Dwarf forest, elfin forest, or pygmy forest is a rare ecosystem featuring miniature trees, inhabited by small species of fauna such as rodents and lizards. They are usually located at high elevations, under conditions of sufficient air humidity but poor soil. There are two main dwarf forest ecosystem types, involving different species and environmental characteristics: coastal temperate and montane tropical regions. Temperate coastal dwarf forest is common for parts of Southern California. Montane tropical forests are found across tropical highlands of Central America, northern South America and Southeast Asia. There are also other isolated examples of dwarf forests scattered across the world.
Elfin forests of California are the primary example of coastal temperate dwarf forests. They are expansive, and cover most of the mountains in the southern half of California, extending into Mexico, Nevada, and Arizona. Other expanses of elfin forest are found throughout the state, in the northern and central regions.
In northern California, Henry Cowell Redwoods State Park is home to an elfin forest with Mendocino cypress (Cupressus pigmaea), and Sargent's cypress (Cupressus sargentii), which is partially within a section of the Zayante Sandhill Area. On the Central Coast of California, on the southeastern shore of Morro Bay, Los Osos contains the El Moro Elfin Forest Natural Area. The area is approximately 90 acres. It derives the “elfin forest” title from the short California live oaks, which range in height from 4 – 20 feet, compared to the typical 30–80 feet. This region also contains the federally endangered Morro shoulderband snail (Helminthoglypta walkeriana). At a higher altitude, on Cuesta Ridge, the Land Conservancy of San Luis Obispo County manages the San Luis Obispo Elfin Forest of dwarf cypresses (Cupressus)