Post-Revegetation Carbon Dioxide Emissions from Various Peatland Cover Types in the Sriwijaya Botanical Gardens, South Sumatera, Indonesia

Abstract

Tropical peatlands are vital carbon reservoirs, yet their degradation and partial revegetation leave uncertainties about post-revegetation carbon dynamics, particularly CO2 emissions across different vegetation types. This study aimed to assess the emissions from four revegetated peatland cover types in the Sriwijaya Botanical Gardens, South Sumatra. Emission measurements representing soil-atmosphere CO2 fluxes using soil chambers were conducted weekly from September 18, 2024, to February 12, 2025, in conjunction with observations of groundwater levels, soil temperatures, and air temperatures. Weekly emission rates were extrapolated to estimated annual CO2 emission expressed in ton ha-1 year-1. Emission data were collected using an infrared gas analyzer on four peatland cover types: Shorea belangeran (belangeran) stands planted in 2015 and 2020; Fagraea fragrans (tembesu) stands planted in 2015; and a secondary forest dominated by Melaleuca leucadendron (gelam). Measurements were conducted in triplicate for each cover type. The results showed that the highest CO₂ emissions were recorded in the Belangeran 2020 stand, closely followed by the Tembesu 2015 stand, with nearly identical values of 36.6 and 36.0 t CO₂ ha⁻¹ year⁻¹, respectively. However, these values were not significantly different from emissions measured in other peatland cover types. The elevated emissions in the Belangeran 2020 stand correlate with higher annual average soil and air temperatures (30.2 °C and 31.1 °C, respectively), resulting from a fire event in 2019. In the Tembesu 2015 stand, elevated emissions are primarily linked to a deeper groundwater level (-52 cm) and potential contributions from root respiration. Environmental variables, such as groundwater level, soil temperature, and air temperature showed significant relationships with CO₂ emissions across all peatland cover types in the Sriwijaya Botanical Gardens, although their relative influences varied among stands. These findings offer additional insights into the biophysical drivers of peatland carbon fluxes and underscore the importance of species selection, canopy structure, and groundwater level dynamics in enhancing revegetation outcomes and supporting peatland management strategies.