Disturbance effect on Ceratozamia fuscoviridis demography: notes about conservation

Disturbance changes the availability of resources over time. Ceratozamia fuscoviridis W. Bull, an endangered endemic Mexican cycad, has intrinsic characteristics that increase its susceptibility to environmental changes. Therefore, the aim of this work was to evaluate the effect of human disturbance on C. fuscoviridis populations. Four sites were monitored over three years using analysis of spatial structure, matrix projection, life table response experiments and a metric disturbance indicator index, that consider a mixture of factors as logging, cattle grazing, erosion, etc. The disturbance increased spatial aggregation and seedling mortality, reducing both density and population growth rates, and eliminated transition between size classes and adult fecundity. Even when populations of C. fuscoviridis can persist over short periods, disturbance is affecting their demographic variables and long-term survival. For effective conservation strategies, the relocation of some plants with high fecundity potential is necessary, the implementation of backyard nurseries is important to guarantee the recuperation of seedlings in depauperated populations aimed at sustainability. Our results are remarkable in the conservation of long-lived plants that depend on the persistence of adults, because the elimination of vegetation cover to establish crops or pasture, without the adult's translocation, eliminates any possibility of regeneration, so the diffusion of this type of works helps the design of environmental education programs and management of natural resources.