FOREST SURVEY OF INDIA
Inventory of forest/tree resources

An accurate assessment of forest and tree resources in the country is essential for formulating sound strategy for forestry sector. Precise data and latest information on forest cover and volume of growing stock of forests/trees and trends of changes therein are basic ingredients for policy and planning purposes. FSI has been conducting field inventory for estimating the growing stock (volume) and other parameters of the forests by laying out systematic sample plots since PISFR project began in 1965. So far about 80% of the country's forest areas have been inventoried including some areas more than once and about 140 reports have been published. However, under Xth Five Year Plan during 2002-2007, FSI is conducting field inventory of forest resources inside and outside forest including vegetation survey and estimation of soil carbon in forest.
 
Measurement of diameter during forest inventory
Map depicting inventoried forest area
 
 
A methodology has been developed for a comprehensive assessment of forest resources inside and outside forest areas at national level by stratifying the country into physiographic zones and to take a sample of 10 percent districts for detailed inventory during a cycle of two years. This information, thus generated, will form a part of the biennial State of Forest Report. These estimates will be further improved in the subsequent reports as another set of 10 percent districts are sampled and surveyed, and so on. Together with forest inventory, assessment of herbs & shrubs (vegetation survey) is being carried out. In addition, assessment of regeneration status, biodiversity indices and soil carbon in forest areas are being carried out.
 
Map depicting physiographic zones
   

Methodology
A.    Forest Inventory

MANUAL OF FOREST INVENTORY   

            
 

The country is stratified into 14 physiographic zones as depicted in the figure above according to tree species composition and other physiographic and ecological parameters.  In strata, districts are considered first sampling units and grids of size 1 ¼* x 1 ¼* as secondary sampling units.  Ten percent of districts are being inventoried every year.

(i) 1:50,000 scale Survey of India toposheet is divided into 36 grids of 2 ½* x 2 ½*, further each are divided into 4 sub-grids of 1 ¼* x 1 ¼* forming the basic sampling units.  Two of these sub-grids are randomly selected and corresponding sub-grids in all the 2 ½* x 2 ½* grids are selected to form the sample.  The intersection of diagonals of such sub-grids are marked as center of plot on the map.  At the center of selected subgrid a plot of 0.1 ha area is laid out in each such grid and data are collected from the plots falling in forest area only.

(ii) For collecting data on soil, forest floor (humus & litter carbon), sub-plots of 1m x 1m are laid at each corner within the 0.1 ha plot.

(iii) The data regarding herbs and shrubs (including regeneration) are collected from four square plots of 1m x 1m and 3m x 3m respectively.  These plots are laid out at 30 meters from the centre of 0.1 ha plot in all four directions along diagonals in non-hilly area and along trails in hilly areas.

Data is collected from randomly selected sample plots.  The data on checking is entered in the computer and after rectification it is sent to headquarter for processing.  Processing will be carried out for different parameters such as area estimation, stand and stock tables, standard error estimation etc.


B.  TOF (Rural)   
 

FIELD MANUAL OF TOF RURAL
 

          
Extensive tree wealth exists outside continuous forested areas in every country. Termed as "Trees Outside Forests (TOF)", these are in the form of small woodlots and block plantations, trees along linear features, such as roads, canals bunds, etc. and scattered trees on farmlands, homesteads, community lands and urban areas. Inventory of trees outside forest areas is of great importance in planning as this, together with the forest inventory, provides a complete picture of wood/forest resources. FSI has been carrying out TOF assessments since early 1990s. However, an accurate estimate at the national level at a specific time frame was given for the first time in State of Forest Report 2001.
Roadside Plantation under TOF

The study area for this survey is considered as rural areas outside forest areas of the district. For any survey, an investigator requires a sampling frame. Sampling frame for rural areas has been prepared by headquarter with the help of remote sensing technique and Digital Image Processing (DIP).  PAN data for the respective districts taken up for assessment of TOF (Rural) is procured from NRSA, Hyderabad.  Toposheets for the same district are identified and geo-referenced.  These toposheets are then used to rectify panchromatic data.  After rectification, these PAN data are used to rectify the multi-spectral data (LISS).  The panchromatic and multi-spectral data are then fused together and classified into various classes to obtain the three stratum of TOF i.e. block, linear and scattered.

 
TOF Classified Map


Stratified random sampling is being employed for the survey. The country is stratified into 14 physiographic zones and the physiographic zones are strata and the district is a first stage sampling unit. The district is further stratified into three strata namely, block, linear and scattered. Plots are the sampling units and frame of such blocks, linear and scattered stratum of each district are prepared by the headquarter.  The number of sample plots and size in blocks; linear and scattered stratum to be surveyed in the non hilly district are as follows:

a) 35 square plots of 0.1-hactare sizes in block stratum are randomly selected in the block plantations after classification of fused PAN data for each district and surveyed in the field.

b) 50 rectangular plot of 10m x 125m of sizes in linear stratum are selected from the fused PAN data for each district and surveyed.

c) 50 square plots of 3.0-hactare sizes in scattered stratum are selected from the fused PAN data for each district and surveyed.

