Demography and population structure of Dioon angustifolium (Zamiaceae) in northeastern Mexico

Abstract

Background: Dioon angustifolium is an endemic species distributed in the northernmost Sierra Madre Oriental in Mexico. It is classified as an endangered species due to anthropogenic activities like illegal extraction for commercial purposes. Question: What is the current status of Dioon angustifolium populations structure in its distribution range? Species under study: Dioon angustifolium Miq. (Zamiaceae), an endemic species of the Sierra Madre Oriental in Mexico. Study area and years of study: The study was conducted in three populations of D. angustifolium in Nuevo León and Tamaulipas during the summer of 2018. Methods: The density and population structure of D. angustifolium was determined by transects of 100 m long. For each of the analyzed populations, a static life table was built. Results: The highest density corresponded to the DA1 population and the lowest to DA3. This last population is dominated by individuals in the juvenile phase. The life tables indicate a high mortality rate in the first stages of establishment, which causes the populations to be in decline due to the lack of recruitment of new individuals. Conclusions: The extraction of individuals for commercialization, as well as the change of land use decreases the size of the populations. According to information provided by locals, seeds are used to cook food like tortillas and atole, without having data on extraction volumes to quantify the effect on population dynamics.