Abies hidalgensis: Effect of forest extraction on a threatened and microendemic species

Abstract

Demography is a key area for obtaining information for monitoring and conserving threatened plants. Abies hidalgensis is a microendemic species of Hidalgo state, listed as threatened in the category VuD2 in the IUCN Red List but not mentioned in the Mexican regulation NOM-059-SEMARNAT due to low existing information. The aim of this research was to evaluate the effect of forest extraction on demographic aspects of Abies hidalgensis. Individuals over 1.5 m tall and with diameters at chest height over 2.5 cm were censused in nine populations with different management conditions. Seedlings were counted in 0.1 ha circles, and their age was registered. Taller individuals were grouped with a cluster analysis and contrasted between extraction treatments by a generalized discriminant function analysis. These groups were used to build static life tables showing fecundity by stage, and the individual numbers from each treatment and population were resampled with a Markovian 10,000-step bootstrap procedure to calculate a stochastic population growth rate. The seedling data was also contrasted by a generalized discriminant function analysis. An age estimation model was fitted to determine age based on diameters. Forest exploitation causes loss of the biggest trees, leading to a notable change of the population structure with an increase of seedlings, loss of fecundity, dominance of small plants, average age decrease, and a decrease in the stochastic population growth rate. However, even when the nine populations are growing, management activities generate a greater risk of mortality in the initial stages and loss of fertile adults.