Seedling establishment of Quercus insignis: A critically endangered oak tree species in southern Mexico

Quercus insignis has some of the largest acorns of any oak in the world and according to current red lists is considered critically endangered in Mexico and near threatened in Guatemala and Panama. In spite of this there have been no studies of its regeneration ecology with the aim of implementing species recovery plans. In this study, one-year-old seedlings were introduced into an abandoned grassland where Q. insignis adults were present in small remnant forest patches. A total of 1044 seedlings were planted and their survival and growth monitored over four years. An experiment was designed to test the relative effects of seeding location (open area vs. under vegetation cover) and soil treatment (native soil vs. soil with compost). After 50 months, only 26% of the seedlings planted survived; plants growing in shade had higher survival (34.4 vs. 18.6%) and increased more in height (0.0264 ± 0.010 vs. 0.0207 ± 0.011 cm cm−1 month−1, respectively) than seedlings growing in full light (P < 0.05). Seedlings growing in full light died more rapidly than seedlings growing under vegetation cover (P < 0.05). Mortality was due to several interacting factors, mainly herbivory by voles and gophers, and desiccation under extreme temperatures. A higher proportion of the dead seedlings had been damaged by gophers and voles in the open area compared to seedlings growing under vegetation cover (P < 0.05). The implications of these results are discussed with respect to conservation and restoration strategies for this species.