Alan G. Nelson, 80, passed away peacefully on the evening of November 10, 2013, with the love of his life by his side.He was born and raised in Bismarck, North Dakota, and obtained his BA in Biology from Westmar College in Le Mars, Iowa. During his time in Le Mars he served for two years in the U.S. Army. He earned a Masters degree at Montana State University in Bozeman, after which he began his teaching career. He taught biology at Havre High School for two years, Paris Gibson Junior High School in Great Falls for four years and C. M. Russell High School in Great Falls until his retirement. He was always happy and proud to run into his former students around town, to meet their spouses and families, and to see the careers they chose.In addition to teaching, he also spent 13 summers in Glacier National Park as a ranger naturalist, and authored the popular guide, Wildflowers of Glacier National Park. Alan's avocation was nature photography, and he was known around the world as one of the best, winning many awards and competitions. His photography took him as far north as the Arctic Circle and as far south as the jungles of Peru. True to his teacher's nature, he freely shared his technical knowledge, techniques, and favorite scenic and birding spots with other photographers.He was preceded in death by his father and mother, Viran and Florence Nelson, and his sister, Marjorie Nelson.He is survived by his wife, Jeanne Hansen, beloved Aunt Irene Nelson, former wife Kay Dell Clark, several close cousins and their families, and many dear friends and fellow photographers. His good nature, generous spirit, and fine friendship have made our lives richer for having known him.An open house and celebration of Alan's life will be held December 7 at 3 p.m. at the Lewis and Clark Interpretive Center, 4201 Giant Springs Road, in Great Falls.