The different colored fields has indeed intrigued me. My guess is that different microorganisms living off the dead tree offers this mixed with the occasional burnt areas.
And yes, working with a Hasselblad 500 is kind of special. You are on the own managing the excellent Zeiss optics and mechanical precision of the camera. No electronic assistance apart from the cropped CMOS digital back. A rather slow undertaking. But actually Victor Hasselblad was a bird photographer in his spare time. You have to focus on the one shot. No machine-gun firing camera.