Line Intersect Sampling
- Establish straight-line transects across a study area and record each intersection between the transect and individual organisms or vegetation.
- Provides a systematic, standardized way to estimate and compare species abundance and distribution across areas.
- Can misrepresent true abundance if transects are poorly placed, organisms are unevenly distributed, or organisms are difficult to detect or highly mobile.
Definition
Section titled “Definition”Line-intersect sampling is a sampling method used in ecology and environmental science to assess the abundance and distribution of vegetation, wildlife, and other organisms within a particular area. The method involves establishing a series of straight lines, or transects, across the study area and recording the number of times the lines intersect with individual organisms or vegetation.
Explanation
Section titled “Explanation”Researchers lay out one or more straight transects through the study area and travel along each transect, noting every point where the transect intersects an organism or plant. Counts of intersections are then used to estimate overall abundance and the spatial distribution of species within the area. The approach enables systematic and standardized sampling over large areas and supports comparisons of abundance and distribution among species or locations. Accuracy depends on strategic placement of transects and on the detectability and spatial behavior of the organisms being sampled.
Examples
Section titled “Examples”Bird populations
Section titled “Bird populations”A researcher establishes several transects across a forested area and walks along each transect, recording the number of times the line intersects with a bird. These intersection counts are used to infer the abundance and distribution of bird species within the forest.
Grassland vegetation
Section titled “Grassland vegetation”A researcher establishes transects across a grassland and records the number of times the lines intersect with individual plants or plant species. These counts are used to assess overall plant diversity and distribution within the grassland.
Use cases
Section titled “Use cases”- Informing conservation and management decisions.
- Monitoring changes in the abundance and distribution of species over time.
Notes or pitfalls
Section titled “Notes or pitfalls”- If transects are not placed strategically, sampling may not represent true abundance or distribution.
- The method may be ineffective for organisms that are difficult to detect or that move frequently (for example, small invertebrates or highly mobile birds).
- Uneven spatial distribution of organisms within the study area can bias results.
Related terms
Section titled “Related terms”- Transect
- Sampling
- Systematic sampling
- Abundance
- Distribution