I hate to be the one to tell you, but you could have avoided being attacked by Spriggans altogether in that quest, saving the lives of the people below as well. =x There's someone who is interested in travelling with you when you get that part of the quest, and if you take him with you, he will offer an alternative storyline for that quest once you are at the tree - if you talk to him before getting the sap.
On a sidenote, isn't that place one of the most beautiful spots in the game? Gorgeous!