Comparison of the seasonal and successional variation of asymbiotic and symbiotic nitrogen fixation along a glacial retreat chronosequence

Jun Zhang; Thomas H DeLuca; Zhenni Chenpeng; Andi Li; Genxu Wang; Shouqin Sun

doi:10.1016/j.scitotenv.2023.165163

Comparison of the seasonal and successional variation of asymbiotic and symbiotic nitrogen fixation along a glacial retreat chronosequence

Sci Total Environ. 2023 Oct 20:896:165163. doi: 10.1016/j.scitotenv.2023.165163. Epub 2023 Jun 29.

Authors

Jun Zhang¹, Thomas H DeLuca², Zhenni Chenpeng³, Andi Li⁴, Genxu Wang³, Shouqin Sun⁵

Affiliations

¹ State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, No.24 South Section 1, Yihuan Rd, Chengdu 610065, China; Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
² College of Forestry, Oregon State University, Corvallis, OR 97331-5704, USA.
³ State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, No.24 South Section 1, Yihuan Rd, Chengdu 610065, China.
⁴ South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
⁵ State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, No.24 South Section 1, Yihuan Rd, Chengdu 610065, China. Electronic address: shouqinsun@scu.edu.cn.

PMID: 37391152
DOI: 10.1016/j.scitotenv.2023.165163

Abstract

Climate change is resulting in accelerated retreat of glaciers worldwide and much nitrogen-poor debris is left after glacier retreats. Asymbiotic dinitrogen (N₂) fixation (ANF) can be considered a 'hidden' source of nitrogen (N) for non-nodulating plants in N limited environments; however, seasonal variation and its relative importance in ecosystem N budgets, especially when compared with nodulating symbiotic N₂-fixation (SNF), is not well-understood. In this study, seasonal and successional variations in nodulating SNF and non-nodulating ANF rates (nitrogenase activity) were compared along a glacial retreat chronosequence on the eastern edge of the Tibetan Plateau. Key factors regulating the N₂-fixation rates as well as the contribution of ANF and SNF to ecosystem N budget were also examined. Significantly greater nitrogenase activity was observed in nodulating species (0.4-17,820.8 nmol C₂H₄ g^-1 d^-1) compared to non-nodulating species (0.0-9.9 nmol C₂H₄ g^-1 d^-1) and both peaked in June or July. Seasonal variation in acetylene reduction activity (ARA) rate in plant nodules (nodulating species) and roots (non-nodulating species) was correlated with soil temperature and moisture while ARA in non-nodulating leaves and twigs was correlated with air temperature and humidity. Stand age was not found to be a significant determinant of ARA rates in nodulating or non-nodulating plants. ANF and SNF contributed 0.3-51.5 % and 10.1-77.8 %, respectively, of total ecosystem N input in the successional chronosequence. In this instance, ANF exhibited an increasing trend with successional age while SNF increased only at stages younger than 29 yr and then decreased as succession proceeded. These findings help improve our understanding of ANF activity in non-nodulating plants and N budgets in post glacial primary succession.

Keywords: Acetylene reduction activity; N(2)-fixation; Nodulating and non-nodulating plants; Primary succession; Tibetan Plateau.

MeSH terms

Ecosystem*
Nitrogen / analysis
Nitrogen Fixation* / physiology
Nitrogenase
Seasons
Soil

Substances

Soil
Nitrogen
Nitrogenase