Species-specific responses of C and N allocation to N addition: evidence from dual 13 C and 15 N labeling in three tree species

• Published in: The Science of the total environment 2024-06, Vol.927, p.172164
• Main Authors: Zhou, Xiaoqian, Ouyang, Shengnan, Saurer, Matthias, Feng, Mei, Bose, Arun K, Duan, Honglang, Tie, Liehua, Shen, Weijun, Gessler, Arthur
• Format: Article
• Language: English
• ISSN: 1879-1026
• DOI: 10.1016/j.scitotenv.2024.172164

Soil nitrogen (N) availability affects plant carbon (C) utilization. However, it is unclear how various tree functional types respond to N addition in terms of C assimilation, allocation, and storage. Here, a microcosm experiment with dual C and N labeling was conducted to study the effects of N addition (i.e., control, 0 g N kg ; moderate N addition, 1.68 g N kg ; and high N addition, 3.36 g N kg soil) on morphological traits, on changes in nonstructural carbohydrates (NSC) in different organs, as well as on C and N uptake and allocation in three European temperate forest tree species (i.e., Acer pseudoplatanus, Picea abies and Abies alba). Our results demonstrated that root N uptake rates of the three tree species increased by N addition. In A. pseudoplatanus, N uptake by roots, N allocation to aboveground organs, and aboveground biomass allocation significantly improved by moderate and high N addition. In A. alba, only the high N addition treatment considerably raised aboveground N and C allocation. In contrast, biomass as well as C and N allocation between above and belowground tissues were not altered by N addition in P. abies. Meanwhile, NSC content as well as C and N coupling (represented by the ratio of relative C and N allocation rates in organs) were affected by N addition in A. pseudoplantanus and P. abies but not in A. alba. Overall, A. pseudoplatanus displayed the highest sensitivity to N addition and the highest N requirement among the three species, while P. abies had a lower N demand than A. alba. Our findings highlight that the responses of C and N allocation to soil N availability are species-specific and vary with the amount of N addition.