The number of sample plots and size in blocks; linear and scattered stratum to be surveyed in the hilly district are as follows:

a) 35 square plots of 0.1-hactare sizes in block stratum are randomly selected in the block plantations after classification of fused PAN data for each district and surveyed in the field.

b) 50 rectangular plot of 10m x 125m of sizes in linear stratum are selected from the fused PAN data for each district and surveyed.

c) 95 square plots of 0.5-hactare sizes in scattered stratum are selected from the fused PAN data for each district and surveyed.

Note: It has been concluded from the study conducted for determination of plot sizes and sample size for all the three strata that 35 plots in blocks and 50 and 50 plots from linear and scattered are to be surveyed for non hilly districts whereas 35, 50 and 95 are to be surveyed in block, linear and scattered stratum respectively for hilly districts. However, some points may not be traceable on the ground or are inaccessible or status of points may not match with the stratum or fall in forest/ urban areas.  To augment this, additional points needs to be surveyed.  Field parties will collect information for these plots indicating status of plot in appropriate column of the form.
 
C.  TOF (urban)   

FIELD MANUAL OF TOF URBAN

         
 

           The study area for this survey is considered as urban centers defined in district census book. Sampling frame for urban areas has been prepared by an agency called National Sample Survey Organisation (NSSO) under the Ministry of Statistics and Programme Implementation Government of India. This organization conducts surveys by the name of Urban Frame Survey (UFS). They divide the whole urban centers of a district in blocks called UFS blocks. These blocks are having clear-cut well defined natural boundaries. These blocks are formed on the basis of 600-800 population or 120-160 households and cover the whole area within the geographical boundary of town including vacant lands.

The sampling technique, which is being used is stratified random sampling. The district is divided into five categories of town as defined below, as strata. Urban Frame Survey Blocks (UFS Blocks) are the sampling units. Frame of such blocks for each district are obtained from the National Sample Survey Organisation.  The number of sample blocks to be surveyed in the district is to be decided by the following method.

(a) In the district 10 % of total blocks will be selected and proportionately distributed in five class of town when available UFS blocks in the districts are less than 500. Minimum number of blocks should not be less than twenty in a district.

(b) In the district 5 % of total blocks will be selected and proportionately distributed in five class of town when available UFS blocks in the districts are between 500 and 1000.

(c) In the district 2.5 % of total blocks will be selected and proportionately distributed in five class of town when available UFS blocks in the districts are more than 1000. After selecting the UFS blocks, data are collected, entered and processed in the same way as it was done in case of Forest Inventory/TOF Rural.

D.  Preparation of Manuals for Forest and TOF Inventory Areas

As per the approval of Tenth Five Year Plan, Forest Survey of India has been entrusted with a new mandate of carrying out inventory of Forest Areas, TOF inventory in rural and urban areas, and estimation of different parameters like Regeneration status, Soil carbon, NWFP and vegetation survey of shrubs, herbs and climbers.

The methodologies for forest inventory and TOF have already been evolved and a field manual has been prepared and communicated to the field units for carrying out inventory.  The manual of instructions is primarily meant for the guidance of personnel concerned with field inventory like JTA, STA's, Draftsman, Supervising staff and Data processing officers at HQ's.  The manual takes into account almost all aspects involved in the inventory right from the start of survey to the stage of final dispatch of data to the Zonal Head Quarters for entry.

Target

As per Tenth Five Year Plan proposal, FSI will be assessing forest and tree cover in 10% of the total districts of the country in a cycle of two years.  Accordingly, 60 districts have been inventoried completely during 2004-2005 and 2005-2006.  

Electronic Data Processing    

Preparation of National Forest Inventory Database System (NFIDS) As per the Tenth Five Year Plan approval, FSI is conducting National Forest/Tree Inventory along with vegetation survey. As the objectives of the inventory have been redefined with inclusion of several new parameters, the methodology has also been significantly modified.  As per the revised methodology a National Forest Inventory Database System (NFIDS) based on database software (MS Access) using front end on Visual Basic has been prepared.  The data base system has the following modules:

(i) National Forest Inventory/TOF Data Entry module

(ii) National Forest Inventory/TOF Data Processing module

(iii) National Forest Inventory/TOF Reporting module

(iv) National Forest Inventory/TOF Result database module

(v) GIS interface with forest cover

Work on the first two modules has already been completed and successfully installed in all the zonal offices.  Work on the remaining modules is under progress.

Forest Inventory Unit of this organisation processes the data collected by different zones during the inventory through the above modules. 

 

 

 
 
FSI Copyright 2007