Chronic Disturbance Affects the Demography and Population Structure of Beaucarnea inermis, a Threatened Species Endemic to Mexico Article uri icon

abstract

  • Beaucarnea inermis is a threatened plant of the seasonally dry tropical forests of the northeastern Sierra Madre Oriental mountains. It has been affected by habitat loss and fragmentation, mainly from changes in land use and poaching. The number of B. inermis plants, sexual proportion, and structural parameters were recorded in natural populations inside the Sierra del Abra Tanchipa Biosphere Reserve and unprotected sites. Effects of chronic disturbance on demography parameters and asymmetry coefficient were estimated. Average population density is 280 ind*ha−1 inside the protected area and 186 ind*ha−1 in unprotected sites. Life tables indicate a high seedling to juvenile mortality rate, but life expectancy increases in juveniles, suggesting a survival type III curve. Population size distribution skewness indicates differences associated with disturbance. Sex ratio was 0.93:1 (m:f) inside the protected area and 0.76:1 (m:f) in unprotected sites. Anthropogenic disturbance affects life expectancy and the survival and mortality rates mainly in early life classes; however, once the adult stage is reached, mortality rate is reduced and survival rate increases. The natural protected area represents a refuge for the species from the effects of anthropogenic disturbance and illegal poaching. Additional studies are needed to evaluate the genetic diversity in B. inermis in protected and unprotected sites, and how it is affected by disturbance. Also, it is important to highlight other species inside the protected area such as Dioon edule, Zamia fischeri, and Stanhopea tigrina, which are considered as endangered or threatened. © The Author(s) 2018.

publication date

  • 2018-01-01