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The aim of this work was to describe and compare the arbuscular mycorrhizal fungal (AMF) morphospecies community and root colonization in three Polylepis australis forest disturbance types (degraded forest, young forest and mature forest). Rhizosphere soil samples were collected during wet and dry seasons in three sites located at the high mountains of central Argentina. A highly diverse AMF community was detected with 32 different morphospecies. AMF richness, density, Shannon diversity and evenness were neither influenced by forest disturbance type nor by season. Nevertheless, indicator species analyses showed two AMF taxa mostly associated with the degraded forest, one with the young forest and two linked preferentially to the mature forest. Moreover, the latter forest type showed the highest biovolume of Gigaspora spp., a genus representative of conserved ecosystems. P. australis root colonization was similar among forest disturbance types and seasons. However, higher abundance of vesicles was observed during the dry season than during the wet season. This study showed that AMF community composition was relatively similar among forests with distinct structural complexity. These results suggest that the AMF community may be resistant to the kind of disturbances that shaped the forests compared, or that natural successional processes may permit AMF to recover from these disturbances. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine patterns of arbuscular mycorrhizal (AM) colonization of Alnus acuminata Kunth at two natural forests in relation to soil parameters at two different seasons (autumn and spring). The soil parameters studied were field capacity, pH, electrical conductivity, available P, total N and Organic matter. The percentage of AM colonization was estimated and correlated to soil properties and to two different seasons. The results indicate that the percentage of AM colonization varied among soil types and was higher in spring than autumn. A significant positive correlation was found between AM colonization and electrical conductivity, organic matter and total Nitrogen. Results of this study provide evidence that AM colonization of A. acuminata can be affected by some soil parameters and seasonality. [ABSTRACT FROM AUTHOR]