England english exercise forest Great Britain natural nature path shadow sunlight Sussex track trees walk winter woodland blue canada conifers lake landscape mountain peak Rockies Rocky Mountains shore snow summit Betula birch deciduous spring trunks white brushwood fog silouette sunrise sunset underbrush vector current flow green river summer view water fall mountains rocks scenics tree brown ground mount sky Fir game mouflon national reserve nobody ram sheep spruce untouched wildlife boardwalk ecology ferns habitat moss temperate trail Vancouver Island wild