Introduction to Transect Data
Besides displaying remote sensing data as spectra or as map images, they can also be displayed as as a function of distance along a transect to monitor patterns in cover and to also examine temporal changes in individual metres as opposed to the entire transect. Typically, an individual vegetation index such as NDVI or WBI will be used since it is somewhat cumbersome to display entire spectra. In many cases, there are still patterns in the indices to distinguish between empty soil (see the section on spectra for review) and vegetation types.

A sample set of transect runs is below, one for NDVI and the other for WBI. Both cover the transect prior to the fire; one is from a normal precipitation year, while the other is from a drought year. (from Claudio et al 2006, SpecNet special edition of Remote Sensing of Environment)

By displaying data in this manner, it is possible to not only identify individual shrubs and bare soil patches, but also changes in these shrubs over time. The first forty or so meters are dominated by Adenostoma fasciculatum (chamise), while meters forty five through about ninety have many individual Arctostaphylos pungens (manzanita), which show up as peaks of high NDVI and WBI, and the last ten or so meters are dominated Adenostoma sparsifolium (redshank). For a picture of these shrubs and their leaves, you can click here and go to the bottom of that page.

To recall the larger-scale picture, click here for a map of the WBI with the transect marked or here for a false-colour contour map

To return to the main page, click here

To continue to the next part, click here

(Note to self: add the post-fire data too!)

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