Inundation and salinity regimes support blue carbon conditions in Australian temperate supratidal forests
Data files
Aug 20, 2025 version files 19.45 MB
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dat_biomass.csv
169.78 KB
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dat_cores.csv
55.83 KB
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dat_decomposition_BC.csv
993 B
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dat_decomposition_TP.csv
990 B
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dat_groundwater_CI_mangrove.csv
720.04 KB
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dat_groundwater_CI_saltmarsh.csv
721.06 KB
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dat_groundwater_CI_supratidal_forest.csv
1.73 MB
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dat_groundwater_MINN-FP.csv
2.26 MB
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dat_groundwater_TIL-F.csv
5.71 MB
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dat_groundwater_TP.csv
6.68 MB
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dat_sites.csv
2.52 KB
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dat_surface_BC_mangrove.csv
159.58 KB
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dat_surface_BC_saltmarsh.csv
155.48 KB
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dat_surface_BC_supratidal.csv
153.60 KB
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dat_surface_MINN_fringe.csv
108.75 KB
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dat_surface_MINN_interior.csv
108.32 KB
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dat_surface_MINN_mangrove.csv
110.08 KB
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dat_surface_MINN_saltmarsh.csv
108.66 KB
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dat_surface_SWAN-I.csv
474.67 KB
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README.md
17.40 KB
Abstract
In this study we report on new datasets of vegetation structure, carbon cycling parameters, inundation and salinity patterns across 18 sites spanning more than 4,000 km of Australia’s temperate coastlines. We report site-specific ecosystem carbon stocks ranging from 169 to 635 Mg Corg ha-1, with mean aboveground biomass (134 ± 63 Mg DW ha-1) and belowground carbon stocks to 1 m soil depth (193 ± 98 Mg Corg ha-1), which are within the range of national estimates for mangrove and saltmarsh ecosystems. While there are variations in vegetation structure between sites dominated by the genera Melaleuca and Casuarina, this does not lead to discernible differences in above- or belowground carbon stocks. Organic matter decomposition trends within supratidal forest substrates were similar to adjacent mangrove and saltmarsh, though there were differences among study sites and between labile versus recalcitrant tea litters. Soil-atmospheric flux measurements conducted at one site were also within the range of adjacent blue carbon ecosystems. We hypothesise that the high degree of preservation of belowground carbon and low soil-atmosphere flux of greenhouse gases is driven by a combination of infrequent surface inundation, high water tables and typically saline groundwater in supratidal forests, as measured across multiple settings. Supratidal forests are carbon-rich ecosystems influenced by coastal processes associated with tidal inundation. While further research is required to understand the full distribution, carbon cycling and abiotic drivers of supratidal forests, our findings strongly support their inclusion in blue carbon and other management initiatives that support the response and recovery of these endangered ecological communities in a time of change.
Dataset DOI: 10.5061/dryad.1g1jwsv9c
Description of the data and file structure
Files and variables
File: dat_biomass.csv
Description: Field biomass survey datasets of supratidal forest sites
Variables
- Record: Data entry number (unique value)
- Plot_ID: Field plot ID
- Site: Study side ID (see dat_sites.csv for full details)
- Species: species of measured plant
- Dominant_genus: dominant canopy species of the plot
- Quadrat: quadrat ID within site
- Tree: Tree number within plot. n/a = not available (see Stem number instead)
- Stem: Stem number within plot. n/a = not available (see Tree number instead)
- Status: Tree health status (L = Live; D = Dead; S = Stressed)
- Height_m: Tree height. Unit = m. n/a = not recorded
- D10_cm: Trunk/stem diameter at 10cm above ground surface. Unit = cm. n/a = not recorded
- DBH_cm: Trunk/stem diameter at Breast Height (137cm above ground surface). Unit = cm. n/a = not recorded
- AGB_kg: Tree aboveground biomass estimate based on scaling with allometric equation. Unit = kg
File: dat_cores.csv
Description: Supratidal forest sediment sample dataset for the calculation of soil organic matter, soil organic carbon and related parameters
n/a = not available
Variables
- Record: Data entry number (unique value)
- Site: Study side ID (see dat_sites.csv for full details)
- Core_ID: sediment core ID
- Dominant_genus: dominant canopy species of the plot.
