The climate top in Paris focused on how we can reduce climate change by reducing carbon emissions, or by increasing carbon uptake. It now turns out that tropical secondary forests that re-grow after forest clearance or agricultural abandonment can sequester large amounts of carbon. Is this a unique, additional opportunity to meet the global commitments made in Paris?
A large international team of forest ecologists, 2ndFOR , led by researchers from Wageningen University shows this week in Science Advances that the carbon uptake potential of regrowing tropical forests is tremendous. They analysed the area and distribution of tropical secondary forests across Latin America, and modelled their carbon sequestration potential over the coming 40 years. Senior author Prof. Lourens Poorter says ”Second-growth forest (younger than 60 years) cover as much as 2.4 millon km2, which corresponds to 28% of the land in Latin America. These young and fast-growing forests can store in 40 years as much as 8.5 Petagrams (that is, 8.5 billon tonnes) of carbon in aboveground biomass. Simply by letting these forests regrowing naturally, they can compensate for all the carbon emissions from fossil fuel use and industrial processes by Latin American countries over the past 22 years”.
Secondary tropical forests
Secondary forests are forests that regrow after nearly complete removal of forest cover for agricultural use (for shifting cultivation or cattle ranching). Currently over half of the world’s tropical forests are not old-growth, but naturally regenerating forests of which a large part is secondary forest.
Second-growth forests differ dramatically in their carbon uptake, which is especially high in areas with high rainfall and water availability throughout the year. Co-author Professor Frans Bongers: “There are global commitments to restore 3.5 millon km2 of forests worldwide by the year 2030. We have produced maps for Latin America, showing where exactly these secondary forests are, and how much carbon they can sequester. Regional and national policy makers can use this information to identify areas where natural forest regrowth has a high carbon sequestration potential, or where active forest restauration or tree planting has a high chance of success.”
Lead author Prof. Robin Chazdon: “We need active policies that reduce carbon emissions and increase carbon uptake. Therefore we urge to halt deforestation and protect old-growth tropical forests, and to promote natural forest regrowth in deforested areas. Natural regeneration of second-growth forest provides a low-cost opportunity for carbon sequestration in the tropics, while at the same time they conserve biodiversity and deliver many ecosystem services. Natural regrowth is a cheap and nature-based solution with a tremendous carbon mitigation potential.”
This research is a product of the 2ndFOR collaborative research network on secondary forests. It involves 65 researchers from 15 different countries. The network focuses on the ecology, dynamics, and biodiversity of secondary forests, and the ecosystem services they provide in human-modified tropical landscapes. The 2ndFOR network is coordinated by Prof. Lourens Poorter and Prof. Frans Bongers (Wageningen University, the Netherlands) and Dr. Danaë Rozendaal (University of Regina, Canada).