Abstract

VELASCO-GARCIA, Mario Valerio et al. Estructura, heterogeneidad de estadios y patrón de dispersión espacial de Dioon holmgrenii (Zamiaceae). Bot. sci [online]. 2016, vol.94, n.1, pp.75-87. ISSN 2007-4476.  https://doi.org/10.17129/botsci.258.

The aims of this research were to determine the structure, heterogeneity of stages, and spatial dispersion pattern of ten populations of Dioon holmgrenii, an endangered species endemic to southern Oaxaca, for conservation purpose. Eleven and nine sampling units were established in conditions without apparent land use change and change in land use, respectively. The developed stages were identified in non-reproductive and reproductive plants, and inside each of them the development stages. The average density of individuals was higher in conditions without apparent land use change (782 plants ha-1) than in change in land use (353 plants ha-1). High percentage of seedlings and adults was occurring in conditions without apparent land use, and low pre-reproductive and juveniles; however, high percentage of adults and low percentage of seedlings, saplings and pre-reproductive were found in condition change in land use. The heterogeneity of stages was higher (P = 0.048) under conditions without apparent land use change (H’ = 1.57) than with change in land use (H’ = 1.38). The similarity was higher in conditions without apparent land use change (I M-H = 0.93, IS CT = 0.81) and within change in land use (I M-H = 0.83, IS CT = 0.61) than among both conditions (I M-H = 0.70, IS CT = 0.53). The spatial dispersion pattern of individuals was primarily aggregate (65 %). Reproductive and non-reproductive individuals were distributed in aggregates 12 and 14 out of 20 sampling units, respectively. The results show that agriculture and grazing affect the structure, heterogeneity of stages and the spatial dispersion pattern; so these should be considered in the future management of populations.

Keywords : density; land use change; perturbation agents; Shannon index; similarity; Ripley.