Estimating the density and biomass of trees in Khao Yai rainforest.
Biomass can be estimated according to a formula based on the diameter of the tree at 1.3m above the ground. This is called “diameter at breast height” or DBH for short. It is not very accurate but is probably better in environmental terms than cutting down all the trees in a given sample, digging up their roots and weighing them (which is the method used for smaller and faster growing plants such as grasses)

Mark an area 100 sq m. This can be 10 x 10 or in forest difficult to access 50 m along the path x 2m which is 1 m each side of the path.

Record the diameter of each tree in your 100 sq.m. by using metre rules or by measuring the circumference at 1.3m above the ground and dividing by Pi (3.14). For trees with multiple trunks (common with Ficus) measure each trunk and calculate as for a separate tree, adding the totals together.

Apply the formula for each tree to calculate the biomass of each part of the tree in Kg.

Add W for each part of the tree together and you have the biomass of that tree (or hopefully something reasonably close).

Add the biomass of each tree in the area together to get the total tree biomass in 100 sq m.

Multiply by 1000 to get the tree biomass in 1 sq km

One use of biomass data is to make calculations of the amount of CO2 absorbed by different types of ecosystems.