Biodiversity and functional role of biological soil crusts II

Project phase 2017-2020

 

Scientific investigators:

Prof. Dr. Ulf Karsten

Dr. Karen Baumann (assoc.)

Dr. Karin Glaser

Dr. Martin Albrecht

Samira Khanipour Roshan

(Uni Rostock)

Prof. Dr. Michael Schloter

Julia Kurth

(TU München)

Dr. Stefanie Schulz

(Helmholtz Zentrum München)

 

Background

Biological soil crusts are complex communities consisting of photosynthetically active green algae, cyanobacteria, bryophytes and lichens, heterotrophic fungi, protozoa and bacteria, which cover the top few millimetres of soil.

The organisms and their by-products create a micro-ecosystem, whose ecological function is of great importance in particular on bare soils (e.g. nitrogen fixation by cyanobacteria, primary production, water retention, soil stabilisation or allocation of plant available nutrients).

Although soil crusts are ecologically important, investigations have been mainly focused on arid and semiarid habitats so far. In the first phase we focused on the biodiversity in soil crusts and their function in biogeochemical phosphorus turnover. These correlations will be analysed in greater depth during the current phase.

 

Aims

We plan to link phosphorous turnover and nitrogen cycling in biological soil crusts to the abundance and diversity of genes coding for selected functions driving N and P transformation processes and relate the data to the structure of the crust communities. This project will improve our understanding on the biodiversity and interactions of ALL organisms in BSCs from forest plots of the BEs.

A combination of metagenomic and fatty acid profiling of the community structure of bacteria, archaea, fungi, cyanobacteria and algae will be evaluated for the first time in taxonomic depth (who is there in what numbers?).

The functional role of BSCs will be evaluated in the biogeochemistry of P and N. The concentrations and chemical species of these elements will indicate whether BSCs act as sink or source for P-and N-compounds and identify the drivers for the unstudied P-biogeochemical cycling in BSCs and their quantitative contribution to the P-fluxes (who is doing what?).

 

Hypotheses


1. Increasing SMI will decrease biodiversity, and interactions in microbial network structures will be reduced.

2. Differences in community structure will affect the functionality of the BSC.

3. Microbial diversity in BSCs in the three BEs is comparable at sites with similar land use intensity.

4. BSC communities are involved in transformation from inorganic to organic fractions in the biogeochemical cycling of P and N.

 

Methods

  • Metagenomic and transcriptomic analyses
  • qPCR targeting specific genes for N- and P-turnover
  • fatty acids analyses
  • total C, N, P determination

Biodiversity and functional role of biological soil crusts

Project phase 2014 - 2017

 

Scientific investigators:

Prof. Dr. Ulf Karsten

Prof. Dr. Peter Leinweber

Dr. Karen Baumann

Dr. Karin Glaser

Samira Khanipour Roshan

(Uni Rostock)

 

Background

Biological soil crusts are complex communities consisting of photosynthetically active green algae, cyanobacteria, bryophytes and lichens, heterotrophic fungi, protozoa and bacteria, which cover the top few millimetres of soil.

The organisms and their by-products create a micro-ecosystem, whose ecological function is of great importance in particular on bare soils (e.g. nitrogen fixation by cyanobacteria, primary production, water retention, soil stabilisation or allocation of plant available nutrients).

Although soil crusts are ecologically important, investigations have been mainly focused on arid and semiarid habitats so far. Hence, in this project soil crust species assemblages of temperate regions should be elucidated and a possible correlation with land use intensity and soil parameters should be investigated.

 

Aims

Investigation of biodiversity within the soil crust should contribute to the identification of relationships among organisms and their reactions to external factors such as e.g. land use intensity.

The functional role of soil crusts in biogeochemical cycles of C and N should be analysed by carrying out mass spectrometric fingerprints (Py-FIMS, pyrolysis field ionisation mass spectrometry) and XANES (X-ray Absorption Near Edge Structure). Different C- and N-containing component classes originating from crusts and adhering soil will be identified and quantified so that an effect of land use intensity on molecules or component classes can be investigated statistically.

P fraction analyses of crust and adhering soil should reveal the ecological function of the soil crust as mineral soil P mobilizer.

 

Hypotheses


1. With increasing land use intensity the abundance of nitrogen fixing cyanobacteria decreases causing a shift in the partner organism community (ammonium oxidizing bacteria and archeae).

2. Increasing land use intensity decreases the biochemical diversity of molecules derived from soil organic matter while at the same time stable, N-containing molecules accumulate.

3. The biological soil crust transforms mineral P fractions into organic fractions. An increase in land use intensity increases the organic P fraction in the soil crust.

 

Methods

  • Cultivation of photosynthetically active organisms
  • Light-microscopy
  • PCR and 454 sequencing
  • Py-FIMS (pyrolysis field ionisation mass spectrometry)
  • C-, N-, P – XANES (X-ray Absorption Near Edge Structure)
  • P-fractionation
  • 31P-NMR (nuclear magnetic resonance)

 

 

Previous project contribution of Prof. Dr. Ulf Karsten: Soilcrust
Previous project contribution of Karin Glaser: ACTIFLAG

Further project contribution of Prof. Dr. Michael Schloter: KiWion, MicroBEEs
Previous project contribution of Prof. Dr. Michael Schloter: INDILAP, InDiLaNi, ForNit

Previous project contribution of Dr. Stefanie Schulz: ForNit

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