Project Details
Projekt
Quantitative molecular assessment of the soil biota in high-latitude grasslands impacted by long-term warming
Applicant
Mathilde Borg Dahl, Ph.D.
Subject Area
Microbial Ecology and Applied Microbiology
Term
since 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 433256088
Soils contain more than three times as much organic carbon (C) than is currently in the atmosphere. Soil organisms are directly responsible for nearly all biogeochemical transformations and play a dual role in the soil C cycle – on the one hand promoting C release through catabolism, and on the other hand preventing its release by channeling C into stable compounds. Soil temperature is an important control of the composition and activity of soil organisms, and in the context of climate change, among the most important abiotic drivers. Generally, warmer conditions promote microbial activity, and short-term warming is known to stimulate net CO2 loss to the atmosphere. However, the apparent sensitivity of microbial respiration to temperature may decrease over time due to the depletion of labile organic substrates. In addition, secondary consumers, such as protozoa, nematodes and collembola may respond to increased temperature by changes in body mass and activity, resulting in altered food web structures. The proposed study area is part of an established research infrastructure in Iceland: the 'ForHot' site. It is a grassland site where geothermal vent flow has consistently warmed the soil for more than 50 years, thereby representing the world’s largest scale (temporal and spatial) natural soil warming experiments. To understand the links between the soil biota and environmental conditions, it is necessary to assess the responses of the whole soil food web to different environmental conditions. However describing the whole system is a challenge, and does not scale well to multi-site and multi-time studies. We will use a metatranscriptomics approach, which allows for a holistic (cross-domain) high-resolution taxonomic characterization of soil (micro-)biota by a PCR-independent simultaneous analysis of messenger (m)RNA and ribosomal (r)RNA. The project is a collaboration with an international consortium with complementary expertise in soil science, soil microbiology and metagenomics. We will obtain a census of the soil biota in ambient and heated sites across all seasons, to identify warming-induced changes in all relevant players of the microbial food web. Furthermore, we will combine this with quantitative measures of RNA and RNA-to-cell mass measures form laboratory pure cultures. This will allow us to estimate biomass and calculate potential energy flux of the soil food web. We hypothesize that structural differences in the food web introduced by season (e.g. dormancy of plants and larger fauna in winter due to sub-zero degrees under ambient conditions) and/or warming (e.g. due to changes in soil organic matter content and porosity) results in different net energy flux in the food webs. Such results will provide ground-breaking analysis potential for a time-efficient, consistent and comparable methodology to be used for a broad assessment of the below-ground (micro-)biota and for predicting energy flow and carbon fate in any given soil environment.
DFG Programme
Research Grants
International Connection
Austria, Belgium, Iceland, Netherlands, Norway
Co-Investigator
Professor Dr. Tim Urich
