I have ~90 .tif files that are rasters of known fire boundaries from the last 90 years. I want to merge them so that each pixel has the value of the number of fires occurring at that pixel. I can merge the raster files OK, but then each layer becomes a band, "nodata" sections become 0s, and the value of each pixel is the year (see table below from the identify function).
As you can see, this has "worked" in that I can click any pixel and see where there has been fires and when. What I now need to do is either sum or stylize this layer so that is shows the number of fire events (intervals not important). I cannot sum the value column as the value is the year rather than a "1" to correspond to a fire event.
Zonal statistics doesn't help me here because I need a viewable map rather than a table.
I have very little experience with raster-based GIS.