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Soil bacteria follow seasonal variation in rainforest phenology

Posted on 05-04-2018 by József Geml, Hilde Pracht

Seasonality influences the presence & abundance of soil bacteria. Also soil chemistry has effect on the composition of bacteria.

The composition of soil bacteria communities in tropical rainforests appears to be following the patterns in phenology of the canopy. These findings were recently published in the journal Scientific Reports.  For the first time ever, the composition of bacterial communities in the tropical rainforest (Amazon), was studied in relation to time and space. József Geml from Naturalis is one of the co-authors.

Soil bacteria represent one of the largest groups of living organisms and play a major roles in ecosystem processes. While seasonal changes in soil bacterial communities have been studied in temperate regions, knowledge of the seasonality of soil bacterial communities in tropical forests were lacking before. Therefore, the researchers,led by Erika Buscardo and Laszlo Nagy at the University of Campinas, Brazil decided to go to the Amazon rainforest to study the spatial and temporal dynamics of the soil bacterial communities here.

Photo: Typical Amazon rainforest at the sampling site near Manaus, Brazil. (Photo: Laszlo Nagry).

To see whether the varying degrees of precipitation and litterfall indeed influence the composition of soil bacteria communities, the researchers generated and analyzed DNA sequence data from soil bacteria collected throughout one year at a long-term research site in the Amazon rainforest. The data was then compared to precipitation seasonality and spatial variability in soil characteristics, to see whether there were any relations between the two.

The study has found distinct patterns of seasonality in the presence / abundance of soil bacteria. These patterns were confirmed to be related to precipitation peaks and troughs during the year, directly affecting soil moisture, and to seasonality in nutrient availability as a result of litterfall dynamics. In addition, many bacteria representing various functional groups showed patchy distributions related to variability in local soil chemistry.

The full article that was published in Scientific Reports can be found here:

https://www.nature.com/articles/s41598-018-22380-z