Fern and lycopod spores rain in a cloud forest of Hidalgo, Mexico

The aim of this study was to determine the composition of the “spore rain” of ferns and lycopods in a cloud forest. We tested whether the canopy impedes spore dispersal to surrounding areas and how spore dispersal is affected by rainfall. The spores were captured with a modified Bush–Gosling trap placed at 30 cm above ground level in forested and non-forested sites from March 2009 to February 2010. We collected 2462 fern spores from 158 morphospecies of which 76 were identified to species level. Thirty-seven species were found exclusively in the spore rain, and 39 were found as sporophytes as well (local component). Mean daily spore density (spores m −2 ) was calculated to find the sporulation period for each species. Twenty species showed seasonal patterns of sporulation. The highest spore density was found at the forested site (70 morphospecies and 1856 spores), of which 39 morphospecies (1482 spores) corresponded to the local vegetation. Fifty-five taxa were shared between the forested and non-forested site. In the non-forested site, 605 spores were captured belonging to 64 species. The density of spore rain between sites was significantly different. The rainfall amount was the same at both sites, with a dry period in March, April, and July 2009, and February 2010. There was a negative effect of rainfall on spore rain. The main sporulation occurred in the dry season with strong winds. Although the canopy inhibits airborne dispersal of fern spores, a small amount of spores can disperse beyond the canopy and reach surrounding areas. The rainfall might wash spores to ground and favor the colonization and the establishment of new populations.