Carbon stocks in the wetlands of a tropical near-costal lake: Bacalar, Mexico.

Description

This dataset supports a study comparing methods for estimating carbon stocks in tropical freshwater karst wetlands associated with the Bacalar Lagoon system, Quintana Roo, southeastern Mexico. Five wetland types were surveyed (gallery forest, mangrove fringe, mangrove swamp, and petenes). The study tested which combination of allometric equations best estimates aboveground tree biomass, and which soil organic carbon method (loss-on-ignition, LOI, vs. dry combustion, Dumas) is more suitable for these karst substrates. The file is a single Excel workbook (.xlsx) with five worksheets: (1) geographic coordinates of the sampling sites; (2) LOI data and derived soil carbon content; (3) Dumas (dry combustion) soil carbon content; (4) tree- and site-level aboveground and belowground biomass and carbon calculations; and (5) synthesized aboveground and belowground carbon stock results (Mg C/ha) per wetland site. Only the results obtained with the mixed allometric-equation approach are reported for aboveground biomass, since this combination (mangrove-specific, region-specific, and general tropical equations) was identified as the set with the lowest estimation uncertainty among the alternatives evaluated. Notable findings: gallery vegetation showed the highest aboveground carbon stocks, related to larger tree size, while petenes and mangroves stored more belowground carbon, associated with hydrology and clay-rich substrates. The LOI method consistently overestimated total soil carbon concentration relative to the Dumas method, although both methods showed similar spatial patterns and high agreement. Interpretation: values are expressed in megagrams of carbon per hectare (Mg C/ha) and can be compared directly across wetland types and between soil-carbon methods (LOI vs. Dumas) at each site. The dataset is intended to support further comparative or synthesis analyses of carbon stocks in karst freshwater wetlands.

Steps to reproduce

Fieldwork: five wetlands of the Bacalar Lagoon system were sampled using 20 x 20 m quadrats established with minimum-area methods. Within each quadrat, tree species, diameter at breast height (DBH), height, and condition (alive/dead) were recorded, following Kauffman & Donato (2012). Aboveground biomass: calculated using species- and region-specific allometric equations, applying wood-density values per species (Reyes et al., 1992; World Agroforestry Centre database). Only the mixed equation set is reported, combining the tropical dry-forest equation of Chave et al. (2005), the mangrove-specific equations of Howard et al. (2014), and the regional small-diameter-tree equation of Puc-Kauil et al. (2020). Litter and deadwood were quantified as dry weight. Belowground biomass: estimated through two complementary approaches: (1) sediment cores extracted with PVC tubes (50 cm long, 70 mm diameter), following Adame et al. (2013); and (2) non-destructive allometric estimation of structural root biomass, using the equation of Komiyama et al. (2008) for mangroves and of Cairns et al. (1997) for tropical wetland trees. Carbon conversion: aboveground biomass was converted to carbon using a factor of 0.5 (Kauffman & Donato, 2012); belowground biomass used a factor of 0.39 (Howard et al., 2014). Values were scaled to megagrams of carbon per hectare (Mg C/ha) using plot area. Soil organic carbon – LOI: soil samples were oven-incinerated at 550°C for 4 h, following Breithaupt et al. (2023). Percent organic carbon (%Corg) was derived from %LOI using the mangrove-specific equation of Kauffman et al. (2011) and environment-specific equations for terrigenous-lagoon and carbonate-estuarine settings (Breithaupt et al., 2023). Soil organic carbon – Dumas: soil samples were oven-dried at 70°C for 12 h (Etheridge et al., 1998), then combusted at 1300°C in a PerkinElmer 2400 Series II elemental autoanalyzer (Mukul et al., 2020). Soil carbon pools: bulk density was calculated per core section from dry mass and known volume, and combined with %Corg (LOI and Dumas) and section thickness to estimate soil carbon pools, scaled to Mg C ha⁻¹. Data compilation and calculations were carried out in Microsoft Excel; no specialized software was required to reproduce the tabulated values beyond the equations and conversion factors listed above.

Institutions

• El Colegio de la Frontera Sur

  Campeche, Campeche
• Tecnológico Nacional de México

  Mexico City, Mexico City

Categories

Funders

• Secretaría de Ciencia, Humanidades, Tecnología e Innovación

  Mexico City, Mexico City

Licence