Fern spore dispersal: A methodological review and experimental field study

Abstract Spore dispersal is one of the most important but perhaps the least investigated and understood processes in determining the geographical distribution of fern species. After a methodological review of the aerobiology of fern spores, we examined the impact of spore characteristics and meteorological factors on their airborne dispersal. We conducted experiments of spore release‐recapture for five fern species at distances of up to 60 m under different meteorological conditions and outside of their natural habitats to determine whether their dispersal potential is related to their morphological characteristics (e.g., ornamentation, size, terminal velocity, and mass). Spore dispersal was affected by spore size and terminal velocity, relative air humidity, wind speed, and wind direction. At all sampling distances, most spores were recaptured in the highest traps (1.4 m), indicating a higher dispersal capacity than previously assumed. The spores with the lowest settling speed were the least recaptured in all spore traps, indicating their high airborne potential to disperse over even greater distances. In future studies, it will be necessary to determine the seasonal variation of spore release of individual plants, as well as the potential dispersal of fern spores in situ (e.g., forest understory) and ex situ under controlled conditions (e.g., in wind tunnels).