Difference Between Belt and Line Transect

The key difference between belt and line transect is that belt transect uses a rectangular area centred on a line to collect information while line transect uses a straight line to gather data.

Ecological sampling helps to understand the distribution and abundance of organisms in their environment. During an ecological survey, sampling takes place at regular intervals within a particular habitat, over an extended period of time. Ecological sampling methods can be random sampling or systematic sampling. In systematic sampling, samples are taken at intervals along a line drawn across areas where there are clear environmental gradients. There are two types of systematic sampling methods as line transect method and belt transect method. Both line and belt transects show zonation of species along some environmental gradient.

CONTENTS

1. Overview and Key Difference
2. What is Line Transect
3. What is Belt Transect
4. Similarities Between Belt and Line Transect
5. Side by Side Comparison – Belt vs Line Transect in Tabular Form
6. Summary

What is a Belt Transect?

Belt transect is a systematic sampling method. It is a rectangular area centred on a line that is set across an area having a clear environmental gradient. In other words, a belt transect can be considered as a widening of the line transect to form a continuous belt or a series of quadrats. Hence, this method produces more data than a line transect. This method uses a quadrat to collect data. Quadrats are placed over the line to collect the data. Once the plants and/or animals inside the quadrat are identified, their abundance can be estimated. It also can be taken as a permanent sampling plot to gather data for a longer period of time.

Generally, belt transects provide a lot of data on individual species at different points along the line and their range. It allows the construction of bar charts to show how the abundance of each individual species changes within its range. Moreover, the belt transect method is useful to determine the relative dominance of species along the line.

What is Line Transect?

Line transect is another systematic sampling method similar to the belt transect method. In the line transect, a line is drawn across a habitat. It can be simple as a string or rope placed on the ground across a habitat. The organisms that actually touch the line are considered in this method.  Therefore, sampling is restricted only to organisms that touch the line.

Though this method is similar to the belt transect, it produces limited information. It only shows the changes taking place along the line. The presence and absence of species are recorded. It illustrates a particular gradient or linear pattern along the line. The data is displayed in the form of a diagram, using symbols for different species, which are drawn to scale. Line transect does not produce information on the relative densities of individual species. But this method is quicker than the belt transect method.

What are the Similarities Between Belt and Line Transect?

• Belt and line transects are types of systematic sampling.
• They are similar methods.
• In both methods, a sampling line is set across the sampling area where there are clear environmental gradients.
• Samples are taken at fixed intervals in both methods.
• The sampling intervals depend on the individual habitat, the time and effort that can be allocated to the survey in both methods.
• Sampling can be done through the whole length of the line or at particular points along the line.

What is the Difference Between Belt and Line Transect?

Belt transect is a systematic sampling method that uses a rectangular area centred on a line set across a habitat. Meanwhile, the line transect is a systematic sampling method that uses a straight line marked across a habitat. So, this is the key difference between belt and line transect. Furthermore, in the belt transect method, quadrats are sampled all the way down the transect line or quadrats are placed over predetermined intervals and sampling is done. But, in the line transect method, sampling is rigorously confined to organisms that actually touch the line. Hence, this is another significant difference between belt and line transect.

Moreover, the belt transect method is time-consuming. But, the line transect method is quicker than the belt transect.  Most importantly, the belt transect method will supply more data than a line transect. In addition to these, belt transects produce data on the relative densities of individual species. But, line transects do not produce as much information on the relative densities of individual species.

The below infographic lists more differences between belt and line transect in tabular form.

Summary – Belt vs Line Transect

In summary, the belt transect method utilizes a rectangular area centered on a line to collect data. It uses a quadrat. The plants and/or animals inside the quadrat are identified, and their abundance is estimated. In contrast, the line transect uses a straight line to collect data. In the line transect method, organisms that touch the line are recorded. Moreover, the belt transect method provides information on the relative densities of individual species, while the line transect method does not produce as much information on the relative densities of individual species. However, in both methods, data collection can be continuous or interrupted (at regular intervals). They help to determine a gradual change of species in a habitat. So, this concludes the summary of the difference between belt and line transect.

Reference:

1. “How to Carry out Ecological Sampling” Countrysideinfo. Available here.
2. “Why Use Line Transects?” Countrysideinfo. Available here.

Image Courtesy:

1. “Quadrat veg analysis” By sandwich (CC BY-NC-ND 2.0) via Flickr
2. “Mega Marine Survey: Working along the transect line” By Ria Tan (CC BY-NC-ND 2.0) via Flickr