Growth rates and relative change in non-structural carbohydrates of dipterocarp seedlings in response to light acclimation

Background Light is a driver of tropical forest dynamics and key to understanding the coexistence of dipterocarps, and how their key demographic rates and traits trade-off with acclimation to light. Aims Light is a driver of tropical forest dynamics and key to understanding the coexistence of dipterocarps, and how their key demographic rates and traits trade-off with acclimation to light. Methods We examined the relationship between size-specific growth rates (SGR), wood density and total non-structural carbohydrate (NSC) concentration under experimental shade house conditions. Results Based on their functional response to light acclimation we grouped dipterocarps into light demanders, shade-tolerants and a generalist species. Light demanders respond to a simulated gap opening with increased growth, whereas shade-tolerants and the generalist show a higher relative change in wood density and NSC concentration, including starch and water soluble carbohydrates. Iditol–a hitherto unknown alditol in dipterocarps–was identified across all six species, and the generalist responded to a gap opening with a significantly reduced relative change in alditol concentration compared to light demanders and shade-tolerants. Conclusions Selected dipterocarps can be grouped into light demanders and shade-tolerants based on their acclimation to light, however, the generalist species did not follow the proposed growth-storage trade-off.