abstract background bare bark black brown colors colours dry gnarled gray grey grooves layers lines mottled peeling rough shadows shapes sunlight surface texture textured textures tree tree trunk trunk backdrop detail fence knot macro nature old timber weathered wood bamboo garden natural pattern rotan stick sticks wall crack cracked rural winter autumn dark gothic grunge grungy decay gloomy natural texture structure trees urban decay wooden wooden fence Acer fissure groove sycamore ancient bristlecone conifer contorted grain pine twisted usa