Researchers from Stirling University looked at the effects a small group of beavers had on a wetland in Tayside originally drained for farming.
Over a period of 12 years local plant richness rose by 46 per cent and the total number of different plants recorded more than doubled.
Species which normally grow in areas with high nitrogen levels decreased, indicating a return to more natural soil conditions.
Professor Nigel Willby, of Stirling University, said: “Wetlands are tremendously important environments for biodiversity.
“They also serve to store water and improve its quality – they are the ‘kidneys of the landscape’.
“However, the world’s wetlands are disappearing at an alarming rate. The latest estimates suggest that almost two-thirds have been lost since 1900.
“Beavers are renowned for their engineering skills, like dam building, and are now being considered as tools for restoring wetlands. They have been reintroduced widely, including in Scotland, partly for this purpose and our findings demonstrate the surprisingly large benefits they can bring to biodiversity.”
The study, partly-funded by Scottish Natural Heritage (SNH) and published in the international journal Science of the Total Environment, is said to be the first to fully measure these environmental benefits over time.
Between 2003 and 2015, the beavers constructed 195 metres of dams, 500 metres of canals and an acre of ponds, surrounded by a mosaic of vegetation which increased in complexity by 71 per cent.
Four hundred years after being hunted to extinction in the UK, beavers were readmitted to Scotland last year, based on experience from trial re-introductions.
Stirling co-author Dr Alan Law said: “Beavers offer an innovative, more hands-off, solution to the problem of wetland loss - provided their populations are suitably managed and protected.
“Seeing what beavers can do for our wetlands and countryside highlights the diverse landscape we have been missing for the last 400 years.”
SNH will use the findings of the study to inform discussions about how the animal can be integrated within the Scottish countryside.