Wood density, deposits and mineral inclusions of successional tropical dry forest species

Wood water content, wood dry mass fraction, wood deposits and mineral inclusions separately affect wood mechanical properties, as well as plant survival and growth rates. Tree species occurring in recovering vegetation from deforestation face water stress, which is a particularly strong environmental filter in tropical dry forest regions. In this study, we analyze wood density and its associated variables of tree species present in early and late successional communities. We assessed and compared their wood density, wood water content, wood dry mass fraction, as well as wood cellular deposits, secretory elements and mineral inclusions which were described through anatomical sections. Wood density ranged from 0.10 g/cm3 (Jacaratia mexicana in late successional community) to 0.92 g/cm3 (Lysiloma divaricatum in early successional community). Successional species showed low intraspecific variability, despite large differences in the environmental conditions in the communities where they grow. Species with high wood water content were restricted to late successional communities, and pioneers showed higher wood density than non-pioneer species, which supports the linkage between high wood density and harsh environmental filtering through hydraulic safety. Wood density did not differ between columnar cacti (Pachycereus pecten-aboriginum and Pilosocereus collinsii) and tree species such as Bursera simaruba. Starch, tannins and crystals were abundant in most successional species and some species had gums; these deposits could potentially influence wood density and hydraulic, defense and storage plant functions. Our results suggest that modifications in the life cycle of successional tropical dry forest tree species due to anthropogenic activities may not be an important source of wood density variation.