CITIZEN scientists” could help experts produce more accurate data on the global “biodiversity crisis”, it is claimed.

The call comes in a new paper challenging data collected in a key publication.

The Living Planet Index (LPI) was launched 20 years ago to document trends in the proliferation of species around the world.

According to the latest paper, published last year, species populations of vertebrate animals fell by almost 60 per cent between 1970 and 2012, with habitat loss and degradation to blame. The rate of loss is said to be unprecedented and the index predicts numbers will have fallen by two-thirds on 1970s levels by 2020.

However, Professor Steve Buckland of St Andrews University and Dr Alison Johnston of New York’s Cornell University claim statistics in this and the separate UK priority species indicator may present a misleading picture of the state of the natural world.

In a paper published in the Biological Conservation journal, Buckland said: “The world is currently in the middle of a biodiversity crisis, with substantial reductions in biodiversity in many regions. To understand the changes in biodiversity and develop conservation programmes that will be suitable to mitigate or reverse the losses, it is critical to have good quality surveys that satisfy criteria to produce reliable trends in biodiversity.

“Many of the biodiversity indicators used globally fail to meet these criteria. Standards must be raised.”

The LPI findings are published every two years by the World Wide Fund for Nature (WWF), which works with partners including the Zoological Society of London on the project.

Buckland and Johnston claim it is not representative of the world overall, with Europe and North America “heavily over-represented”. The “geographic imbalance” is said to make a “dramatic difference” to the results.

The paper claims “citizen science” could help provide more thorough data through the gathering of images of plants and animals for submission online.

Johnston said: “There are still many places and species for which we do not have good information on biodiversity.

“There are statistical tools that we can use to account for this missing data, but statistical methods can only take us so far. It is essential that we also assess the ways we collect data.”

She went on: “Environmental decisions rely on accurate information about the state of biodiversity. We should continue to collect high- quality data and create the best measures we can about the natural world.”

The call follows claims last year from conservation scientist Stuart Pimm of Duke University in North Carolina, who compared the LPI to putting data sets from around the world “in a blender”.

But launching last year’s report, WWF International director general Marco Lambertini said the evidence “has never been stronger”.