Arbuscular mycorrhizal fungi associated with the babassu palm (Attalea speciosa) in the eastern periphery of Amazonia, Brazil

Abstract

Babassu, Attalea speciosa (Arecaceae) is a ruderal palm native to Amazonia, which turned dominant in frequently burned lands throughout the ‘arc of deforestation’ and other degraded lands, in extreme cases attaining complete dominance. This study investigated arbuscular mycorrhizal fungi (AMF) as one possible explanation for the outstanding ecological success of this exceptional palm. We explored the relationships between the babassu palm and native arbuscular mycorrhizal fungi and babassu effects on the AMF richness and mycorrhizal inoculum potential (MIP) in the eastern periphery of Amazonia. For this purpose, we sampled topsoil (0-20 cm) at the onset of the rainy season from a 5-year-old secondary forest regrowth (SEC) area with three levels of babassu dominance (sites with 10, 50 and 70% babassu biomass shares), and at three distances (0, 2.5 and 4 m) from isolated babassu patches within a degraded pasture (PAS), both with five replications per treatment. Glomerospore density varied from 100 to 302 per gram of soil, 56% higher in SEC than PAS. We identified a total of 16 AMF species, with dominance of Acaulospora (six species) followed by Glomus (three species). AMF richness increased with babassu dominance in SEC sites, and reduced with distance from babassu patches within the PAS. The colonization rate of babassu roots was higher in SEC than in PAS, whereas MIP was similar in both areas and without treatment differences. Our study points to strong mycorrhizal association of the babassu palm as a potential mechanism for its outstanding ecological success in degraded lands.

Mycorrhizal status of Coccothrinax crinita (Arecaceae), an endangered endemic species from western Cuba

“…Coccothrinax crinita has a high AMF richness similar to that reported by Nobre et al (2018) in A. speciosa under natural conditions, but lower than that found in palm plantations in Oman (25 species) (Al-Yahya'ei et al, 2011). Glomus was the most frequently found genus in the C. crinita rhizosphere, as was observed in other palms (Fisher & Jayachandran, 1999;Guevara & López, 2007;Al-Yahya'ei et al, 2011).…”

“…Acaulospora has also been found in palms in the Brazilian Amazonia (Nobre et al, 2018;Silva et al, 2006;Trufem et al, 1994). Consequently, some Glomus and Acaulospora species could be considered as generalist AM fungi, although further studies would be necessary in order to confirm this specialist status.…”

“…The richness and density of spores, as well as mycorrhizal colonization, are important variables to infer the ability of the soil to produce mycorrhizae and to assess soil health (Cuenca, 2015). The spore density in rhizospheric soil of C. crinita was higher than that of the Amazon palms Attalea speciosa Mart (100 to 302 spores 100 g-1 dry soil) (Nobre et al, 2018) and B. gasipaes (54 to 96 spores 100 g-1 dry soil) (da Silva Júnior & Cardoso, 2006). On the other hand, the density was lower than that of E. guineensis (1,289-1,741 spores 100 g-1 dry soil) in coastal and Amazonian zones of Ecuador (Maldonado et al, 2008), S. repens (260-2,200 spores 100 g-1 dry soil) from the southeastern USA (Fisher & Jayachandran, 1999) and D. orthacanthos (250 and 350 spores 100 g-1 dry soil) from Quintana Roo, Mexico (Ramos-Zapata et al, 2006a).…”

Litter decomposition and nutrient release dynamics of leaves and roots of the babassu palm in eastern Amazonia

“…Babassu roots had maximum C:N-ratios, which may be a key for soil organic material buildup in babassu-dominated areas. In contrast, babassu-root C:Pratios were significantly lower than in both reference species, pointing to the prevalence of N limitation over P limitation, possibly the outcome of the strong association of babassu with arbuscular mycorrhizal fungi (Nobre et al 2018).…”

Temporal distribution of fruit-feeding butterflies (Lepidoptera, Nymphalidae) in the eastern extreme of the Amazon region

“…The predominance of monospecific forests of A. speciosa in most of the PAB also indicates that this area has suffered environment impacts over the years, resulting in changes in the native vegetation (Pinheiro et al 2013). In fact, this palm is generally found in low densities in mature rainforests, but is dominant on degraded land, specially throughout the eastern and southern peripheries of the Amazon region (Nobre et al 2018).…”