written by Karen Colson and Jason Karl
Description and Uses
Plant production can be determined using a variety of methods or combination of methods including estimating, harvesting, or by estimating and harvesting (double-sampling). With the Harvesting Method all vegetative matter in each quadrat is clipped, sorted into species, then dried and weighed and a conversion of harvested weight to air-dry pounds per acre or kilograms per hectare is performed. The Harvesting Method is the most accurate of all three production methods but it is time consuming and is destructive to the vegetation.
Advantages and Limitations
The Harvesting Method is the most accurate of all three production methods listed above and reduces personal error caused by estimation of utilization levels found in other methods. However, it is both time and labor intesive and requires disturbing the vegetation to perform the monitoring.
Similar to the other two methods, plants grow at different times of the year so when the sampling is conducted is important since sampling at different times of the year can change the results. When measuring annual production, current year’s growth can be hard to separate from previous year’s growth. Likewise, seasonal and annual climatic fluctuations affect biomass, and therefore production is not a suitable measure for long-term trend studies that compare data taken in different years. It also requires adjusting for material that has not been produced yet or has been removed which is difficult.
An advantage of this method is that it does not require as much training as the other two production methods.
- NRCS National Range and Pasture Handbook, Chapter 4, Inventory and Monitoring Grazing Land Resources, pages 4-3 through 4-13 (USDA-NRCS 1997).
- Plant Production – Estimating
- Plant Production – Double-Sampling.