At the Climate Conference in Paris (CoP 21), all attention was focused on how humanity can reduce the emissions of greenhouse gases, especially Carbon Dioxide, that are driving climate change, either by reducing emissions at source or by increasing sequestration of carbon. One of the most important ways of reducing Carbon Dioxide in the atmosphere is to trap the Carbon in the woody matter of living vegetation. For this reason forests, with their vast numbers of trees, are an especially important carbon sink. The importance of ‘new’ or secondary forests – forests that are regrowing or being restored in areas where mature forest had been cleared – has not been given the importance it deserves as a strategy for trapping carbon from the atmosphere. This is set to change.

In a scientific article in Nature, Biomass resilience of Neotropical secondary forests, a large international team of forest ecologists led by researchers from Wageningen University are reporting that regrowing tropical forests can store large amounts of carbon. Based on their analysis of 1500 forest plots and 45 sites across Latin America lead author Prof. Lourens Poorter concluded that ”Carbon uptake is surprisingly fast in these young forests that regrow on abandoned pastures or abandoned agricultural fields. After 20 years, these forests have recovered already 122 tons of biomass per ha. This corresponds to an uptake of 3.05 ton carbon per ha per year, which is 11 times the uptake rate of old-growth forests”.

Second-growth forests differ dramatically in their biomass resilience; in 20 years between 20 and 225 ton biomass has recovered. The study reveals that biomass recovery is high in areas with high rainfall and water availability throughout the year, other factors such as soil fertility or the amount of forest cover in the surrounding landscape were less important. Interpreting the results for decision makers, World Agroforestry Centre (ICRAF) scientist Dr Madelon Lohbeck, one of the article’s co-authors, notes that “Regional and national policy makers can use the biomass recovery maps in the study to make informed decisions about suitable restoration strategies that also work to mitigate greenhouse gas emissions. Where natural regrowth is rapid, the costly activity of tree planting may not be necessary.  The information in the study now allows them to harness natural regeneration processes that could save them money and deliver longer lasting, resilient results”.

As the world looks for efficient and affordable ways to combat climate change and meet the burgeoning demands of its inhabitants they would do well to heed Prof. Frans Bongers, one of the study’s principal investigators: “Forest regrowth clearly deserves more attention of (inter)national policy makers. Rather than working against nature we should work with nature; natural regrowth is a cheap and nature-based solution with a tremendous carbon mitigation potential.”

Publication:

Lourens Poorter, Frans Bongers, T. Mitchell Aide, Angélica M. Almeyda Zambrano, Patricia Balvanera, Justin M. Becknell, Vanessa Boukili, Pedro H. S. Brancalion, Eben N. Broadbent, Robin L. Chazdon, Dylan Craven, Jarcilene S. de Almeida-Cortez, George A. L. Cabral, Ben H. J. de Jong, Julie S. Denslow, Daisy H. Dent, Saara J. DeWalt, Juan M. Dupuy, Sandra M. Durán, Mario M. Espírito-Santo, María C. Fandino, Ricardo G. César, Jefferson S. Hall, José Luis Hernandez-Stefanoni, Catarina C. Jakovac, André B. Junqueira, Deborah Kennard, Susan G. Letcher, Juan-Carlos Licona, Madelon Lohbeck, Erika Marín-Spiotta, Miguel Martínez-Ramos, Paulo Massoca, Jorge A. Meave, Rita Mesquita, Francisco Mora, Rodrigo Muñoz, Robert Muscarella, Yule R. F. Nunes, Susana Ochoa-Gaona, Alexandre A. de Oliveira, Edith Orihuela-Belmonte, Marielos Peña-Claros, Eduardo A. Pérez-García, Daniel Piotto, Jennifer S. Powers, J. Rodríguez-Velázquez, I. Eunice Romero-Pérez, Jorge Ruíz, Juan G. Saldarriaga, Arturo Sanchez-Azofeifa, Naomi B. Schwartz, Marc K. Steininger, Nathan G. Swenson, Marisol Toledo, Maria Uriarte, Michiel van Breugel, Hans van der Wal, Maria D. M. Veloso, Hans F. M. Vester, Alberto Vicentini, Ima C. G. Vieira, Tony Vizcarra Bentos, G. Bruce Williamson & Danaë M. A. Rozendaal. 2016. Biomass resilience of Neotropical secondary forests. Nature doi: 10.1038/nature16512.

2ndFOR - 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).

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.

Read full article on nature.com

See Related blog : Working with nature: tropical forest regrowth and its potential for mitigating climate change