A team of researchers established that approximately half of all trees planted to restore tropical forests in Asia do not survive beyond five years. The researchers included experts from 29 universities and research centers who analyzed data from 176 forest restoration sites in tropical and subtropical Asia. Most of the sites under study included those where human activities had led to a decline in tree numbers.
They found that up to 18% of samplings died within the first year of planting. After five years, about 44% of all the samplings had died. They also observed that the survival rate for the trees planted depended on the species and location where planted. Some species were found to have a survival rate higher than 80% after five years. In other sites, almost all the trees died.
According to the study whose findings are published in the Journal Philosophical Transactions of the Royal Society B: Biological Sciences, tree planting should follow a tailored approach to be successful.
“What’s clear is that success is very site-dependent – we need to understand what works and why and share that information, so we can bring all sites up to the level of the most successful and harness the full potential for restoration,” said study author Dr. Lindsay Banin of the U.K. Centre for Ecology and Hydrology.
While the rate of tree survival was found to be low, the study found that planting offers faster results than leaving forests to regrow naturally. As a matter of fact, in some areas where forests are left untouched, it could take decades before any trees start growing.
“We need to understand better how to improve the survival chances of saplings on these sites, to ensure restoration has positive outcomes,” said study coauthor David Burslem, a professor at the University of Aberdeen in the U.K. “But the study also provides a warning, to protect our remaining forests as much as possible, both because restoration outcomes are uncertain and to provide the diverse seed sources needed for restoration activities.”
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