric characteristics, particularly C:P balance, which may have influenced microbial nutrient acquisition and contributed to slower carbon turnover; moreover, leaf litter and fine roots showed distinct response patterns. Leaves and fine roots exhibited contrasting responses: K. paniculata leaves were more constrained by P availability, while C. sinensis fine roots maintained higher decomposition efficiency through enhanced P redistribution. These findings highlight organ-specific adaptive strategies under O₃ stress and provide novel insights into stoichiometric regulation of litter decomposition under global change.

Key words: ecological stoichiometry, litter decomposition, ozone stress, C:N:P, leaf, fine root

HOU Xiao-Fan, MA Chen-Han, SUN Yu-Qian, GAO Yu-Han, LI Pin. Differential ecological stoichiometry of leaf and fine root litter decomposition under ozone stress[J]. Chin J Plant Ecol, 2026, 50(2): 268-278.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2025.0229

https://www.plant-ecology.com/EN/Y2026/V50/I2/268

Figures/Tables 6

Fig. 1 Effects of ozone treatments on the mass remaining (%) of leaf and fine root litter from two tree species after 1, 3, and 12 months of decomposition (mean ± SE). A, the ambient decomposition environment; E, the elevated ozone environment; NF, litter derived from plants grown under ambient air; NF60, litter derived from plants exposed to ambient air + 60 nmol·mol-1 O3. Different lowercase letters indicate significant differences among treatments within the same decomposition stage (p < 0.05).

Fig. 2 Changes in carbon (C) (A-D), nitrogen (N) (E-H), and phosphorus (P) (I-L) contents in leaf litter across different decomposition stages (mean ± SE, n = 3). T0, T1, T3 and T12 denote decomposition times of 0, 1, 3 and 12 months, respectively. CS, Camellia sinensis; LS, Koelreuteria paniculata. Different lowercase letters indicate significant differences among treatments within the same decomposition stage (p < 0.05). A two-way ANOVA was used to examine the effects of treatment (T), species (S), and their interaction (T × S) on the chemical components: *, p < 0.05; **, p < 0.01; ***, p < 0.001; ns, no significant difference.

Fig. 3 Changes in carbon (C) (A-D), nitrogen (N) (E-H), and phosphorus (P) (I-L) contents in fine roots across different decomposition stages. T0, T1, T3 and T12 denote decomposition times of 0, 1, 3 and 12 months, respectively. CS, Camellia sinensis; LS, Koelreuteria paniculata. Different lowercase letters indicate significant differences among treatments within the same decomposition stage (p < 0.05). A two-way ANOVA was used to examine the effects of treatment (T), species (S), and their interaction (T × S) on the chemical components: *, p < 0.05; **, p < 0.01; ***, p < 0.001; ns, no significant difference.

Fig. 4 Changes in stoichiometric ratios in leaf litter across different decomposition stages. T0, T1, T3 and T12 denote decomposition times of 0, 1, 3 and 12 months, respectively. C, carbon; N, nitrogen; P, phosphorus. CS, Camellia sinensis; LS, Koelreuteria paniculata. Different lowercase letters indicate significant differences among treatments within the same decomposition stage (p < 0.05). A two-way ANOVA was used to examine the effects of treatment (T), species (S), and their interaction (T × S) on the chemical components: *, p < 0.05; **, p < 0.01; ***, p < 0.001; ns, no significant difference.

Fig. 5 Changes in stoichiometric ratios in fine roots across different decomposition stages. T0, T1, T3 and T12 denote decomposition times of 0, 1, 3 and 12 months, respectively. C, carbon; N, nitrogen; P, phosphorus. CS, Camellia sinensis; LS, Koelreuteria paniculata. Different lowercase letters indicate significant differences among treatments within the same decomposition stage (p < 0.05). A two-way ANOVA was used to examine the effects of treatment (T), species (S), and their interaction (T × S) on the chemical components: *, p < 0.05; **, p < 0.01; ***, p < 0.001; ns, no significant difference.

Fig. 6 Correlations among the mass remaining of leaf litter (A-C) and fine roots (D-F) and their stoichiometric characteristics of C, N, and P. A, natural decomposition environment; E, elevated O3 decomposition environment; NF, decomposition substrate under ambient air; NF60, decomposition substrate pretreated with 60 nmol·mol-1 O3. *, p < 0.05; **, p < 0.01; ***, p < 0.001.

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