Mature Andean forests as globally important carbon sinks and future carbon refuges

Álvaro Duque ,María I Loza-Rivera,William Farfán-Ríos,Marco Calderón-Loor,Alfredo Fuentes,Jonathan A Myers,Jürgen Homeier,J Sebastián Tello,Ricardo Grau,Yadvinder Malhi,Oliver L Phillips,Cecilia Blundo,Sassan Saatchi,Manuel Peralvo,Miles R Silman ,Peter G Kennedy ,Andrea Terán-Valdéz ,Sebastián González‐Caro ,Oriana Osinaga‐Acosta ,Lucio R Malizia ,Johanna Andrea Martínez‐Villa ,M.a Peña ,Agustina Malizia,Esteban Pinto,Julieta Carilla,Francisco Cuesta,Leslie Cayola,Kenneth J Feeley

doi:10.1038/s41467-021-22459-8

Abstract

It is largely unknown how South America’s Andean forests affect the global carbon cycle, and thus regulate climate change. Here, we measure aboveground carbon dynamics over the past two decades in 119 monitoring plots spanning a range of >3000 m elevation across the subtropical and tropical Andes. Our results show that Andean forests act as strong sinks for aboveground carbon (0.67 ± 0.08 Mg C ha−1 y−1) and have a high potential to serve as future carbon refuges. Aboveground carbon dynamics of Andean forests are driven by abiotic and biotic factors, such as climate and size-dependent mortality of trees. The increasing aboveground carbon stocks offset the estimated C emissions due to deforestation between 2003 and 2014, resulting in a net total uptake of 0.027 Pg C y−1. Reducing deforestation will increase Andean aboveground carbon stocks, facilitate upward species migrations, and allow for recovery of biomass losses due to climate change.

Highlights

It is largely unknown how South America’s Andean forests affect the global carbon cycle, and regulate climate change
Our estimate of net annual change in aboveground carbon (AGC net change) for tropical and subtropical Andean montane forests (0.67 ± 0.08 Mg C ha−1 y−1) compares with much more uncertain change rates previously estimated using different and substantially smaller datasets of secondary (0.23 ± 0.87 Mg C ha−1 y−1; mean ± SD) and old growth (0.82 ± 0.37 Mg C ha−1 y−1) montane forests in North and South America[2], which are the default values employed by the intergovernmental panel on climate change (IPCC)
Our results indicate that the Andes are similar to other tropical forests in that they are acting as AGC sinks, but the overall relative strength of the Andean C sink (1.01% annually) is even stronger than that of mature lowland tropical forests in Amazonia[3], Africa[4], or southeast Asia[32]

Summary

Introduction

It is largely unknown how South America’s Andean forests affect the global carbon cycle, and regulate climate change. Quantifying the extent to which tropical and subtropical montane forests contribute to C uptake is essential for generating comprehensive estimates of global C cycling, as well as for helping to motivate the preservation of these forests and the multiple ecosystem services[5] that these biodiversity hotspots[6] provide. Unique among the world’s continents, many of the mostpopulous cities in South America (e.g. La Paz, Cuzco, Quito, Bogotá, Santiago) are located in the mountains at elevations above 500 m asl[11]. This feature reflects both the distributions of pre-Hispanic indigenous populations and patterns of post-. Global warming is generating directional changes in forest composition via the upslope shift of some species’ ranges[13]

Methods

Results

Conclusion