C04-How Critical Are Early Life-cycle Stages in Pop. Ecol. of Cycads? MEM 106

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7/10/2020 1:08:37 AM

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The distribution range of Dioon merolae is restricted to the Mexican states of Chiapas and Oaxaca. The number of individuals remaining in the wild is below 5000. Thus, it is considered a vulnerable species. Yet, its main ecological features are unknown. In this study we address the ecology of its early life-cycle stages: seed set, seed removal, and seedling survival under different light intensity and soil depth conditions. The population structure is dominated by adults, whereas seedlings and juveniles were scarce. Seed set was 76%. Seedling survival was 37% after eight months and was not affected by either of the experimental factors. Seed removal reached 10– 20% after only five days and was affected by time and seed density. Apparently, seed production and seedling survival (at least within the seedling sizes explored) do not limit population growth. The critical life-cycle process must be the survival of recently emerged seedling.