OC-8.3: Change in rangeland ground cover

Owned by Enrico Bonaiuti
May 05, 2020
2 min read

Definition: This indicator is a measure of the percentage of plant cover on the land surface.

Unit of Measure: Percentage

Disaggregated by: Geographic location (national, sub-national), Rangeland name, Rangeland area, method (line intercept, digital vegetation charting)

Method of Calculation:
Step 1: Compute ground cover using any of the two methods below:

  1. Line intercept method: Cover is calculated by adding all intercept distances and expressing this total as a proportion of tape length and multiplying by 100.

  2. Digital vegetation charting method: Ground cover is estimated using a set of protocols for taking digital images and analysing them using specialized image processing software.

    Step 2: Compute the change in the shannon index across the reporting periods (applicable to all but the first reporting period)
    Change in cover=Covertn-CovertoCoverto×100
    t0 denotes the first reporting period (e.g baseline) and tn denotes subsequent reporting periods (e.g mid-term, end-term).

Data sources: Rangelands

Data collection methods Further guiding notes on the methods refer to Louhaichi et al. (2016). Methodology for assessing and monitoring rangeland vegetation in Central Asia. Amman, Jordan: International Center for Agricultural Research in the Dry Areas (ICARDA). Available here.:
Line intercept method: A tape is extended to create a transect across the site. Transect length depends on the vegetation and type of plants which are to be measured. In many instances, 15 m transects have been found suitable in dense vegetation, while 30-50 m is needed to obtain a representative sample in sparse vegetation. The observer proceeds along the line-transect, identifies ground cover intercepted by the tape, and records intercept distance. Each transect is regarded as one sample unit, so multiple transects must be measured to estimate sample variance and conduct statistical analyses of cover data.
Digital vegetation charting method: A more reliable and cost-effective technique is the use of digital vegetation charting technique where the cover is computed by the computer based on the number of pixels each class represents within a fixed area.

Data collection and reporting responsibility: Program leader, project leader, project M&E focal point person

Data Collection and Reporting Frequency: Annual, bi-annual, baseline, mid-term, end-term.
It is recommended that data collection is conducted during peak standing crop (Spring season).

Evidence required: Data collection forms (raw data), dataset

Rationale: Plant cover is ecologically important because plant leaves and branches protect the soil from the damaging effects of heavy rainfall and reduce soil erosion. Furthermore, the greater the vegetation cover, the more vegetation is available for livestock and wildlife.Tracking ICARDA's work in restoration of rangelands is critical for determining the gains made in optimizing the productivity of grazing lands.

Comments and limitations: The line intercept method requires the use of more transects as site heterogeneity increases, and this could significantly increase the cost and time required to gather data for reporting this indicator.