Now Reading
Tropical forests can recover surprisingly quickly on deforested lands – and letting them regrow naturally is an effective and low-cost way to slow climate change

Tropical forests can recover surprisingly quickly on deforested lands – and letting them regrow naturally is an effective and low-cost way to slow climate change

Cattle graze in pasture filled with tree stumps

Tropical forests are among the world’s best tools for fighting climate change and the loss of wild species. They store enormous amounts of carbon and shelter thousands of animals and plants. They also provide homes for Indigenous peoples who maintain them. That’s why more than 100 world leaders pledged to halt deforestation by 2030At the recent United Nations conference in Glasgow on climate change.

Many communities and organizations are working together to restore native forests. They are reclaiming land that isn’t being used or productive and carrying out restoration work. costly tree-planting efforts.These efforts are meant to encourage native plants and animals to return to their natural habitats and to restore the ecological functions, and economic benefits that forests once provided. Many forests can be restored naturally with very little or no assistance from humans.

We are forest ecologists and members of a collaborative research network that studies secondary forests – those that regrow naturally after an area has been cleared and cultivated or grazed. You can find out more at newly published study in the journal ScienceOur group pioneers a method of forest recovery that uses over 2,200 plots from naturally regrowing tropical rainforests across the American and West African Tropics.

Our research has shown that tropical forests can recover quickly. They can regrow on unused lands and recover many old-growth features such as soil health and tree attributes. To support effective forest restoration, planning and planning, it is important that we understand how fast different forest functions and attributes recover.

Cattle graze in pasture filled with tree stumps

Cattle graze on cleared rainforest land in the Amazon region, Pará, Brazil.
Education Images/Universal Images Group via Getty Images

Forests are back

Many forests have regrown today after natural and human disturbances such as floods, fires, and logging. For example, forests recoveredIn Europe in the 18th and 19th centuries, and in the eastern U.S. during the early to mid-20th centuries. The northeastern U.S. has more forest coverIt’s more than it did 100-200 years ago.

Now, across the world’s tropical regions, forests are regrowingOn approximately 3 million acres (8 million km2) of former ranch and farm land. Scientists policymakersIt is widely agreed that it is crucial to protect these regrowing forest and prevent further destruction and conversion of older-growth forests.

Tropical forests are more than just trees – they are complex, dynamic networks of plants, animals and microbes. Forest recovery is a slow process, but it can happen. unpredictable outcomes and variable pathways. Recovery patterns differ between wet and dry tropical forests.

This active research area has focused on studies that focus on how specific features of forestsChanges in, such as the number or tree biomass, can be seen. over time and space. It is important to understand forest restoration as an integrated process that is shaped and influenced by historical, local, and landscape conditions.

Puerto Rico’s tropical forests were heavily deforested through the mid-20th century but have regrown on abandoned farmlands.

A multidimensional perspective of tropical forest recovery

Our study focused upon 12 essential attributes for healthy forests. They include:

  • Soil: How dense is the soil? What amount of organic carbon and nitrogen do they contain? Soil that is too densely compacted – for example, by the hooves of grazing cattle – is hard for plant roots to penetrate and doesn’t absorb water well, which can lead to erosion.

  • Ecosystem functioning. How does the forest grow? What role does the root association play in forest regrowth? nitrogen-fixing bacteria? What does regrowth do to the average wood density and the durability of the leaf tissues?

  • Forest structure: How do maximum tree size, variation in tree size, and total biomass – the quantity of plant matter above ground in tree trunks, branches and leaves – change as forests regrow?

  • Diversity and composition: How do tree species’ numbers and abundance patterns change, and how can they be more similar to those in nearby old-growth forests?

We compared attributes between forests that were grown on different farmlands and compared the regrowth of forests with those in old-growth forests to assess long-term recovery rates. We developed a new model to estimate how quickly each attribute recovered.

Many of these attributes are dependent on each other. For example, trees may regrow quickly and produce a lot leaf litter. This will help restore organic carbon in the soil as it decomposes. These connections were analyzed by comparing how strongly different forest attributes were linked.

The forests we studied were found in areas with low- to moderate-intensity soil use. This meant that soils weren’t exhausted or eroded and were able to support regrowing native vegetation. For example, in Brazil’s Atlantic Forest region, 10,425 square miles (2.7 million hectares) of forest regrew naturallyFrom 1996 to 2015. There is less chance for tropical forests in areas where they are not already recovering. soils are heavily overworked and no neighboring forests remain.

Graphic showing how regrowing forests regain functions over time.

This graphic shows how four groups of forest attributes – soil, ecosystem functioning, forest structure and tree biodiversity – recover as tropical forests regrow on former farm and pasture lands. The image shows the average recovery rate for each category compared to old-growth forests after 20, 40 and 80 years. The percentages in black squares indicate the average recovery for each interval of the forest.
Pixels&Ink, CC BY-ND

All the forest attributes we examined were recovered within 120 years. Some trees recovered 100% of the old-growth value within the first 20 year of regrowth.

See Also
Women cooking using an open fire stove

We found that soil attributes reached 90% of their old-growth values in 10 years, and 98% to 100 percent in 20 years. This means that after 20 years, the soils of the forests contained almost as much organic matter and had a similar bulk density to soils from old-growth forests.

This rapid recovery is due to the fact that soils at our study locations had not been severely degraded before forest regrowth began. Ecosystem function attributes also recovered quickly, with 82% to 100 percent recovery in 20 years.

Tree structure attributes such as maximum tree diameter recovered slower. After 80 years of regrowth they reached 96% on average. After 120 years, the tree species composition and above ground biomass were both recovered.

[You’re smart and curious about the world. So are The Conversation’s authors and editors. You can read us daily by subscribing to our newsletter.]

We identified a set of three attributes – maximum tree size, overall variation in tree size and the number of tree species in a forest – that, viewed together, provide a reliable snapshot of how well a forest is recovering. These indicators are easy to measure and can be used by forest managers to monitor restoration. With the help of data collected by, it is possible to monitor tree structure and size over large areas. satellites and drones.

The importance and benefits of natural regrowth

Our findings reveal that tropical forest regeneration is a cost-effective, nature-based strategy. promoting sustainable development, restoring ecosystems, slowing climate change protecting biodiversity.
And since regrown forests in areas where the land has not been heavily damaged quickly recover many of their key attributes, forest recovery doesn’t always require planting trees.

In our view, a range of suitable reforestation methods can be implemented, depending on local site conditions and local people’s needs. We recommend that natural regrowth be used whenever possible and that active restoration planting is used when necessary.

Masha van der SandeWageningen University Dylan CravenAt the Universidad Mayor in Chile, data compilation and analyses were performed for this study.

View Comments (0)

Leave a Reply

Your email address will not be published.