Fungos Micorrízicos Arbusculares (Glomeromycota) em vegetações distintas em um brejo de altitude no nordeste brasileiro

Abstract

The “Brejos de altitude” are “islands” of humid forests surrounded by dry vegetation, characterized as part of the Atlantic Forest, in the Caatinga Domain. These environments are areas with privileged characteristics and conditions in terms of soil and air humidity, temperature and vegetation cover. Those factors influence the development of microorganisms. However, these areas are scarce in studies on diversity, mostly Arbuscular Mycorrhizal Fungi (AMF). These fungi, which form extensive symbiosis with plant roots, are important for increasing nutrient absorption zone and promoting plant growth. However, knowledge of the diversity, richness and ecological strategies of these fungi in high altitude areas still incipient and requires further research. For this reason, we compare AMF communities between different phytophysiognomies in an brejos de altitude of the Caatinga Domain. For this, soil and litter samples were collected during the rainy season of January/2022, in the Ubajara National Park, Ceará State. Two approaches were used to assess richness and diversity of AMF in different phytophysiognomies, (i) extraction of glomerospores by wet sieving and centrifugation in water and sucrose (70%) for the soil and (ii) collection of glomerocarps, using tweezers and the aid of a magnifying glass hand to the litter. Species were evaluated for frequency of occurrence and abundance and classified as dominant, common, very common or rare. They were subjected to diversity indices, in addition to assessing differences in community composition with a PERMANOVA and ANOVA to test differences in absolute species richness. Fifty-four AMF species were found, of which 39 occurred in the humid forest soil and 39 in the dry forest soil. Only 14 species occurred in the litter; being 10 in the humid forest and seven in the dry forest. Some species were identified only for one type of vegetation and/or substrate. The predominant community consisted of rare and few dominant species. PERMANOVA showed that AMF communities differ between vegetation types, between substrate types and in their interactions. This indicates that AMFs have a preference for environments and/or strips of the terrestrial substrate. It also demonstrates the importance of environments such as Brejos de altitude as reservoirs of biodiversity. In addition, new methods can expand knowledge about the ecology of the group.