he presence of grazing animals can be both a help and a hindrance to reaching the UK’s tree planting targets, new research has found.
A study by ecologists from the University of Plymouth has found that there is no one-size-fits-all approach to livestock management if Britain is to successfully replant its lost rainforests.
The UK’s upland coniferous and broadleaf forests, such as oak, are considered “temperate rainforests” due to the amount of rainfall they receive each year.
The government’s environmental policy relies on trees to provide an array of natural solutions to the climate crisis, including carbon storage, biodiversity boosting and flood mitigation.
In England, the government plans to increase tree planting to 30,000 hectares a year by the end of Parliament, spending £500m between 2020 and 2025 to achieve this target.
But hundreds of thousands of trees are currently being planted in plastic corsets to protect them from grazing, which are drawing criticism for their visual impact and the litter problem they create.
Many environmental organizations are developing biodegradable alternatives, and in some cases planting without protection and accepting the loss of part of their young trees.
But research in oak woodlands on Dartmoor in Dorset found that very few saplings survived on grazed upland, and those that did were stunted and unlikely to live beyond eight years without additional protection.
In fern-thick landscapes, the plants can protect sprouting oak trees because they are toxic to livestock, but also hinder survival because young trees are forced to compete for light.
Cattle or ponies grazing in these areas can trample the ferns, helping to support the self-seeding conditions of temperate rainforests, research suggests.
Natural regeneration of oak forests is currently limited to within 20 meters of the nearest mature tree, the study finds, making it too slow a process for UK environmental goals.
But the authors said “strategically targeted interventions” could increase tree cover, such as selectively planting older saplings in certain vegetation to avoid relying on guards or fencing.
He found that livestock grazing, especially by cattle, at the edge of oak forests can reduce dense, competitive vegetation and allow the forest to expand naturally.
When one- to three-year-old saplings have successfully established, livestock should be excluded for at least 12 years to increase survival, the study authors said.
In degraded landscapes that need to rapidly increase tree cover, such as high valley slopes, they recommended that land managers be encouraged to implement a specific grazing strategy.
Dr Thomas Murphy, who led the research, said: “Planting trees and ending deforestation are increasingly being promoted as low-cost, environmentally friendly mechanisms to combat climate change. climatic.
“These measures have been factored into the net zero programs of the UK and other governments, with world leaders also committing to tackle the issue at Cop26 in Glasgow last year.”
Dr Murphy continued: “Our findings suggest, however, that the expansion of oak forests into UK upland grazing systems is not a simple process.
“They may have a critical role to play, but these important temperate rainforests have historically been degraded and are now very fragmented.
“Reversing this trend will likely require strategic planting and enlightened livestock management.
“However, getting it right will require a delicate balance and close cooperation with a range of stakeholders, including landowners and pastoralists, at a time when mountain farms are facing severe financial pressures and incentives are constantly changing.