Native forests in India are disappearing at a rate of up to 2.7% per year. The figure stand in stark contrast to the official figures, provided by The India State of Forest Report 2009 pby the Forest Survey of India (FSI), which said that forests have expanded by 5% over the past decade.
William Laurance, a conservation biologist at James Cook University in Cairns, Queensland, Australia, and one of the authors of the analysis, to be published in the journal Conservation Letters, says that while the figures showing that forest cover in India has grown are "technically correct", they are also misleading.
"We found a very real and serious loss of native forest," he says in an interview to Nature, adding that it could put India ahead of most other countries in terms of deforestation.
India has been busy planting trees, including non-native eucalyptus and acacia, to provide timber and fuel wood - and in some cases to earn money from selling carbon credits under the Clean Development Mechanism established in 2001 as part of the Kyoto Protocol. The country now ranks second globally in terms of total land area under plantation. India's claimed growth in forest cover has come from plantations, masking a fall in native forests.
"The Indian government has made a big deal of increasing forest cover. But they are not distinguishing between natural and artificial forests," Laurance added.
This is bad for the environment because replanting native forests with non-native trees damages local biodiversity, says Neil Burgess, a conservation biologist at the University of Copenhagen.
"Most plantations of non-native trees have very low biological value. They are only good to store carbon," he says. This distinction between native and non-native trees is important for an accurate picture of the state of the world's forests, says Laurance.
In the analysis, the researchers assessed data on the growth in Indian plantations collected for the Food and Agricultural Organization (FAO) of the United Nations. It estimates that plantations grew by around 15,400 square kilometres a year between 1995 and 2005. The researchers subtracted the rates of plantation expansion from the growth in total forest cover as measured by remote-sensing imagery, and found that coverage of native Indian forests actually declined by 1.5-2.7% between 1995 and 2005, an "alarming" average of 2.4% a year and a loss of more than 124,000 square kilometres over the decade.
The researchers checked these figures against changes in forest biovolume (the volume of wood and other above-ground forest material), estimated from field observations in the FSI report. They found a loss in native forest biovolume of around 2.7% per year.
Laurance says that some assessments of forest cover, such as that carried out by the FAO, do not distinguish between native forests and plantations. They rely on relatively coarse data from sources including the US National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer satellites, which have a resolution of 1.1 square kilometres per pixel.
But the Indian Remote Sensing satellites used by the FSI have a much higher resolution - up to 23.5 square metres per pixel - so the agency has the means to distinguish native forests from plantations of non-native trees.
Laurance says he is hopeful that the United Nations' REDD+ initiative to reduce carbon emissions from deforestation and forest degradation - which includes a focus on conservation and sustainable management of forests - will encourage India and other countries in similar situations to distinguish between native and artificial forests.