Dissertation

Microbial communities in Pampa soils; impact of land use changes, soil type and climatic conditions

Promotor: J.A. van Veen, Co-promotor: E.E. Kuramae

Author: Manoeli Lupatini
Date: 15 December 2015
Links: Leiden University Repository

This thesis investigate the impact of land-use changes in conjunction with soil type and seasonal climatic variations on the diversity and dynamics of the soil microbiome in the Pampa ecosystem, a subtropical grassland. To access the soil microbiome, a combined approach of sampling strategy, molecular fingerprinting, high-throughput sequencing, the separation of active and dormant populations, and network approach was employed. Land use and soil type are both drivers of bacteria; fungal and archaeal diversity and community structure, and also result in shifts in microbial biomass and metabolic activity. However, the measures of broad-scale functions did not converge with the community structures, evidencing that functioning and structure are not necessarily linked. A large overlap of microbial taxa between land usages were detected indicating the presence of a stable core microbiome resistant to anthropogenic disturbances. The dynamics of microbiome in response to seasonal cl imatic variations showed that moisture was the most important influencing community diversity and structure, with a larger effect on the active, dormant and total community than temperature. The network topology highlighted that each land-use system has a different and specific set of putative key species which might play a role intermediating microbial groups associations.