Nitrous oxide as second most important greenhouse gas in tropical peatlands

Abstract

Earth’s climate largely depends on carbon and nitrogen exchange between the atmosphere and tropical peatland ecosystems. Permanently wet peatlands take up carbon dioxide in plants and accumulate organic carbon in soil but release methane. Man-made drainage releases carbon dioxide from peat soils. Carbon and nitrous gas exchange and their relationships with tropical peatland conditions are poorly understood. We analysed natural peat swamp forests and fens, moderately drained and dry peatlands under a wide variety of land uses. The tropical peat swamp forests were large greenhouse gas sinks while tropical peatlands under moderate and low soil moisture levels emitted carbon dioxide and nitrous oxide. Carbon dioxide uptake of 160 mg m–2 h–1 dominated the net greenhouse gas budgets overall, while nitrous oxide emission of 90 mg CO2-equivalent m–2 h–1 on average was the second most important contributor (ahead of average methane emissions of 36 mg CO2-equivalent m–2 h–1) across the whole tropical peat moisture range.