Effect of seed collection on the structure and dynamics of wild populations of Dioon edule (Zamiaceae)1,2

Abstract

Abstract. The near-threatened cycad Dioon edule (Zamiaceae) is distributed in the Sierra Madre Oriental in Mexico. An important ancestral cultural tradition in the region is seed collecting by indigenous and nonindigenous communities to prepare food up to more than six times a year, without the regulation of the frequency of collection and the number of seeds extracted. In natural conditions, 90% of plants die in the early stages of their life cycle, because of natural and anthropic factors. The objectives of this study were to assess the structure and dynamics of populations where seeds are frequently collected and compare with populations where seed collection does not occur to determine the effect. According to our study of demography, seed collection affects the dynamics and structure of the populations by altering the male:female ratio of plants. This could affect the continuity of the species in the long term, since the number of seeds available for incorporation into the population with the possibility of becoming reproductive adults decreases. It is suggested to design plans that allow the sustainable use of this resource and, in turn, allow the conservation of the traditional knowledge of the Xi iuy indigenous group. Management of sustainable seed collection could be achieved by rotating collection in stands over a minimum period of 15 years, which is long enough to recover the minimum seed production.