Variation in Soil Properties Regulate Greenhouse Gas Fluxes and Global Warming Potential in Three Land Use Types on Tropical Peat

Abstract

This study investigated spatial factors controlling CO2, CH4, and N2O fluxes and compared global warming potential (GWP) among undrained forest (UDF), drained forest (DF), and drained burned land (DBL) on tropical peatland in Central Kalimantan, Indonesia. Sampling was performed once within two weeks in the beginning of dry season. CO2 flux was significantly promoted by lowering soil moisture and pH. The result suggests that oxidative peat decomposition was enhanced in drier position, and the decomposition acidify the peat soils. CH4 flux was significantly promoted by a rise in groundwater level, suggesting that methanogenesis was enhanced under anaerobic condition. N2O flux was promoted by increasing soil nitrate content in DF, suggesting that denitrification was promoted by substrate availability. On the other hand, N2O flux was promoted by lower soil C:N ratio and higher soil pH in DBL and UDF. CO2 flux was the highest in DF (241 mg C m−2 h−1) and was the lowest in DBL (94 mg C m−2 h−1), whereas CH4 flux was the highest in DBL (0.91 mg C m−2 h−1) and was the lowest in DF (0.01 mg C m−2 h−1), respectively. N2O flux was not significantly different among land uses. CO2 flux relatively contributed to 91–100% of GWP. In conclusion, it is necessary to decrease CO2 flux to mitigate GWP through a rise in groundwater level and soil moisture in the region.

CO2 emissions from an undrained tropical peatland: Interacting influences of temperature, shading and water table depth

“…In other cases, daytime measurements could also underestimate CO 2 fluxes, as observed byIshikura, Darung, et al (2018). The Damit peat dome studied here was selectively logged and retains scattered forest cover and areas of shade.…”

“…This site is an area of regenerating peatland that was logged by rail in 200 m × 200 m blocks from 1972 to 2010 but was not drained, and has been described in Kobayashi (2000), Gandois et al (2013) and Gandois et al (2014). Although the site was not drained, its vegetation resembles that of drained and degraded peatlands of Central Kalimantan (Blackham, Thomas, Webb, & Corlett, 2013;Ishikura, Darung, et al, 2018) The woody peat at the site is highly organic, with a loss on ignition of 99% and percent carbon of 51% (Gandois et al, 2013). However, all but a few remnant trees were removed during logging, and the site now hosts mostly low-statured vegetation at varying stages of regeneration.…”

“…Perhaps in part due to sparse data sets, efforts to characterize the diurnal cycle and temperature dependence of CO 2 fluxes have found mixed results. However, Hergoualc'h et al (2017 did not detect a diurnal cycle in CO 2 flux, and Ishikura, Darung, Inoue, and Hatano (2018) measured the lowest average hourly CO 2 fluxes at midday. Higher midday fluxes were also detected in manual chamber measurements over more limited time periods (1 day-2 weeks) by Ali, Taylor, and Inubushi (2006), Husnain et al (2014), Marwanto and and Comeau et al (2016).…”

“…However, all but a few remnant trees were removed during logging, and the site now hosts mostly low-statured vegetation at varying stages of regeneration. Although the site was not drained, its vegetation resembles that of drained and degraded peatlands of Central Kalimantan (Blackham, Thomas, Webb, & Corlett, 2013;Ishikura, Darung, et al, 2018): the tree species Combretocarpus rotundatus, a liana (Uncaria sp.) and ferns (Nephrolepis sp.)…”

“…Decomposition of near-surface peat could begin to be reduced by desiccation at very low water tables (e.g. Hirano et al, 2009;Ishikura, Darung, et al, 2018), leading to a plateau in peat decomposition rates. In contrast, at wetter sites like this one, surface peat decomposition could increase monotonically with drying over the range of soil moisture contents.…”