Disentangling the influence of ecological and historical factors on seed germination and seedling types in a Neotropical dry forest

Abstract

In tropical dry forests, although seed germination and seedling establishment are in general limited by the seasonal availability of water, high interspecific variability, nonetheless, exists in terms of seedling traits and germination dynamics. Differences among species in seed germination and seedling traits may be related to other plant life-history traits, such that assessing these relationships may increase our understanding of factors influencing plant establishment, which would affect the regeneration pathways of tropical dry forest communities. In this study, taking into consideration the effect species' phylogeny, we evaluated the relationships of seed germination metrics (percentage, lag time, and rate of germination) and seedling types (i.e. cotyledons functional morphology), with plant life-history traits (growth form, seed mass, dispersal syndrome and dispersal phenology) for 110 species in a Neotropical dry forest in Mexico. A total of 92% of the species studied disperse their seeds during the dry season, mainly at the beginning of this season (66%), a strategy mostly associated with autochorous herbs. Seed germination was more frequent in species that dispersed seeds at the end of the dry season. Germination percentage was not related to any of the traits studied. However, germination lag time and rate were negatively related to seed mass, a trait that in turn depended on growth form and dispersal syndrome. The dominant seedling type in the community was phanerocotylar epigeal with foliaceous cotyledons (56%), which was mostly associated with small seed mass and herbaceous growth form. Our results provide evidence that several plant life-history traits explain an important part of the variation in seed germination and seedling characteristics observed among species. Therefore, these plant life-history traits may be useful for grouping species in terms of their establishment strategies and roles on the regeneration of tropical dry communities.

Linking Seed Traits and Germination Responses in Caribbean Seasonally Dry Tropical Forest Species

“…Mass and volume had similar behavior predictors of germination responses (Figure 1A-D). The relationship found with 𝑣̅ and T50 for mass and volume supported previous results in other tropical ecosystems where small seeds tend to germinate faster than large ones [30,40]. Unlike other studies, mass and volume did not predict germinability or synchrony [41].…”

Germinação e morfologia de frutos, sementes e plântulas de seis espécies abundantes de Philodendron Schott na Amazônia Central, Brasil

“…Philodendron is known to have the smallest seeds in Araceae (BOWN, 1988;MAYO et al, 1997;COELHO, 2000), and we confirm small seeds (0.7 -1.4 mm) for the six species of this study of which P. tortum, P. melinonii and P. elaphoglossoides are described here for the first time. Tiny seeds in succulent berries organized in an infructescence may lure a variety of animals and be dispersed endozoochorously and exozoochorously, when maintained in the fruit pulp attached to animals.…”

Biogeographic regionalization by spatial and environmental components: Numerical proposal

“…In the case of Asteraceae, the effect of the precipitation seasonality could also be of great relevance; 58.5% of the SDTF Asteraceae species are herbaceous, thus the rainy season must regulate several aspects of their life cycle, for example reproductive phenology [ 74 , 75 ]. In SDTF, precipitation pulses trigger the biological cycle of many herbaceous taxa, especially the annual species that germinate and reproduce in short periods in synchronization with the climatic patterns [ 76 , 77 ].…”

“…This attribute gives them a competitive advantage [ 80 , 82 ], but there is no information about the fuctional strategies of Asteraceae species in tropical-dry environments. Nevertheless, the approaches made for other taxonomic groups with predominantly arboreal growth forms [ 76 , 83 ] may be useful to explain the patterns observed in the species members of group 4 whose distribution is restricted to Lower Balsas. These Asteraceae species have developed mechanisms for survival to drought that may include deep rooting, loss of leaves during the dry season or face this last unfavorable season for their survival in the seed bank.…”