Above- and below-ground carbon accumulation in cultivated macauba palm and potential to generate carbon credits

Agriculture provides an array of ecosystem services including the sequestration and storage of carbon in the biomass of plants. Research has focused on commercial crops, especially tree crops, for their potential to mitigate the impacts of climate change. In Brazil interest is growing in the commercial cultivation of macauba (Acrocomia aculeata), a palm native to the tropical regions of the American continents with fruit that can be used as the primary ingredient in the production of oils and bioenergy. However, we did not find any prior studies that had assessed macauba’s carbon sequestration potential nor any exploration in the literature of the income generation potential for commercial macauba producers to sell carbon credits. In order to understand opportunities to commercialize carbon credits from macauba, research was needed on the palm’s long-term carbon sequestration and stock capacity. In this study we measured the accumulation of carbon in commercially cultivated macauba’s biomass both below and above-ground using a selection of plants of different ages. An assessment was also made of the crop’s potential to generate carbon credits. Macauba plants were sampled in a nursery with seedlings aged 3 and 8 months, and with more mature plants cultivated in fields aged 1.6, 4.8, and 9 years. The samples were fully harvested by complete removal (including roots and above ground structures), followed by separation, quantification and carbon analysis of the different plant biomass components. The data obtained allowed for estimating the production of carbon credits and the resulting annual income. Findings indicated a differential distribution of both biomass and carbon below and above-ground in field-cultivated macauba palms. The stock of carbon in the plants aged 9 years reached 61.6 t C ha−1 with a corresponding sequestration of 226.17 t CO2 eq ha−1. The expected generation of carbon credits of palms from 1.6 to 9 years was 28.73 t CO2eq. ha− 1 per year, which could result in an annual gross income of € 761.06 per hectare. Significant amounts of stored carbon were found in both the above and below-ground biomass, suggesting that the macauba has significant potential to generate carbon credits and contribute to the mitigation of the effects of climate change.