Forest restoration plans should prioritise the restoration of native forests to maximize climate and environmental benefits. However, these benefits require a trade-off against wood production in comparison to tree plantations.
A major new study in the journal Nature today revealed that diverse native forests store more carbon above ground, provide more water to nearby stream, and better support biodiversity than simple tree plantings. ScienceNevertheless, plantations are able to produce wood at a higher rate than other types of wood production.
The study compared the relative benefits of restoring native forest versus establishing simple tree plantations. These key functions, also known as ‘ecosystem services,’ are four that are of great value to humans: carbon storage and soil erosion control, water provisioning, wood production, and water provisioning.
Forest restoration is growing in popularity around the world, partly because it is a way to combat climate change. Deforestation is a major source for carbon emissions and forest restoration could be a ‘nature based climate solution’ to global warming. Forest restoration is often used to provide water for forests and flood control functions. It also serves as a way to prevent soil erosion and make wood products.
“Establishment of a tree plantation is useful to produce wood, but not so much for restoring biodiversity. This is a huge missed opportunity to conserve,” said Dr Fangyuan Hua. He was a researcher who used to be based at the University of Cambridge’s Department of Zoology and was the first author of this paper. Hua now works for the Institute of Ecology at Peking University in China.
She said, “When a forest restoration program includes wood production, then there is a trade-off between environmental and production outcomes.”
Forest restoration schemes that aim to provide ecosystem services tend not to involve tree plantations of more than one or a few species of trees. This is because it is assumed that tree plantations are equally effective in delivering these ecosystem services. However, the authors state that there is not strong scientific evidence to support this.
The current synthesis was done by a cross-disciplinary international team of researchers from seven different countries. It is based on a huge database that contains almost 26,000 records from 264 studies in 53 countries.
“This is the very first time that different forest restoration strategies have been evaluated simultaneously in delivering forests’ most valuable services. We now have the ability to see the trade-offs and synergies across different restoration goals. This will help us make informed decisions,” said Professor Andrew Balmford from the University of Cambridge’s Department of Zoology.
The study revealed that native forests deliver more ecosystem services than tree plantations, including aboveground carbon storage, soil erosion control, as well as water provisioning. Plantation-style forest restoration is particularly bad for soil erosion control. The shortfall in plantations in water provisioning is worse in drier climates, where water is more scarce.
Hua said, “When restoration goals are for environmental benefits, even though not specifically for the sake biodiversity conservation, then we should aim to restore indigenous forests — and biodiversity will benefit as a cobenefit.”
For wood production however, there was limited evidence that tree plantations could outperform native forests. This highlights a crucial trade-off.
Tree plantations around the world often use fast-growing species, such as pines, or firs. Eucalyptus. These trees tend to grow taller and straighter, and are often encouraged to grow in plantations that are actively managed.
Native forests, on the other hand, contain a variety of tree, shrub, or herbaceous species and are not managed for growth. This creates a more suitable environment with diverse food and other resources that allow a wider range of animals and plants to thrive. However it may also mean that wood production may be less efficient.
“The trade-off between environmental and production benefits that a forest can provide has never been discussed much before. “Restoration probably cannot achieve all goals at once,” said Professor David Edwards from the University of Sheffield’s School of Biosciences, and another senior author of this study.
This finding means that plantations could indirectly provide environmental benefits. Plantations can be used to prevent other forests of higher biodiversity from being cut down for wood products.
Balmford said that plants need to be integrated into a coherent plan of land-use, so that their better performance in producing wood can translate into improved conservation of other environmentally valuable forests.”
The study also revealed that many abandoned or defunct plantations around the globe are less environmentally friendly than native forests. These plantations are quite common and could be restored to their native forests, which would have significant environmental benefits.
