Scientists say trees have a role to play in tackling noise pollution in urban environments and have identified the best species for the job.
Larch has proven to be the most effective tree for absorbing noise with its bark.
The conifer was most effective on 13 tree species in a laboratory sound absorption test.
Researchers say the results can help planners use trees to control noise.
The results were published in the journal Applied Acoustics.
The study evaluated 76 samples from 13 tree species that exhibited a variety of different bark characteristics.
Co-author Jian Kang of University College London (UCL) said: “In addition to focusing on the effects of vision and shade, urban greening should also be taken into account for reduce noise during propagation. “
He told BBC News: “Using plants as a” silent “potential for urban noise could combine environmental and landscape protection. “
The samples were selected using a range of criteria, including the thickness of the bark, the age of the tree and the diameter of the trunk.
Trunk disks were collected from recently felled trees.
“The main goal was to have a sufficient variety of species, including hardwoods and conifers,” observed Professor Kang.
In laboratory tests, the team tested species that are often found in urban areas, such as cherry, pine, beech, willow, poplar and alder.
The team found that the larch sample was the most efficient species, while conifers acted more efficiently when it came to absorbing sound than hardwoods.
“The factors influencing noise reduction by tree bark are bark thickness, tree age and bark roughness,” said Professor Kang.
“The age of the trees and the roughness of the bark seemed [to be] the parameters with the most predictive powers. “
He said that small changes in the sound absorption characteristics of the bark could influence the efficiency of dense tree belts.
“So the selection of species with slightly more absorbent bark can effectively [reduce] noise pollution and possibly mitigate the harmful effects of traffic and industrial noise. “
Professor Kang added that trees could be used as natural “mufflers” to limit the impact of traffic noise in cities.
“Because the bark of conifers absorbs sound slightly better than that of deciduous trees, conifers could be used more in urban green spaces,” he said.
“In addition, tree density is important for reducing noise from a tree belt, and species will also influence the densities that can be achieved in a tree belt. “