Soil organic carbon stocks in estuarine and marine mangrove ecosystems are driven by nutrient colimitation of P and N

authored by

Christian Weiss, Joanna Weiss, Jens Boy, Issi Iskandar, Robert Mikutta, Georg Guggenberger

Abstract

Mangroves play an important role in carbon sequestration, but soil organic carbon (SOC) stocks differ between marine and estuarine mangroves, suggesting differing processes and drivers of SOC accumulation. Here, we compared undegraded and degraded marine and estuarine mangroves in a regional approach across the Indonesian archipelago for their SOC stocks and evaluated possible drivers imposed by nutrient limitations along the land-to-sea gradients. SOC stocks in natural marine mangroves (271–572 Mg ha⁻¹ m⁻¹) were much higher than under estuarine mangroves (100–315 Mg ha⁻¹ m⁻¹) with a further decrease caused by degradation to 80–132 Mg ha⁻¹ m⁻¹. Soils differed in C/N ratio (marine: 29–64; estuarine: 9–28), δ¹⁵N (marine: −0.6 to 0.7‰; estuarine: 2.5 to 7.2‰), and plant-available P (marine: 2.3–6.3 mg kg⁻¹; estuarine: 0.16–1.8 mg kg⁻¹). We found N and P supply of sea-oriented mangroves primarily met by dominating symbiotic N₂ fixation from air and P import from sea, while mangroves on the landward gradient increasingly covered their demand in N and P from allochthonous sources and SOM recycling. Pioneer plants favored by degradation further increased nutrient recycling from soil resulting in smaller SOC stocks in the topsoil. These processes explained the differences in SOC stocks along the land-to-sea gradient in each mangrove type as well as the SOC stock differences observed between estuarine and marine mangrove ecosystems. This first large-scale evaluation of drivers of SOC stocks under mangroves thus suggests a continuum in mangrove functioning across scales and ecotypes and additionally provides viable proxies for carbon stock estimations in PES or REDD schemes.

Organisation(s)

Institute of Soil Science

External Organisation(s)

Martin Luther University Halle-Wittenberg
Institut Pertanian Bogor (IPB)

Type

Article

Journal

Ecology and evolution

Volume

6

Pages

5043-5056

No. of pages

14

ISSN

2045-7758

Publication date

19.07.2016

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Ecology, Evolution, Behavior and Systematics, Ecology, Nature and Landscape Conservation

Sustainable Development Goals

SDG 14 - Life Below Water, SDG 15 - Life on Land

Electronic version(s)

https://doi.org/10.1002/ece3.2258 (Access: Open)