Well honestly, I'm not entirely sure there's anything that will make me ever go into a forest, you'd think that seeing as I'm African I'd conform to the stereotype that suggests that Africans have alot of forests and wild life reserves that we explore, well no, I'm utterly terrified of forests and even more of getting lost in a forest.
Well for the sake of this question, if I ever happened to be in a forest and I saw a dead body, I'd probably take to my heels and run as far away from the place as possible. After my fear had calmed down, I'd stop and think, my actions after that would be based on who was with me at the time, how decomposed the body was and how fast I can alert the authorities.
If the body was fresh then chances are that unless the person died of natural causes, who ever or whatever killed it might still be in the area so I'd actually leave the forest and return with a lot more people. If the body was decomposing and old, I'd still be weary of going back because its smell might attract animals like wild dogs and hyenas to the place and that can be dangerous for me, but if there aren't any, I'd put a call through to the authorities then try and find my way back to the body so that when they arrive, I can easily show them where I saw it.
Obviously, the body could be somebody's loved one who's gone missing and the thought of leaving the body there and running away would be on my mind, especially if I get blamed for the crime(yes that actually happens in Nigeria), but my humanity wouldn't let me leave it like that seeing as that might be someone's loved one who they've been looking for.
Whatever the case, I'd at least inform the authorities so that they can come and pick the body up, identify it and hopefully find the person's next of kin or family.
If I was lost and couldn't find my way to the authorities, I'd look for any reasonable land mark around, like a particular type of tree or a fallen tree or a large rock formation or something and use it as my marker to know if I'm getting close to the body when I alert the authorities and bring them to it.
If I have my phone on me and the GPS is working, then I'll save the location and keep on looking for a way out of the forest.
I hope this helps.
This is a question that makes me think of humanity, while I am in a difficult situation in the middle of the forest. I have to choose between seeking help moving a body or trying to find a solution that I am facing.
if this happens to me, the thing I will do is find a way out of the forest first and then tell the social countermeasures about the corpse that I did not recognize in the forest, with before I secured the body so it wouldn't be eaten by wild animals.