Acclimation of seedlings of Gnetum leyboldii Tul. (Gnetaceae) to light changes in a tropical rain forest
Celis G; Avalos G
Revista de Biologia tropical
The neotropical liana Gnetum leyboldii (Gnetaceae) is a gymnosperm that resembles \r\nangiosperms in wood anatomy overall morphology and seed dispersal mechanism. Like other woody lianas \r\nseedlings germinate in the shaded forest understory and start climbing towards the canopy being exposed to \r\nsites with extreme differences in light conditions. However the extent of physiological and structural adjustment to contrasting light conditions in the early regeneration stages of Gnetumis unknown. To answer this \r\nquestion we analyzed seedling growth and photosynthetic responses using a common garden experiment with \r\ntwo light regimes: full sun and low light (20% of full sun) at La Selva Biological Station Costa Rica. We also \r\ncharacterized the germination pattern of this species. We monitored one and half-month old seedlings for four \r\nmonths. Leaf structure finely adapted to light treatments but gas exchange properties were buffered by large \r\nseed reserves which dominated biomass distribution (about 50% of the total biomass) followed by stem (27%) \r\nleaf (16%) and root biomass (6%) across light conditions. The presence of large seeds and the low photosynthetic rates of seedlings in both environments show that G. leyboldii is specialized to exploit deep shade. More \r\nresearch is needed to determine if the patterns found in G. leyboldiiare typical of similar lianas that initially \r\nexploit deep-shaded understories in their ascension to the canopy.