(CN) – When it comes to restoring tropical forests across the world, Mother Nature’s process trumps human intervention, a new study finds.
Despite concerns that natural forest regeneration has limited conservation value, a report published Wednesday in the journal Science Advances suggests that the spontaneous recovery of tropical forests is generally a more effective strategy both in terms of cost and pace of recuperation.
The new findings challenge the widely held notion that human intervention – planting seedlings – should be the default strategy for healing damaged forests.
To investigate the effectiveness of these approaches, a team of researchers analyzed more than 130 studies and compared levels of restoration of forest structure and biodiversity at sites that were classified as either natural regeneration or active restoration.
The team, led by Renato Crouzeilles, found natural regeneration was more effective at repairing bird, plant and invertebrate biodiversity, as well as vegetation growth as measured by factors like plant density and height.
While the studies reviewed did not control for living and nonliving – biotic and abiotic – environmental factors, the report includes results in which those factors are controlled and not controlled.
“No aspects (biodiversity or vegetation structure) were higher for active restoration than for natural regeneration when the biotic and abiotic factors were controlled for,” Crouzeilles, a researcher at the International Institute for Sustainability in Brazil, said in an email. “When we did not control for these factors, active restoration and natural regeneration did not differ for vegetation structure – as many papers have been reported.
“We were surprised because in the literature most of the papers report higher restoration success for active restoration than for natural regeneration, or no difference between both.”
The studies reviewed for the analysis may not have accounted for variables like precipitation or the time given to a restoration effort, which the team says could explain the discrepancy.
Some forests may not be suitable for natural regeneration due to low precipitation levels, reduced forest cover or other factors, Crouzeilles said.
The team also notes combining both restoration approaches could be critical to establishing and developing a wider range of species in these areas.