Acclimation of seedlings of Gnetum leyboldii Tul. Gnetaceae to light changes in a tropical rain forest

• Main Authors: Gerardo Celis, Gerardo Avalos
• Format: Article
• Language: English
• Published: Vicerractoría Investigación 2013-12-01
• Series: Revista de Biología Tropical
• Subjects: Gnetum leyboldii; lianas; aclimatación fotosintética; adaptación a la sombra; distribución de biomasa; germinación criptocotilar; Costa Rica
• Online Access: http://www.scielo.sa.cr/scielo.php?script=sci_arttext&pid=S0034-77442013000500023&lng=en&tlng=en

The neotropical liana Gnetum leyboldii Gnetaceae is a gymnosperm that resembles angiosperms in wood anatomy, overall morphology, and seed dispersal mechanism. Like other woody lianas, seedlings germinate in the shaded forest understory and start climbing towards the canopy, being eposed to sites with etreme differences in light conditions. However, the etent of physiological and structural adjustment to contrasting light conditions in the early regeneration stages of Gnetum is unknown. To answer this question, we analyzed seedling growth and photosynthetic responses using a common garden eperiment with two light regimes: full sun and low light 20 of full sun at La Selva Biological Station, Costa Rica. We also characterized the germination pattern of this species. We monitored one and half-month old seedlings for four months. Leaf structure finely adapted to light treatments, but gas echange properties were buffered by large seed reserves, which dominated biomass distribution about 50 of the total biomass, followed by stem 27, leaf 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 eploit deep shade. More research is needed to determine if the patterns found in G. leyboldii are typical of similar lianas that initially eploit deep-shaded understories in their ascension to the canopy.