London, Feb 17 (IANS): Beavers -- a herbivorous group of rodents -- are beneficial to the environment, a study says.

With their talent to re-engineer the landscape, beavers can improve biodiversity, minimise pollutants and reduce downstream flooding.

An abundance of plant life was the most noticeable effect of beaver behaviour. The interconnected pools created by beaver dams increased the retention of organic matter by up to seven times and the level of aquatic plant life 20 fold. Multi-pool systems also supported 20 times more aquatic plant life.

Levels of agricultural pollutants were also reduced in areas occupied by beavers. More vegetation translates to cleaner water. Streams hosting beavers featured more than 40 percent lower levels of phosphorous and nitrates.

"Our study found that beaver behaviours have several benefits for the environment. Their dam building skills help restore degraded streams and increase the complexity of the surrounding habitat, consequently increasing the number of species found by 28 percent," said lead researcher Nigel Willby from the University of Stirling in Scotland, Britain.

The new findings -- published in the journal Freshwater Biology -- suggest beavers can prove especially valuable to low-quality stream habitats.

Examining headwater streams, which drain water from 13 hectares of Scottish countryside, scientists compared areas where beavers had been active with areas in which they were absent.

The study formed part of a programme of research at this site by Stirling scientists that has been ongoing since 2003.