Germination responses to light of four Neotropical forest tree species along an elevational gradient in the southern Central Andes

Abstract

Seed germination is a key part of plants´ life cycle and is mostly affected by thegenetic background, the environmental conditions experienced by the motherplant and the seedbed conditions. The germination response to light is essen-tial to optimize germination and seedling establishment in space and time. Inaddition, the germination response to light is a trait often related to theresponse of the seeds to their position in the soil (uncovered/buried). Here, westudied the germination response to light of four key tree species of the Yungasforest (Anadenanthera colubrina, Enterolobium contortisiliquum, JacarandamimosifoliaandHandroanthus impetiginosus) sampled along an elevationaland environmental gradient with contrasting vegetation cover and distur-bance. Relative light germination (RLG) and mean germination time (MGT)were determined. Final germination was tested under cycles of light (8 h) anddarkness (16 h) versus complete darkness (24 h) and elevation, and MGT wastested as a function of elevation of the provenance. The RLG increased fromsmaller to larger-seeded species. The MGT of three of the studied species wasaffected by the elevation of the provenance. Complete darkness negativelyaffected final germination, while two species exhibited a significant interactionbetween the provenance and light. The variable germination responses to lightalong the elevational gradient highlights the influence of the environment ongermination as a key factor that should be considered for forest management,conservation and restoration projects.