I have a a study area of 2 Landsat scenes from 2013 which were classified for a specific natural community, and these areas have been isolated and extracted and digitized into vectors so that they can be integrated into a GIS. These communities exist as features all throughout the scene, kind of like islands, if you will. I am working with landsat data, so I want to see if these areas have grown/expanded through time, preferably over two or three decades.
What is the best way to accomplish this? I was thinking turning the natural communities polygons into a raster, using that as a mask for landsat data, and running a pixel change detection to see how they have changed. But would that give me results for if they had shrunk from previous times, since the mas would only represent current size? Or perhaps is fragstats a better option? I have no experience with fragstats. Thanks for your help and ideas
Edit for being too broad: the vectorization was for creating a detailed map for a GIS using a basemap with much higher resolution than landsat, and the change detection is a separate part of the project. I ran a supervised support vector machine classification in ENVI to obtain the results. The images I classified were corrected for atmosphere, so I will do that with the following temporal years.
Sorry for the misunderstanding, I suppose my main question is: instead of reclassifying and performing a change detection on the whole scene, what would be the most efficient way to determine land change for only areas of interest? The areas in question are isolated swamp ecosystems, from about 1-10 hectares in size. I'd like to see if they have grown or shrunk over time. Thanks and I hope this isn't too broad or difficult to understand.