An introduction to Transecto.
Transecto is a program which was written to help researchers at the Reserva Natural da Serra da Malcata, in Portugal. They needed software to help them manage, visualise and perform preliminary analyses on plant community data.
Many data-collection transects have been established, all having an area of 10 square meters, and each transect is surveyed from time to time. Each survey produces a detailed set of plant maps and some context information. So, there's a lot of data. The job of Transecto is to put the data together in a way which is as understandable as possible, and then to provide visualisation and analysis tools for working with the data.
The data set
The field workers collect data describing the arrangement of aerial plant canopies and the types of cover found at the ground layer. The aerial plants are recorded in 1..n maps describing the 2-D outlines of leaf masses. The species, maximum height, phenological state and grazing damage of each leaf mass is recorded. The ground layer is recorded by dividing the surface up into a grid with cells of 0.5 x 0.5 m2. For each ground cell, the (Braun-Blanquet) abundances of various species is recorded, together with their mean height, phenological state and grazing damage. Most of the spatial information is therefore horizontal, but each record includes a height datum, so there is scope for making inferences about the 3-D organisation of the canopies.
The program
Version 1.0 of Transecto was developed in February 1997, working on-site at Malcata with the researchers.
The data as recorded in the field require some work before they can be used in the program. The aerial plant maps need to be digitised and the tabular data for the aerial and ground vegetation need to be entered into a spreadsheet. The program accepts all of the data prepared and builds up an internal representation of the plants and their arrangement. The user can then request the display of various views of that representation. The program can also be instructed to perform analyses of the data.
Here's a screen shot of the program, showing the internal arrangement of the data for one transect data set.
The user can insert new data to the transect as it is collected.
The plant data are brought together to provide various views of the vegetation surveyed.
Once the data are loaded in, the program can perform some preliminary analyses.
What next for Transecto?
World in a Box was involved in digitizing and entering some of the data in 1998. Since then, most of the rest of the collected data have been entered by local research workers. The researchers intend to continue digitizing data collected in the future. There's already an inpressive dataset ripe for further analysis, and it's growing every year.
We have just updated the program to version 2.0. It now includes some extra analysis modules which perform summary analyses of the ground vegetation layer and attempt some transition matrix analysis.
In future, new analysis options will be added to those currently available.