On the cunoniaceae seed (non) dormancy of ten species in seven genera and its persistencen the seasonal but unpredictable environment of New Calidonia

Abstract

Seed dormancy is stated to contribute to species survival. It is common in Angiosperms as well as seed nondormancy. The proportion of species having nondormant seeds differs among biomes. Seed nondormancy is expected to present specific advantages in predictable and stable biomes like in tropical regions. One of the most important abiotic factors within the environment is the climate. Indeed, abiotic factors as selection force could trigger seed dormancy strategies. Using available data in Cunoniaceae, we found that ten species in seven genera can be considered to have nondormant seeds. These species are widespread all over the family phylogenetic tree. These findings enhance our knowledge for plant conservation and ecological restoration since dormancy and germination are key issues in these domains. Oceania is the richest place in the world for Cunoniaceae and is overrepresented in New Caledonia, making them an interesting case to study. New Caledonian climate is tropical but expresses seasonal pattern and has unfavourable seasons for plant establishment. The Gondwanian family Cunoniaceae tends to display seed nondormancy, although species can fruit and disperse not only during the suitable season. Dispersion of nondormant seeds could occur outside the wet and favourable season. Together with heterogeneity over time and space, species have to face remarkable different conditions. Temperature is elevated most of the year yet rainfall can differ dramatically between years. The irregularity of the rainfall could offer an explanation for this previously unidentified strategy of phenology{dollar})" nondormancy, regards of the climate. The hypothesis that unpredictable rainfall could trigger seed nondormancy or allow its persistence, as one efficient strategy that may be adequate in this unique environment that is New Caledonia.