Native forests serve best in restoration projects, study finds


Native forests with a mix of diverse vegetation offer more environmental benefits than monoculture plantations and should be prioritized in climate mitigation efforts, according to a new study released Thursday.

While tree planting initiatives and reforestation campaigns have been seen as an essential tool to mitigate some of the impacts of climate change, not all forest restoration efforts yield the same results, according to the study published in the scientific journal Science. The researchers said this was the first global study comparing the performance of two reforestation approaches.

Researchers from seven countries – including China, the UK and Brazil – assessed 25,950 records from 264 studies in 53 countries and found that various native trees ‘consistently’ performed better in key ecological services compared monoculture tree plantations. The former have fared better in carbon storage, soil erosion prevention and water supply than the latter.

With its mix of different trees, shrubs and grasses, natively vegetated forests have provided a diverse ecosystem, helping to slow global biodiversity loss that is “accelerating” species extinction, according to the study.

“Policymakers have an implicit assumption that all forests provide the various ecosystem services…but this is not supported by science,” said Hua Fangyuan, a researcher at the Institute of Ecology at the University of Beijing and lead author of the study, at Sixth Tone.

She said the study found that although tree plantations produced more wood, they provided fewer environmental benefits than restored native forests. The researchers identified soil erosion control as the “biggest loser” among key ecosystem services when planting trees with simple compositions – plantings made up of one or more varieties of trees – that could otherwise have been used to restore native forests.

China has invested heavily in increasing tree cover in its deforested areas. The country now has 220 million hectares of forest, with man-made forests accounting for 36% of the total share, according to official data.

However, many existing reforestation projects in China prefer mass plantings of trees with fast-growing species. For example, China’s famous “Grain For Green” program aims to turn cropland on sloping land into forests to control soil erosion, but extensive monoculture forests have mainly occupied the new cover in core areas, according to Hua.

“This is actually a largely missed opportunity for conservation,” Hua said. “Forest restoration is in full swing and the environmental and social benefits it can bring are enormous. But an obvious problem here is that (tree plantations) not only provide insufficient biodiversity, but too often risk reducing it.

China had 133 million hectares of natural forests in 2010, but that number fell by 328,000 hectares in 2020, according to Global Forest Watch. The loss is equivalent to 131 million tonnes of carbon emissions that could otherwise be collected and stored to curb climate change.

In 2017, China implemented a nationwide ban on commercial logging of natural forests to halt deforestation, then introduced a law to trace the legal source of timber two years later. However, the due diligence inspection has not yet been extended to the timber import sector, raising criticism that China’s demand for timber products in the country is driving illegal logging overseas.

Researchers in the new study suggested that policy makers should weigh competing goals – timber production against environmental benefits – when deciding on different approaches to reforestation. Hua said planted forests could actually become an auspicious part of a country’s national forest management program, which would not only provide livelihoods for communities, but also “save” native forests from being cut down. high biodiversity.

“If we are working to restore a diverse ecosystem, tree planting could also be an active tool,” she said.

Publisher: Bibek Bhandari.

(Header image: People plant trees in a village in Yichang, Hubei province, February 19, 2021. VCG)


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