Sample Units for Direct Methods to Determine Biomass

Direct methods to determine biomass typically involve sampling procedures using a sample unit with defined boundaries (ie., some type of quadrat), so that biomass can be expressed relative to a known area. In this way, the biomass values obtained from a small area are subsequently converted to a more conventional scale, such as kilograms/hectare or pounds/acre.

When determining biomass, it is important to consider the sample unit used to collect biomass data in its three-dimensional form ie, having height as well as area, to properly account for all plant material within a given area. Therefore, ground rules describing boundary decisions should make clear that many situations can be found where only the part of a plant falling within the quadrat volume will be sampled, regardless of its rooted location.

References and Further Reading

(Note: pdf files require Adobe Acrobat (free) to view)

Bonham, C.D. 1989. Measurements of terrestrial vegetation. John Wiley Sons, New York, NY. pp 33-40.

Coleman, S.H. 1959. A useful device for laying out forage production plots. Journal of Range Management 12:138-139. (pdf)

Kennedy, R.K. 1972. The sickledrat: A circular quadrat modification for use in grassland studies. Journal of Range Management 25:312-313. (pdf)