Changes in arbuscular mycorrhizal fungal communities along a river delta island in northeastern Brazil Iolanda Ramalho da Silva a, * , Danielle Karla Alves da Silva b , Francisco Adriano de Souza c , Fritz Oehl d , Leonor Costa Maia a a Programa de P os-Graduaç~ ao em Biologia de Fungos, Universidade Federal de Pernambuco, Av. da Engenharia, s/n, Cidade Universit aria, CEP 50740-600, Recife, PE, Brazil b Laborat orio de Microbiologia, Universidade Federal do Vale do S~ ao Francisco, Campus de Ci^ encias Agr arias, Rodovia BR 407, Km 12, Lote 543, Projeto de Irrigaç~ ao Nilo Coelho, s/n, ‘‘C1’’, Petrolina, PE CEP 56300-990, Brazil c Embrapa Milho e Sorgo, Núcleo de Biologia Aplicada, Rod. MG 424 KM 45 - Bairro Esmeraldas, SN, Caixa Postal 285, CEP 35701-970, Sete Lagoas, MG, Brazil d Agroscope, Ecotoxicology, Schloss 1, CH-8820 W€ adenswil, Switzerland article info Article history: Received 28 July 2016 Received in revised form 20 December 2016 Accepted 30 December 2016 Keywords: Arbuscular mycorrhiza AMF community structure Coastal ecosystems Soil factors abstract Arbuscular mycorrhizal fungi (AMF) play a key role in the maintenance of the balance of terrestrial ecosystems, but little is known about the biogeography of these fungi, especially on tropical islands. This study aims to compare AMF community structure along a transect crossing a fluvial-marine island and relate these communities with soil and vegetation parameters to shed light on the forces driving AMF community structure on a local scale. We tested the hypothesis that the composition of AMF commu- nities changes across the island, even within short distances among sites, in response to differences in edaphic characteristics and vegetation physiognomies. We sampled roots and soils in five different natural and degraded habitats: preserved mangrove forest (MF), degraded mangrove forest (MD), natural Restinga forest (RF), and two regeneration Restinga forests (RR1 and RR2) on Ilha da Restinga, north- eastern Brazil. We determined the mycorrhizal colonization rate and AMF community structure based on morphological spore identification. The island soils were sandy with pH varying from acid to neutral; higher levels of organic matter were registered in RF and lower in MF; other chemical and physical soil attributes differed along the habitat types on the island. In total, 22 AMF species were identified, without any difference in species richness. However, the diversity and composition of AMF communities, spore abundance per families, and mycorrhizal colonization were statistically different among the habitats. The composition of AMF communities was strongly related to soil characteristics, especially the sum of exchangeable bases. Our results indicate that the different habitat types have diverse AMF communities even within short distances among habitats. In conclusion, islands with high spatial heterogeneity in soil parameters and diverse vegetation are potential refuges for the diversity conservation of AM fungi. © 2017 Elsevier Masson SAS. All rights reserved. 1. Introduction Several factors may affect species community structure and distribution along spatial and temporal scales (Gotelli and Graves, 1996; Chase, 2003). On a local scale, environmental heterogene- ity, abiotic, edaphic and micro-climatic factors are responsible for the maintenance of biological communities, while at larger scales, the historical-geological processes and regional climatic conditions are the main factors affecting community structure and influencing speciation, colonization and extinction of species (Buckley and Jetz, 2007; Dobrovolski et al., 2012). Islands have been considered key environments to perform studies on ecological and evolutionary aspects of species. Terres- trial (or continental) islands are separated from the mainland en- vironments by geographic barriers, decreasing accessibility and connection between island and mainland biological communities (MacArthur and Wilson, 1967; Walter, 2004). These islands * Corresponding author. Departamento de Micologia, Universidade Federal de Pernambuco, Av. da Engenharia, s/n, Cidade Universit aria, CEP 50740-600, Recife, PE, Brazil. E-mail address: iolandaramalho@yahoo.com.br (I.R. da Silva). Contents lists available at ScienceDirect Acta Oecologica journal homepage: www.elsevier.com/locate/actoec http://dx.doi.org/10.1016/j.actao.2016.12.011 1146-609X/© 2017 Elsevier Masson SAS. All rights reserved. Acta Oecologica 79 (2017) 8e17