Biomass is the wt. of above ground vegetative matters produced per unit area. Thus, wood, branches, bark and leaves produced by trees, shrubs and herbs and other vegetation growing above the ground are included in biomass but it does not include roots, tubers etc; growing below ground.

• Girth measurement at 50 cm above ground gives consistently reliable results.
• All measurements should be done during the period when the trees are in stage of dormancy.

Biomass Estimation

Necessary to carry out destructive sampling to establish correlations for estimating biomass of standing trees.

Sample trees: Trees should be grouped in 5cm girth and 50cm height classes, About 30 trees should be selected in all. Trees should be felled and separated into main stem, branch wood, twigs and leaves. Main stem should be considered upto the thin end of 10 cm girth. Rest should be included in branch wood. Each portion should be bagged separately in cloth and kept in shade. They should be weighed at intervals till the weight becomes constant. This is dry-weight.

Some terms related to Biomass

• Biomass: Biomass is defined as the total amount of above ground living organic matter in trees expressed as oven-dry tonnes per unit area. This includes the bole, branch, twigs and foliages biomass as well as root, soil.
• Carbon Sequestration: Carbon Sequestration is the capture and secure storage of carbon that would otherwise be emitted to or remain in the atmosphere. The removal of CO₂ from atmosphere by increasing its uptake in soils and vegetation or in the ocean is a form of carbon sequestration.
• Emission: Emission means the release of greenhouse gases and or their precursors into the atmosphere over a specified area and period of time.
• Reservoir: Reservoirmeans a component or components of the climate system where a green house gases or precursor of green house gases is stored.
• Green House Gases: The carbon dioxide (dominant 50 %), methane, nitrous oxide, hydroflurocarbons, perflurocarbons and sulphurhexafluoride are collectively form the green house gases which is considered as a main source of climate change. The burning of fossil fuels and forest degradation as well as deforestation considered as source of green house gases.

Constraints in biomass measurement

• Destructive sampling is difficult
• Root shoot ratio varies by different literature
• Some time hard to show the relation
• Different parts have different moisture content so biomass is differed
• Green/ air dry & oven dry vary wt

In Nepal & India, some regression equations for biomass calculation. Eg., Schima wallichi

Ln W= a+b Ln DBH

Where, W is the weight of green parts (foliage, branch and stem)
W (air dry wt of wood)= a+b DBH²*h