autumn changes changing color colors fall leaf leaves season seasons tree trees aspen aspen trees CO colorado landscape west western bark cones Fir firs green nature pine cone spring trees branch alder bark board felled trees forest fuel stack tree trunks wood fungus HDR log mushroom Nyberg sponge sponges toadstool crop dordogne farm France hillside irrigation Juglans nut orchard plant walnut agriculture animal cow farming grass herbivore pool summer water bare bleak blizzard cold England snow stripe Sussex white winter Roots stilt Stilt-rooted Terrestrial plant trunk twig