Line-Point Intercept Method Overview

Sep 16, 2024

Line-Point Intercept Method

Overview

  • A rapid and accurate method for quantifying soil cover
    • Includes vegetation, litter, rocks, and biotic crusts
  • Related to environmental factors such as wind and water erosion, water infiltration, and site recovery from degradation

Procedure

Initial Setup

  • Start at zero end of the line, read from left to right
  • Stand on the right side of the line
  • Keep numbers on the tape right side up

Measurement Process

  • Locate first point on tape
    • Pin should be vertical to the ground
    • Pin height: 6 inches above tallest vegetation or soil surface
  • Let pin fall freely
    • Aim for the point on the tape
    • Use randomness in pin placement
  • Observe and record hits
    • Follow pin from top to ground
    • Look for any contact with species or objects
    • Record species and objects (e.g., BOER grass, litter, soil) in data form

Important Considerations

  • Species Identification
    • Know all species on site beforehand
    • Reduces time spent deliberating at a point
  • Avoiding Parallax Error
    • Read the line vertically
    • Keep eyes above the graduated side of the tape
  • Body Positioning
    • Bend over at a 90-degree angle
    • Enables visibility of small items on the soil surface

Data Recording

Basal Hits

  • If point falls within the imaginary circle around grass culm, it’s a basal hit
  • Record hits accordingly (e.g., BOER, litter)

Describing Points

  • No canopy cover: no top canopy contact, soil surface contact
  • Litter: organic material not rooted to the ground
    • Woody litter: 5mm or larger in diameter
  • Rocks: 5mm or larger are recorded
  • Biotic Crusts
    • Visible cyanobacterial crusts or lichens recorded as "LC"

Multiple Hits

  • Record each species once from a top-down view
  • Follow pin and record first contact of each species

Special Cases

  • Dense vegetation: bend and remove vegetation if necessary to observe ground level
  • Wind: take visual snapshots quickly to avoid disturbances

Example Readings

  • Point 1: BOER4, BOER4
  • Point 2: PSTA, litter, soil
  • Point 4: None, soil
  • Point 7: Iva, Croton, litter, soil
  • Point 14: None, litter, soil

Techniques for Accurate Measurement

  • Inside Shrubs/Thorny Vegetation
    • Stay on top of the tape
  • Wind Considerations
    • Quick determination at each point

This method requires skill and practice to execute efficiently, ensuring accurate environmental assessments.