Format: ORAL

Catalina Flores-Galvn1, Judith Mrquez-Guzmn2, Martn Mata-Rosas3, James E. Watkins Jr.4, Klaus Mehltreter1

1 Red de Ecología Funcional, Instituto de Ecología, A.C., Xalapa, Veracruz, México 2 Departamento de Biología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México, México 3 Red de Manejo Biotecnológico de Recursos, Instituto de Ecología, A.C., Xalapa, Veracruz, México 4 Department of Biology, Colgate University, Hamilton, New York, USA

Many plants grow only on specific soil types. Ferns are no exception. In the family Pteridaceae, many fern species are limited to alkaline limestone or acidic volcanic soils. Although the reasons for soil specialization of plants have received some attention, our knowledge about the consequences of growing on alkaline or acidic substrates is poor. Consequently, we studied the distribution of 19 fern species on 37 sites and the mineral nutrient composition of the shallow soils as well as calcicole (limestone-loving) and calcifuge (limestone-avoiding) fern species in central Mexico, supposing that the former will have higher Ca and lower Al and P concentrations than the latter. All fern species, except the soil-indifferent Myriopteris aurea, were restricted to one soil type. As expected, calcicole fern species had higher nutrient contents except for P and Mn, but surprisingly they also contained higher amounts of Al and Fe. This was even more surprising because limestone soils had only higher pH and Ca concentrations, but lower concentrations of exchangeable Fe and P. These results indicate that calcicole fern species possess limited or no mechanism to avoid the uptake of Al but are more efficient in absorbing Fe and P, even when those concentrations are lower than on acidic soils. On the other hand, calcifuge fern species can limit the uptake of Al but are not as efficient as calcicole fern species in absorbing Na, K, Mg, S, and N even if these nutrient elements are available at similar concentrations as on limestone soils. However, there is a considerable variation in the nutrient concentrations of each fern species, which implies that they also differ in their nutrient metabolism independently from the exchangeable nutrient concentrations of the soils.