Image caption The UK Butterfly Monitoring Scheme is a long-running project that relies on volunteers

A review of more than 230 "citizen science" projects says the involvement of volunteers offers "high value to research, policy and practice".

It added that such schemes had the potential to help meet the demands of monitoring the UK's environment.

The review's authors also produced a guide offering advice on how to get the most out of citizen science projects.

The review and guide was commissioned by the UK Environmental Observation Framework (UK-EOF).

The authors, from Nerc Centre for Ecology and Hydrology (CEH) and the Natural History Museum, London, reviewed 234 projects - ranging from small one-off local surveys to large-scale long-term programmes.

'Cost effective'

"Participation with environmental science and natural history has a long history, especially in Britain, long before it was termed 'citizen science'," project leader Dr Helen Roy, an ecologist from the CEH, told BBC News.

"However, the development of communication technologies through the internet offers many new options which will help even more people to get involved in contributing information for monitoring our environment, which is under increasing pressure."

The review reached a number of conclusions about the value of data collected by volunteers:

The development of technologies was "revolutionising citizen science", for example through online recording and smartphone apps;

Data quality could be excellent, but was not fully recognised by all researchers or policymakers;

It is a cost-effective way of collecting environmental data

There was potential to make considerably more use of citizen science that currently was the case.

The guide, published alongside the review, offers the scientific community advice on how to develop, implement and evaluate citizen science projects.

The guide's lead author, Dr John Tweddle from the Natural History Museum, said participating in the monitoring and observation was a "fun and rewarding pastime" for volunteers.

"Our guide aims to support anyone with an interest in developing their own citizen science project - and new communication technologies, like mobile phone apps and environmental sensors, mean that it has never been easier to get involved."