REGENERATION NICHE OF ABIES RELIGIOSA (KUNTH) SCHLTDL. & CHAM. ON MOUNT TLáLOC, IZTACCíHUATL-POPOCATéPETL NATIONAL PARK, MéXICO

Abstract

Background: The physical and biological factors involved in the survival and mortality risks of seedlings are important to understand the natural processes associated with their establishment in a spatio-temporal context. Objectives: Identify which environmental factors define the regeneration niche of Abies religiosa based on the survival and mortality risks of its seedlings. Methods: Seventeen plots of 1 m2 were established and all the seedlings of the 2019 cohort were located, numbered and measured in height, number of embryonic leaves, number of nodes and visible damage and followed for a year. The properties of the soil surrounding the plots were determined. In each plot, hemispheric photographs were taken and based on them, the canopy was stratified into two categories: partially closed and open. Analyses were performed with the SAS LIFETEST and LIFEREG procedures. Results: The seedling survival curves were different between the canopy categories (Log-Rank: c2 = 8.35, gl = 1, P < 0.05). The probability of survival under open canopy was higher (0.29 ± 0.01) than under partially closed canopy (0.20 ± 0.01). The variables with positive effects on survival times were: height and number of nodes; proportion of direct sunlight, bulk density of the soil, mean temperature, mean humidity and its coefficient of variation, and the variation of the soil saturation point. Conclusions: These covariates define the regeneration niche of A. religiosa.