Potential carbon sequestration in rubber tree plantations in the northwestern region of the Parana State, Brazil

Rubber tree plantations may improve the soil's physical and chemical properties, and they may sequester atmospheric carbon in the biomass or the soil. However, the potential role of these plantations in sequestering carbon in the soil and plant biomass has not been fully evaluated. This study evaluated rubber tree plantations at Paranapoema, which is located in the northwestern region of the Parana state of Brazil, to measure the biomass in plantations of different ages and to determine the organic carbon content and delta C-13 in the soils. Biomass accumulation was evaluated using the destructive method in plantations of different ages. The total carbon stock in the top 60 cm of the soil was 63.4 Mg C ha(-1) for the pasture adjacent to the plantations and 66.8 and 79.3 Mg C ha(-1) for the 4- and 15-year-old rubber tree plantations, respectively. These values are equivalent to an annual increase in soil carbon stocks of 0.85 and 1.06 Mg ha(-1), respectively, and they do not include the accumulation of carbon as tree woody biomass. The soil delta C-13 indicated a relatively fast conversion from the previous C4-C ( pasture; Brachiaria-Urochloa brizantha) to C3-C ( rubber tree). The results from this study suggest that rubber tree plantations have untapped potential to sequester carbon over a relatively short time period.