In recent times, and given the urgent need to limit global warming due to the increase in concentrations of greenhouse gases in the atmosphere (particularly carbon dioxide or CO₂), voices have arisen in favor of the massification of forest monocultures commercial. However, despite the fact that the planting of trees for the capture of CO₂ makes a lot of sense as a simple solution and with economic benefits, the collateral effects of these monocultures have not always been considered in all their dimensions. We will discuss this climate change mitigation measure, emphasizing the case of Chile, where forest plantations constitute one of the country’s economic growth axes.
It’s not just about planting and harvesting
It has recently been proposed that, for forest monocultures to be effective in mitigating climate change, growing trees is not enough. It is also necessary to massify the use of energy obtained from forest biomass and certain biomaterials derived from plantations, for example, substituting concrete for sawn wood or replacing synthetic textile fibers with others derived from wood pulp (eg, viscose). ). Therefore, for forest monocultures to be an effective tool to mitigate climate change, the development of new technologies and their implementation through changes in the business structure aimed at developing a circular bioeconomy is required. If such technological, economic and social advances are not possible at the expected speed, the objective of these monocultures could not be reached in the foreseen time (120 years). In this sense, it is important to note that forest monocultures take years to become net accumulators of carbon, and therefore monocultures with short rotation rates (such as those used for pulp production) are not effective in mitigating climate change.
Using one nail to pull out another
Forest monocultures were an emergency strategy for the control of erosion of highly degraded soils spread in different countries of the world from the 70s. However, the associated industrial practices (clearcutting and road network) increased erosion in many cases, with significant negative impacts on biodiversity and the functioning of ecosystems.
Massive dense tree plantations for an industrial purpose alter the local hydrological cycle, since the species used maintain high growth rates through a non-conservative use of water. In addition, the mechanized management of industrial plantations modifies the physical properties of the soil, which decreases your ability to store water, increases surface runoff (hence also erosion) and modifies invertebrate communities and soil microorganisms. Finally, in an increasingly warmer world, the artificial increase in forest biomass will lead to increasingly severe and extensive fires, particularly in densely populated regions, where sparks capable of starting a fire are frequent. exist recent evidence in this regard, such as the mega-fires that in 2017 spread through more than 280 thousand hectares of forest monocultures in central Chile, leaving 11 fatalities in their wake, or the large fires that that same year cut the lives of dozens of people on a road immersed in a sea of plantations in Portugal. Paradoxically, emissions from the sudden burning of carbon from monocultures are not offset by the storage rates of planted trees. For example, the 2017 fires in Chile emitted almost as much CO₂ into the atmosphere as was emitted during the entire previous year, being the burning of forest monocultures responsible for more than 75% of these emissions.
The use of forest monocultures for commercial purposes constitutes a short-sighted climate change mitigation strategy in the face of other current environmental crises, such as the mass extinction of biodiversity. There is clear evidence that forest plantations harbor less biological diversity than many neighboring natural communities. In addition, they play a central role in the process called biological homogenization, where diverse communities of native species become dominated by a few, usually exotic species. This impoverishment of biodiversity affects above all the trophic elements that most directly benefit people and that directly support the ecological system, such as primary producers (plants) and detritivores (for example, the edaphic fauna). What’s more, biologically impoverished communities have less value in terms of non-tangible ecosystem services, such as less resilience to disturbances or greater susceptibility to invasions by alien species.
Towards sustainable mitigation strategies
There is a general consensus among the scientific community on the need for a regulatory framework and environmental policies that guarantee the protection of natural ecosystems that conserve biodiversity and carbon in biomass and soils, as well as effective ecosystem restoration strategies to increase carbon sequestration and reach to mitigate climate change by improving people’s livelihoods. In this sense, it is necessary to consider that there are multiple scientific evidences that the restoration and conservation of many natural vegetation formations produce a better balance between carbon fixation and emission, without negatively affecting the contributions of ecosystems to people. AND it’s not just about forests: Ecosystems not dominated by trees (such as the Patagonian steppe, tropical savannas or alpine grasslands) store most of the carbon in the soil, in some cases this carbon storage being greater than that accumulated in the biomass of the tropical forests.
For the comprehensive impact of commercial forest monocultures to be positive, the non-explicit negative impacts of these plantations must be eliminated and the degradation of pristine natural ecosystems (whether arboreal or not) must be halted. Only under these premises could managers consider the use of forest monocultures as one option, among others, to mitigate climate change.
Susana Paula, Plant ecology, Austral University of Chile; Álvaro G. Gutiérrez, Assistant teacher. Department of Environmental Sciences and Renewable Natural Resources, University of Chile; Cecilia Smith Ramírez, Researcher at the Laboratory of Communities and Ecological Restoration, University of Los Lagos and Juan Armesto, Researcher in Ecology, Catholic University of Chile
This article was originally published on The Conversation. read the original.
Reference-www.eleconomista.com.mx