A pine tree plantation in Aysen Patagonia belonging to the Spanish winery Miguel Torres. Photo: Miguel Torres
In a public statement on August 12, members of 11 Chilean scientific centers made an urgent call to suspend reforestation projects in Patagonia that utilize exotic species for carbon sequestration.
In relation to the recent initiatives of reforestation with exotic species in the Chilean Patagonian steppe with the objective of carbon sequestration, the undersigned would like to express the following:
Climate change is a global phenomenon that is affecting ecosystems and societies around the world with still unpredictable consequences that represent a threat to human well-being and the integrity of nature. In this scenario, it is urgent to reduce greenhouse gas emissions (CO2, methane, etc.) and to increase carbon sequestration through conservation, restoration and ecosystem management. Among nature-based solutions for carbon sequestration, the establishment and restoration of lost or degraded forest cover has received special attention, as it is a simple, relatively inexpensive mechanism with multiple other ecological and social benefits. However, scientific evidence has shown that tree planting can also have negative impacts if it is not carried out according to strict standards that ensure adequate compatibility between the species used and the ecosystems to be reforested or restored. A clear example of the negative impact that can result from conifer forestations introduced for carbon sequestration purposes are large fires that can suddenly release much of the stored carbon.
In Chile, several reforestation projects are being promoted and analyzed to increase carbon sequestration. Undoubtedly, these initiatives can be beneficial when the social and ecological impacts are evaluated and considered, and decision-making at the local scale is done in a participatory and open manner, but it is crucial to also consider the negative impacts of these actions.
Recently, some initiatives have become known that seek to mitigate climate change by planting exotic species in steppe ecosystems in Chilean Patagonia. In this regard it is important to consider:
1) The Patagonian steppe is an endemic ecosystem of the southern cone of South America, and contains a high number of unique flora and fauna species. Given the uniqueness of its fauna and flora, and the high degree of environmental stress to which they are subjected, the Patagonian steppe has been classified as one of the world's priority ecoregions for conservation by the Global 200 program of the World Wildlife Fund (WWF). The Patagonian steppe is an ecosystem that has evolved since the glacial era in the absence of tree cover, which does not represent any environmental problem; on the contrary, it generates a unique landscape of inestimable ecological, historical, social and cultural value, as well as economic importance for livestock and tourism.
2) Scientific evidence indicates that, because the pines used in these forestry plantations come from the orthern Hemisphere and have evolved under other climatic and ecological conditions, pine plantations in the Patagonian steppe generate a multiplicity of negative impacts such as: (a) reducing habitat for native species and the biodiversity of herbaceous and shrub species that cannot withstand competition or shade from tree species; (b) reducing the availability of water in the soil, water tables and water flows, which is critical in these semi-arid ecosystems; (c) reducing the scenic and tourism value of these southern areas by interfering with the view of the landscape, affecting the sociocultural value of these vegetational formations that are part of the identity of the inhabitants of Patagonia; d) promoting the invasion of planted species, such as pines, into neighboring areas where they have not been planted, generating dense stands that quickly homogenize the landscape and are very costly to control; finally, and of utmost concern given the scenario of climate change, e) the combination of plantations and invasions of pines in the Patagonian steppe can alter the forest fire regime, increasing the frequency, extent and severity of these fires.
3) Regarding carbon fixation and sequestration, there is no conclusive evidence regarding how much carbon is released or sequestered by replacing the diverse Patagonian steppe with a monospecific pine plantation. Studies in other natural grassland environments show that a significant amount of carbon is stored below the surface in soil, roots, and other soil organisms. Evidence indicates that more diverse ecosystems are capable of sequestering more carbon in the medium and long term.
Against this background, we urgently call for the suspension of the use of exotic species.
Signatory Institutions:
SOCIEDAD DE ECOLOGÍA DE CHILE
SOCIEDAD DE BOTÁNICA DE CHILE
SOCIEDAD DE BIOLOGÍA DE CHILE
INSTITUTO DE ECOLOGÍA Y BIODIVERSIDAD (IEB)
CENTER FOR CLIMATE AND RESILIENCE RESEARCH (CR)2
CENTER OF APPLIED ECOLOGY AND SUSTAINABILITY (CAPES)
ASOCIACIÓN CHILENA DE ECOLOGÍA DEL PAISAJE (IALE-CHILE)
CENTRO DEL FUEGO Y RESILIENCIA DE SOCIOECOSISTEMAS (FIRESES)
PROGRAMA VINO, CAMBIO CLIMÁTICO Y BIODIVERSIDAD (VCCB)
FUNDACIÓN CENTRO DE LOS BOSQUES NATIVOS FORECOS RED CHILENA DE RESTAURACIÓN ECOLÓGICA
References
Di Sacco, A., Hardwick, K. A., Blakesley, D., Brancalion, P. H. S., Breman, E., Cecilio Rebola, L., Chomba, S., Dixon, K., Elliott, S., Ruyonga, G., Shaw, K., Smith, P., Smith, R. J., & Antonelli, A. (2021). Ten golden rules for reforestation to optimize carbon sequestration, biodiversity recovery and livelihood benefits. Global Change Biology, August 2020, 1–21. https://doi.org/10.1111/gcb.15498
Hisano, M., Searle, E. B., & Chen, H. Y. (2018). Biodiversity as a solution to mitigate climate change impacts on the functioning of forest ecosystems. Biological Reviews, 93(1), 439-456.
Nuñez, M. A., Davis, K. T., Dimarco, R. D., Peltzer, D. A., Paritsis, J., Maxwell, B. D., & Pauchard, A. (2021). Should tree invasions be used in treeless ecosystems to mitigate climate change?. Frontiers in Ecology and the Environment. https://doi.org/10.1002/fee.2346
