Date: May 26, 2026
Guangzhou, China: A research team led by Prof. Xiankai Lu at the South China Botanical Garden, Chinese Academy of Sciences, investigated how tropical forest plants adapt to chronic high N addition by regulating root exudates and rhizosphere phosphorus dynamics in a primary broadleaf forest. Chronic high N addition increased root carbon exudation, stimulating phosphatase activity to mineralize organic P, and enhanced organic acid release to dissolve mineral-bound P. The organic acid pathway drove twice as much P release as the phosphatase pathway. This is the first evidence that tropical plants actively up‑regulate root exudation to adapt to long-term N deposition, explaining their sustained high productivity and offering crucial insights for predicting forest carbon sinks under climate change.
Intensifying global nitrogen (N) deposition has disrupted the N-P balance in ecosystems, particularly in tropical and subtropical regions where available P is relatively scarce. Extensive studies in temperate N-limited ecosystems have led to a classic paradigm: N addition alleviates plant competition for N, thereby reducing the allocation of photosynthates belowground, especially decreasing the release of root exudates. However, whether this paradigm can be directly applied to "N-rich" but P-deficient tropical and subtropical forests has long lacked experimental evidence, becoming a critical knowledge bottleneck for predicting forest C-P feedback and ecosystem stability under high N deposition.
To address this issue, a research team led by Prof. Xiankai Lu at the South China Botanical Garden, Chinese Academy of Sciences, conducted an in-situ study to investigate how tropical forest plants adapt to chronic high N addition by regulating root exudates and rhizosphere P dynamics in a primary broadleaf forest. The results showed that plants evolved an active adaptation mechanism when facing chronic high N addition: (i) increased root C exudation rate to stimulate microbial phosphatase activity and accelerate the mineralization of organic P; (ii) enhanced the release of organic acids to promote the dissolution of mineral-bound P. More importantly, the organic acid pathway played a dominant role, driving approximately twice as much P release as the phosphatase pathway.
This study provides the first evidence that tropical plants can adapt to long-term high N deposition by up-regulating root exudation, revising the traditional view that N deposition reduces belowground C allocation. This finding not only explains how "N-rich" tropical forests maintain high productivity and stability, but also suggests that ecosystems may possess more complex proactive adaptation strategies when facing chronic environmental stress. This insight is crucial for predicting the dynamics of tropical forest carbon sinks under future climate change.
Original Source：
Zhu X., Zhang Z., Turner B. L., Chen W., Mao Q., Li A., Mo J., Lu X., 2026. Enhanced Root Exudation as an Adaptation Mechanism to Facilitate Phosphorus Mobilization in a Primary Tropical Forest Under Chronic Nitrogen Deposition. Global Change Biology 32(5): e70912
https://doi.org/10.1111/gcb.70912
Keywords: carbon allocation, N-induced P deficiency, nitrogen addition, root exudation, soil P cycling, tropical forests
About the Author
Xiaomin Zhu (First author): South China Botanical Garden, Chinese Academy of Sciences. Research interests include global change ecology, mycorrhizosphere ecology, plant-soil-microbe interactions, and soil carbon sequestration.
Xiankai Lu (Corresponding author): South China Botanical Garden, Chinese Academy of Sciences. His research focuses on responses and adaptative mechanisms of forest ecosystem structure and function to global environmental change.
About the journal
Global Change Biology is an environmental change journal dedicated to shaping the future and solving the world's most challenging problems by tackling sustainability, climate change and environmental protection, food and water security and supply, as well as global health. The journal aims to advance understanding of the impacts of global change on biological systems and solutions. Examples include:
- rising tropospheric ozone, carbon dioxide and sulphur dioxide concentrations
- increasing UV-B irradiation
- global climate change
- biological sinks and sources of atmospheric trace gases
- eutrophication
- land use change
- biodiversity loss
- biological feedback to climate change
- biological mitigation of atmospheric change
About the Institution
Affiliated with the Chinese Academy of Sciences, South China Botanical Garden (SCBG) is one of China's earliest botanical research institutions. It was founded in 1929 by Academician Huan-Yong Chen (Woon-Young Chun) and officially designated as a national botanical garden in 2022. Focusing on South China, it commits to plant conservation, scientific research and science popularization across tropical and subtropical regions, and provides scientific underpinnings for ecological and green development. As a leading institution for plant germplasm conservation, SCBG has attained outstanding achievements since 1988: it has published over 540 monographs, issued more than 6,900 SCI-indexed papers, won over 350 scientific awards, obtained more than 630 patents, and bred over 410 new plant varieties. Its research work is strongly supported by three core academic divisions and a number of field research stations.