- Depth_upper_cm: sample section upper depth. Unit = cm.
- Depth_lower_cm: sample section lower depth. Unit = cm.
- Depth_mid_cm: sample section mid depth. Unit = cm.
- DBD_gcm-3: sample dry bulk density. Unit = g cm-3.
- OM_percent: sample percent organic matter. Unit = %.
- Corg_percent: sample percent organic carbon. Unit = %..
- Corg_density: sample density of organic carbon. Unit = g C cm-3.
File: dat_decomposition_BC.csv
Description: Dataset of controlled decomposition experiments conducted at Berowra Creek (BC) study site across mangrove, saltmarsh and supratidal forest ecosystem types.
n/a = not available
Variables
- site: Study side ID (see dat_sites.csv for full details)
- time_days: time of sample collection since deployment. Unit = days
- Mangrove_green: Proportion of original mass remaining at time of sample collection. Ecosystem = mangrove; Material = green tea
- Mangrove_rooibos: Proportion of original mass remaining at time of sample collection. Ecosystem = mangrove; Material = rooibos tea
- Saltmarsh_green: Proportion of original mass remaining at time of sample collection. Ecosystem = saltmarsh; Material = green tea
- Saltmarsh_rooibos: Proportion of original mass remaining at time of sample collection. Ecosystem = saltmarsh; Material = rooibos tea
- Supratidal_forest_green: Proportion of original mass remaining at time of sample collection. Ecosystem = supratidal forest; Material = green tea
- Supratidal_forest_rooibos: Proportion of original mass remaining at time of sample collection. Ecosystem = supratidal forest; Material = rooibos tea
File: dat_decomposition_TP.csv
Description: Dataset of controlled decomposition experiments conducted at Towra Point (TP) study site across mangrove, saltmarsh and supratidal forest ecosystem types.
n/a = not available
Variables
- site: Study side ID (see dat_sites.csv for full details)
- time_days: time of sample collection since deployment. Unit = days
- Mangrove_green: Proportion of original mass remaining at time of sample collection. Ecosystem = mangrove; Material = green tea
- Mangrove_rooibos: Proportion of original mass remaining at time of sample collection. Ecosystem = mangrove; Material = rooibos tea
- Saltmarsh_green: Proportion of original mass remaining at time of sample collection. Ecosystem = saltmarsh; Material = green tea
- Saltmarsh_rooibos: Proportion of original mass remaining at time of sample collection. Ecosystem = saltmarsh; Material = rooibos tea
- Supratidal_forest_green: Proportion of original mass remaining at time of sample collection. Ecosystem = supratidal forest; Material = green tea
- Supratidal_forest_rooibos: Proportion of original mass remaining at time of sample collection. Ecosystem = supratidal forest; Material = rooibos tea
File: dat_sites.csv
Description: Summary of all field study sites used across various aspects of this study. Includes names, ID, location and geomorphic and vegetation attributes. Note that not all measurements/experiments were undertaken at all sites.
Variables
- Site name: full site name
- Site ID: Study side ID
- Latitude: Approximate latitude of study site (degrees S)
- Longitude: Approximate latitude of study site (degrees)
- Estuary type: Estuary geomorphic type
- Entrance opening conditions: description of whether estuary mouth is permanently, or intermittently open.
