A PRELIMINARY STUDY ON THE EFFECT OF FIRE ON CHEMICAL PROPERTIES AND CARBON (CO2) PRODUCTION IN TROPICAL PEATLAND

Abstract

With more than half of the tropical peatlands found in Southeast Asia, their role as carbon sinks is increasingly threatened by warmer environmental conditions and anthropogenic activities (e.g. burning). Fires have been widely used in Southeast Asia as a land-clearing tool, resulting in long-lasting smouldering peat fires that penetrate deeply. Consequently, carbon dynamics and soil properties in tropical peatlands are altered. Yet, there has been limited studies examining carbon dioxide (CO2) production from tropical peat soil. Therefore, this thesis aims to evaluate the effect of fire on peat chemical properties and CO2 production from various depths in aerobic conditions. Peat was sampled from a burnt and an un-burnt (Control) site within a peat swamp forest in Brunei. Some Control samples were burnt in the laboratory to analyse the carbon production of freshly burnt samples. Hence, three types of treatments (Control, Naturally Burnt and Experimentally Burnt) were examined. A 36-day incubation was done to assess the CO2 production rates of the three treatments at 5 depths (0-10cm, 10-50cm, 50-90cm, 90-130cm and 130-170cm). TOC levels were high across the treatments and was lowest on the surface layer. All peat samples were highly acidic with Naturally Burnt peat having the highest mean pH value. Overall, pH decreased as peat depth increased. CO2 production rates across the treatments generally decreased as the incubation proceeded except for Experimentally Burnt. At the start of the incubation, CO2 production rates increased with depth while the opposite trend was observed at the end. Due to the lack of difference in pH and TOC levels between Control and Experimentally Burnt, it can be deduced that experimentally burning tropical peat samples at 200°C for an hour did not result in irreversible changes to chemical properties. These findings contribute preliminary knowledge on the carbon dynamics of burnt peatland in Southeast Asia.