Indonesia’s blue carbon: a globally significant and vulnerable sink for seagrass and mangrove carbon

Abstract The global significance of carbon storage in Indonesia’s coastal wetlands was assessed based on published and unpublished measurements of the organic carbon content of living seagrass and mangrove biomass and soil pools. For seagrasses, median above- and below-ground biomass was 0.29 and 1.13 Mg C ha−1 respectively; the median soil pool was 118.1 Mg C ha−1. Combining plant biomass and soil, median carbon storage in an Indonesian seagrass meadow is 119.5 Mg C ha−1. Extrapolated to the estimated total seagrass area of 30,000 km2, the national storage value is 368.5 Tg C. For mangroves, median above- and below-ground biomass was 159.1 and 16.7 Mg C ha−1, respectively; the median soil pool was 774.7 Mg C ha−1. The median carbon storage in an Indonesian mangrove forest is 950.5 Mg C ha−1. Extrapolated to the total estimated mangrove area of 31,894 km2, the national storage value is 3.0 Pg C, a likely underestimate if these habitats sequester carbon at soil depths >1 m and/or sequester inorganic carbon. Together, Indonesia’s seagrasses and mangroves conservatively account for 3.4 Pg C, roughly 17 % of the world’s blue carbon reservoir. Continued degradation and destruction of these wetlands has important consequences for CO2 emissions and dissolved carbon exchange with adjacent coastal waters. We estimate that roughly 29,040 Gg CO2 (eq.) is returned annually to the atmosphere–ocean pool. This amount is equivalent to about 3.2 % of Indonesia’s annual emissions associated with forest and peat land conversion. These results highlight the urgent need for blue carbon and REDD+ projects as a means to stem the decline in wetland area and to mitigate the release of a significant fraction of the world’s coastal carbon stores.

[1]  D. Alongi,et al.  Contribution of mangroves to coastal carbon cycling in low latitude seas , 2015 .

[2]  N. Marbà,et al.  Sediment deposition and production in SE-Asia seagrass meadows , 2003 .

[3]  K. Hirakawa,et al.  Mangrove shoreline responses to Holocene environmental change, Makassar Strait, Indonesia , 2004 .

[4]  Daniel M. Alongi,et al.  The Energetics of Mangrove Forests , 2009 .

[5]  G. Saputro,et al.  Peta mangroves Indonesia , 2009 .

[6]  P. Macreadie,et al.  Quantifying and modelling the carbon sequestration capacity of seagrass meadows--a critical assessment. , 2014, Marine pollution bulletin.

[7]  D. Alongi,et al.  The influence of stand age on benthic decomposition and recycling of organic matter in managed mangrove forests of Malaysia , 1998 .

[8]  James W. Fourqurean,et al.  Seagrass ecosystems as a globally significant carbon stock , 2012 .

[9]  E. Meelis,et al.  Seagrass distribution and seasonal biomass changes in relation to dugong grazing in the Moluccas, East Indonesia , 1995 .

[10]  D. Cahoon,et al.  Global carbon sequestration in tidal, saline wetland soils , 2003 .

[11]  Ong Jin Eong Mangroves - a carbon source and sink , 1993 .

[12]  D. Alongi,et al.  Benthic microbial metabolism in seagrass meadows along a carbonate gradient in Sulawesi, Indonesia , 2008 .

[13]  P. Erftemeijer Differences in nutrient concentrations and resources between seagrass communities on carbonate and terrigenous sediments in South Sulawesi, Indonesia , 1994 .

[14]  M. Telszewski,et al.  Coastal blue carbon: methods for assessing carbon stocks and emissions factors in mangroves, tidal salt marshes, and seagrasses , 2014 .

[15]  J. Vonk,et al.  Abundance, edge effect, and seasonality of fauna in mixed-species seagrass meadows in southwest Sulawesi, Indonesia , 2010 .

[16]  C. Duarte,et al.  Changes in community structure and biomass of seagrass communities along gradients of siltation in SE Asia , 1998 .

[17]  H. Sekiguchi,et al.  Environment Problems in the Coastal Zone , 2008, Asia-Pacific Coasts and Their Management.

[18]  P. Herman,et al.  Seasonal changes in environmental variables, biomass, production and nutrient contents in two contrasting tropical intertidal seagrass beds in South Sulawesi, Indonesia , 1994, Oecologia.

[19]  A. Amri Status of Coral Reefs in Southeast Asia 2008 , 2008 .

[20]  C. Lovelock,et al.  CO2 Efflux from Cleared Mangrove Peat , 2011, PloS one.

[21]  T. Bouma,et al.  Early warning indicators for river nutrient and sediment loads in tropical seagrass beds: a benchmark from a near-pristine archipelago in Indonesia. , 2011, Marine pollution bulletin.

