Forest carbon stock in private landholdings in the State of Pará, Brazilian Amazon

In the Brazilian Amazon, 53% of deforestation from 2012 to 2020 occurred on private landholdings (PL). This highlights the need to protect the primary (PF) and secondary (SF) forests in PLs, which are important carbon stocks and sinks for mitigating climate change. Quantifying carbon stocks in private PRP can help the development of Reducing Emissions from Deforestation and Forest Degradation (REED+) projects, and renvironmental service payments (ESP), promoting landowner access to carbon markets. These mechanisms are novel tools for environmental conservation, besides protection actions to safeguard the compliance of environmental legislation.

We aimed to understand the role of PRP in the Brazilian state of Pará, (PA) which concentrated 39% of the deforestation in the Brazilian Amazon from 2012 to 2020, in protecting carbon stocks and sinks, by using multi-satellite data products, including: a) Primary forest cover in 2020 from PRODES/INPE; b) SF age maps from the MapBiomas project (1985-2020); c) Aboveground Carbon map for 2020  from European Space Agency CCi project (2020); and d) Rural proprieties boundaries in 2018 from the Radiography of the Forest Code Project.

PL covers about 26.1% of PA. Large rural properties account for 59% of the total (32.2 Mha) and this class alone retains 8 million ha (Mha) of PF. In terms of carbon stocks, all PRP size classes (small, medium, and large) concentrate 1.44 PgC, of which 71.5% (1.03 PgC) is found on large properties. Small and medium-sized properties stock only 28.5% of the total. When evaluating vegetation surplus in legal reserves (LRs), a kind of mandatory protected area for every PL under Brazilian law, large properties also accumulate the largest areas (1.8 Mha vs. 741 thousand ha in mediun and smallholding), representing a carbon stock of ~794.2 TgC that could be emitted under legal deforestation requests. When evaluating the vegetation deficit in PA, large properties accumulate 1.5 Mha (57%), medium and small-sized properties accumulate 872 thousand ha (34%) and 268 thousand ha (9%), respectively.

Of PA's total SF areas (6.6Mha), 2.8 Mha are under PL, representing a removal potential of about 5.18 TgC year^-1. Large properties host 1.4 Mha of SF (50.5%), while small and medium-sized properties account for 1.38 Mha (49.5%). Restoring SF on PL could meet 50% of the state's restoration target for 2030 but only 21% if considering the rules of current PA State Policy on Climate Change (SF > 10 years old).

We conclude that large rural properties hold significant carbon stocks in PF and SF, being important targets of environmental regularization under the Brazilian law, which could also assist PA with meeting the environmental goals of its climate agenda. We indicate that areas with forest surpluses must be protected to reduce environmental liabilities, through the institution of LR quotas, and incentives to forest restoration and ESP projects.