18 Feb GT2 (Leader NEIKER other partners: IIAG-CSIC, USC, INRA, CEA, UCP-CRP, UPV/EHU)
The global objective of GT2 is to identify the links between structural (taxonomic, phylogenetic) and functional biodiversity in phytomanaged soils, compared to non-phytomanaged contaminated and non-contaminated soils. Due to the importance of soil biota for soil functionality and ecosystem services, one of the key questions will be whether soil functioning depends on species richness, key species, species traits or community composition.
During the first year of development of the PhytoSUDOE project, studies were initiated in GT2 to determine the structural biodiversity of the soil microbial communities in selected long-term trials that had been established prior to the beginning of the project. The aims are to elucidate the possible effects of the different phytomanagement strategies implemented in these field sites on the diversity of soil microorganisms (eg, bacteria, archaea, fungi). The soils analyzed in relation to their microbial structural biodiversity were sampled in the following locations:
Field site S1 – St Médard d’Eyrans (France)
- The tree species studied (with or without mycorrhizal associations) include, among others, poplar (Populus nigra L.), willow (Salix caprea L. and Salix viminalis L.), Scots pine (Pinus sylvestris), and false indigo (Amorpha fruticosa L.). The main objective consists in the stabilization of copper (assisted by soil amendments) in the soil, alongside the production of plant biomass (timber). Additional objectives are to enhance biodegradtion of PAHs and to improve the biological functions of the soil.
- Regarding the herbaceous species, they include Miscanthus spp., Chrysopogon zizanioides (vetiver), Agrostis capillaris, A. delicatula, A. gigantea, Dactylis glomerata, Deschampsia caespitosa, Sporobolus indicus, Vulpia myuros and Festuca pratensis. In this case, the main objective is to stabilize copper (with the help of an amendment) and, in some cases, to produce biomass (e.g. Miscanthus spp.).
- The annual crops studied, in a rotation system, are Nicotiana tabacum and Helianthus annuus. The main objective in this case is to reduce the labile pool of Cu, while producing bioenergy crops.
Field site S7 – Rubiais Mine (Piedrafita de Cebreiro, Spain)
At this site, the Cd / Zn phytoextraction capacity and the biomass production potential of a short rotation coppice system are being evaluated using woody species. The experimental plots include plantations of Salix smithiana BOKU 03 CZ-001, a Cd / Zn accumulator plant, in monoculture (10,000 estaquillas ha-1), an intercropping of S. smithiana with Alnus glutinosa, and the application of organic fertilization (composted sewage sludge, 5% on a weight basis) or inorganic fertilization (NPK). The aim is to evaluate (i) the benefits in terms of growth and nutrition to the metal-accumulator plants when co-cultivated with species forming associations with nitrogen-fixing microorganisms; and (ii) the improvement of the edaphic conditions associated with the application of organic amendments together with plant growth.
Field site S8 – Touro (Spain)
In the plots (long-term trials) of this site, the effect of the application of composted sewage sludge and of two technosol mixtures (prepared by the company Treatments Ecologicas de Noroeste, TEN S.L.) as soil amendments is being studied. A short rotation coppice system with woody species was established, using clones of Populus nigra and Salix viminalis (plantation density of 10,000 cuttings ha-1), and comparing it with a herbaceous cover (Agrostis capillaris cv. Highland). The overall objective is to phytostabilize Cu in the soil and produce plant biomass, as well as to improve soil fertility and functionality.
During this first year of GT2, the determination of different microbial parameters to estimate the functional biodiversity in the selected soils, corresponding to long-term trials (S1, S7 and S8), has also begun. Analyses of soil enzymatic activities (catalase, urease, phosphatase, dehydrogenase, arylsulfatase, glucosidase, etc.), physiological-metabolic profiles at the community level with BIOLOG Ecoplates (profiles of utilization of carbon sources), and microbial respiration were performed.
During the second year, GT2 focused on characterising the structural and functional biodiversity of the microbial communities present in the soils of the long-term field trials which were already established at the beginning of the project (including sites S1, S7 and S8 managed by INRA, IIAG-CSIC and USC). For this, the soil samples have been sequenced by “next generation sequencing” (Illumina) in order to analyze the microbial structural biodiversity. In order to determine the microbial functional diversity, a list of genes with functional value has been selected for analysis with the Biomark HD platform of Fluidigm Corporation. In parallel, analysis of conventional microbiological parameters (enzymatic activity, etc.), and the identification of macro- and meso-fauna have been carried out. Finally, analysis of the determination of photosynthetic pigments and antioxidants in the different plant species cultivated at each site has been carried out.
In the final months of the project, the analysis of the data obtained continued and the “Guide of best phytomanagement practices for the recovery of biodiversity in degraded and contaminated sites” was prepared. This guide is available in the publications section.
In October, 2018, PhytoSUDOE officially ended. The Project deliverables were finalized along January-February, 2019, including the Layman report and the project’s video that were uploaded to the webpage’s news section (blog). Other relevant publications can be accessed also in the web along with the presentations (PDF) of the series of events organized by PhytoSUDOE. This website will be online until 2023.