Multispecies afforestation is an imperative need to reduce carbon dioxide and protect biodiversity

One of the main outcomes of the UN Climate Change Conference (COP 26) was the agreement to stop logging forests. The countries that have signed the pledge, including Brazil, Canada, China, the Democratic Republic of Congo, Indonesia, Russia and the United States, are home to around 85 percent of the world’s forests.

This agreement is an important achievement as retaining these natural forests are critical for a number of reasons. Old-growth or primary forests provide many services to mankind, such as the provision of water and soil protection, acting as refuges for endangered plants and animals, as well as their critical carbon sequestration role.

Clearing natural forests to create plantations, as has happened in many countries, is a harmful practice, and hopefully the new COP 26 agreement will curb it. But where natural forests have been logged in the past, where the remaining forests are degraded or where land is being eroded, planting trees is an important way of restoring the essential natural processes.

The scientific advisory body to the Paris Accord, the Intergovernmental Panel on Climate Change, has recognized tree planting as a particularly effective way of reducing carbon dioxide. In light of this, many countries have embarked on afforestation drives.

Planting trees to create carbon sinks to offset current emissions is, however, not enough. Offsets should be the last resort to deal with residual emissions, after serious efforts have been taken to mitigate and reduce ongoing emissions. The intention to reach carbon-neutrality within the coming years is actually far from sufficient to support the aim of keeping global warming within 1.5 C, as this means little or no reduction has taken place and the ongoing emissions are simply balanced by offsets.

Critics of tree planting for carbon sequestration also point out that there are serious questions about the environmental value of such planted woodlots as they are often monoculture plantations. Scientific studies have shown that woodlots of one or two species are more vulnerable to pests and diseases than mixed forests, and monoculture forests also have lower biodiversity benefits than mixed forests.

The choice of species is another aspect that can raise concerns. The introduction of eucalyptus gum trees throughout the world has not been beneficial in all cases. Leaf-fall from the gum trees does not help soil fertility as the leaves are poisonous, and not many plants can be intercropped with eucalyptus for the same reason. Eucalyptus plantations therefore have limited benefits, apart from fuel wood and poles for construction and infrastructure.

There is often a question of local ownership of new plantations, and without local involvement, planted forests may not flourish. One of the key challenges to planting trees on common land is the maintenance of the plantation, as young trees can be eaten by browsing animals, or uprooted by trespassers, and they typically need irrigation during the first years of growth. There are many examples of well-intended afforestation projects that failed because the trees did not survive. Involvement of local people is critical for the establishment and survival of planted woodlots.

But, there is more to planting trees than CO2, as China has shown during its “Grain for Green” afforestation program that was launched in 1990. Grain for Green involved 124 million people in 1,897 counties in 25 provincial-level regions and by 2010, around 15 million hectares of farmland and 17 million hectares of barren mountainous wasteland were restored for natural vegetation.

Some of these forests have bamboo as the main species, and bamboo development is another area where China is leading the world. According to the National Forestry and Grassland Administration, China now has nearly 7 million hectares of bamboo, half of which was planted specifically for human and industrial use. Their fast growth, resilience to changing weather patterns, extensive root structure and the ability to flourish in soils that are not of much use for other crops, have created the foundation for a national economic sector in China that is worth the equivalent of $50 billion. The trade comprises food, furniture, construction and interior design materials, textiles, pulp and paper and other products made from bamboo and bamboo fiber.

It is important to consider reforestation and afforestation in a wider landscape context. Many modern land use systems are a patchwork of natural protection areas, agriculture developments and other rural development, including infrastructure and villages. Plantations can form an important component of such a diverse landscape, and a combination of different species in different sections of the area will contribute to the overall health of the environment.

Tree planting should not be restricted to the rural landscape alone. A lot of recent research has indicated that trees are good for well-being and health, and trees in cities provide shade and keep the streets cool.

During its recent urbanization programs, China introduced the concept of sponge cities, an approach that is now being followed in other countries too. This type of urban development involves the restoration or creation of wetlands and green spaces to help with drainage and water absorption during periods of heavy rain. This is critical, especially in low-lying cities, with the increase in extreme weather events as a result of climate change.

Trees can also be used to help restore brownfields and regenerate polluted land. Existing forests must be protected where possible, but degraded land must be restored and cleared areas reforested.

Not all trees are good for every situation though. We need to find the right trees for the right place and the right time. And whatever initiatives are promoted, the involvement of local people is critical to ensure a successful establishment of a healthy woodlot.