- Tidal range: categorical classification of site tidal range
- Mean annual rainfall (mm): mean annual rainfall as indicated by nearest Bureau of Meteorology weather station. Unit = mm per year
- Dominant woody species: list of the most dominant supratidal forest species within the study site
File: dat_groundwater_CI_saltmarsh.csv
Description: water level dataset collected within a groundwater standpipe located within central zone of saltmarsh at Corner Inlet (CI) study site
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- temp_SALTMARSH: logged temperature. Units = degrees Celsius
- level_surface_SALTMARSH: water level relative to soil surface at location of logger. Unit = m
- level_mAHD_SALTMARSH: water level relative to Australian Height Datum (AHD). Unit = m
File: dat_groundwater_CI_supratidal_forest.csv
Description: water level and salinity dataset collected within a groundwater standpipe located within seaward fringe and interior zones of supratidal forest at Corner Inlet (CI) study site
n/a = not available
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- level_surfaceFRINGE*:* water level relative to soil surface at location of logger. Unit = m
- level_mAHD_FRINGE: water level relative to Australian Height Datum (AHD). Unit = m
- temp_FRINGE: logged temperature. Units = degrees Celsius
- EC_FRINGE: electrical conductivity (EC) of porewater. Units = µS/cm
- SC_FRINGE: specific conductance (SC) of porewater. Units = µS/cm at 25 degrees C
- salinity_FRINGE: salinity of porewater. Units = PSU
- level_surface_INTERIOR: water level relative to soil surface at location of logger. Unit = m
- level_mAHD_INTERIOR: water level relative to Australian Height Datum (AHD). Unit = m
- temp_INTERIOR: logged temperature. Units = degrees Celsius
- EC_INTERIOR: electrical conductivity (EC) of porewater. Units = µS/cm
- SC_INTERIOR: specific conductance (SC) of porewater. Units = µS/cm at 25 degrees C
- salinity_INTERIOR: salinity of porewater. Units = PSU
File: dat_groundwater_CI_mangrove.csv
Description: water level dataset collected within a groundwater standpipe located within central zone of mangrove at Corner Inlet (CI) study site
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- temp_MANGROVE: logged temperature. Units = degrees Celsius
- level_surface_MANGROVE: water level relative to soil surface at location of logger. Unit = m
- level_mAHD_MANGROVE: water level relative to Australian Height Datum (AHD). Unit = m
File: dat_surface_BC_mangrove.csv
Description: water level dataset collected on surface within central zone of mangrove at Berowra Creek (BC) study site
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- Temp: logged temperature. Units = degrees Celsius
- Depth_m: water depth above logger positioned on soil surface. Unit = m
File: dat_surface_BC_supratidal.csv
Description: water level dataset collected on surface within fringe zone of supratidal forest at Berowra Creek (BC) study site
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- Temp: logged temperature. Units = degrees Celsius
- Depth_m: water depth above logger positioned on soil surface. Unit = m
File: dat_surface_MINN_interior.csv
Description: water level dataset collected on surface within interior zone of supratidal forest at Minnamurra River (MINN-FP) study site
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- Temp: logged temperature. Units = degrees Celsius
- Depth_m: water depth above logger positioned on soil surface. Unit = m
File: dat_surface_BC_saltmarsh.csv
Description: water level dataset collected on surface within central zone of saltmarsh at Berowra Creek (BC) study site
n/a = not available
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- Temp: logged temperature. Units = degrees Celsius
- Depth_m: water depth above logger positioned on soil surface. Unit = m
File: dat_surface_MINN_fringe.csv
Description: water level dataset collected on surface within fringe zone of supratidal forest at Minnamurra River Rocklow Creek (MINN-RC) study site
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- Temp: logged temperature. Units = degrees Celsius
- Depth_m: water depth above logger positioned on soil surface. Unit = m
File: dat_surface_MINN_mangrove.csv
Description: water level dataset collected on surface within central zone of mangrove at Minnamurra River Rocklow Creek (MINN-RC) study site
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- Temp: logged temperature. Units = degrees Celsius
- Depth_m: water depth above logger positioned on soil surface. Unit = m
