How many goes did it take? The 'ghost' consists of two ellipses placed together and then shaded using colours from the adjacent trees. Though people don't look like trees, many examples of misperception have involved trees apparently looking like people! At this resolution it could also have been a bush or small tree.
There is an expanded version of the 'ghost' in the photo here. The 'ghost' is right in the centre. It looks fairly prominent now and resembles a huge mushroom more than a human figure! It stands out against the grass and could conceivably be a bush or small tree. However, because it uses colours taken from the rest of the photo, it is not blatantly obvious.
The 'ghost' is near the limit of the resolution of the photo (typical of many anomalous photos). This 'noise' factor often increases the impression of a face or a figure in an otherwise random shape in a photo.
To return to the photo, click here. The 'ghost' will probably look painfully obvious in the original photo now that you've found it.