Ecological aspects and conservation status of Mammillaria theresae (Cactaceae)

We analyzed some aspects of the ecology, distribution, and conservation status of Mammillaria theresae Cutak (Cactaceae), a narrow endemic to the Sierra de Coneto in central Durango, Mexico. Because its isolation, this sierra has ecological and phytogeographical importance. It is located at the east of the Sierra Madre Occidental and on the western boundaries of the Chihuahuan Desert, and it is the only known locality for M. theresae and for a genus recently described (Megacorax, Onagraceae). Mammillaria theresae is a highly appreciated species which is locally known as peyote and peyotillo. Its population is being severely affected mainly due to the construction of a road. We evaluated the present situation of the species as well as the environmental factors with which it is related. We studied the population size from seven plots sampled across its distribution area. Density, cover and frequency of M. theresae and its associated species were measured, and 126 individual plants were monitored to record its fenology and dispersal mechanisms. The species grows over 1.7 ha distributed over approximately 2.5 square km along an elevational range between 2180 and 2320 m a.s.l. Because its restricted distribution, size of the population, and increasing destruction and fragmentation of its habitat, it is considered as an endangered species. This information can be used to design a plan to protect the species from further decline.