File: dat_surface_MINN_saltmarsh.csv
Description: water level dataset collected on surface within central zone of saltmarsh at Minnamurra River Rocklow Creek (MINN-RC) study site
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- Temp: logged temperature. Units = degrees Celsius
- Depth_m: water depth above logger positioned on soil surface. Unit = m
File: dat_surface_SWAN-I.csv
Description: water level dataset collected on surface within fringe zone of supratidal forest at Swan River Intermediate (SWAN-I) study site
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- Depth_m: water depth above logger positioned on soil surface. Unit = m
File: dat_groundwater_MINN-FP.csv
Description: water level and salinity dataset collected within a groundwater standpipe located within seaward fringe (_FRINGE) and interior (_INTERIOR) zones of supratidal forest at Minnamurra River Floodplain (MINN-FP) study site
n/a = not available
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- temp_FRINGE: logged temperature. Units = degrees Celsius
- EC_FRINGE: electrical conductivity (EC) of porewater. Units = mS/cm
- SC_FRINGE: specific conductance (SC) of porewater. Units = mS/cm at 25 degrees C
- salinity_FRINGE: salinity of porewater. Units = PSU
- level_mAHD_FRINGE: water level relative to Australian Height Datum (AHD). Unit = m
- level_surface_FRINGE: water level relative to soil surface at location of logger. Unit = m
- temp_INTERIOR: logged temperature. Units = degrees Celsius
- EC_INTERIOR: electrical conductivity (EC) of porewater. Units = mS/cm
- SC_INTERIOR: specific conductance (SC) of porewater. Units = mS/cm at 25 degrees C
- salinity_INTERIOR: salinity of porewater. Units = PSU
- level_mAHD_INTERIOR: water level relative to Australian Height Datum (AHD). Unit = m
- level_surface_INTERIOR: water level relative to soil surface at location of logger. Unit = m
File: dat_groundwater_TIL-F.csv
Description: water level and salinity dataset collected within a groundwater standpipe located within central zones of (1) saltmarsh of Salicornia quinqueflora (SMSAL); (2) saltmarsh dominated by Juncus kraussii (SMJUNC); (3) saltmarsh dominated by Phragmites australis (SMPHRAG); and (4) supratidal forest dominated by Melaleuca ericifolia at Tilba Tilba Lake Fluvial (TIL-F) study site
n/a = not available
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- temp_SMSAL: logged temperature. Units = degrees Celsius
- EC_SMSAL: electrical conductivity (EC) of porewater. Units = mS/cm
- SC_SMSAL: specific conductance (SC) of porewater. Units = mS/cm at 25 degrees C
- salinity_SMSAL: salinity of porewater. Units = PSU
- level_mAHD_SMSAL: water level relative to Australian Height Datum (AHD). Unit = m
- level_surface_SMSAL: water level relative to soil surface at location of logger. Unit = m
- temp_SMJUNC: logged temperature. Units = degrees Celsius
- EC_SMJUNC: electrical conductivity (EC) of porewater. Units = mS/cm
- SC_SMJUNC: specific conductance (SC) of porewater. Units = mS/cm at 25 degrees C
- salinity_SMJUNC: salinity of porewater. Units = PSU
- level_mAHD_SMJUNC: water level relative to Australian Height Datum (AHD). Unit = m
- level_surface_SMJUNC: water level relative to soil surface at location of logger. Unit = m
- temp_SMPHRAG: logged temperature. Units = degrees Celsius
- EC_SMPHRAG: electrical conductivity (EC) of porewater. Units = mS/cm
- SC_SMPHRAG: specific conductance (SC) of porewater. Units = mS/cm at 25 degrees C
- salinity_SMPHRAG: salinity of porewater. Units = PSU
- level_mAHD_SMPHRAG: water level relative to Australian Height Datum (AHD). Unit = m
- level_surface_SMPHRAG: water level relative to soil surface at location of logger. Unit = m
- temp_SUPRATIDAL_FOREST: logged temperature. Units = degrees Celsius
- EC_SUPRATIDAL_FOREST: electrical conductivity (EC) of porewater. Units = mS/cm
- SC_SUPRATIDAL_FOREST: specific conductance (SC) of porewater. Units = mS/cm at 25 degrees C
- salinity_SUPRATIDAL_FOREST: salinity of porewater. Units = PSU
File: dat_groundwater_TP.csv
Description: water level and salinity dataset collected within groundwater standpipes located within central zones of (1) mangrove of *Avicennia marina *(MANGROVE); (2) saltmarsh dominated by Salicornia quinqueflora and Sporobolus virginicus (SMSASP); (3)saltmarsh dominated by Juncus kraussii (SMJUNC); and (4) supratidal forest dominated by Casuarina glauca at Towra Point (TP) study site
n/a = not available
Variables
- Date_Time: Date and time of record in local time zone (no daylight savings). Date Format = dd/mm/yyyy. Time format = hh:mm
