arbuscular mycorrhizal fungi in successional stages of caatinga in the semi-arid region of brazil

http://dx.doi.org/10.5902/1980509813331

Caatinga is an exclusively Brazilian biome with areas in accentuated process of desertification. Arbuscularmycorrhizal fungi (AMF) act in plant succession by favoring the establishment of plant species typical ofsuccessional stages and by accelerating recovery leading to a climax stage. The objective of the present workwas to evaluate the occurrence and diversity of AMF in successional stages of caatinga in the semi-aridregion of Paraíba State. Experimental plots (30 x 60 m) were delimitated in 2007 in areas corresponding todifferent caatinga successional stages: early caatinga succession (natural revegetation during the previous15 years); intermediate (natural revegetation for about 35 years); late (mature caatinga with more than50 years without major disturbances;) and also in pasture areas fenced and protected to represent the initialphase of succession. Plots of all four stages were implemented with three replicates. Soil and root sampleswere collected in the experimental plots, from the 0-15 cm soil layer in the dry and in the rainy seasons.All areas presented low infectivity potential suggesting that the introduction of mycorrhizal seedlings mayaccelerate the process of revegetation of degraded soils in this region. Except for the areas of late stage, theglomalin reservoirs increased along with the advancement of the succession process. Areas in the late stageof succession presented greater richness of AMF species, indicating that the establishment of the vegetationalso exerts a significant effect in the fungal community. Glomus and Acaulospora species were predominantin both seasons, possibly because they are well adapted to semi-arid conditions