Due to habitat degradation and extensive hunting, the desert bighorn sheep is seriously threatened throughout the southwestern United States. As this distinct subspecies became rarer and harder to obtain, the value for trophy hunting of desert bighorn sheep has increased dramatically (the permit for one sheep can cost as much as $200,000). Consequently, wealthy private land owners have purchased extensive mountain ranges from various ejidos in order to privately manage profitable hunting reserves, known as Ranchos Cinegeticos. The mountain ranges to the east (Sierra Viejo), and to the south (Sierra Julio) of San Lorenzo, are currently active examples of these private hunting ranches. The ejido of Avila Camacho has the area of San Lorenzo registered as a hunting ranch. This is not because bighorn sheep are actively hunted there, but rather in order to allow the neighboring hunting ranches (Sierra Viejo, and Sierra Julio) to follow and kill a sheep on the land, if they need to. If a kill does occur on the land of San Lorenzo, the ejido would receive 10% (about $20,000) of the value of the hunting permit.

In addition to large herds of desert bighorn sheep, the area of San Lorenzo also harbors other threatened and endangered species, such the Gila monster (Heloderma suspectum), and the desert tortoise (Gopherus agassizi), both of which are species sensitive to arthropogenic impacts, and illustrates the fact that the area of San Lorenzo encompasses a vast expanse of pristine Sonoran desert.

The vegetation of the area supports this contention, especially by the fact that nonnative species have yet to be found (West, pers. comm.). The vegetation of San Lorenzo is remarkably diverse, representing transition zones of various Sonoran Desert subdivisions. This is exemplified by the columnar cacti, represented by four species, saguaro (Carnegia gigantea), sinita (Lophocereus schottii), organ pipe (Stenocereus thurbei), and cardon (Pachycereus pringlei). Some of the floral assemblages reach their northern most extension here such as foothills thornscrub in the mountains, and mangrove estuaries in the vicinity of Puerto Lobos (Brown and Lowe 1980, Brown 1994). The predominant vegetation is that of the Central Gulf Coast subdivision, which contain a significant number of species of disjunct populations that are localized to this area in Sonora, yet widely distributed on the Baja California peninsula (Brown 1994). Of particular interest is the boojum tree (Foqueria columnaris), which is characteristic of the Vizcaino region on the Baja California peninsula and occurs in the mountain range of Sierra Cirrio, just south of San Lorenzo (Humphrey 1974). Unfortunately, Sierra Cirrio is now a private hunting ranch and access is prohibited or very limited at best, even to the local communities that have historically used the land.

Also found on San Lorenzo, are extensive growths resembling forests of cardon cacti (Pachycereus pringlei) and elephant tree (Bursera microphylla, and B. hindsianum). The cardon is an awesome columnar cactus that dwarfs the saguaro (Carnegia gigantea), both in height and mass. Please note the size of the person bellow the cardon cactus in the following picture.