- level_surface_MANGROVE: water level relative to soil surface at location of logger. Unit = m
- level_mAHD_MANGROVE: water level relative to Australian Height Datum (AHD). Unit = m
- temp_MANGROVE: logged temperature. Units = degrees Celsius
- SC_MANGROVE: specific conductance (SC) of porewater. Units = mS/cm at 25 degrees C
- salinity_MANGROVE: salinity of porewater. Units = PSU
- level_surface_SMSASP: water level relative to soil surface at location of logger. Unit = m
- level_mAHD_SMSASP: water level relative to Australian Height Datum (AHD). Unit = m
- temp_SMSASP: logged temperature. Units = degrees Celsius
- SC_SMSASP: specific conductance (SC) of porewater. Units = mS/cm at 25 degrees C
- salinity_SMSASP: salinity of porewater. Units = PSU
- level_surface_SMJUNC: water level relative to soil surface at location of logger. Unit = m
- level_mAHD_SMJUNC: water level relative to Australian Height Datum (AHD). Unit = m
- temp_SMJUNC: logged temperature. Units = degrees Celsius
- SC_SMJUNC: specific conductance (SC) of porewater. Units = mS/cm at 25 degrees C
- salinity_SMJUNC: salinity of porewater. Units = PSU
- level_surface_SUPRATIDAL_FOREST: water level relative to soil surface at location of logger. Unit = m
- level_mAHD_SUPRATIDAL_FOREST: water level relative to Australian Height Datum (AHD). Unit = m
- temp_SUPRATIDAL_FOREST: logged temperature. Units = degrees Celsius
- SC_SUPRATIDAL_FOREST: specific conductance (SC) of porewater. Units = mS/cm at 25 degrees C
- salinity_SUPRATIDAL_FOREST: salinity of porewater. Units = PSU
Code/software
datasets can be analysed in any package or software which supports .csv files
Access information
Other publicly accessible locations of the data:
- NIL
Data was derived from the following sources:
- NIL
This study collates datasets collected between 2017 and 2023 from 18 study sites spanning a diversity of settings along these coastlines. Within each setting, sites were prioritised where there was adjoining saltmarsh and/or mangrove communities, to allow comparative analyses with either existing or new datasets of those communities. Therefore, our collation of study sites may be under representative of supratidal forests occurring in isolation from intertidal mangrove and saltmarsh, and should not be considered a systematic or comprehensive coverage of forest settings. The measured parameters, measurement frequency and sampling designs varied among study locations according to their specific data collection objectives.
Water level and salinity
Groundwater standpipes were installed opportunistically across five sites (TP, MIN-FP, TIL-F, CI and ONK) to enable continuous logging of water level and/or salinity concentrations and explore the role of tidal inundation and rainfall on these parameters across diverse geomorphic settings. Standpipes were constructed from PVC tubes (1.5 m long; 50mm diameter) perforated with small (2mm) holes and covered with a nylon stocking to minimise infilling by sediments. Standpipes were installed into an augured hole (~50mm diameter with any gaps around the pipes backfilled using extracted sediments) to a depth of approximately 120 cm, enabling data-logging sensors to be suspended at a depth of 100 cm below the wetland surface. Exceptions to this included the mangrove standpipe at TP (sensors at 50cm depth below surface) and the supratidal forest standpipe at ONK (salinity sensor at 87 cm; water level sensor at 69 cm). In all cases, standpipe perforations were limited to sections below the wetland surface. Water table level and groundwater salinity measurements were taken at 15-minute intervals using either integrated loggers with pressure, temperature and electrical conductivity sensors (SOLINST LTC Edge), or via the simultaneous deployment of individual pressure (HOBO U20-001-04) and temperature / electrical conductivity sensors (HOBO U24-002-C).
Surface water-level loggers were deployed at BC, MIN-RC and MIN-FP sites to capture variations in surface inundation across adjacent mangrove, saltmarsh and supratidal forest communities at the scale of individual spring tide cycles. A surface logger was deployed on the surface of fringing supratidal forest at SWAN-I to capture inundation associated with either tides and/or seasonal rainfall at this location. At each site, an additional pressure logger (HOBO U20-001-04) was deployed in a tree well above the inundation limit to enable correction for atmospheric pressure and determination of water depths.
