contributed by Karen Colson and Jason Karl
Description and Uses
Site condition assessments are simply subjective interpretations of the condition of a site at a particular point in time. These assessments are generally based on qualitative observations. Very large changes can sometimes be monitored using repeated assessments. This method is largely free-form – meaning that the attributes being observed can be defined in almost any way. As such, site condition assessment can be useful for assessing or monitoring a wide range of things like: presence or emergence of disturbed areas, impacts of off-road vehicles, invasive species, animal disturbance, and condition of fences or roads. The individual assessments can focus on one specific aspect of the site or activity, or a range of disturbances, actions, or characteristics.
Elzinga et al. (2001) provide a number of suggestions to improve the reliability of site condition assessments:
- Site condition assessments work best when monitoring objectives can be states as explicitly and quantitatively as possible.
- The use of visually-estimated classes based on quantitative definitions generally produces better results than simple qualitative descriptions. For example, broad percent cover classes that are visually estimated will yield better results than descriptions like “common” or “rare.”
- Site condition assessments should always be done using a standard field form defined according to the management objective. Such forms can contain definitions or examples of what should be observed and recorded and can prompt the recorded to pay attention to certain things.
- given the large degree of variability between observers, site condition assessment is more effective at detecting new disturbances than it is in detecting change in existing disturbed areas.
The most important factor affecting the quality of an assessment is the availability of accurate reference information for the particular soil and climate conditions (i.e. ecological site).
Advantages and Limitations
The biggest advantage to site condition assessment is that it is fast and easy to implement. It can work for areas and situations where assessment and/or monitoring objectives are well defined and tied to readily identifiable attributes that show a large degree of change in response to natural or management processes.
The obvious limitation of this method is that it is very subjective and generally does not involve quantitative measurements. Also, the degree of change that must take place before it can be detected using site condition assessment can be very large. For these reasons, this method can be prone to bias, and it is also not possible to characterize uncertainty or express confidence in inferences drawn from site condition assessment data. It also lacks a standard reference, such as the ecological site-specific reference sheets used with “Interpreting Indicators of Rangeland Health.”
- Elzinga et al. (2001) Measuring and Monitoring Plant Populations: http://www.blm.gov/nstc/library/pdf/MeasAndMon.pdf
Technical and Application References
The term “Site condition assessment” applies to any single or repeated set of observations of the condition of a plot. Interpreting Indicators of Rangeland Health and Pasture Condition Scoring were developed to standardize the assessment process.