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Leaf nonstructural carbohydrate concentrations of understory woody species regulated by soil phosphorus availability in a tropical forest
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  • Qifeng Mo,
  • Yiqun Chen,
  • Shiqin Yiu,
  • Yingxu Fan,
  • Zhongtong Peng,
  • Wenjuan Wang,
  • Li Zhi'an,
  • Faming Wang
Qifeng Mo
South China Agriculture University
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Yiqun Chen
South China Agriculture University
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Shiqin Yiu
South China Botanical Garden
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Yingxu Fan
South China Botanical Garden
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Zhongtong Peng
South China Agriculture University
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Wenjuan Wang
South China Agriculture University
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Li Zhi'an
South China Botanical Garden
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Faming Wang
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Peer review status:ACCEPTED

03 Apr 2020Submitted to Ecology and Evolution
05 Apr 2020Assigned to Editor
05 Apr 2020Submission Checks Completed
12 Jun 2020Review(s) Completed, Editorial Evaluation Pending
12 Jun 2020Editorial Decision: Accept

Abstract

Leaf soluble sugars and starch are important components of nonstructural carbohydrates (NSCs), which are crucial for plant growth, development, and reproduction. Although there is a large body of research focusing on the regulation of plant NSC (soluble sugars and starch) concentrations, the response of foliar NSC concentrations to continuous nitrogen (N) and phosphorus (P) addition is still unclear, especially in tropical forests. Here, we used a long-term manipulative field experiment to investigate the response of leaf NSC concentrations to continuous N and P addition (3-, 5-, and 8-year fertilization) in a tropical forest in southern China. We found significant species-specific variation in leaf NSC concentrations in this tropical forest. Phosphorus addition dramatically decreased both leaf soluble sugar and starch concentrations, while N addition had no significant effects on leaf soluble sugar and starch concentrations. These results suggest that, in plants growing in P-limiting tropical soil, leaf NSC concentrations are regulated by soil P availability rather than N availability. Moreover, the negative relationships between NSC concentrations and leaf mass per area (LMA) revealed that NSCs could supply excess carbon (C) for leaf expansion under P addition. This was further supported by the increased structural P fraction after P fertilization in our previous study at the same site. We conclude that soil P availability strongly regulates leaf starch and soluble sugar concentrations in the tropical tree species included in this study. The response of leaf NSC concentrations to long-term N and P addition can reflect the close relationships between plant C dynamics and soil nutrient availability in tropical forests. Maintaining relatively higher leaf NSC concentrations in tropical plants can be a potential mechanism for adapting to P-deficient conditions.