India's forests: growing or shrinking?

Mapping the forest growth 2001- 2021 and an overview

Data Maps    03-Mar-2022
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With status of forest survey (SFR) done by Government every two years, one can expect to have a ' Yes or No' type clarity about the question. Surprisingly, there are enough naysayers to challenge those who claim the growth of forest. Multiple terms are used and interpreted differently to draw various conclusions. Before diving deep into it let us have a look at the primary points.
Why the survey? 
Our forests shelter more than 80,000 known species of animals and 45,000 species of plants, of which 15,000 are known to be of medicinal value.
But the importance of forest is much beyond bio-diversity for India. The livelihood issue of around 8 crore tribal and more than 20 crore non-tribal rural population is linked with the forest.
At international level, in September 2015 the world’s leaders agreed on the 2030 Agenda for Sustainable Development with its 17 Sustainable Development Goals. The 2030 Agenda is now guiding the development of policies worldwide. Forests are at the heart of the 2030 Agenda. They are a source of food, medicines, biofuel, various products and livelihood for more than 1 billion people. They protect soils and water, host more than three-quarters of the world’s terrestrial biodiversity, and help tackle climate change.
Forests have immense potential to support sustainable development pathways, and the key to realizing this is reliable evidence. The evidence comes from Accurate information on forest resources. The food and agriculture organization FAO of United Nations monitors and analyzes the relevant data. 
Government of India has been carrying out Assessment of forest resources since 1965. From 1986, forest cover of the country is surveyed on a two-year cycle and the information is published as "State of Forest Report" (SFR). The first in the series was SFR 1987. In 1988 'National forest policy' was formulated which defines some goals. The SFR helps in monitoring our progress in achievement of those goals.
For all these reasons the analysis of SFR and whether forests are growing are Shrinking becomes an important issue.
Since it is a survey, there is a specific terminology. We have included the definitions of terms in tabs at relevant places. You can safely skip them if you are just interested in the main story.
What is counted in the survey?
The state of the forest report counts forest cover, tree cover, mangroves and scrub area of the country. Mangroves are counted separately but are included in forest cover.
What is counted? 

Food and Agriculture Organisation of United Nations (FAO) defines forest as land with a tree canopy cover of more than 10 percent and area of more than 0.5 ha. The SFR counts forest cover as all lands more than 1 ha in area having tree canopy density above 10 percent irrespective of the tree species and its legal status or ownership or land use.

For tree cover, only those trees in non-forest areas with less than 1 ha area are considered. All perennial woody vegetation is included. i. e. Bamboos, palms, coconut, apple, mango, neem, peepal, etc. are treated as tree in SFR. All non-perennial non-woody species (e.g. banana) and tall shrubs or climbers (e.g., lantana or canes) are excluded. The trees are classified into eight categories viz. farm forestry, village woodlots, block plantations, road side, pond side, railway side, canal side and others.

Scrub denotes lands having bushes and/or poor tree growth with canopy density less than10 percent. Such lands are delineated largely within or around continuous forest areas.

Mangroves are salt-tolerant forest ecosystems found mainly in tropical and sub-tropical inter-tidal regions. They are trees or shrubs growing in shallow and muddy salt water or brackish waters, especially along quiet shorelines and in estuaries. They are counted separately but are included in forest cover.

How it is counted?
Forest cover is counted using satellite image data and digital image processing software. Tree cover is counted using field inventory data.

Initially, FSI assessed the forest resources through ground inventory and interpretation of aerial photographs. Then in the early eighties, it started using satellite data. The interpretation of data was done manually, i.e. visual interpretation. Since 2001, survey is done by using satellite imagery and image processing software since 2001. Quality of data also improved. In1987, resolution of data used was 80m x80m and scale of interpretation 1:1 million. From 2001 resolution of data is 23.5m x 23.5m and scale is 1:50,000, respectively.
Digital interpretation at 1:50,000 scale has several advantages in terms of accuracy. As a result, all the areas down to 1 ha in extent and having forest cover have been included -irrespective of whether they are within or outside the recorded forest areas. Similarly, blanks in excess of 1 ha in the forest areas can be identified and excluded, thereby giving more accurate information on forest cover.
For accuracy check, 'ground truthing' of this data i.e. actual verification is done. In 2021 survey, using a custom digital app the ground truthing was done at 3400 locations.

Field inventory data have been used to assess tree cover in the country. Substantial tree resources exist in the country in the form of linear plantations along roads, canals, etc., scattered trees on farmlands, homesteads and urban areas and blocks of plantations and woodlots smaller than 1 ha that could not be captured by remote sensing data used in the present assessment. For assessment of such tree cover, data collected from field inventory, based on appropriate stratification and sampling techniques, is used.

How the data is classified?
Forest area and forest cover are the two key terms to understand the classification and presentation of SFR data. Further classification is done as hill districts, tribal districts and physiographic zones.
The forest area: also known as recorded forest area is an area recorded as forest in the government records. It is categorized into "Reserved Forest", "Protected Forest" and "Unclassed Forest". 
The forest cover: is classified as very dense forest (VDF), moderately dense forest (MDF) and open forest. 

An area notified under the provisions of Indian Forest Act or the State Forest Acts having full degree of protection. In Reserved Forests all activities are prohibited unless permitted.

An area notified under the provisions of Indian Forest Act or the State Forest act with limited protection. In protected forests all activities are permitted unless prohibited.

An area recorded as forest but not included in reserved or protected forest category.

Includes all lands with a forest cover of trees with a canopy density over 70 percent.

Includes all lands with a forest cover of trees with a canopy density from 40 percent to 70 percent.

All lands with a forest cover of trees with a canopy density between 10 to 40 percent.

Based on the permutations and combinations of these classifications, ample arguments are created for and against the growth of forest. e.g. "Forest cover is growing but very dense forest is decreasing". "Total forest cover is increasing but what about forest in tribal districts?" etc.
Before entering this debate, it is necessary to see what the data says on all these parameters. Let us begin with forest cover. Although survey is done every two years, forests do take considerable time period to grow or diminish. That is why we are comparing SFR 2001 and SFR 2021 data. Beginning of the Century is a good starting point and 20 years is a reasonable period for review of forest growth.
Daman and Div has 12.03 % forest cover in 2021, not shown separately in map. For Andhra and Telangana we have used data of SFR 2019 instead of 2001. Jammu & Kashmir data includes Ladakh.
The table shows that the total forest cover of the country in last 20 years has increased but the dense forest has decreased. The 2001 SFR defines dense forest as all lands with a forest cover of trees with a canopy density greater than 40 percent. We have used the same here.
Where do we stand in global comparison?
As mentioned earlier, FAO collects, analyzes and monitors the global forest data. According to it's latest report Global forest resources assessment 2020 The global forest area in 2020 is estimated at 4.06 billion ha, which is 31 percent of the total land area. The world has lost a net area of 178 million ha of forest since 1990. Therefore it is significant that since 2010 India has retained its position in world's top ten countries.
It can be seen that even in top ten countries, some have lost forest cover in last ten years.
What is the position of forest in hill districts? tribal districts? What do we mean by physiographic zones and why are they important? What is the situation in recorded forest area? These and many such topics will be covered in this series in upcoming articles. Stay tuned.