Delhi’s green cover, comprising forest cover and tree cover, increased from 297.7 sq km or 20.08 per cent in 2015 to 305.4 sq km or 20.22 per cent in 2017, according to the India State of Forests Report (ISFR) 2017 released recently.
The situation, however, isn’t as promising as it appears to be. While the forest cover in the city increased from 188.7 sq km in 2015 to 192. 4 sq km in 2017, two out of three categories of forests that constitute forest cover, namely Very Dense Forests and Moderately Dense Forests, saw a decline — from 6.94 sq km and 57.15 sq km in 2015 to 6.72 sq km and 56.24 sq km in 2017, respectively. It was only the third category of forests, namely Open Forests, that increased from 124.68 sq km in 2015 to 129.45 sq km in 2017.
According to ISFR 2017, conservation and plantation activities have led to an increase of 3.64 sq km of forest cover in the city whereas developmental activities led to a decrease in forest cover.
Very Dense Forests and Moderately Dense Forests are the actual carbon sinks. For a city like Delhi where the pollution levels are extraordinarily high, losing out such forests is not a good sign because it reduces the city’s capacity to sequester carbon, stated the Economic Survey of Delhi 2017-2018.
Forest cover is classified in terms of canopy density. All lands with tree cover of canopy density of 70 per cent and above fall in the category of Very Dense Forests (VDF). Lands with tree cover of canopy density between 40 and 70 per cent comprise Moderately Dense Forests (MDF) and those with tree cover having canopy density between 10 and 40 per cent are classified as Open Forests (OF). Forest lands with poor tree growth having canopy density less than 10 per cent are classified as scrubs.
Delhi has the second highest tree cover as a percentage of the total geographical area among states. Tree cover, the second component of green cover, in the city has increased from 111 sq km i.e. 7.49 per cent of the total geographic area in 2015 to 113 sq km i.e. 7.62 per cent of the total geographical area in 2017, as per the report.
Overall, India’s total forest cover has increased from 21.34 per cent of the total geographical area in 2015 to 21.54 per cent of the total geographical area in 2017. While Delhi’s contribution to the country’s forest cover has been minuscule, states like Andhra Pradesh, Karnataka and Kerala have contributed to one-third of the total increase in forest cover. Other states which have significantly improved their forests cover are Assam, Telangana, Odisha, Rajasthan, Himachal Pradesh, Uttar Pradesh, Manipur and Jammy and Kashmir, according to ISFR 2017. Mizoram, Nagaland and Arunachal Pradesh have reported a reduction in forest cover.
How are forest resources assessed?
The India State of Forests Report (ISFR) is published biennially by the Forest Survey of India (FSI), an organisation under the Ministry of Environment, Forests and Climate Change (MoEF), which is engaged in the assessment of the country’s forest resources.
“FSI maps forest cover using satellite technology at a scale of 1: 50000 with a Minimum Mappable Unit (MMU) of 1 hectare,” said Assistant Director at FSI, Dehradun, Abhay Kumar Saxena.
The assessments of forest cover is the field validation of the interpreted data at appropriate points.
“Ground verification of the interpreted satellite data takes more than six months, wherein the FSI closely works with State Forest Departments (SFDs) to prepare maps to identify reasons for an increase or decrease in forest cover. Reference data is collected during the ground truthing process, and field experience of the interpreter is used to classify forest cover patches in terms of canopy density,” he added.