Natural and anthropogenic impacts on mangrove carbon dynamics: a systematic review protocol

Figures & data

Table 1. Summary of terminologies used in the study.

Variables	Description/Definition	Reference
Carbon dynamic	Describing the spatial and temporal becoming/behaviour of mangrove produced/derived carbon (through primary production), in its organic, inorganic, particulate, dissolved and gas forms.	(Bouillon et al., 2008)
Carbon stock/storage	Describing the spatial and temporal becoming/behaviour of mangrove produced/derived carbon (through primary production), in its organic, inorganic, particulate, dissolved and gas forms.	(Bouillon et al., 2008)
Carbon pools	Carbon reservoirs, such as: Aboveground pools (tree biomass, dead downed wood, litter and understorey) Belowground pools (root biomass, organic soil)	(IPCC, 2000; Kauffman & Donato, 2012)
Tree biomass	Mangrove trees, reliable assessment based on the standardized protocol	(Komiyama et al., 2008) (Kauffman & Donato, 2012)
Dead downed wood	All dead and felled biomass above forest floor	(IPCC, 2000; Kauffman & Donato, 2012)
Root biomass	Belowground roots, pneumatophores and prop roots	(Komiyama et al., 2008) (Kauffman & Donato, 2012)
Organic soil	Carbon stored in belowground organic matter	(Howard et al., 2014)
Carbon fluxes	Transfer/exchange of carbon between different pools: Lateral flux (towards adjacent environments, towards the hydrosphere) Vertical flux (towards the geosphere, the atmosphere)	(Bouillon et al., 2008)
Net Primary Production	Net organic matter production by plants in an ecosystem	(IPCC, 2000)
Litterfall	Litterfall as a proxy for net primary production (accounting for one third of total NPP), clear latitudinal zonation with higher rate between 0° and 10°	(Bouillon et al., 2008)
Carbon emission	CO2 efflux from creek waters during release of dissolved CO2 in oversaturated water	(Bouillon et al., 2008) (Borges et al., 2003)
Mineralization	CO2 efflux from sediment during mineralization of mangrove-derived organic matter	(Bouillon et al., 2008) (Borges et al., 2003)
Carbon export	Tidal export, tidal pumping, subsurface groundwater discharge, outwelling theory, lateral exchange	(Lee, 1995)
Carbon burial	The actual amount of mangrove-derived carbon sequestered in the soil. Usually defined as organic carbon accretion rates per hectare per unit of time	(Twilley et al., 1992; Jennerjahn et al., 2004; Breithaupt et al., 2012)
Land use	The type of activity being carried out on a unit of land	(IPCC, 2003)
Land cover	The types of vegetation covering the Earth’s surface	(IPCC, 2003)
Deforestation	The conversion of forested land to non-forested land by direct anthropogenic activities	(IPCC, 2003)
Degradation	The loss of forest values from forest-cover reduction owing anthropogenic activities	(IPCC, 2003)
Rehabilitation	Ecosystem recovery processes, which may involve non-native species	(Chazdon et al., 2016)
Restoration	Ecosystem recovery processes that involve native species’ composition and historic ecological integrity	(Chazdon et al., 2016)
Biomass	Amount of living material contained in trees expressed in tonnes of dry weight per unit area	(Brown, 1984)
Carbon content/absorption ability	How much CO2 a plant binds from the air	(IPCC, 2021)
Ecosystem service	Benefit that an ecosystem provides to humans	(MEA, 2005)
Species’ distribution/dispersion	The manner in which a biological taxon is spatially arranged, caused by biotic or abiotic factors	(Turner, 2006)
Species’ diversity	Variety, and relative abundance, of species present in an ecosystem	(Bitantos et al., 2017)
Aboveground biomass	defined as the dry weight of the live or dead woody component of aboveground vegetation	(Duncanson et al., 2021)

Figure 1. The native distribution of mangrove species richness across the globe. The introduced ranges are not shown in color: Rhizophora stylosa in French Polynesia, Bruguiera sexangular, Conocarpus erectus, and Rhizophora mangle in Hawaii, Sonneratia apelata in China, and Nypa fruticans in Cameroon and Nigeria (Source Polidoro et al. 2010).

Table 2. Search strings to be used with main bibliographic databases.

Category	Search term
Subject	mangrove* OR "coast* ecosystem*" OR Rhizophora OR Avicennia OR “coast* wetland*” OR “Intertidal wetland*” OR “tidal wetland*” OR “estuarine wetland”
Outcome	carbon OR biomass OR dynamic* OR flux* OR emission* OR stock* OR storage* OR NPP OR respiration OR litterfall OR NEP OR GPP OR efflux OR sequest* OR absorption
Geographical focus	tropic* OR subtropic* OR China OR Japan OR Mongolia OR NorthKorea OR SouthKorea OR Bangladesh OR Bhutan OR India OR Maldives OR Nepal OR Pakistan OR Sri Lanka OR Brunei OR Cambodia OR Indonesia OR Laos OR Malaysia OR Myanmar OR Philippines OR Singapore OR Thailand OR TimorLeste OR Vietnam OR Australia OR NewZealand OR Fiji OR PapuaNewGuinea OR Solomonisland OR Polynesia OR Micronesia OR Melanesia
Mangrove species	Species OR Rhizophora OR Rhizophora* OR R.* OR Avicennia OR A.* OR Bruguiera OR B.* OR Xylocarpus OR x.* OR Ceriops OR C.* OR Lumnitzera OR L.* OR Sonneratia OR S.* OR Nypa OR N.* OR Aegiceras OR Osbornia OR O.* OR Heritiera OR H.* OR Excoecaria OR E.*
Intervention	agricultur* OR aquacultur* OR "land use*" OR "oil palm" OR "shrimp farm*" OR "shrimp pond*" OR “rice cultivation” OR “rice farm*” OR “rice production” OR “rice field*” OR “rice area*” OR "fish farm*" OR "fish pond*" OR mining OR degrad* OR disturb* OR "land cover*" OR "urban development" OR deforest* OR conversion OR rehabilit* OR restor* OR pollut* OR erosion OR waste* OR sewage

Table 3. The populations, interventions, comparators, and outcomes.

Relevant populations	Intervention	Comparator	Outcome
Mangrove ecosystems in Asia Pacific regions; including species clusters such as mangrove palm (Nypa fruticans) and mangrove associates.	Any types of anthropogenic drives including land-use and land-cover changes and restoration impacting mangrove areas, such as: Aquaculture Oil palm Agriculture Urban development Deforestation Rehabilitation or restoration Coastal disturbance (storm events, shoreline erosion, climate change impacts) Organic and inorganic pollution	Undisturbed or natural mangroves used as ‘controlled’ comparator plots that were established and analyzed at the same time, or before and after comparisons of the same areas or plots Natural mangroves used as ‘controlled’ comparator plots with other types, such as degraded-drivers and restoration-approach that were established and analyzed at the same time, or before and after comparisons of the same areas or plots	Any measured change in above- and belowground carbon stocks, fluxes, and biomass allometry of natural and impacted mangroves Any measured carbon sequestration ability, fluxes, sequestration and stocks in different climate zones and habitat characteristics Mapping of the distribution and diversity range of mangrove species to latitude, history, and topography shifts Climatic variables between mangrove sites in Asia Pacific region

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