The tome, which will be adapted for the screen by David Ward, centers on Hill's two-year stint living in a tree she called Luna in an attempt to thwart Pacific Lumber's plans to destroy a forest of California redwoods. In December 1997, Hill climbed the tree and refused to come down, hoping to bring attention to her cause and save the forest.

She came down 738 days later, after reaching an agreement that provided permanent protection for the tree and a buffer zone around it. Her book is described as part diary, part treatise and part New Age spiritual journey.

Documentary filmmaker Doug Wolens chronicled Hill's "tree sit" in his 2000 film "Butterfly."

For the upcoming feature, company topper Howard Baldwin said the producers plan to film on a very green set. "We want to show than an ecology-minded production is doable. We hope it will start a trend in the film industry by encouraging others to follow suit," Baldwin said.