Seedling bank dynamics of Fagus grandifolia var. mexicana before and after a mast year in a Mexican cloud forest

Abstract

Abstract. Fagus grandifolia var. mexicana seedling dynamics were studied in a relict forest inside the crater of a volcano where it is the only canopy tree species. The objectives of the study were (1) to determine changes in seedling density before and after a mast year, as well as to monitor seedling recruitment, mortality and growth rate in relation to the micro‐environment, and (2) to discuss the impact of masting on seedling dynamics of the population. Before masting, seedling density was 8.8 seedlings m–2, afterwards seedling density peaked at 51.5 seedlings m–2, then decreased by 50% in 3 months and by 85% after 8 months, down to levels of before the mast year (9.9 seedlings m–2) after 16 months. Seedlings in the forest floor before the mast‐seeding event showed a low relative growth rate – 0.14 mm mm–1 mo–1 against 1.27 mm mm–1 mo–1 for seedlings that emerged immediately after masting. Seed germination was high (83%) and rapid (L50= 7 days) following masting. Seedling growth was positively correlated with soil water content but not with temperatures and relative humidity. Data suggested that seed production in mast years is important in maintaining the seedling bank, and thus the viability of relict Fagus populations.