Soil properties and bamboo cover drive the structure of the woody plant community along a forest–savanna gradient

Abstract

Understanding the role of environmental conditions and geographic space on species distributions is a major goal of ecological studies. Here, we investigate the effects of soil properties, a native bamboo (Actinocladum verticillatum (Nees) McClure ex Soderstr) ground cover and geographic distance on species richness and turnover in the Brazilian Cerrado. We established three transects along a forest-savanna gradient (14°41 0 S and 52°20 0 W), from the lowland next to a stream to the top of a hill, where we sampled the woody plant community (DBH ≥ 3 cm), soil properties and ground cover of A. verticillatum. We evaluated changes in species composition with a principal coordinates analysis, and the effects of the environmental predictors on species richness using generalised linear models and on species turnover using generalised dissimilarity modelling. We found that species richness increases with K concentration in the soil and decreases with Zn concentration in the soil and bamboo cover. The predictors explained 62% of species turnover, with environmental parameters (soil properties, bamboo cover and altitude) having the most significant contribution (80%), followed by the spatially structured environmental variation (20%). The most important environmental predictors of woody species turnover were soil concentration of Zn, P and K, altitude, and bamboo cover. Changes in species richness and composition in the studied gradient were strongly associated with plot height, bamboo cover and soil content of K, Zn and P. Our findings indicate that nutrient availability and competition with bamboo explain vegetation structure and composition in this region.

Fire regimes, fire experiments and alternative stable states in mesic savannas

“…( 2017 ) paper does, however, make important observations on the importance of variations in soil resources and their influence on tree density in the Kokondekro trial. These wholly support our own analysis pointing out the importance of edaphic factors as important influences interacting with precipitation regime to modulate variations in tree cover extent and the position of the forest–savanna boundary in the tropics at local, continental and/or global scales (Lloyd et al, 2015 ; Veenendaal et al, 2015 ; Ametsitsi et al, 2020 ; Gonçalves et al, 2021 ), a concept that now seems to be becoming increasingly well appreciated (see, for example, Case & Staver, 2018 ).…”

Influence of soil properties on woody vegetation structure, diversity and seasonality in Neotropical savannas

“…We showed that K, Al, and Fe content were the three edaphic variables that best explained the lower species richness in the two habitats; however, only K conclusively explained the differences between habitats. Other studies that also evaluated woody Cerrado communities in the region showed that sites with the highest richness of woody species (Gonçalves et al, 2021;Maracahipes et al, 2015;Neri et al, 2012) had the highest K content. Potassium seems to allow greater tolerance of plants to drought, as previously described, and this may also help explain the greater richness of species in interfluvial savannas than in alluvial savannas.…”

“…(2017), vegetation type and plant species composition in the Cerrado Biome are determined by a combination of water availability, soil fertility, and fire regime. Other studies have confirmed that the properties of Cerrado plant communities are determined by soil or substrate (Eiten, 1994; Haridasan, 2000; Oliveira‐Filho et al., 1989), topographic relief (Furley, 1999; Gonçalves et al., 2021; Lenza et al., 2015; Moeslund et al., 2013), and the occurrence of fires (Coutinho, 1990; Ribeiro et al., 2019).…”

“…According to Bueno et al (2017), vegetation type and plant species composition in the Cerrado Biome are determined by a combination of water availability, soil fertility, and fire regime. Other studies have confirmed that the properties of Cerrado plant communities are determined by soil or substrate (Eiten, 1994;Haridasan, 2000;Oliveira-Filho et al, 1989), topographic relief (Furley, 1999;Gonçalves et al, 2021;Lenza et al, 2015;Moeslund et al, 2013), and the occurrence of fires (Coutinho, 1990;Ribeiro et al, 2019). Two basic soil features have been shown to be most important in predicting the flora and vegetation of savannas: texture, which influences water availability and nutrient retention due to percolation (Case & Staver, 2018;Frost et al, 1985;Marimon Junior & Haridasan, 2005), and mineral composition, which is related to nutrient availability (Haridasan, 2000).…”

“…Additionally, there are still geographical knowledge gaps regarding savannas, such as the Cerrado, the largest savanna in South America, and the most biodiverse savanna in the world (Françoso et al., 2016; Murphy Brett et al., 2016; Silva & Bates, 2002). This biome is characterized by great variation in vegetation structure, composition, and species richness (Françoso et al., 2015; Ratter et al., 2003; Silva et al., 2006) at both regional and local scales (Abadia et al., 2018; Gonçalves et al., 2021; Maracahipes‐Santos et al., 2017). One of these knowledge gaps lies in the Cerrado, which is located in a zone of ecological tension (ZET) with the Amazonian vegetation biome, where the flora composition reflects the influence of both tropical forests and savannas (Marimon et al., 2006; Méio et al., 2003).…”