Create a mixed media collage of a forest that embodies the grunge aesthetic through the use of rough textures and elements of decay. Begin with a base layer of rough bark to establish the foundation of the forest scene. Layer crumpled leaves in various shades of deep greens and browns to add depth and texture, and incorporate dirt or soil to ground the composition. In the background, apply soft gradients of earthy tones (deep greens, browns, and grays) to enhance depth and create a sense of atmosphere. Focus on the interplay of light filtering through the trees, highlighting the textures of decay and inviting viewers to explore the beauty found in the imperfections of nature. The overall mood should evoke a sense of mystery and reflection, encouraging contemplation of the forest's untamed beauty. In post-production, enhance the earthy tones for seamless flow, emphasizing the light and shadow interplay. Add a subtle texture overlay, such as a light grain or soft vignette effect, to unify the piece and enhance the mysterious atmosphere.