Habitat filtering and interspecific competition influence phenological diversity in an assemblage of Neotropical savanna grasses

Abstract

Phenology in plants is closely related to the environmental features of their habitats, which can act as habitat filtering, clustering species with particular adaptations. On the other hand, aggregation of species can lead to competition between them, segregating their niches. We investigated if habitat filtering and interspecific competition influence phenological diversity in an assemblage of grass species in savanna grasslands of central Brazil. We conducted phenological observations, in 15-day intervals, of ten species of savanna grasses. We used circular statistics to ascertain the seasonality of the phenology and null models to estimate the phenological overlap between species. The reproductive period of grasses was seasonal and concentrated in the rainy season, corroborating the habitat filtering hypothesis; however, within the rainy season, the phenological niche overlap between species was less than expected at random. Flowering was more segregated than fruiting and seed dispersal. Although grasses have similar architectural feature and share similar above and underground niche, these results suggest that grasses are under competition pressure and this can result in phenological segregation, allowing coexistence between them.

Fire cues trigger germination and stimulate seedling growth of grass species from Brazilian savannas

“…Grasses are among the dominant taxa in grassland and savanna physiognomies of the Cerrado Felfili, 2006, 2007a), and seeds of most species are likely to have PD (Ramos et al, 2016(Ramos et al, , 2017. Seed dispersal occurs in general from the middle of the wet season to the beginning of the dry season (Munhoz and Felfili, 2007b;Ramos et al, 2014).…”

Examining variation in the leaf mass per area of dominant species across two contrasting tropical gradients in light of community assembly

“…Through examining functional diversity metrics related to interand intraspecific variation in the Brazilian pampa forest community, Carlucci et al (2015) found that conspecific individuals varied more in communities where trait variability was typically high, that is, in the large forest patch, and less where trait variability was typically low, that is, in the small forest patches. Additionally, in Brazilian savannas, a phenological study showed that grasses are under competition pressure that can result in larger niche segregation, allowing coexistence between them (Ramos et al 2014).…”

How does fire affect germination of grasses in the Cerrado?

“…Another important trait to evaluate is longevity and the capacity of seeds to resist high temperatures since most fires in the Cerrado occur during the dry season (Ramos-Neto and Pivello, 2000;Pivello, 2011) and most grass species disperse during the rainy season (Munhoz and Felfili, 2007;Ramos et al, 2014). Therefore, dormant seeds are assumed to be in the seed bank when the fire occurs.…”