Question: Which large, widely distributed pine species is dominant on the west side of the Ochoco Mountains of Oregon?
Context: Trout Creek is a 51 mi long tributary of the Deschutes River in the U.S. state of Oregon.  It drains approximately 692 mi2 of Crook, Jefferson, and Wasco counties.  Arising in the Ochoco Mountains, it flows north and then west to its confluence with the Deschutes River. Pinus ponderosa, commonly known as the ponderosa pine, bull pine, blackjack pine, or western yellow-pine, is a very large pine tree species of variable habitat native to the western United States and Canada.  It is the most widely distributed pine species in North America. Willow Creek is a tributary, about 26 mi long, of the Deschutes River in central Oregon in the United States.  Arising near Foley Butte in the western Ochoco Mountains in Crook County, it flows generally northwest into Jefferson County and through the Crooked River National Grassland.  The creek continues through the city of Madras and becomes the dividing line between two plateaus, Agency Plains and Little Agency Plains.  It then enters the Deschutes above Pelton Dam and its impoundment, Lake Simtustus, about 105 mi from the river's confluence with the Columbia River. The North Fork Crooked River is a tributary, 46 mi long, of the Crooked River in the U.S. state of Oregon.  Beginning in the Ochoco National Forest and the Ochoco Mountains east of Prineville, it flows north, then east, then south-southwest to meet the larger stream between Post and Paulina.  The confluence is 111 mi upstream of where the Crooked River flows into the Deschutes River. The Ochoco Mountains are a mountain range in central Oregon in the United States, located at the western end of the Blue Mountains.  They were formed when Permian, Triassic, and Jurassic rocks were slowly uplifted by volcanic eruptions to form the Clarno Formation.  Today, the highest point in the range is Lookout Mountain.  The dominant vegetation on the west side of the range is old-growth ponderosa pine; on the east side, western juniper is common.  The western area of the mountains is administered by the Ochoco National Forest, while the southeastern section is part of the Malheur National Forest.  The Ochoco Mountains are used for hiking, camping, bird watching, rockhounding, and hunting, as well as cross-country skiing in the winter. The Jack Pine is a well-known oil painting by Canadian artist Tom Thomson.  A representation of the most broadly distributed pine species in Canada, it is considered an iconic image of the country's landscape, and is one of the country's most widely recognized and reproduced artworks. Lomatium ochocense is a rare species of flowering plant in the carrot family known by the common name Ochoco lomatium.  It is endemic to Oregon, where it is limited to the Ochoco Mountains of Crook County. The John Day Formation is a series of rock strata exposed in the Picture Gorge district of the John Day River basin and elsewhere in north-central Oregon in the United States.  The Picture Gorge exposure lies east of the Blue Mountain uplift, which cuts southwest–northeast through the Horse Heaven mining district northeast of Madras.  Aside from the Picture Gorge district, which defines the type, the formation is visible on the surface in two other areas: another exposure is in the Warm Springs district west of the uplift, between it and the Cascade Range, and the third is along the south side of the Ochoco Mountains.  All three exposures, consisting mainly of tuffaceous sediments and pyroclastic rock rich in silica, lie unconformably between the older rocks of the Clarno Formation below and Columbia River basalts above. The Allison Ranger Station is a Forest Service compound consisting of eight rustic buildings located in the Malheur National Forest in the Ochoco Mountains of eastern Oregon.  It was originally built as a district ranger station for the Snow Mountain Ranger District.  It was later converted to a summer guard station.  Today, it is an active Forest Service guard station with a crew of twelve fire fighters on station during the summer fire season.  The ranger station’s oldest building, the "Donnelly Cabin", is currently listed on the National Register of Historic Places.  Most of the other buildings at the Allison Ranger Station are eligible for historic designation, but are not yet listed on the national register. Bridge Creek Wilderness is a wilderness area located in the Ochoco Mountains of central Oregon, within the Ochoco National Forest.  It was established in 1984 and comprises 5400 acre , making it one of the smallest Wilderness areas in the state.
Answer: Pinus ponderosa