Carbon storage stars

Mangrove forests could be the key to reducing carbon, according to a new study.

Researchers studying mangrove forests on Hainan Island, China, found that having diverse species in these forests enhanced both the quantity of organic matter and storage of carbon in soil. 

“Our findings suggest that mangrove forests with greater diversity also have higher carbon storage capacities and conservation potential,” says senior author Guanghui Lin, of Tsinghua University.

“Thus, mangrove biodiversity conservation is crucial for ensuring mangrove forests are able to mitigate climate change. We can increase mangrove diversity through restoration and conservation projects, especially those that promote local native species.”

Mangroves are a carbon-rich ecosystem that grow well in tropical regions. There are over 70 species of mangroves worldwide; the area – which was studied during 2017–18 – contained 26 of the 27 Chinese species and accounts for 20% of China’s mangrove forest

The study, published in Functional Ecology, showed that the island’s east side had highest mangrove biomass and diversity, and carbon storage was around 547 tonnes per hectare (measured as Mg C ha-1). The remainder of the island stored 328 Mg C ha-1, below the world mangrove forest average of 386 Mg C ha-1.

By comparison, carbon storage in Australian pasture sites across Victoria have been measured between 15-165 Mg C ha-1.

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Fast Facts: Mangroves

• Mangrove forests count for less than 1% of Australian forests.
• Mangroves range from 2-10 metres in height
• Soil in these forests is fantastic at storing carbon
• Some mangroves can also catch microplastics

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Mangroves are efficient as storing carbon, and diversity increases that efficiency. 

The research also found that areas with high soil nitrogen and rainfall had a higher potential for carbon storage, which suggests both soil and climate affect the capacity to store carbon in the ground.

Potentially, higher mangrove forest diversity also leads to a more complex ecological community, which requires more carbon resources and thus more storage.

Lin explains that studying other areas will help illuminate how plant diversity contributes to this cycle and how to preserve forests in the future. 

“Worldwide, particularly in developing countries such as China, mangroves have been lost or degraded over the last several decades,” says Xiaoshan Zhu, also of Tsinghua University.

“Restoration of mangrove forests and their habitats are urgently needed – not only for preservation of biodiversity, but also to increase carbon storage potentials.”