The Sierra Nevada ecoregion harbors one of the most diverse temperate conifer forests on Earth, displaying an extraordinary range of habitat types and supporting many unusual species. They are home to an enviable variety of conifers including the Giant sequoia
). Giant sequoias are the largest trees on Earth in terms of total volume, with some trees 83 meters (273 ft) tall, over 10 meters (36 ft) in diameter, and over 3,200 years old.
Most conifers here are adapted to a climate of cool, wet winters and warm, dry summers. Other conifer species, such as ponderosa pine, are more tolerant of hot, dry ridges, while species such as Jeffrey pine dominate the Sierra Nevada’s' eastern slopes where colder, drier winters are the norm.
Four National Parks, Lassen, Yosemite, Sequoia, and Kings Canyon, and some National Forest Wilderness Areas, harbor the largest remaining blocks of relatively intact montane mixed conifer forests.