Seed germination and seedling establishment of Neotropical dry forest species in response to temperature and light conditions

Background

Site conditions in restoration projects vary widely, with proper conditions for germination not always available for a given species. This study examines the germination requirements of Cedrela odorata, Guaiacum sanctum and Calycophyllum candidissimum seeds under varying light conditions beneath the canopy of a dry forest in Nicaragua.

Research goals & methods

Seeds of C. odorata, G. sanctum and C. candidissimum were sown in a nursery under variable temperature and light conditions. Germination of C. candidissimum seeds was significantly higher in light than darkness at constant temperatures ranging from 20–35 C. Both C. odorata and G. sanctum seeds germinated in light and darkness, and the optimal germination temperature was around 20-25 C. C. odorata and G. sanctum seedlings were also planted in open, partially-open and closed dry-forest canopy. Survival of G. sanctum seedlings was 70% beneath the canopy and 80% in the open, with slightly faster diameter growth in the open. Survival was generally poor for C. odorata, particularly in the understory.

Conclusions & takeaways

We concluded that light is an absolute requirement for the germination of C. candidissimum seeds while germination of C. odorata and G. sanctum seeds are more sensitive to temperature. Owing to its high survival rate on open site, G. sanctum could serve as a candidate species for reforestation of degraded sites.