Woody species distribution across a savanna-dry forest soil gradient in the Brazilian Cerrado.

G A Paula,M Silveira,H Almeida,E Fischer,E Van Den Berg

doi:10.1590/1519-6984.243245

Abstract

Although richness and distribution of woody species in the Cerrado physiognomies have been extensively studied, the shifts of woody species from savanna physiognomies to dry forests have not yet been addressed. Here, we investigate the effect of soil physical-chemical traits on the woody species turnover between adjacent cerrado stricto sensu and dry forest physiognomies. Woody species were surveyed, and soil and topographic variables measured, in 30 10×40 m plots systematically distributed, with 15 plots in each physiognomy. We found a spatially structured distribution of woody species, and differences of soil traits between cerrado stricto sensu and dry forest areas, mainly related to the aluminum saturation, base saturation, and available phosphorus. Aluminum saturation increased toward the savanna area, while base saturation increased toward the dry forest. Most woody species predominated in one physiognomy, such as Callisthene major in the cerrado stricto sensu and Anadenanthera colubrina in the dry forest. Only 20% of the species were widely distributed across both physiognomies or, not often, restricted to the intermediary values of the soil gradient. General results indicate that contrasting soil traits between cerrado stricto sensu and dry forest produce a strongly spatially organized and sharp transition in terms of species distribution between these physiognomies.

Highlights

The Cerrado domain contains different phytophysiognomies, varying from largely open grasslands with scattered trees or shrubs to forests with a continuous canopy stratum and shaded understory, harbouring a high diversity of plant species and life forms (Ribeiro and Walter, 2008)
Our results support a spatial structure of woody species distribution that locally separates the cerrado stricto sensu and dry forest areas, and show that soil chemical characteristics consistently differ between these two physiognomies
We found a small pure effect of soil traits on species distribution when jointly accounting for spatial effect

Summary

Introduction

The Cerrado domain contains different phytophysiognomies, varying from largely open grasslands with scattered trees or shrubs to forests with a continuous canopy stratum and shaded understory, harbouring a high diversity of plant species and life forms (Ribeiro and Walter, 2008). Forested habitats in the Cerrado domain include semideciduous forests, and distinctive deciduous forests (dry forests hereafter). Regions where savannas and dry forests presently exist largely experienced interchanges of species through evolutionary time, which supposedly contributed for contemporary species adapted in some extent to both habitats, besides species that are distinct in each vegetation type (Bueno et al, 2016; Cordeiro et al, 2017). The dry forests currently constrained to small areas constitute refugia for several endemic taxa (Prado and Gibbs, 1993; Gentry, 1995; Gonzaga et al, 2016); they are a topmost threatened ecosystem (Miles et al, 2006; Vieira and Scariot, 2006)

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Conclusion