From the shape of the fin I would say the aircraft was an RE8 .... which is about as useful as saying the pilot was probably right-handed. If it was an RE8, there should be another grave, or a very lucky POW.
I agree with Adrian about the aeroplane looking like an RE 8. Plenty of them were shot down both from the air and ground in 1918, so further identification without a date is very difficult. The only other clue is that the photo comes from someone who was in Fliegerabteilung 278; this unit was attached to the German 1.Armee at least in the last months of the War. So if FA 278 was with 1.Armee during the 1918 offensives we can probably narrow the search to that army's front, which was more or less along the Aisne River. Some RAF squadrons (Nos 27, 32, 43, 49, 73, 80 and 103, plus No 2 AFC) were transferred to that part of the front in June - but none of those squadrons operated the RE 8. Is there a date on the photograph? Gareth