The study, conducted at Pontbren in mid Wales between 2005 and 2012 and published in the journal Hydrological Processes, found that soil infiltration rates were 67 times faster and surface run-off volumes were reduced by 78 per cent under trees compared with grassland.
"A degree of caution is required when extrapolating the significance of our findings, particularly if one is planning major changes to existing countryside management policies," lead author Dr Miles Marshall of the Centre for Ecology and Hydrology (CEH) catchment management and soils systems group wrote on the CEH blog.
"We didn't measure whether there was any change in the ability of the soil to store water and whether the water was able to penetrate deeper into the soil profile as a result of the presence of tree roots," he explained.
The study revealed that infiltration rates and run-off volumes "were highly variable even between sites with broadly similar soil characteristics", he said. "We cannot say with any certainty what impacts planting trees would have on different types of soil. One cannot simply upscale the results measured in plot-scale studies like ours to the catchment scale to predict the impacts that planting trees might have on flooding."