Conservationists ‘missing out on great opportunity to significantly speed restoration projects’, study says
It comes after a survey of almost 2,600 restoration efforts found that most projects fail to recognize and control one of the new plants’ chief threats: hungry critters that eat plants.
Restoring vegetation to degraded areas, either through planting or by encouraging natural generation, is a prominent strategy for conservation and nature-based climate solutions. But restoration efforts are not always successful and can take a long time to reach pristine conditions. Therefore, an international team of researchers affiliated with 20 universities and institutions examined thousands of restoration projects from nearly every type of ecosystem on Earth.
“While most of the projects took steps to exclude competing plant species, only 10% took steps to control or temporarily exclude herbivores, despite the fact that in the early stages these plants are like lollipops — irresistible little treats for grazers,” said Brian Silliman, Rachel Carson Distinguished Professor of Marine Conservation Biology at Duke University’s Nicholas School of the Environment, who helped conceptualize the study and was one of its co-authors.
By not protecting plants in their early states, conservationists are missing out on great opportunity to significantly speed restoration, improve its outcomes, and lower its costs, he said.
“Our analysis of the surveyed projects shows that introducing predators to keep herbivore populations in check or installing barriers to keep them at bay until plantings become more established and less vulnerable, can increase plant re-growth by 89% on average.”
Those gains are equal to or greater than the gains realized by excluding competing plant species, the new survey shows.
According to Xu et al.’s synthesis, excluding herbivores at restoration sites increased vegetation abundance by an average of 93 and 158% at natural regeneration and planted restoration sites, respectively, and introducing predators increased abundance by 138 and 372% at natural regeneration and planted restoration sites, respectively.
“This begs the question: Why aren’t we doing it more?” he asked.
The survey’s findings have far-reaching implications for efforts to restore vegetation at a time of climate change. “Herbivores’ effects were particularly pronounced in regions with higher temperatures and lower precipitation,” Silliman noted.
The ‘untapped’ methods to keep herbivores in check at restored sites
All of which leads to one inescapable conclusion. “If we want more plants, we have to let more predators in or restore their populations,” Silliman explained. “Indeed, the decline of large predators, like wolves, lions, and sharks, that normally keep herbivore populations in check, is likely an important indirect cause of high grazing pressures.”
“Conventional restoration is slowing our losses, but it’s not expanding vegetation in many places, and climate change could make that even more difficult,” he said.
“Using predators to keep herbivores in check at restored sites is a relatively untapped approach that could help us boost plant diversity and restore ecosystems that are vital to human and environmental health, in less time and at lower costs,” Silliman said. “It’s like learning a new gardening trick that doubles your yield.”
Once a planting is established, the herbivores are essential too, he added. “Plants just need a small break from being eaten to get restarted making ecosystems. Once they establish, herbivores are key to maintaining plant ecosystem diversity and function.”
But apart from the use of predators, are there any other methods or technological advancements that exist that may allow plants to be better protected in their early stages?
“Yes,” Qiang He, professor of coastal ecology at Fudan University, who co-led the study, told AgTechNavigator.
“Predator mimics, sounds, or chemical signatures could be used where using live predators is not feasible,” he explained. “In many other cases, plants could be protected through fencing or installing plastic tube protectors. Plastic tube protectors are already widely used for tree plantings in the UK, for example.”
Source: Science
“To restore ecosystems, think about thwarting hungry herbivores”
Authors: Qiang He, et al.
