CO2 FLUXES FROM SECONDARY FOREST, OIL PALMS, ALOE VERA, AND SHRUB PEATLAND ON DRAINED TROPICAL PEAT

摘要

Drained tropical peats are widely used for agriculture, and become a major source of CO2 emissions. However, measurements of CO2 fluxes from these peats are rarely carried out and reported. We investigate CO2 fluxes from different land uses, i.e., secondary forest (SF), young oil palm (OP), aloe vera (AV), shrub peatland (SL), on drained peats of Rasau Jaya in West Kalimantan Province, Indonesia. The site of smallholder oil palm plantation (OP) is adjacent to secondary forest (SF). Shrub and aloe vera sites are about 1 and 2 km far from the secondary forest. All sites are located on the same peat complex. We have conducted this research since July 2015, and will continue this research for several years. We used an EGM-4, an infrared gas analyzer, to measure CO2 fluxes from six plots at each land use. We employed Analysis of Variance, and contrast tests to detect mean differences among land uses. Average values of CO2 fluxes in SF, OP, AV, and SL are 0.292 ± 0.122; 0.467 ± 0.217; 0.674 ± 0.302; and 0.467 ± 0.185 g CO2m~2 hr~（-1）. Results of ANOVA show that CO2 fluxes are significantly different from one land use to another land use. CO2 fluxes from SF and SL sites are significantly different from OP and AV sites, and SF from SL sites. Low water contents in Aloe vera plantation and shrub lands imply more water loss than in secondary forest and oil palm plantation. In conclusion, we confirm that one of important factors determining CO2 flux is type of crops. We show that crops with open canopy as in case of Aloe vera enhance more CO2 emissions than other closed canopy tree crop.