19 Jul, 2022.
• As the world searches for solutions to environmental degradation, tree planting has become increasingly popular, with ambitious campaigns aiming to plant millions of trees.
• More often than not, these projects have other environmental goals, too, like regulating water
cycles, halting soil erosion and restoring wildlife habitat. Alleviating poverty is another socioeconomic factor which also has an influence over such drives.
• But for many large-scale tree-planting initiatives, the focus is on the number of new trees that end up in the ground, not on planting the right trees in the right places or caring for them after planting to ensure they survive.
We define reforestation as planting trees to restock depleted or clear-cut forests, regardless of whether the resulting landscape is a monoculture plantation or a biodiverse forest ecosystem. By contrast, we define forest restoration as actively attempting to return an area to its previous naturally
forested state; the priority is the recovery of a forest ecosystem, not just tree cover.
“Today reforestation projects are basically only concerned with the number of trees planted. It’s like it’s the end goal, But the number of trees you planted is just the start of a long-term process” says Pedro Brancalion, a professor at the University of São Paulo who is both a forest restoration researcher and practitioner.
There are also documented cases of tree planting having unintended and even negative environmental consequences. Starting in the 19th century, South Africa began planting non-native Australian acacias to stabilize dunes and produce timber. But the acacias quickly spread across wid
swaths of South Africa’s native grasslands and heathlands, lowering the water table and reducing water availability. The country now spends millions of dollars every year to remove the troublesome trees. “That’s a clear example of where exotic species used in monoculture plantations got out of hand, became invasive, and caused problems,” says Kate Hardwick, a conservation scientist at the Royal Botanical Gardens.
China’s Grain for Green program is instructive in a number of ways.
In response to a series of devastating floods in the late 1990s that killed more than 4,000 people, the Chinese government embarked on the most extensive tree-planting effort the world had ever seen. The Grain for Green program was launched in 1999 with the primary goals of mitigating flooding, reducing soil erosion, and boosting the livelihoods of the rural poor in Western China. The government provided households with technical support, cash and food in exchange for planting trees in areas of
degraded farmland, especially those most prone to landslides and erosion.
Based on its primary goals of reducing erosion and runoff, the program has been a success. As of 2019, the project cost roughly $73 billion and participants had planted trees on 32 million hectares (79 million acres) of cropland and barren scrubland. Today, more than 23% of China’s landmass is covered in trees, up from 19% in 2000. A 2012 study1 found that “runoff and soil erosion significantly decreased because of an increase in the area of farmland-converted forestlands.” Many of the trees provide timber, fruit and other forest products, enhancing the livelihoods of local communities. Research2 showed the GFGP “largely increased” soil organic carbon stocks.
But overall, the results of this ambitious reforestation effort have been decidedly mixed. A 2018 study led by Beijing University’s Fangyuan Hua while she was at the U.K.’s University of Cambridge determined that, as of 2015, gross tree cover had grown by nearly a third, with 1,93,500 hectares newly treed. However, that increase was due almost entirely to degraded farmland being converted into monoculture tree plantations of one single species like bamboo, eucalyptus, or Japanese cedar.
Despite all of the tree planting, Hua and her team found that native forests had declined by 6.6%, or some 13,800 Hectares at the same time. “Thus, instead of truly recovering forested landscapes and generating concomitant environmental benefits, the region’s apparent forest recovery has effectively displaced native forests, including those that could have naturally regenerated on land freed up from agriculture,” Hua and co-authors write in their study. Tree plantations, of course, cannot compare to native forests in terms of their capacity to support wildlife and provide other ecological services. A few GFGP forests are what researchers call “compositionally simple mixed forests” containing two to five tree species, and these did experience modest gains in the number of bird and bee species compared to the cropland they replaced, according to a 2016 study that Hua also led. Monocultures, on the other hand, which comprise the overwhelming majority of GFGP forests, harbour fewer bird and insect species than croplands. Both monoculture and mixed-species reforested areas had lower bee diversity than croplands, the researchers found, probably due to the lack of flowers. And neither type of GFGP forest had anywhere near the biodiversity of native forests.
Change of Habitat
We classify land into various types like tropical grasslands (Indo Gangetic Plains), temperate grasslands (Savannahs), Steppes (Eastern Europe and Central Asia to parts of China), Prairies of Canada, Arctic Tundra, shrubs, moist deciduous, dry deciduous, coniferous and such other. Each of these land types support a particular ecosystem comprising of insects, birds and mammals. Any change in land use will have an undesired effect. For example, the Indo Gangetic Plains stretching from Haryana to Bihar passing through Delhi, Uttarakhand and Uttar Pradesh supports various species of Snakes, Rodents and Birds. The rodents predominantly feed agriculture produce which are grown in these parts. These pests are kept in check by their predators like snakes, raptors like Kites, Eagles and some vulture species and even several species of Owls. Replacing these grasslands or even parts of it by tall trees will increase the rodent population significantly as their predators especially the birds are unable to sight them. Since these rodents carry a lot of vectors, food contamination is one such outcome besides giving rise to uncontrolled population outbreak of rodents like Bandicoots, Rats and Mice. This isn’t limited to the Indo Gangetic Plain though. It has happened and continues to happen in large urban swathes like Bangalore.
So, the next time you see rats or bandicoots in your home or neighbourhood, you know why.
- Hua, Fangyuan; Wang, Xiaoyang; Zheng, Xinlei; Fisher, Brendan; Wang, Lin; Zhu, Jianguo; Tang, Ya; Yu, Douglas W.; Wilcove, David S. (2016-09-06). Opportunities for biodiversity gains under the world’s largest reforestation programme | Nature Communications
- China’s Grain for Green Program: A Review of the Largest Ecological Restoration and Rural Development Program in the World, Springer, Nov 2014, ISBN: 978-3-319-11504-7, Claudio Delang, Hong Kong Baptist University
- 1 Effects of the grain-for-green program on soil erosion in China – ScienceDirect
- 2 Chinese Grain for Green Program led to highly increased soil organic carbon levels: A meta-analysis | Scientific Reports (nature.com)