Impact of Amazon land use on the community of soil fungi

Giselle G M Fracetto,Felipe J C Fracetto,Lucas C.B Azevedo,Marcio R Lambais,Ludwig H Pfenning,Fernando D Andreote

doi:10.1590/s0103-90162013000200001

Abstract

Considered as one of the most biodiverse biomes, the Amazon has a featured role in the discovery of new species of plants, animals and microorganisms, which may be important for the functionality of different ecosystems. However, studies on the impacts resulted from changes in the Amazon land use on microbial communities and their functions are still limited. In this context, the soil fungal diversity can act as an important indicator of environmental stress caused by land use of the Amazon. This study describes changes in soil fungal communities caused by different systems of land use (primary forest, secondary forest, agroforestry, agriculture and pasture). Communities were observed in each of the areas using denaturing gradient gel electrophoresis (DGGE) of 18S rRNA gene combined with the non-metric multidimensional scaling (NMDS). Unique bands indicated the dominance of particular fungal groups in each of the specific treatments, mainly in areas converted to pasture, which differed greatly from samples of other systems of land use (SLU). The analysis of partial sequence of the 18S rRNA gene of fungi in soils under primary forest, agriculture and pasture showed differences (p = 0.001), evidencing the fungal community response to such changes. Most abundant phyla were the Zygomycota in the soil under primary forest and agricultural land, and Basidiomycota in the soil under pasture. The results show that the Amazon soil is an ecosystem susceptible to environmental changes in regarding the fungi community inhabiting this niche.

Highlights

The Amazon is considered a major reserve of biodiversity, mainly of plant species which may contribute to a greater diversity of microorganisms inhabiting the soil (Brodie et al, 2003; Jesus et al, 2009)
Analysis of fungal communities by PCR-denaturing gradient gel electrophoresis (DGGE) The fungal communities represented by the bands profile after DGGE were more similar between samples of the same system of land use than samples of different land use systems (Figure 2)
Some of the replicates were distinct from the majority of samples in a determined treatment, which can indicate the natural variation in the soil of a land use

Summary

Introduction

The Amazon is considered a major reserve of biodiversity, mainly of plant species which may contribute to a greater diversity of microorganisms inhabiting the soil (Brodie et al, 2003; Jesus et al, 2009). The intensification of anthropogenic activities, which culminate with the conversion of forests into extensive pastures, results in loss of biodiversity, possibly influencing the biological processes important for maintaining productivity and sustainability of ecosystems (Islam and Weil, 2000; Moreira et al, 2006). The fungi can act in nutrient cycling and develop symbiotic or pathogenic associations with plants and animals besides interacting with other microorganisms (Anderson and Cairney, 2004; Bridge and Spooner, 2001; Thorn, 1997). In addition to the limitations of cultivation, there is lack of taxonomic knowledge making the identification of some species in the soil difficult (Kirk et al, 2004)

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Conclusion