Biodiversity and distribution of arbuscular mycorrhizal fungi in Araucaria angustifolia forest

Abstract

Araucaria angustifolia (Bert.) O. Ktze. is an endangered Brazilian coniferous tree that has been almost exterminated in the native areas because of uncontrolled wood exploitation. This tree has been shown to be highly dependent on arbuscular mycorrhizal fungi (AMF) and, therefore, AMF may be essential for forest sustainability and biological diversity. Root colonization, density and diversity of AMF spores were assessed in two Araucaria forest stands at the State Park of Alto Ribeira (PETAR), at two sampling dates: May and October. A comparison was made between a mature native stand composed of Araucaria trees mixed into a variety of tropical trees and shrubs, without any sign of anthropogenic interference (FN) and an Araucaria stand planted in 1987 (R), which has been used as a pasture. Assessments included percent root colonization, AMF spore numbers and species richness, Simpson's dominance index (Is), and Shannon's diversity index (H). Mycorrhizal root colonization did not differ between ecosystems in May. In October, however, the native stand (FN) presented a higher colonization than the planted forest (R), and the root colonization was more intense than in May. When considering both sampling periods and forests, 27 species of AM fungi, with higher numbers of spores in FN than in R were found. Canonical discriminant analysis (CDA) indicated Shannon's diversity index as the ecological attribute that contributed the most to distinguish between forest ecosystems, with higher value of H in FN in relation to R. CDA showed to be a useful tool for the study of ecological attributes. Key words: Brazilian Pine, diversity, spore density, root colonization, multivariate analysis BIODIVERSIDADE E DISTRIBUIÇÃO DE FUNGOS MICORRÍZICOS ARBUSCULARES EM FLORESTA DE Araucaria angustifoliaRESUMO: O pinheiro brasileiro, Araucaria angustifolia (Bert.) O. Ktze é uma espécie arbórea ameaçada de extinção, quase exterminada pela exploração descontrolada de madeira. Essa espécie demonstra alta dependência de fungos micorrízicos arbusculares (FMA), de grande importância para a estabilidade do ecossistema e manutenção da biodiversidade. Avaliou-se a colonização radicular, a densidade e a diversidade de esporos de FMA em duas florestas com araucária, distintas no processo sucessional, em duas épocas de amostragem: maio e outubro. As florestas, localizadas no Parque Estadual Turístico do Alto do Ribeira (PETAR), correspondem a 1) Floresta Ombrófila Mista nativa (FN), em estágio clímax, sem sinais de interferência antrópica, e a 2) floresta de araucária plantada em 1987 (R), submetida a pastoreio. Foram avaliados: colonização radicular, número de esporos e riqueza de espécies de FMA e calculados os índices de dominância de Simpson (Is) e de diversidade de Shannon (H). A colonização radicular não diferiu entre as duas comunidades na primeira amostragem (maio). Na segunda amostragem (outubro), houve maior colonização radicular na floresta nativa do que na floresta plantada e a colonização radicular foi mais intensa em comparação c...

Species richness of arbuscular mycorrhizal fungi in forests with Araucaria in Southern Brazil

“…Although these data might be overestimated, due to the possible inclusion of non-infective and dead spores in the count, the comparison among sites is still valid. In contrast to Moreira-Souza et al (2003) and Moreira et al (2007a), but in agreement with Moreira et al (2006), we found greater spore abundance in the Araucaria reforestation than in the native forest. These contrasting observations are probably related to historical and structural differences between the examined forests.…”

Arbuscular mycorrhizal fungal communities in native and in replanted Araucaria forest

“…AMF sporulation at the same sampling point is very dynamic in relation to different seasons of the year; therefore number of spores may not always be a reliable parameter to define the composition of the AMF community in an ecosystem (Moreira et al, 2007a). There are fungi that sporulate more, while others sporulate less, and others yet, do not sporulate or do so only during certain periods of the year (Table 1).…”

“…They are distributed through the most diverse ecosystems (Janos, 1980;Klironomos et al, 1999), and can determine the structure and composition of plant communities (Heijden et al, 1998;Klironomos et al, 2000;O'Connor et al, 2002;Heijden, 2002); plant communities, in turn, can affect the survival and reproduction of AMF communities (Sanders & Fitter, 1992;Eom et al, 2000). Any soil disturbance, such as the occurrence of fire, may change the structure of AMF or even decrease the number of AMF species (Moreira et al, 2007a). However, the structure of AMF communities and distribution in natural Araucaria ecosystems in Brazil is little known and has not been sufficiently studied.…”

“…However, several studies on AMF in Araucaria angustifolia have been carried out (Milanez & Monteiro, 1950;Oliveira & Ventura, 1952;Bononi et al, 1989;Breuninger et al, 2000;Moreira-Souza et al, 2003, Moreira et al, 2006Moreira et al, 2007a). Moreira-Souza & Cardoso (2002) demonstrated that Araucaria is a mycotrophic plant.…”

Taxonomic studies of Amanita muscaria (L.) Lam (Amanitaceae, Agaricomycetes) and its infraspecific taxa in Brazil

“…(URM 75827). However, the latter two tree species are reported to associate predominantly with arbuscular mycorrhizal fungi (Oliveira & Ventura 1952;Breuninger et al 2000;Moreira et al 2007) and basidiomes of A. muscaria var. fl avivolvata may be only occasionally present, although collectors do not mention the presence of Pinus nearby or excavating the rhizosphere where the basidiomes were in order to ascertain the ectomycorrhizal association.…”