Stung by the latest Forest Survey of India (FSI) report - the India State of Forest Report 2011 - that said green cover in the Capital went down by 0.38 sqkm between 2006 and 2008, the Delhi forest department has questioned "the methodology and limitations of the study".
The forest department has taken up the matter with the FSI and pointed out factors such as sample size, resolution and sampling design that it believes has led "to errors in green cover estimation". The department has also emphasised the need "to reduce the errors so that actual status of green cover can be put forward".
The ISFR 2011, released last year, was based on the interpretation of satellite images captured in 2008 and put Delhi's green cover at 296.20 sqkm. The ISFR 2009, based on satellite imagery captured in 2006, had put Delhi's green cover at 296.58 sqkm.
While south and southwest Delhi lost green cover by .32 sqkm and .65 sqkm, respectively, northeast and northwest Delhi gained greenery by .51 sqkm and .08 sqkm, respectively. Other five zones did not record any changes.
The FSI has clearly said the loss in green cover was mainly because of the felling of trees for development purposes. Under the union ministry of environment and forests, the FSI has been publishing the biennial ISFRs since 1987.
"Estimates for tree cover are only an indication and may have lower levels of precision because of sample size. Plantations that are at least five years old are captured by satellite. The saplings we have planted in the past few years would surely figure in the next survey and we're sure there would be substantial increase in the overall green cover, which currently stands at 20 per cent," said a senior forest department official.
The forest department has, however, admitted that the loss of .38 sqkm on account of legitimate development activities can be amply compensated.
Despite several promises, the Delhi government has failed to conduct a city-wide tree census, which can quantify green cover with precision. Officials depend only on satellite data, which is subject to technical interpretations.