Exploring Dissolved Organic Carbon Variations in a High Elevation Tropical Peatland Ecosystem: Cerro de la Muerte, Costa Rica

Abstract

Tropical peatlands are distributed mainly in coastal lowlands; however high elevation regions exhibit a large prevalence of small and fragmented peatlands that are mostly understudied. Artificial drainage of peatlands to expand the area of cattle farming, horticulture, and urbanization is increasing carbon losses to the atmosphere and streams worldwide. Here, we present an exploratory characterization of dissolved carbon optical properties in ombrotrophic peat bogs of the Talamanca range of Costa Rica, across an altitudinal gradient (2,400–3,100 m a.s.l.) during the rainy season. Dissolved organic matter (DOM) sources and decomposition processes were evaluated in the light of dissolved organic and inorganic carbon (DOC and DIC), optical properties, and major water chemistry. DOC concentrations ranged from 0.2 up to 47.0 mg/L. DIC concentrations were below 2 mg/L and δ13CDIC values indicated a mixture between soil organic matter, CO2 in soil water, and to a lesser degree DIC derived from bacterial CO2. Absolute fluorescence intensity of humic-like peaks was 6–7 times greater than fresh-like peaks across all sites. Fluorescence peak ratios coupled with the biological and humification indexes point to a greater relative contribution of recalcitrant soil-derived DOM. Excitation/Emission matrices denoted a high prevalence of humic and fulvic acids in the peat bogs, with moderate intensities in soluble microbial by-products-like and aromatic protein regions at three sites. Our data provides a baseline to underpin tropical carbon dynamics across high elevation peatlands.

Dry season plant water sourcing in contrasting tropical ecosystems of Costa Rica

“…For the dry forest region, surface water from the Tempisque River ( N = 139, 2018–2021; weekly unpublished data) and rainfall in Liberia ( N = 421, daily; 2014–2020; Sánchez‐Murillo, Esquivel‐Hernández, Birkel, et al, 2020) were included. Páramo rainfall ( N = 516; daily, 2015–2021) and surface water ( N = 85; biweekly and monthly, 2015–2021) were obtained from a continuous monitoring effort in the Chirripó National Park (Esquivel‐Hernández et al, 2021) and Cerro de la Muerte (Sánchez‐Murillo et al, 2022). Rainfall ( N = 308, weekly 2013–2021) and spring water ( N = 661; daily and weekly 2014–2021) data were obtained from the Sacramento station in the Barva volcano cloud forest (Salas‐Navarro et al, 2019; Sánchez‐Murillo, Esquivel‐Hernández, Birkel, et al, 2020).…”

“…In this high-elevation ecosystem of central Costa Rica, rainfall is mainly modulated by enriched rain events during cold fronts (December-March) and depleted incursions during the influence of the ITCZ and the indirect impact of tropical cyclones (Sánchez-Murillo, Esquivel-Hernández, Birkel, et al, 2020). They sustained a carbon-rich ecosystem (Sánchez-Murillo et al, 2022) with a larger soil water retention capacity (Blanco et al, 2018). In this ecosystem, soil isotope compositions were more enriched (À2.5‰ to À5.0‰) between 0 and T A B L E 1 Bayesian mixing model source contributions (mean, standard deviation SD, quartile and interquartile percentages) to stem water for all ecosystems except the dry forest cacti 25 cm, representing the recent pulse of cold fronts.…”

Composición de los macroinvertebrados según la calidad del agua en turberas de altura, Costa Rica

“…En relación con los anterior, Sánchez-Murillo et al (2022), estudiaron la composición química del agua, y determinaron que las turberas de altura de Costa Rica contienen altas concentraciones de materia orgánica en suelo y agua, altos niveles de carbono orgánico disuelto, lentas tasas de meteorización de la roca, y bajos efectos de la acción antropogénica local. Lo que permite entender que las turberas poseen las condiciones fisicoquímicas y ecológicas adecuadas del agua, que podrían favorecer el establecimiento de los diferentes taxones, además lo que explicaría una mayor presencia de familias de macroinvertebrados especialistas en consumir materia orgánica particulada.…”

“…Las turberas estudiadas se forman a partir de depósitos de materia orgánica en descomposición, con reducido oxígeno, escasos nutrientes y poca profundidad. Se clasifican como turberas ombrotróficas debido a que su principal aporte de agua es mediante las precipitaciones (Gastezzi-Arias et al, 2021;Sánchez-Murillo et al, 2022). Son de tipo estacional, caracterizados por ambientes heterogéneos y cuerpos de agua poco visibles.…”