As part of my thesis, I'm looking at the atmospheric and landscape effects of the 2018 wildfire in the Algarve. As part of the process, I want to estimate total biomass loss so I have classified two Landsat 8 images (pre and post-fire, 5 and 6 classes respectively) and performed a land cover change analysis using SCP plugin. I'm still fairly new to QGIS/remote sensing so am struggling to understand the output from the change detection and how I can produce a layer showing classes which have changed/calculating total biomass loss from the vegetation classes.
How to calculate change in total biomass
Use a spreadsheet to make the following calculations.
- Assign a
biomass per square metervalue to each landcover category. These are the fundamental assumptions on which your analysis is based, so they need to be the best estimates you can make. If your
biomass per square metervalues aren't reasonable, then your final calculated
change in total biomassresults will be equally unreasonable. Since you're doing a thesis on this topic, I assume you have enough information and knowledge to make this estimate. If not, that should probably be an entire separate question.
- For the pre-fire raster, multiply
biomass per square meterby the
area (in square meters) of that landcover type. This gives you
total biomass in landcover type 1,
total biomass in landcover type 2etc. Repeat for the post-fire raster.
- Add up the
total pre-fire biomass in landcover type xvalues calculated in step two. Repeat for post-fire values. This gives you
total biomass pre-fireand
total biomass post-fire.
total biomass pre-firefrom
total biomass post-fire. This gives you
change in total biomass.
have a look at this:
choose singleband pseudocolor for your percentage band.