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Matching soil biodiversity with global biogeochemical cycles

Final Report Summary - SOBIGLOBIC (Matching soil biodiversity with global biogeochemical cycles)

The general objective of this project was “to model effects of soil food webs on C and N mineralization, including effects of soil fauna, and to couple this model with soil organic matter decomposition models and with soil-plant models”. By doing so, we aimed to enhance the predictive ability of terrestrial biogeochemical cycle models.
This objective was split into three specific research objectives: Objective 1 was “to improve the model of the soil food web of a semi-arid prairie by including data of the whole soil biota, N-mineralization and C and N gaseous fluxes from soil. In Objective 2 we pretended “to couple this model with the SOM submodel of a soil-plant ecosystem model”. Finally, in Objective 3 we proposed “to test models for performance through comparing derived results with field data obtained from grazed and non-grazed prairies”.
Besides this research objectives, the project intended to satisfy some important interests of the Horizon 2020 framework be helping to raise the competitiveness and level of excellence of European Science through reinforcing the interaction between European and United States’ scientists.
With this aim, the research work was performed at the Colorado State University (CSU, Fort Collins, Colorado, USA) from September 2013 to September 2015. In worked at two centers of the CSU: the College of Natural Sciences, and the Natural Resource Ecology Laboratory. Dr. Diana Wall and Dr. John C. Moore were my main mentors, but I enjoyed the friendly cooperation of a deal of researchers always ready to share their expertise in diverse complementary fields of knowledge.
The first year was devoted to bring myself up to date with recent advances in soil food web models, soil microbial ecology and soil biota identification techniques. As a result of this effort, I was able to formulate the two starting hypothesis of my research and found a suitable research area to test them. The area was a former Long Term Ecological Research Station (currently the “Semiarid Grasslands Research Center” Long-term land management manipulations had been started in this area in 1939, including field plots grazed at different intensities, and a great volume of data were available.
The research hypotheses were: (1) grazing affects soil food web biodiversity, structure and metabolism through modifying above and belowground plant spatial patterns and through altering quantity and quality of carbon inputs to soil, and (2) soil food webs of grazed and non-grazed semi-arid grasslands differ by their resilience to climate change and particularly to increasing duration of drought.
To address the first hypothesis, at the end of my first winter at CSU (the field work was impeded during the winter because the soil was buried under a thick layer of frozen snow) I sampled several grazed and non-grazed sites and analyzed samples for abundance of soil biota sorted in trophic functional groups. I also analyzed and incubated soil samples for different forms of carbon, nitrogen and other nutrients. I used the resulting data to load the most recent version of the soil web model created by Hunt et al. (Dr. Moore included) in 1987. Based on my field data, we modified the model to consider separately the labile and the resilient soil organic matter pools, to include new functional groups and to link soil fungi and bacteria to soil carbon pools with different alimentary preferences depending on carbon resistance to mineralization. Running the resulting models, we modeled C and N mineralization by the soil biota under different grazing regimes and also, based on the architecture of the energy flux, the effects of grazing on soil food web stability.
To test Hypothesis 2, in the spring of 2014 we started a one-year long greenhouse experiment consisting of exposing soil monoliths extracted from the research site to simulated rainfall patterns representing the current rainfall regime in the experimental area and the most probable future rainfall regime after climate change models. This forecasted regime consists of concentrating total annual precipitation in fewer but greater rain events. The same models used to test hypothesis 1 were applied here to determine effects of interaction between grazing intensity and rainfall regime on soil organic matter mineralization by the soil food web and on soil food web stability.
At the end of my stay at CSU, three papers were in preparation and several communications had been sent to international conferences.
Together with a thrilling scientific activity, the USA period of the project gave me a unique opportunity to enlarge my skills in leadership by attending the Training and Organizational Development Department (CSU) programs for “Communication and Conflict Resolution”, “Leadership” and “Personal Effectiveness”.
Back to Europe in September 2015, I started the (one-year long) ongoing project period. The work program for this phase focused on transfer of the obtained skills and knowledge, with a work program that included activities aimed to publicize scientific results, to initiate networking with European research groups, and to raise funds for new research.
Concerning networking, almost immediately after landing in Barcelona (Spain), I was invited to London for a four-month stay in a joint research unit of the Imperial College and the Natural History Museum. The molecular biologists working there were interested at studying belowground food webs but did not know how to handle them. For my part, I was looking for molecular methods to respond new questions born from my results in USA (belowground trophic links, soil biota metabolic response to drought, etc.). Thus, we were clearly complementary. For four months, we prepared samples in different ways and amplified invertebrate and microbial DNA by different methods. We sent the final samples for analyses with Illumina and we are now treating the results. Hopefully we have found an efficient way to reduce uncertainties in soil food web modelling.
Networking and fundraising brought me to interact with a number of researchers around the world. Together with a large interdisciplinary team of researchers (from Belgium, France, Germany, Portugal, Czech Republic, Latvia, Romania, Switzerland, Sweden and Spain) I submitted a joint proposal to the EC 2016 BiodivERsA call. I also participate in two proposals that have been submitted to the 2016 call of the Science and Technology Ibero-American Program (CYTED). Both proposals focus international networking for research on ecological restoration. The networks pretend to coordinate efforts of diverse actors (policy makers, scientists, farmers, forest managers, local communities, etc.) in the search for nature-based adaptive solutions to societal challenges derived from climate change.
Regarding dissemination and outreach, besides five papers published (two of them) of in preparation (three more) in international scientific journals, I have contributed as an author to the edition of the EC “Global Soil Biodiversity Atlas” that is addressed to a wide variety of readers as an introduction to soil biodiversity services and to threats and opportunities for preservation of soil ecosystem services.
Finally, as a recognition of the relevance of our work for policy making, in 2016 I have been admitted as a support member of the Stakeholder Advisory Board (StAB) for the FACCE-JPI Joint Action “Thematic Annual Programming Network on Soil Functionality” (TAP SOIL
There is so much to be done! The work has just started!