Functional antagonism between nitrogen-fixing leguminous trees and calcicole-drought-tolerant trees in the Cerrado

Abstract

Th e Cerrado is the largest savanna of South America and its physiognomy varies from savanna to woodlands. Th ere are two main types of woodlands in the Cerrado: dystrophic woodlands, dominated by N-fi xing leguminous trees (LEG), and mesotrophic woodlands dominated by non-leguminous drought-tolerant trees (DRY), which are calcicoles and sensitive to Al . Th e working hypothesis is that LEG and DRY are functional antagonists in terms of the acidifi cation/alkalization processes involving diff erent forms of inorganic nitrogen and pH, Ca 2+ and Al 3+ in soil. Tree species basal area and soil properties were used to investigate the antagonism between LEG and DRY using generalized linear models. Th e results suggest that LEG and DRY are antagonists. Th e LEG were positively associated with Al 3+ , NO 3-and NH 4+ content and negatively related to increasing Ca 2+ content, whereas the DRY were negatively associated with Al 3+ , NO 3-and NH 4+ and positively associated with increasing Ca 2+ content. Th e upper soil layer in plots dominated by LEG species became more acidic and the upper soil layer in plots dominated by DRY species became more alkaline. Th e results suggest that LEG and DRY are functional antagonists and their preferences for NH 4+ or NO 3-might infl uence the way the Cerrado woodland changes.

The environmental triangle of the Cerrado Domain: Ecological factors driving shifts in tree species composition between forests and savannas

“…are characterized by thick corky bark and subterranean meristems that protect them from high temperatures and allow resprouting after fires (Gottsberger & Silberbauer‐Gottsberger, ). In addition, the occurrence of these species is correlated with soils of low fertility and high aluminium levels and some of these species are obligate aluminium accumulators (Araújo & Haridasan, ; Haridasan, ; Meira‐Neto et al., ).…”

“…Of the chemical elements in the Cerrado soil, one of the most important is aluminium, as emphasized by Haridasan (). This element, often toxic to plants, occurs at high concentrations in dystrophic soils and native plants of cerrado savanna formations show high levels of aluminium tolerance (Meira‐Neto et al., ; Neri et al., ). In contrast, species occurring only in areas with higher levels of calcium and magnesium and lower levels of aluminium are characteristic of some kinds of forest in the Cerrado Domain, such as seasonally dry tropical forests (SDTF) and evergreen and semideciduous forests (Oliveira‐Filho & Ratter, ; Oliveira‐Filho, Cardoso, et al., ; Oliveira‐Filho, Pennington, et al., ; Ribeiro & Walter, ).…”

Species representativeness of Fabaceae in restrictive soils explains the difference in structure of two types of Chaco vegetation

“…They are, for example, more efficient in obtaining potassium, calcium and magnesium (McLean et al 1956), and more tolerant to aluminium (Blamey et al 1992;Yang & Goulart 2000) due to their higher cation exchange capacity (CEC) when compared to other species (Silva et al 2010). Moreover, due to their ability to fix nitrogen through nodulation, Fabaceae assists the establishment of other species (Sprent 2007;Meira-Neto et al 2017). The contribution of this family to the availability of nutrients, absorption and growth of neighbouring species is indeed well described throughout the scientific literature (e.g.…”

Responses of tree species traits to soil variation in the cerrado

“…A biodiversity hotspot, the Cerrado is one among tropical savannas that occur on acidic soils as some Australian and African savannas (Materechera et al 1998; Hutley et al 2000). In a biodiversity hotspot as the Cerrado, disentangle plant responses to environmental factors is time consuming because the high plant diversity, the soil complexity and a myriad of other environmental variables usually blur the plant-soil patterns and challenge researchers that seek a general interpretation for vegetation responding to soil gradients (de Assis et al 2011; Neri et al 2012; Meira-Neto et al 2017). Grouping species into functional groups with unique ecological attributes (Díaz and Cabido, 2001; Lavorel and Garnier, 2002) frames plant diversity into a few environmentally responsive groups, facilitates the understanding of diverse communities and allows increase complexity step by step.…”

“…As far as we know, the first grouping separated the typical woody species that give phytogeographical unity to the Cerrado from species that occur in the Cerrado but occur mainly in other vegetation types, noticeably Atlantic and Amazon forests (Rizzini 1963). Concerning the soil influence on Cerrado plants, plant functional groups have been understood to comprise woody plants responding to the Al-Ca gradient (i.e., pH gradient) and to the inorganic nitrogen gradient (Ratter et al , 1977; Durigan and Ratter, 2006; Meira-Neto et al 2017). For that, isolating soil from other explanatory environmental variables is important in order to avoid blurring the plant-soil patterns.…”