[22]  D. Murdiyarso,et al.  The potential of Indonesian mangrove forests for global climate change mitigation , 2015 .

[23]  C. Lovelock,et al.  CO2 Efflux from Shrimp Ponds in Indonesia , 2013, PloS one.

[24]  C. Kull,et al.  Melting Pots of Biodiversity: Tropical Smallholder Farm Landscapes as Guarantors of Sustainability , 2013 .

[25]  T. Bouma,et al.  Marine megaherbivore grazing may increase seagrass tolerance to high nutrient loads , 2012 .

[26]  Inigo J. Losada,et al.  The role of coastal plant communities for climate change mitigation and adaptation , 2013 .

[27]  Rachmansyah,et al.  Growth and development of mangrove forests overlying smothered coral reefs, Sulawesi and Sumatra, Indonesia , 2008 .

[28]  P. Erftemeijer,et al.  Sediment-nutrient interactions in tropical seagrass beds : a comparison between a terrigenous and a carbonate sedimentary environment in South Sulawesi ( Indonesia ) , 2006 .

[29]  M. Hillebrand,et al.  Nutrients, trace metals, and organic contaminants in Banten Bay, Indonesia. , 2001, Marine pollution bulletin.

[30]  A. Green,et al.  The Coral Triangle , 2011 .

[31]  Cecep Kusmana,et al.  Distribution and Current Status of Mangrove Forests in Indonesia , 2014 .

[32]  H. Asmus,et al.  CHALLENGING FOR SEAGRASS MANAGEMENT IN INDONESIA , 2012 .

[33]  Mark Spalding,et al.  World Atlas of Mangroves , 2010 .

[34]  Frederick T. Short,et al.  World Atlas of Seagrasses , 2003 .

[35]  P. Herman,et al.  Low-Canopy Seagrass Beds Still Provide Important Coastal Protection Services , 2013, PloS one.

[36]  P. Nienhuis,et al.  Community structure and biomass distribution of seagrasses and macrofauna in the flores sea, Indonesia☆ , 1989 .

[37]  M. Hemminga,et al.  Nitrogen (15N) retention in small Thalassia hemprichii seagrass plots in an offshore meadow in South Sulawesi, Indonesia , 2001 .

[38]  Oscar Serrano,et al.  Variability in the Carbon Storage of Seagrass Habitats and Its Implications for Global Estimates of Blue Carbon Ecosystem Service , 2013, PloS one.

[39]  F. Short,et al.  Monitoring in the Western Pacific region shows evidence of seagrass decline in line with global trends. , 2014, Marine pollution bulletin.

[40]  C. Wilkinson Status of coral reefs of the world , 2000 .

[41]  Zvy Dubinsky,et al.  Coral reefs : an ecosystem in transition , 2011 .

[42]  D. Alongi Carbon cycling and storage in mangrove forests. , 2014, Annual review of marine science.

[43]  M. Kanninen,et al.  Mangroves among the most carbon-rich forests in the tropics , 2011 .

[44]  S. Supriadi Carbon stock of seagrass community in Branglompo Island Makassar , 2016 .

[45]  J. Kauffman,et al.  Carbon stocks of intact mangroves and carbon emissions arising from their conversion in the Dominican Republic. , 2014, Ecological applications : a publication of the Ecological Society of America.

[46]  James N Sanchirico,et al.  Global economic potential for reducing carbon dioxide emissions from mangrove loss , 2012, Proceedings of the National Academy of Sciences.

[47]  S. Crooks,et al.  Carbon Storage in Seagrass Beds of Abu Dhabi, United Arab Emirates , 2014, Estuaries and Coasts.

[48]  Carlos M. Duarte,et al.  A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2 , 2011 .

[49]  Dietrich G Bengen,et al.  Carbon Stock of Seagrass Community in Barranglompo Island, Makassar (Stok Karbon pada Komunitas Lamun di Pulau Barranglompo, Makassar) , 2014 .

[50]  Growth Rate and Production of Tropical Seagrass Enhalus acoroides (l.) f. Royle in The Vicinity of Fish Cage in Awerange and Labuange Bays Barru Regency South Sulawesi , 2006 .

[51]  Sunny L. Jardine,et al.  Blue Carbon: Coastal Ecosystems, Their Carbon Storage, and Potential for Reducing Emissions , 2013 .

[52]  D. Donato,et al.  Estimating Global “Blue Carbon” Emissions from Conversion and Degradation of Vegetated Coastal Ecosystems , 2012, PloS one.

[53]  N. Marbà,et al.  Assessing the capacity of seagrass meadows for carbon burial: Current limitations and future strategies , 2013 .