Durian Tree Inventory - Why and How To Do It

A durian tree inventory is a listing and description of all the durian trees and planting sites in your durian orchard at a particular point in time.
A tag identifying the variety or cultivar
A Thai farmer with his tree tags and a printed copy of his tree inventory. See video..

It should  accurately identify the number of durian trees present, the species, the cultivars/clones, their actual locations and the condition of the trees themselves. The objective is to create a map and a database with all the information collected for each tree.

This durian tree inventory is like a resource inventory evaluation that enables you to count and assess all your trees so that you know the foundation from which you operate your farm.

This information will be used to make decisions regarding specific tree management activities, focus on productive trees, and removal of unproductive ones.

A tree inventory is a powerful management tool because it:

  • provides an overview of the ages, cultivars/clones, and condition of the trees;
  • allows you to make farm management or work schedule (such as fertilizing, disease and insect control, irrigation, harvesting, pruning, thinning etc.) on a solid basis;
  • makes it easy to set priorities for tree pruning and removal work;
  • enables you to assess your trees as a resource for budget planning and yield forecasts
  • enables you to evaluate your farm's performance based on production records such as the relationship of fertilizer to crop yield, or land to total production that are critical to your farm's profits.
Tag should be weather-proof

How To Do A Tree Inventory


    a. Divide the farm into sub-areas following natural boundaries (such as streams), structures (such as drains, farm roads, hill terrace) or according to the durian cultivars/clones planted in the area.
    b. Make a rough map of the area.
    c. Collect the data.

Data to consider collecting (make a paper form or a spreadsheet/database with the data to be collected.)

 a. Tree Number - is a unique number given to a specific tree.  No other tree should have this number. Tag the tree to avoid counting trees more than once. Tag should be weather-proof and permanent.

Tag placed around the tree trunk

Tag placed on lateral branch

Tag painted onto the trunk

 b. Location - use Global Positioning System (GPS) if possible,

 c. Species - scientific name, common name in a second field/cell, and cultivar/clone in the third field/cell.

d. Size - trunk girth (circumference) 4.5 feet above ground
(American Forests Measuring Guide  DBH – refers the Diameter of the tree at Breast Height).  This measurement is taken at 4 ½ feet from the base of the trunk.

 e. Canopy Spread

 f. Height       

g. Condition of tree
                               Tree condition is the overall health of the tree.

  • Good trees are healthy, vigorous, have no apparent signs of insect, disease, or mechanical injury and they require little or no corrective work. 
  • Fair trees are in average condition and vigor for the area, but may be in need of some corrective pruning or repair.  They may need minor corrective work as well as they show minor insect injury, disease, or physiological problems. 
  • Poor trees are trees that are in a general state of decline. They may show severe mechanical, insect, or disease damage, but is not dead.
(This data is entered by placing an ‘X’ under the G,F,or P columns)

h. Digital photo of the tree - You could have the goal to take one in each season to present a complete picture.

All of the above information should be computerized, which would make the inventory more readily available, assist in species selection for revised planting plans and facilitate scheduling of tree maintenance, as well as improve administrative efficiency.

In Western countries, tree inventories are carried out by trained and experienced professionals using computer programs capable of advanced data storage, analysis and reporting.

On the other hand, a fairly good and practical tree inventory can be made by non-professionals using a general spreadsheet such as Excel or a database such as Access.  The information collected is usually less detailed and also less accurate.

The cost of a non-professional tree inventory lies primarily in the collection of ground inspection data. Tree inspection can be carried out by existing staff. All field data can be recorded on tabulated paper forms or collected on an inexpensive PDA that would greatly speed up the process and make the data more consistent.

Tree inventories have to be updated periodically through ground inspection in order to stay current.

High Tech "Health Checks" for Trees

How They Are Carried Out In Singapore

The iconic Tembusu tree at the Singapore Botanic Gardens.ST PHOTO: KUA CHEE SIONG


Some of the scientific instruments used to measure tree health