Root nitrogen uptake capacity of Chinese fir enhanced by warming and nitrogen addition. (1st September 2022)

• Record Type: Journal Article
• Authors: Jiang, Qi; Lin, Chengfang; Guo, Runquan; Xiong, Decheng; Yao, Xiaodong; Wang, Xiaohong; Chen, Tingting; Jia, Linqiao; Wu, Dongmei; Fan, Ailian; Chen, Guangshui; Yang, Yusheng
• Editors: Whitehead, David
• Is Part Of: Tree physiology. Volume 43:Number 1(2023)
• Page Start: 31
• Page End: 46
• Publication Date: 2022-09-01
• Subjects: root nitrogen uptake kinetics -- subtropics; Trees -- Physiology -- Periodicals; 582.16
• DOI: 10.1093/treephys/tpac103
• Languages: English
• ISSNs: 0829-318X

Abstract

Abstract: There is a knowledge gap in the effects of climate warming and nitrogen (N) deposition on root N absorption capacity, which limits our ability to predict how climate change alters the N cycling and its consequences for forest productivity especially in subtropical areas where soil N availability is already high. In order to explore the effects and mechanism of warming and the N deposition on root N absorption capacity of Chinese fir ( Cunninghamia lanceolata ), a subtropical arbuscular mycorrhizal conifer, the fine root 15 NH4 + and 15 NO3 − uptake kinetics at a reference temperature of 20 °C were measured across different seasons in a factorial soil warming (ambient, +5 °C) × N addition (ambient, +40 kg N ha −1 yr −1 ) experiment. The results showed that (i) compared with the control, warming increased the maximal uptake rate of NH4 + ( V max, 20 °C -NH4 + ) in summer, while N addition enhanced it in spring and summer; compared with non-warming treatments, warming treatments increased the uptake rate of NO3 − at a reference concentration of 100 μmol (V100, 20 °C -NO3 − ) in spring. (ii) The analysis of covariance showed that V max, 20 °C -NH4 + was positively correlated with root mycorrhizal colonization rate (MCR) and V100, 20 °C -NO3 − was positively correlated with specific root respiration rate (SRR), whereas no N uptake kinetic parameter was correlated with specific root length, root N and non-structural carbon concentrations. Thus, our results demonstrate that warming-increased root NH4 + uptake might be related to warming-increased MCR, whereas warming-increased root NO3 − uptake might be related to warming-increased SRR. We conclude that root NH4 + and NO3 − uptake capacity of subtropical Chinese fir can be elevated under warming and N deposition, which could improve plantation productivity and mitigate N leaching loss and soil acidification.