Soil microbial diversity in dry woodlands of central-western Argentina: response to ecological conditions

NOE L; ABRIL A

Woodlands: Structure, Species Diversity and Sustainable Management.

Nova Science Publishers

Lugar: New York; Año: 2013; p. 119 - 138

The dry woodlands cover a great area of central-western of Argentina, characterized by an E-W precipitation gradient ranging from 500 to 100 mm. Accordingly, two arid eco-regions with different dry woodland type are defined: Arid Chaco and Monte. Considerable researches have been done on biodiversity comparison between both eco-regions focusing on animal and vegetation communities, whereas the microbial community diversity has been neglected. However, microorganisms play a key role in the organic matter decomposition and nutrient availability, so that the microbial study increases current understanding of the ecosystem functionality. We analized bacteria and actinomycetes diversity of soil and litter in two dry woodlands of central-western Argentina and its response to ecological conditions, including seasonal climatic changes. The study sites were Chancaní Reserve in Arid Chaco woodland (31°22?S and 65°27?W) and Ñacuñan Reserve in Monte woodland (34º03?S and 67º58?W). At each site, three composite samples of soil (0-20 cm deep) and surface litter (0.16 m2) were collected in wet and dry season. Genetic diversity by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) of bacteria and actinomycete communities were performed and interpreted in terms of ribotype richness and frequency and similarity index. The DGGE profile analysis reveals 39 bacteria ribotypes and 31 actinomycete ribotypes, among them 20.5% and 29% respectively, were observed only once. Two actinomycete ribotypes showed 100% of frequency (present in all samples). The ribotype richness of bacteria and actinomycetes were similar in all samples, but actinomycete richness was different between soil and litter (16.75 vs. 9.75, respectively). The low similarity index (