Mangroves are among the world's most carbon-dense ecosystems, but have suffered extensive deforestation, prompting reforestation projects. The effects of mangrove reforestation on belowground carbon dynamics are poorly understood. In particular, we do not know how fine root production develops following mangrove reforestation, despite fine root production being a major carbon sink and an important control of mangrove soil accretion. Using minirhizotrons, we investigated fine root production and its depth variation along a chronosequence of mature Vietnamese mangroves. Our results showed that fine root production decreases strongly with stand age in the uppermost 32 cm of our soil profiles. In younger mangrove stands, fine root production declines with depth, possibly due to a vertical gradient in soil nutrient availability; while root production in the oldest stand is low at all depths and exhibits no clear vertical pattern. A major fraction of fine root production occurs deeper than 30 cm, depths that are commonly omitted from calculations of mangrove carbon budgets. Younger mangroves may accrue shallow soil organic matter faster than older mangroves. Therefore, root productivity and forest stand age should be accounted for when forecasting mangrove carbon budgets and resistance to sea-level rise.
Bibliographical noteFunding Information:
The processing and the analysis of the data, as well as writing the manuscript were self‐funded by M. Arnaud. This research received funding from National Geographic (CP134ER‐17), the Royal Geographical Society with the Institute of British Geographers, the Estuarine & Coastal Sciences Association (Charles Boyden Fund), and the University of Leeds (International Mobility Grant, Climate Bursary Grant and Leeds University PhD Scholarship), all awarded to M. Arnaud. We thank David Ashley from the School of Geography at the University of Leeds for his help with the laboratory analysis and instrumentation support. We also thank the students and staff of the Vietnamese National University of Ho Chí Minh City for their support in the field. The management committee and staff of the Cần Giờ Park gave permission for access to, and use of, the field site and are thanked for their support during the field work, especially Mr Nghia, Mr Sinh, Mr Hung, Mr Hoan, Mr Sang and Mr Kiet.
© 2021 The Authors. New Phytologist © 2021 New Phytologist Foundation
- EnRoot minirhizotron
- belowground carbon
- blue carbon
- coastal wetland
- fine root production
- root trait
ASJC Scopus subject areas
- Plant Science