Deepen understanding of Indian mangrove ecosystems, says mangrove scientist

Getting things right with mangroves, ecosystems that feature on the global climate agenda for their carbon storage capacity, could set the stage for effective climate action and biodiversity protection in coastal areas, says noted mangrove scientist K. Kathiresan.

Kathiresan, who has worked extensively in Tamil Nadu’s Pichavaram mangroves, said restoring mangroves with a focus on biodiversity (diverse mangrove plant species and fauna) and in the right place, instead of growing mangrove monocultures, are crucial to mangrove health.

He said that the involvement of local communities in the planning, execution and monitoring of plantation projects and a deeper understanding of fauna and micro-organisms associated with these amphibious defenders is key to climate action centred on mangrove ecosystems.

Mongabay-India caught up with Kathiresan following his lecture at the Mangrove Research in Indian Subcontinent conference organised by the CIFOR and Wildlife Institute of India; he spoke about the importance of people’s participation in mangrove conservation, illustrating it with the Pichavaram mangrove restoration as an example.

“India has done a marvellous job in biodiversity documentation, but people’s participation is essential in restoring (degraded) mangroves. They should be involved end-to-end from planning (how to protect, how to do hydrological management) to execution and monitoring,” said Kathiresan. In Pichavaram, between 1986 and 2002, 90% of degraded mangrove forests were rehabilitated with people’s participation, he pointed out.

The joint mangrove management (JMM) approach banked on community participation and drew from the principles of joint forest management. The JMM approach and mangrove restoration pilot in Pichavaram were extended to other east coast mangroves in Andhra Pradesh and Odisha and other sites in Tamil Nadu, spanning 1,400 hectares in total.

Restoration efforts, such as those executed in Pichavaram, help sequester carbon (the process of capturing, securing and storing carbon dioxide from the atmosphere). Biological carbon sequestration is the long-term carbon storage in oceans, soils, vegetation (especially forests), and geologic formations.

Kathiresan pushed for more studies to build baseline data on mangrove carbon storage collected across specific geographical areas and time to develop a country-level map “which will build a better picture on the role of mangroves in climate mitigation.”

Research on mangrove restoration and carbon stock are thematic areas that need more attention in India, reveal findings of an analysis of mangrove research spanning five decades (1971-2021) that was discussed during the conference. While studies on vegetation ecology dominate the thematic areas of mangrove research in India, they are distantly followed by studies on mangrove fauna and microbial communities, areas where the knowledge gap needs to be plugged.

Nehru Prabakaran at the Wildlife Institute of India, who carried out the analysis, said “the diverse faunal groups in mangroves are comparatively least studied,” and despite the greater number of vegetation ecology studies, meta-analysis of available studies is almost unavailable. The findings also highlighted a lack of long-term studies.

The analysis included 1,165 publications encompassing research articles, book chapters, Ph.D. theses, review articles, and other categories. Three mangrove ecosystems with the highest number of publications linked to them are the Sundarbans mangroves in India, part of the most extensive continuous mangrove system in the world, Odisha’s mangrove, and Tamil Nadu’s mangroves.

Prabakaran’s analysis also spotlighted an uptick in the number of publications on mangroves that had the word ‘tsunami’ or ‘cyclone’ in the title following the 2004 Asian tsunami.

Kathiresan adds that while the dialogue and protective efforts in mangroves have gained momentum in the coastal protection (disaster risk reduction) and fishery sectors, the mangrove-blue carbon finance dimension has to be accorded greater importance.

 

The protection or restoration of blue carbon — organic carbon sequestered and stored over long timescales by coastal vegetated ecosystems such as mangrove forests, seagrasses, and saltmarshes — is steadily gaining prominence as a key natural climate solution.

Experts have earlier communicated to Mongabay-India that a research/data gap exists in developing blue carbon inventories for Indian mangroves. These limitations need to be addressed if blue carbon’s role in meeting the Paris Agreement’s targets has to be robustly demonstrated, states a September 2020 policy brief by The Energy and Resources Institute.

Among its primary targets, India has pledged to create an additional carbon sink of 2.5-3 billion tonnes of carbon dioxide equivalent through additional forest and tree cover by 2030 in its Nationally Determined Contribution (NDC) in 2015 under the Paris Agreement.

Kathiresan notes that biodiversity conservation with native species will enrich the carbon sequestration potential of India’s mangroves. “In places where one mangrove species is grown, carbon sequestration is low but with many species, the carbon sequestration potential increases. Unfortunately, in many plantations, the focus is only on a few species that grow faster such as Avicennia and Rhizophora,” he said.

India’s mangrove cover extends over 4,975 sq km, including the coasts, Andaman and Nicobar, and Lakshadweep islands, and the sprinkling of urban mangroves as per the India State of Forest Report 2019. The report documented an increase in mangrove cover by 54 sq. km. as compared to the previous assessment but marked a decrease of mangrove cover in Tamil Nadu (by four sq. km.), West Bengal (by two sq. km.) and Andaman and Nicobar Islands (by one sq. km.).

A recent paper that mapped the global potential and limits of mangrove blue carbon for climate change mitigation states that India has 189 square km of ‘profitable mangroves’ that qualify for blue carbon financing and are financially sustainable over 30 years. However, Kathiresan believes the 189 square km (equivalent to four percent of India’s total mangrove cover) is an underestimate.

“India has 30% of dense mangrove forest and, it will have more carbon sequestration potential; we have to identify the financially viable mangrove carbon sites,” he stressed. Appended to that goal is the requirement to improve the measurement of below-ground carbon in adherence to a uniform methodology. In terms of the scope of carbon trade in mangrove ecosystems, Kathiresan adds that the seafood export segment can be tacked onto it. “We need to enrich overall coastal marine biodiversity; they are all interconnected with salt marsh and mangroves,” he added.

Banner image: People’s participation in mangrove restoration and an in-depth understanding of biodiversity associated with mangrove ecosystems are linked to effective climate action. Photo from K. Kandasamy.