Effects of conversion from leguminous acacia to non-leguminous eucalyptus on soil N2O emissions in tropical monoculture plantations

Abstract

Tropical monoculture leguminous tree plantations are important nitrous oxide (N2O) sources, especially in the Asian tropics. We evaluated the effect of conversion from leguminous Acacia mangium to non-leguminous Eucalyptus pellita on N2O emissions. A 4-year monitoring experiment was conducted in three areas in South Sumatra, Indonesia. In each area, we established acacia and eucalyptus plantation sites adjacent to one another after the harvest of acacia trees. In contrast to our expectation, the averaged N2O flux at the eucalyptus stands (1.07 mg m−2 day−1 of N) was not significantly different from that at the acacia stands (0.96 mg m−2 day−1 of N). This result was attributable to the higher soil NO3 content in the eucalyptus stands than that in the acacia stands, which was due to the lower N requirement of eucalyptus than that of acacia. In conclusion, converting leguminous acacia to non-leguminous eucalyptus was not an effective option to mitigate N2O emissions in the short term.