The forests and mountains of western North America stretch east from the Sierra Nevada and Cascade Ranges to the great Rocky Mountains and are among the most magnificent natural wonders in the world. Across western North America, from the Rocky Mountains to the Pacific Ocean, these successive mountain ranges and alternating lowlands form a deeply ridged landscape characterized by extremes of elevation, climate, and vegetation. Most likely created by the collision of tectonic plates millions of years ago, the landscape has been shaped since then by precipitation, temperature, and events such as fire, avalanches, and windstorms.
Western forests are dominated by conifers and boast some of the largest, tallest, and oldest trees found on the planet. The climate varies widely by season and location. The region encompasses natureâ€™s extremes, ranging from hot, dry lands that push the limits for sustaining life, to cold alpine areas perched on high mountains. At present, much of the West is semi-arid and subject to variable precipitation that can result in drought and floods. Throughout much of the region, fires play a critical role in the development of forest, woodland, and shrubland vegetation.
The grand landscapes of the West provide both abundance and scarcity. Diverse habitats found throughout the western forests provide homes to a host of wildlife. During the summer months, bears, elk, and moose stockpile energy for the leaner winter months. However, natureâ€™s extremes also make this ecoregion a difficult place to live. Water, the essential ingredient for life, is scarce when it is most needed and long dry spells set the conditions for wildfire.