Tropospheric ozone (O3) pollution is increasingly recognized as a major stressor to forest ecosystems, particularly through its interference with plant nutrient cycling processes. However, the mechanistic basis by which O3 influences the resorption of multiple essential nutrients remains inadequately characterized. In this study, we conducted a controlled open-top chamber experiment using hybrid poplar ‘107’ (Populus euramericana cv. ‘74/76’) to systematically assess the effects of elevated O3 exposure (ranging from 19.2 to 99.0 ppb) on the resorption efficiency (RE) of six key macronutrients: nitrogen (N), phosphorus (P), sulfur (S), potassium (K), calcium (Ca), and magnesium (Mg). Elevated O3 consistently enhanced the RE of N and S that are fundamental to core metabolic processes while reducing the RE of K, Mg, P, and Ca. Notably, K and Mg accumulated in senesced foliage at high O3 doses, with critical thresholds observed at 46.0 and 41.7 ppm·h, respectively. These results suggest a trade-off in nutrient retrieval priorities, where O3-induced oxidative stress favors the conservation of nutrients central to metabolic integrity (N, S), at the expense of those involved in osmotic balance (K) and photoprotection (Mg). Through a combination of power-law regression and structural equation modeling, we identified a triadic framework of coexisting nutrient resorption controls: (1) nutrient concentration control, influencing RE across N, P, S, K, and Mg; (2) nutrient limitation control, specifically modulating N and P based on their functional scarcity; and (3) stoichiometric control, preserving internal N:P ratios in senescing leaves. Elevated O3 triggered a transition from phosphorus limitation to nitrogen limitation, revealing a disproportionate disruption in nitrogen-related metabolic pathways under oxidative stress. At the mechanistic level, the observed changes in RE were mediated through two interconnected pathways: direct physiological impairment of nutrient translocation processes (e.g., damage to membrane transport systems) and indirect modulation of soil–plant-microbe interactions, including shifts in soil pH and microbial community composition. Collectively, these findings offer new insights into how chronic O3 exposure reshapes nutrient resorption dynamics and regulatory mechanisms in trees. They also provide a conceptual foundation for forecasting forest ecosystem responses to atmospheric oxidative stress. This study underscores the critical need for species-specific investigations and sustained monitoring of nutrient fluxes in O3-impacted environments, with significant implications for adaptive forest management under changing air quality conditions.

Ozone-induced alterations in multi-element nutrient resorption reveal three interacting control strategies in poplar

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发表日期：

2026年3月31日

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Xiaofan Hou,
Pin Li,
Yun Li,
Chenhan Ma,
Qiannan Lin,
Yushu Tian,
Dayong Fan

摘要

Tropospheric ozone (O₃) pollution is increasingly recognized as a major stressor to forest ecosystems, particularly through its interference with plant nutrient cycling processes. However, the mechanistic basis by which O₃ influences the resorption of multiple essential nutrients remains inadequately characterized. In this study, we conducted a controlled open-top chamber experiment using hybrid poplar ‘107’ (Populus euramericana cv. ‘74/76’) to systematically assess the effects of elevated O₃ exposure (ranging from 19.2 to 99.0 ppb) on the resorption efficiency (RE) of six key macronutrients: nitrogen (N), phosphorus (P), sulfur (S), potassium (K), calcium (Ca), and magnesium (Mg). Elevated O₃ consistently enhanced the RE of N and S that are fundamental to core metabolic processes while reducing the RE of K, Mg, P, and Ca. Notably, K and Mg accumulated in senesced foliage at high O₃ doses, with critical thresholds observed at 46.0 and 41.7 ppm·h, respectively. These results suggest a trade-off in nutrient retrieval priorities, where O₃-induced oxidative stress favors the conservation of nutrients central to metabolic integrity (N, S), at the expense of those involved in osmotic balance (K) and photoprotection (Mg). Through a combination of power-law regression and structural equation modeling, we identified a triadic framework of coexisting nutrient resorption controls: (1) nutrient concentration control, influencing RE across N, P, S, K, and Mg; (2) nutrient limitation control, specifically modulating N and P based on their functional scarcity; and (3) stoichiometric control, preserving internal N:P ratios in senescing leaves. Elevated O₃ triggered a transition from phosphorus limitation to nitrogen limitation, revealing a disproportionate disruption in nitrogen-related metabolic pathways under oxidative stress. At the mechanistic level, the observed changes in RE were mediated through two interconnected pathways: direct physiological impairment of nutrient translocation processes (e.g., damage to membrane transport systems) and indirect modulation of soil–plant-microbe interactions, including shifts in soil pH and microbial community composition. Collectively, these findings offer new insights into how chronic O₃ exposure reshapes nutrient resorption dynamics and regulatory mechanisms in trees. They also provide a conceptual foundation for forecasting forest ecosystem responses to atmospheric oxidative stress. This study underscores the critical need for species-specific investigations and sustained monitoring of nutrient fluxes in O₃-impacted environments, with significant implications for adaptive forest management under changing air quality conditions.