Animals hold the key to restoring the world’s forests — ScienceDaily

As the UN climate talks conclude in Egypt and biodiversity talks begin in Montreal, the focus is on forest restoration as a solution to the dual evils plaguing our planet. Forests absorb carbon dioxide from the air and at the same time create habitat for organisms. Until now, efforts to help forests recover from deforestation have mostly focused on increasing one thing – trees – above everything else. But a new report reveals a powerful but largely overlooked driver of forest recovery: animals. The study by an international team from the Max Planck Institute of Animal Behavior, Yale School of the Environment, the New York Botanical Garden and the Smithsonian Tropical Research Institute examined a range of regenerating forests in central Panama spanning 20 to 100 years after the abandonment. . . The unique long-term data set revealed that by bringing a wide variety of seeds to deforested areas, animals are key to restoring tree species richness and abundance to old growth levels after only 40-70 years of regrowth. The article, published in Philosophical Transactions of the Royal Society Bis part of a special issue focusing on forest landscape restoration as part of the UN Decade for Ecosystem Restoration.

“Animals are our greatest allies in reforestation,” said Daisy Dent, an MPI-AB tropical ecologist and the study’s lead author. “Our study is prompting a rethinking of reforestation efforts to be more than just establishing plant communities.”

The report also notes that locating regenerating forests near areas of old growth and reducing hunting encourages animals to colonize and establish themselves. “We show that taking into account the wider ecosystem, as well as landscape features, improves restoration efforts,” said Sergio Estrada-Villegas, a biologist now at the Universidad del Rosario (Bogotá, Colombia) and the first author of the research works.

Seed dispersal by animals is key to forest expansion. In the tropics, more than 80% of tree species can be dispersed by animals, which transport seeds across the landscape. Despite this, forest restoration efforts continue to focus on increasing tree cover rather than restoring the animal-plant interactions that support ecosystem function. “Finding out how animals contribute to reforestation is prohibitively expensive because you need detailed information about which animals eat which plants,” says Estrada-Villegas.

The forest at the Barro Colorado Nature Monument (BCNM), in the Panama Canal, offers a unique solution to this problem. In one of the most well-studied tropical forests in the world, generations of scientists have documented interactions between frugivores to understand which groups of animals disperse which tree species.

In the current study, the team led by Estrada-Villegas and Dent examined this unique long-term data set to determine the proportion of plants dispersed by four groups of animals – flightless mammals, large birds, small birds and bats – and how this proportion changed. during a century of natural recovery.

Their results provide the most detailed data on the recovery of animal seed dispersal over the longest period of natural recovery. “Most studies examine the first 30 years of succession, but our 100-year data gives us a rare glimpse into what happens in the late phase of restoration,” says Dent.

The study found that young regenerating forests consisted mainly of trees dispersed by small birds. But as the forest grew older, the trees scattered by larger birds increased. Surprisingly, however, the majority of plants were dispersed by terrestrial mammals across all forest ages – from 20 years old to old growth. “This result is quite unusual for post-agriculture regenerating forests,” says Dent. “It is likely that the presence of large areas of protected forest near our secondary stands, coupled with low hunting, allowed mammal populations to thrive and brought an influx of seeds from neighboring sites.”

Estrada-Villegas says, “We hope this information can help practitioners structure their restoration practices by enabling herbivorous species to aid the restoration process and accelerate forest recovery.”

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