Part 9: Collecting Monitoring Data

Point Intercept Method

The Point Intercept Method is one of the most common approaches to estimating cover. It is usually completed by placing quadrats with an attached “pin” along a transect and determining the proportion of points that “hit” (or intercept) vegetation. This method can also be completed by walking along a transect tape and recording the number of “hits” of vegetation at the toe of your boot. Using this method, total cover can be calculated as the percentage of hits, relative to the total number of points sampled. Cover of individual species can also be estimated by recording the plant species when intercepted by a point.

It is important to have a complete photo record of the site taking both general view and close-up photos. This method works for most vegetation types, especially when less than 1.5 meters in height. Plant height (shrubs) higher than 1.5 meters can make reading the pin difficult.

Criteria

Guidelines should be determined prior to data collection. Here are some examples:

• One ground cover hit (“positive” if the quadrat pin is touching a plant and “negative” if the pin is not touching a plant) is recorded per quadrat placement. The total number of ground cover hits equals the total number of quadrat placements.
• Bare ground is soil with particles up to ¼ inches, gravel is particles ¼” – 3 inches, rocks are particles greater than 3 inches.
• Litter is dead plant material directly covering the ground, dead perennial vegetative bases, or animal material. If a small stem or piece of litter is not considered large enough to intercept raindrop impact, the hit is the ground covering below it.
• Persistent litter is considered ¼ inch thick. If ground cover is less than ¼ inch, then it will be counted as non-persistent litter.
• Annual forbs are considered non-persistent litter cover when in contact with the ground and large enough to intercept raindrop impact.
• Live vegetation is recorded when the frame point falls on actively growing vegetation.
• Alternative method

Videos


Collecting Data
with Quadrats

 

Line Intercept Transects

 

• Data can be collected by placing a transect tape and recording a “hit” based on the presence of vegetation at the base of a randomly placed flag.

          

Equipment

• Study Location and Documentation Data form (pdf, 16KB)
• Cover Data form (pdf, 20KB)
• Quadrat (40 X 40) with pin
• Hammer
• Permanent yellow or orange spray paint
• Two ¾-1-inch angle irons
• Steel post and driver
• 50- to 200-foot tape

Conducting the study and study sites

• When selecting key areas for setting up these quadrats, be sure the site is located within a single plant community and within a single ecological site.
• Data can be collected using any of the three layout designs.
• It is important to permanently mark each study location and adequately describe the site on the Study Location and Documentation Data form
• Be sure to establish a detailed photo record of the site

Study layout

• If you are using a baseline layout, you should run several transects perpendicular to the baseline. Linear and block layouts can also be used.
• To ensure that both transects and quadrats are independent (do not overlap), spacing between transects and between quadrats should be greater than the average diameter of the largest plants likely to be encountered.

Collecting Data

• At each pace along the transect (regardless of layout), place the quadrat on the ground.
• Record the ground cover directly under or above the pin at the base of the quadrat on the Cover Data form.
• Cover includes vegetation (can be identified by plant species or simply as vegetation), litter, gravel, stone, or bare ground.
• You may simply record the presence or absence of vegetation, although it is more effective to record the actual type of ground cover if vegetation is not present.

Data Analysis

• You can also calculate the percentage of each individual plant species (species composition) by totaling the number of “hits” for that species, dividing that number by the total number of hits along the transect, and multiplying by 100.