Abstract

Germination and soil seed bank traits of Podocarpus angustifolius (Podocarpaceae): an endemic tree species from Cuban rain forests
Pablo Ferrandis, Marta Bonilla & Licet del Carmen Osorio

ABSTRACT

Podocarpus angustifolius is an endangered recalcitrant-seeded small tree, endemic to mountain rain forests in the central and Pinar del R�o regions in Cuba. In this study, the germination patterns of P. angustifolius seeds were evaluated and the nature of the soil seed bank was determined. Using a weighted two-factor design, we analyzed the combined germination response to seed source (i.e. freshly matured seeds directly collected from trees versus seeds extracted from soil samples) and pretreatment (i.e. seed water-immersion for 48h at room temperature). Germination was delayed for four weeks (≈30 days) in all cases, regardless of both factors analyzed. Moreover, nine additional days were necessary to achieve high germination values (in the case of fresh, pretreated seeds). These results overall may indicate the existence of a non-deep simple morphophysiological dormancy in P. angustifolius seeds. The water-immersion significantly enhanced seed germination, probably as a result of the hydration of recalcitrant seeds. Although germination of seeds extracted from soil samples was low, probably due to aging and pathogen effects throughout the time of burial, the study revealed the existence of a persistent soil seed bank (at least short-termed) of ≈42 viable seeds per m² in the upper 10cm of soil. Such a record is noteworthy since references to persistent soil seed banks in recalcitrant-seeded species are scarce in the literature. The population consequences derived from the formation of persistent soil seed banks in this endangered species are discussed.

RESUMEN

Podocarpus angustifolius es un �rbol end�mico de los bosques lluviosos de la regi�n de Pinar del R�o y la parte central de Cuba, que se encuentra en peligro de extinci�n. En este estudio se evalu� la germinaci�n de sus semillas y la naturaleza del banco de semillas del suelo. Espec�ficamente, se analiz� la respuesta germinativa de las semillas a dos factores: su procedencia (recolectadas directamente de los �rboles versus extra�das de muestras de suelo) y el pretratamiento (inmersi�n en agua durante 48h a temperatura ambiente). La germinaci�n no comenz� hasta las cuatro semanas (≈30 d�as) en todos los casos. Adem�s, fueron necesarios 9 d�as m�s para alcanzar un valor elevado de germinaci�n (en el caso de semillas recolectadas del �rbol con pretratamiento), lo que parece indicar la existencia de un letargo de tipo morfofisiol�gico simple no profundo. El pretratamiento increment� significativamente la germinaci�n, posiblemente por hidrataci�n de las semillas recalcitrantes. El estudio demostr� la existencia de un banco de semillas persistente en el suelo, al menos de corta duraci�n de ≈42 semillas viables por m² en los 10 primeros cm del suelo. Dicho hallazgo es destacable, ya que los casos descritos en la literatura sobre bancos persistentes en especies con semillas recalcitrantes son escasos. Adem�s, se discute la importancia que tiene para esta especie amenazada la existencia de un banco de semillas persistente.