Good news from Ecuador: rainforests can recover faster than previously thought. A study by TU Darmstadt shows that biodiversity on abandoned agricultural land in Ecuador returned to more than 90 per cent of its original level within 30 years. However, researchers warn that this recovery only works if intact primary forests are nearby.
Tropical rainforests are among the most biodiverse ecosystems on Earth but also among the most threatened. Deforestation, agriculture and climate change endanger biodiversity and the global ecological balance. A research team from TU Darmstadt studied a rainforest area in the Chocó region in north-western Ecuador over three decades, observing how former agricultural land develops once it is no longer used.
The result: natural regeneration can achieve a great deal, but it cannot replace active forest protection.
Former farmland can recover almost completely within 30 years
The researchers compared 62 sites, including pastures, cocoa plantations, so-called secondary forests (which regrow naturally after deforestation or agricultural use), and untouched primary forests. Some of these areas are protected by the Ecuadorian conservation organisation Jocotoco and are part of a larger reserve.
The secondary forests studied had developed after being used for decades as pastures or cocoa plantations. The researchers analysed 16 groups of organisms, including animals, plants and bacteria, covering more than 8,500 species and bacterial sequences.
Their findings show that biodiversity recovered to more than 90 per cent of its original level within 30 years. In other words, the damage caused by deforestation or intensive agriculture can, to a large extent, be reversed.
Around three quarters of species typical of primary forests returned. However, this does not mean the ecosystem is fully restored after three decades; some species groups take significantly longer to recover.
Animals play a key role in regeneration
Animals with large ranges — such as birds, bats, monkeys and bees — are particularly important. They disperse seeds, pollinate plants and help restore soils. Animal populations themselves also recovered. Over roughly 38 years, they were able to recolonise former farmland or migrate from nearby forests, supporting the return of plant species.
Trees, by contrast, often take longer to recover. Many typical rainforest trees grow slowly, reach reproductive maturity late and are relatively rare. Bacterial communities, however, showed little recovery. Researchers interpret this as a possible long-term effect of intensive agriculture and altered environmental conditions.
Past land use and surroundings are crucial
Not all areas regenerated at the same speed. Former cocoa plantations recovered faster than pastures, likely because trees, shade and leaf litter remained more intact.
The surrounding environment also proved decisive. Rapid rainforest recovery was only possible because intact forests nearby served as reservoirs from which species could return. Without such forests, regeneration would likely be much slower — or might not occur at all.
Study highlights importance of protecting primary forests
The study shows that restoration is possible. In regions with small-scale agriculture, natural regeneration can be an effective and cost-efficient strategy. At the same time, researchers warn against false optimism. Protecting old-growth forests remains essential — they are crucial for the recovery of already degraded land. Globally, four to six million hectares of tropical forest are lost each year — roughly the size of Switzerland or Lithuania.
The findings from Ecuador highlight both the potential and the limits of natural regeneration. Rainforests can return if land is protected, given enough time, and surrounded by intact forests.
