Can converting slash-and-burn agricultural fields into rubber tree (Hevea brasiliensis) plantations provide climate change mitigation?: A case study in northern Laos

The area of rubber tree (Hevea brasiliensis) plantations markedly increased in the 2000s in northern Laos. We estimated the carbon sequestration rates of the rubber trees using a dataset from 15 rubber tree plantations and compared the rates with those in natural vegetation growing in fallowed slash-and-burn land. The stand age-averaged carbon stock in the biomass of the rubber trees was 50.0 Mg-C ha-1, after accounting for emissions from the soil while preparing the site for planting rubber trees, based on an assumed economic life of 30 years for the rubber trees. This value was much greater than fallow period averaged carbon stock for the slash-and-burn agricultural system with a 5-year fallow period (18.6 Mg-C ha-1). However, this benefit is lost when rubber tree plantations replace slash-and-burn agricultural activity that must be replaced by the conversion of natural forest reserved. Consequently, conversion of the land-use system from slash-and-burn agriculture with a short fallow period into rubber tree plantations can mitigate climate change if it does not require consequent conversion of natural forest into slash-and-burn agricultural land. Without that conversion, the rubber tree plantations can help mitigate climate change, although it will be necessary to minimize the environmental and economic risks to residents of this region that are associated with this land use.