Trimble R8s and R10 real-time kinematic global positioning systems (horizontal error < 8 mm; vertical error < 15 mm) was used to survey the location and elevation of each water level measurement location. Where canopy coverage hindered the use of these instruments (i.e. supratidal forests at TP and MIN-FP) elevation was estimated via manual survey from an adjacent open area using a Leica Sprinter 50 Digital Level. In both instances, elevation is reported in the Australian Height Datum (AHD), where 0 m AHD corresponds to an estimate of mean sea level across Australian coastal waters.
Biomass survey
Field vegetation surveys were carried out at 11 sites to assess variations in forest structure and aboveground biomass across study settings. Replicate survey plots were measured within each site, with plot sizes ranging from 12.5 to 400 m2 depending on the density and homogeneity of vegetation at the site. Within each quadrat all trees > 1.3 m height were measured for diameter at breast height (DBH; Casuarinas) or diameter at 10 cm (D10; Melaleucas) to enable biomass estimation following genus-specific allometric equations created by Paul et al. (2013). The inclusion of such low-statured individuals is consistent with the definition of Australia’s forests as vegetation with mature or potentially mature stand height exceeding 2 metres (ABARES 2023). Biomass values for BC, BUTCK, LES and TP are updated estimates, including new additional plots, of those reported in Kelleway et al (2021). Biomass values are presented as dry weight estimates (Mg DW ha^-1^) and were converted to aboveground carbon stock estimates using a conversion factor of 0.488 (Kelleway et al. 2021) to enable calculation of total ecosystem carbon stocks.
Belowground carbon stocks
Soil cores were collected from one or more supratidal forest plots at 12 sites to assess variations in belowground carbon stocks among settings. Core barrels of either aluminium (74 mm internal diameter) or PVC (82 cm internal diameter) were manually hammered into the ground with care taken to minimise compaction. Compaction was estimated by measuring the difference in elevation of the soil surface within the core barrel and the outer soil surface. A linear compaction correction factor was later applied along the length of each core based on these measures. In the laboratory, soil cores were sub-sampled at compaction-corrected depth intervals of ≤ 5 cm along the entire length of the core. Bulk soil was oven dried at 60°C until constant mass and weighed to determine dry bulk density and then homogenized and ground into a fine powder.
Samples from BC, TP, KWP, QI, RHYLL, OYST-M, WIL-F and NORN-F were assessed for organic carbon (%Corg) via an elemental analyser, following removal of carbonates with HCl digestion, where required. Due to resource constraints, all other samples were assessed via loss-on-ignition (LOI) at 550oC for 4 h (Heiri et al., 2001). For these samples %Corg estimates were derived from organic matter concentrations using a previously developed empirical relationship for Casuarina samples (Kelleway et al. 2021), or a new empirical relationship developed for Melaleuca sites from samples subjected to both LOI and elemental analyses (Appendix S1: Figure S1). Soil carbon stocks were estimated for 0-30 cm, 0-100 cm and 100-200 cm depth ranges where core depths allowed. Stock estimates for BC, BUTCK, CRB, LES and TP were previously reported in Kelleway et al. (2021).
Belowground decomposition
We used a modified tea bag index protocol as part of the global TeaComposition H2O program (Trevathan-Tackett et al. 2021) at two study locations (BC and TP) to compare long-term belowground organic matter decomposition in supratidal forest relative to adjacent intertidal mangrove and saltmarsh ecosystems. We monitored the biomass loss of standardised litters: green tea (Lipton; EAN 87 22700 05552 5) and rooibos tea (Lipton; EAN 87 22700 18843 8), which are proxies for more labile and more recalcitrant plant organic matter types, respectively (Trevathan-Tackett et al. 2024). The green tea contains a higher proportion of water soluble compounds (simple sugars and phenolics), while the rooibos tea consists of a higher proportion of acid insoluble compounds (e.g. lignin; Keuskamp et al. 2013). At T0 (December 2017), all pre-weighed tea bags were buried at approximately 15 cm depth. Four tea bags per plot were manually retrieved (2x green; 2x rooibos) from each site, at each of 3, 12, 24, 36 month intervals after initial deployment, though two of the 64 samples could not be found. Tea bags were rinsed in distilled water to remove attached soil, and any visible root in-growth was carefully removed prior to drying of samples (60 °C until constant mass), and re-weighing.