Question: The Sabal uresana is threatened by what is the Sierra Madre Occidental?
Context: The Sierra Madre Occidental is a major mountain range system of the North American Cordillera, that runs northwest–southeast through Northwestern and Western Mexico, and along the Gulf of California.  The Sierra Madre is part of the American Cordillera, a chain of mountain ranges (cordillera) that consists of an almost continuous sequence of mountain ranges that form the western "backbone" of North America, Central America, South America and Antarctica. The Sierra La Esmeralda range, (Emerald Mountains) are a mountain range in northern Sonora, Mexico at the northern region of the Sierra Madre Occidental cordillera.  The region contains sky island mountain ranges, called the Madrean Sky Islands, some separated from the Sierra Madre Occidental proper, and occurring in the northeastern Sonoran Desert, and extreme west-northwestern Chihuahuan Desert.  Many of the ranges occur in southeast Arizona. Sabal uresana, commonly known as the Sonoran palmetto, is a species of palm tree that is native to the foothills of the Sierra Madre Occidental in northwestern Mexico (states of Chihuahua and Sonora).  The specific epithet, ""uresana"", refers to Ures, Sonora, a town within its range.  It is threatened by habitat loss. The Sierra Madre Occidental pine-oak forests are a subtropical coniferous forest ecoregion of the Sierra Madre Occidental range from the southwest USA region to the western part of Mexico.  They are home to a large number of endemic plants and important habitat for wildlife. Mexican Federal Highway 24 ("Carretera Federal 24") is a Federal Highway of Mexico.  Highway 24 is intended to cross the Sierra Madre Occidental from the area of Hidalgo del Parral, Chihuahua, on the east, to the area of Culiacán, Sinaloa, on the west.  A limited central section of about 40 to 50 km is not yet completed or graded.  This section lies between the villages of Los Frailes, Durango, on the east, and Soyatita (also known as El Sabino), Sinaloa, on the west.  Travel is possible through this area, where the road is not yet completed, on unimproved roads using high clearance two-wheel drive vehicles.  The two unconnected segments that extend through Los Frailes and Soyatita are graded, but each segment is unpaved for about the last 75 km.  The central gap in the highway is in the rugged mountains of the Sierra Madre Occidental.  This uncompleted and unpaved portion of the road is not well signed, there are many intersections with other unpaved roads, and it is easy to get lost off the intended route of the highway.  As noted later, getting lost may not be a safe proposition.  Further, the unfinished segment on the west is at about 820 meters elevation at Soyatita.  Just outside Los Frailes, the road coming from the east is at 2,750 meters elevation.  The traveler crossing this gap will have to negotiate this dramatic change in elevation traveling a good deal of the way on unimproved dirt roads.  Travel times in this central section could be quite slow. The Sierra Madre frog, Lithobates sierramadrensis, is a species of frog in the Ranidae family endemic to the Sierra Madre del Sur in Guerrero and Oaxaca states, Mexico.  Its local name is "rana de Sierra Madre Occidental".  Its natural habitats are conifer forests at intermediate elevations.  Breeding takes place in streams.  It is threatened by habitat loss (logging) and possibly chytridiomycosis. Copper Canyon (Spanish: Barrancas del Cobre) is a group of canyons consisting of six distinct canyons in the Sierra Madre Occidental in the southwestern part of the state of Chihuahua in northwestern Mexico.  The canyons were formed by six rivers that drain the western side of the Sierra Tarahumara (a part of the Sierra Madre Occidental).  All six rivers merge into the Rio Fuerte and empty into the Gulf of California.  The walls of the canyon are a copper/green color, which is where the name originates. The Sierra San Luis range is a mountain range in northwest Chihuahua, northeast Sonora, Mexico at the northern region of the Sierra Madre Occidental cordillera.  The region contains sky island mountain ranges, called the Madrean Sky Islands, some separated from the Sierra Madre Occidental proper, and occurring in the northeastern Sonoran Desert, and extreme west-northwestern Chihuahuan Desert.  Many of the ranges occur in southeast Arizona. The Chinipas is a large river of Mexico.  The Chinipas arises deep in the Sierra Madre Occidental in the state of Chihuahua, and then flows through long rugged canyon systems into the state of Sinaloa until it finally joins the main trunk of the Fuerte River in the western foothills of the Sierra Madre Occidental.  The Fuerte River then flows westward over the western coastal plain of Sonora to the Pacific Ocean, emerging very near the port of Topolobampo. Sierra del Tigre is a mountain range in northeastern Sonora, Mexico at the northern region of the Sierra Madre Occidental.  The region contains sky island mountain ranges, called the Madrean Sky Islands, some separated from the Sierra Madre Occidental proper, and occurring in the northeastern Sonoran Desert, and extreme west-northwestern Chihuahuan Desert.  Many of the ranges occur in southeast Arizona.
Answer: habitat loss