Trajectories in nitrogen availability during forest secondary succession: illustrated by foliar δ15N

• Published in: Ecological processes 2022-03, Vol.11 (1), p.1-11, Article 31
• Main Authors: Tu, Ying, Wang, Ang, Zhu, Feifei, Gurmesa, Geshere Abdisa, Hobbie, Erik A., Zhu, Weixing, Fang, Yunting
• Format: Article
• Language: English
• Subjects: Availability; Climate; Earth and Environmental Science; Ecological succession; Environment; Foliar δ15N; Forest secondary succession; Forests; Inflection points; Nitrogen; Nitrogen availability; Nitrogen isotopes; Saturation; Space-for-time substitution; Temperate forests; Tropical climate; Tropical forests
• ISSN: 2192-1709; 2192-1709
• DOI: 10.1186/s13717-022-00374-0

Background Forest succession is an important ecological process and has been studied for more than a century. However, changes in nitrogen (N) availability during succession remain unclear as they may lead to either N saturation or N limitation. Here, we propose a conceptual model to illustrate changes in N availability during four stages of secondary succession using the natural abundance of 15 N in plant leaves (foliar δ 15 N). We predicted that N availability would decline in the early stages of succession and then increase in late stages, coinciding with the changes in foliar δ 15 N, with the inflection point varying in different climate zones. Data on foliar δ 15 N from 16 succession sequences were synthesized to explore changes in N availability during forest succession. Results The compiled data were consistent with the proposed conceptual model. Foliar δ 15 N in boreal and temperate forests decreased significantly in the first two stages of succession (estimated to last at least 66 years in temperate forests), at a rate of 0.18‰ and 0.38‰ per decade, respectively, and decreased slightly in tropical forests in the first 23 years. Foliar δ 15 N is projected to increase in later stages in all forests, which is supported by observations in both temperate and tropical forests. The inflection points of N availability when N limitation peaked during succession were different in different climate zones, implying different ecosystem N turnovers. Conclusions Our study reconciles the controversies regarding changes in N availability during forest secondary succession. Our findings are also useful for predicting the recovery of N and carbon accumulation during succession. Nonetheless, studies on forest secondary succession using foliar δ 15 N have thus far been limited, and more research should be conducted to further verify the conceptual model proposed here.