Tree planting and global climate change

Researchers are pointing out that just planting trees is not a cure-all for tackling global warming and climate change, as recorded by multiple studies. Right from selecting the correct species to then monitoring and maintaining saplings and planning for large-scale tree plantation, effective tree plantation goes beyond just planting of the tree, according to a report by Mongabay-India.

The report also cites a 2022 study in ‘Conservation Letters’ used a machine learning framework to demonstrate that the climate mitigation potential from forest restoration in India has also been exceptionally overestimated. The results of the study indicate that India’s ability to create more carbon sinks via afforestation will meet less than one-fourth of the country’s commitments to the 2015 Paris Agreement.

Citing studies in the Central Himalayas and the Coromandel coast (southeastern coast of India), the report also warns that planted trees showed hugely variable survival rates over 5-10 years. Depending on whether these were native or exotic species, in mixed- or mono-species plantations, the planted saplings’ survival ranged from 51–87% at one site, 0–100% in another, and 35–100% in yet another. While 100% sapling survival over 5 years sounds like a positive trend, this is true only for very few species.

The Mongabay-India report stresses that ill-planned and unscientific tree plantation programs could in fact lead to maladaptation, as pointed out by some authors of the United Nations’ Intergovernmental Panel on Climate Change (IPCC) Working Group II report. Maladaptations are actions that may lead to increased risk of adverse outcomes such as increased greenhouse gas emissions, increased or shifted vulnerability to climate change and inequity. Such actions can also dent biodiversity and ecosystem resilience and constrain ecosystem services.

The report points out that most saplings, after being planted, also need to be watched over and nurtured before they grow strong and independent, and begin their work in sequestering carbon. Caring for and monitoring planting efforts over time are critical, but have not yet become a core part of tree-planting drives and programs. One of the main reasons why saplings often do not survive much longer than a year or two after mass planting drives, is because they are unsuited for the places they are planted in. In many cases, this is due to a lack of good quality seeds and saplings, but in others, it is simply a lack of good planning. For example, planting the wrong kinds of trees in the wrong places.

The MIT Climate portal states that each year since 2000, forests are estimated to have removed an average of 2 billion metric tons of carbon from the atmosphere. This “carbon sink function” of forests is slowing climate change by reducing the rate at which CO2, mainly from fossil fuel burning, builds up in the atmosphere. Careful forest management can therefore be an important strategy to help address climate change in the future. Healthy forests also provide a host of other benefits, from clean water to habitat for plants and animals that can live nowhere else. There is no doubt that these strategies can help remove CO2 from the atmosphere, but their impact is hard to measure.

Moreover, a rush to plant trees ‘for regenerating the ground water table’ or to ‘increase biodiversity’ are leading to unscientific mass tree-planting frenzies using fast-growing eucalyptus, pine, or acacia. Such plantations often consume more water than they help to conserve. In some cases, such planting activities may even reduce biodiversity, rather than improve it, as has happened in Chile, where planting commercially valuable trees has led to losses of biologically valuable forests.

Despite these concerns, the Mongabay-India report says that planting trees can be beneficial in many ways; however, the focus needs to move away from afforestation (planting new forests) to reforestation (restoring forests). Active restoration efforts can help fragmented forests recover and if properly planned, could even support local livelihoods. In addition to reforesting, much greater efforts need to be made to halt deforestation. In India, major changes need to be made in how forests are managed.

The report calls for a clear national forest policy, stating that the costs of clearing out forests are appallingly low. India’s policies on forest cover need to be updated as well. In spite of all these setbacks, which also include issues with poor on-ground data and research, difficulties in correctly identifying available areas for tree planting, conflicts of interest with stakeholders, poverty, and finance, there are still great opportunities for reforestation in India.