Change is part of every ecosystem. Fire, grazing, disease, drought, and earthquakes are examples of variable forces that cause change. Grassland vegetation changes over time in response to these forces. Grassland managers are usually interested in successional changes, which are changes to the plant community that may have resulted from a management action. Assessment and monitoring is required to understand the impact of use and management on changes in the grassland ecosystem.
In 2003, the Grasslands Conservation Council of British Columbia, in partnership with other non-government and government organizations, took the initiative to develop an assessment and monitoring tool that would provide a basic level of grassland evaluation. While the procedure is primarily intended for ranchers to use on their private land, the tool will be consistent with government objectives and can be applied to grasslands anywhere. The simple and rapid procedure allows users to make visual assessments of five principal indicators that determine the relative condition of grasslands compared to reference conditions.
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How is Grassland Status Assessed?
What is Grassland Assessment and Monitoring?
Grassland assessment is simply a process for comparing the present condition of a site to its ecological potential. Monitoring is a process of collecting information from several assessments to detect changes over time. Both assessment and monitoring provide valuable information that determines if management programs are achieving their goals and objectives.
Most grassland assessments compare the present condition of a site to a reference that would exist with little or no disturbance. Generally, the climax plant community, which is primarily controlled by climate, soils and topography, serves as the best benchmark for a site. These communities represent the most stable combination of plant, water and soil factors, and are only minimally disturbed by outside influences. Disturbances such as fire, grazing and recreational activities sometimes cause significant changes in plant communities depending on their intensity, frequency and duration. These events can not only change the composition and structure of plant communities, but they also affect water relations and soil stability.
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Ecological changes in grasslands are often complex and difficult to measure. Therefore, indicators are often used as indices to describe the status of an ecological factor or process that cannot be seen or measured. Grassland status indicators are visually estimated with this procedure, but scientific facts must support the decisions that will be made using each indicator. In order for these indicators to be effective, they must be easily observed, their present condition must be simple to describe, and changes in their condition must be conspicuous. The following five indicators are used to make grassland assessments:
Assessments of grassland sites evaluate each of the five indicators to determine how close, or how far, a site is from the Reference Condition. Changes in each indicator are determined using thresholds that relate the conditions on the site to a set of standards. Each indicator is evaluated and scored independently against the threshold information provided. The sum of the scores for each of the five indicators produces an overall score for the site. The relative status of the site is finally established by comparing this score to a set of standards as follows: Reference Conditions (75-100 percent), Slightly Altered (51-75 percent), Moderately Altered (25-50 percent), and Greatly Altered (<25 percent).
Trend in grassland condition can also be evaluated using this method by making repeat assessments over time. Monitoring for trend also uses a series of photographs that accompany the visual assessments to provide photographic documentation of conditions on the site over time.
For more details on grassland assessment, please visit the the Grassland Monitoring Manual pages.
For more on ecological systems visit the links below.
Plant Response to Grazing
Plant Communities
Grazing Animals
Ecosystem Response to Humans
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