Rangeland Ecology & Management

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Indirect Methods to Determine Biomass

Indirect methods to determine biomass are based on developing a relationship between plant weight and an easier-to-measure attribute such as plant height, rainfall, or cover. This approach is usually performed in three stages. First, preliminary sampling must be conducted to establish the relationship using regression analysis, with biomass as the dependent variable. The preliminary work is then followed by rapid measurement of the indirect attribute in the field. The final stage occurs after the data is collected and it is converted to biomass values using the previously established regression equation.

Indirect methods may be selected over direct methods to determine biomass in inventory or monitoring programs because they are non-destructive, and usually less time consuming. These approaches are most often used for taller trees and shrubs, and when large sample sizes are required to sample extensive or highly variable areas. The disadvantage of these methods is that the relationships between the indirect attribute and biomass are generally restricted in their applicability to the time and place that the preliminary data was collected.

References and Further Reading

Bonham, C.D. 1989. Measurements for terrestrial vegetation. John Wiley Sons, New York, NY. pp 205-213.

Cook, C.W., and J. Stubbendieck. (eds). 1986. Range research: Basic problems and techniques. Society for Range Management, Denver, CO. pp 54-55.

Pieper, R.D. 1988. Rangeland vegetation productivity and biomass. In: P.T. Tueller. (ed). Vegetation science applications for rangeland analysis and management. Handbook of Vegetation Science, Volume 14. Kluwer Academic Publishers, Dordrecht. pp 455-460.