Trees and Wildflowers in Yellowstone and Grand Teton National Parks
Yellowstone National Park and Grand Teton National Parks combined take up a vast area of land (over 3,900 square miles), which houses a wide diversity of terrain, weather, and soils. As a result, flora and fauna can both be found in abundance, and several species are unique to the area. In terms of plant life alone, there are eight species of conifers, approximately 1,700 species of native vascular plants, 170 species of non-native exotic plants that have naturalized in the area and a further 186 species of lichens.
Because of the diversity of the terrain, some species make dry valley beds with hostile soil their terrain, while others are found to predominate in lush meadows and riverbeds. Some thrive in thermal areas, while others do well in alpine areas, near mountain lakes, and in cirques near glaciers.
A Brief History of Plant Life in the Parks
Field and laboratory studies indicate that vegetation has existed in the park for millions of years. Plant fossils show that life in Yellowstone began during the Eocene epoch (which ranged from approximately 58 million to 36 million years ago). Petrified tree stumps in Yellowstone's Lamar Valley have led to the identification of 27 distinct layers of forests, one on top of the other.
Changes in Climactic and Geological Conditions
Climatic conditions during the Eocene period were similar to those now found in the south-eastern and south-central United States. Although it might be difficult to imagine, the area was once a warm, temperate zone in which rainfall averaged 50 to 60 inches per year at what was, at the time, an elevation of only 3,000 feet above sea level.
Vegetation patterns of Yellowstone and Grand Teton regions are now indicative of a cool-temperate to sub-arctic climate. The change from a subtropical climate some 50 million years ago to the present cold climate has been the result of a worldwide lowering of temperature coupled with a geological rise in the entire Rocky Mountain region.
These days, the elevation ranges from 5,000 to 13,000 feet and the average low temperature is approximately 30° F. Hundreds of inches of snow fall each year. Plants have adapted to a growing season that is merely 60 days in duration. As a result, forests which were once populated with hardwoods (such as maple, magnolia, and sycamore) have now been taken over by conifers, the most common of which are pine, spruce, and fir. A smattering of cottonwood and aspen also thrive in the cool park temperatures.
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