Between February and May 2017, the student Héloïse Crompot of the Haute École Condorcet (Belgium) has collaborated with the group Sustainable Use of the Soil-Plant System at IRNAS-CSIC in an evaluation study of the microbial activities under soils contaminated by trace elements.
Héloïse obtained her Master’s title in Industrial Engineering Sciences in Agronomy after presenting her Master’s Thesis titled “Evaluation of soil chemical status, microbial biomass and enzyme activities under three tree species, in soils contaminated by trace elements, in the Green Corridor of the Guadiamar (Seville, Spain) “.
Thanks to this study we found out that in areas covered by trees there is a greater stabilization of the trace elements, and a greater enzymatic activity and microbial growth, than in open areas in the Guadiamar Green Corridor. We have also observed that there is a disturbance in the decomposition cycle of organic matter, which could be an effect of soil contamination.
Last August, the 9th International Conference on Mycorrhiza was held in Prague (Czech Republic). This conference, organised by the International Mycorrhiza Society, provided a global platform for exchanging the latest mycorrhizal symbiosis knowledge (anatomy, molecular mechanisms, mycorrhizal ecology and functioning) as well as its implications for the ecosystems and for the human society.
Researchers from RESTECO Project, together with collaborators, presented their last results in the session “Advances in biological conservation through a better understanding of mycorrhizal ecology”. A poster was presented with the study of the functional traits of ectomycorrhizal fungi (ECM) in holm oak (Quercus ilex) tree species in trace elements contaminated soils of the Guadiamar Green Corridor (Seville, Spain). In this study, two hypotheses were validated: soil contamination affects ECM species composition and their functionality, and ECM functional traits mediate in the effect of soil contamination on plant status.
Plant traits resulting from evolutionary and physiological processes have produced a global and extraordinary functional diversity among the myriad of species colonizing contrasted habitats within the planet Earth.
Trait-based ecology helps us to understand better the community assemblage, ecosystem function and the responses to environmental changes.
1) Functional traits of trees affect soil properties and provision of ecosystem services. A study of seven tree species planted on remediated soils in the Guadiamar Green Corridor (Seville, Spain) has shown significant differences in traits (SLA, SRL, LDMC, RMDC) and chemical composition of leaves and roots. These traits differences influence the tree capacity to immobilize contaminants (trace elements) into the soil, remediation technique called phytostabilization. Traits also influence tree capacity to store carbon into biomass and soil, therefore contributing to climate change mitigation.
2) Within plant traits, roots are little known, despite their crucial role in the plant strategies of resource use and the ecosytem funcioning. Variation patterns of 5 root traits in 80 woody plant species from 18 samplig sites and 5 zones of South Spain have been studied. A strong correlation among traits indicates a main dimension along the root economics spectrum. However, other dimensions such as root diameter and the association with mycorrhizal fungi are also relevant.
The abstract and copy of the poster can be consulted in Digital CSIC repository:
The use of trees to immobilize contaminants (phytostabilization) is a low-cost and effective method of soil remediation.
Researchers of IRNAS, CSIC and New Zealand have evaluated the potential of red gum (Eucalyptus camaldulensis) to phytostabilize soils contaminated by trace elements (TE). Within the research project RESTECO, the ET concentration in soils and in eucalypt leaves and flowers has been investigated in 7 sites along the Gudiamar River valley. In general, the concentration of elements such as As, Cd, Cu, Pb and Zn in aboveground tissues was relatively low, and lower than toxic levels.
Eucalyptus camaldulensis is a fast-growing tree with a large root system; because of its tolerance to TE contamination and the low transfer of metals towards the aboveground tissues it can be considered suitable for phytoremediation of contaminated soils.
In addition, there was significant correlation between the concentration of Cd, Mn and Zn (but neither for Cu nor Pb) in their leaves and in the rhizosphere. Therefore, the eucalypt´s leaves may serve as bioindicators of the soil contamination for Cd, Mn and Zn.
The study has been published on June 30th 2017 in the open access journal PLOS ONE.
The RECARE project is focused on preventing and remediating degradation of soils in Europe.
A Plenary Meeting has been held at Hella (Iceland), from May 29th to June 2nd 2017. Each of the 17 study sites participating in the project presented their results.
The Group SOIL-PLANT, from the IRNAS, CSIC, presented their results about two measures applied for the remediation of contaminated soils at the Guadiamar Green Corridor: a) amendment addition and b) tree plantation.
Those results are part of a joint work by the projects RECARE and RESTECO.
The symbiosis between plants and mycorrhizal fungi is a fundamental factor for the phytoremediation of contaminated soils in the Guadiamar Valley.
From the 15th to the 18th of May 2017, Professor Mark Tibbett (University of Reading, UK) visited the IRNAS-CSIC to participate in a collaborative work on the effects of contamination by trace elements on soil biodiversity.
Professor Tibbett gave a conference in the IRNAS´ Seminar Cycle, entitled “The mysterious world of mycorrhizas: Unrecognized attributes of the commonest plant-fungal symbiosis”. The role of mycorrhizas and the plant-fungi-soil interface was remarked, as well as their importance in plant nutrition and stress tolerance. “Bare roots does not exist in nature” he stated, remarking the universality of plant-fungal associations.
The field visit included a general overview of the Aznalcóllar mine complex and the old tailings dams which collapsed, provoking the spill.
In the experimental plot for the long-term study of the effects of amendment addition on soil remediation, the interactions between soil properties (mainly pH), mycorrhizas and colonizing plants were discussed in contaminated and remediated soils.
Lastly, in La Herrería (Sanlúcar la Mayor) field, the relations of different tree species such as stone pine (Pinus pinea), white poplar (Populus alba) and wild olive (Olea europaea) with the soil organic matter underneath, the phytostabilization of trace elements, and the communities of mycorrhizal fungi were discussed.
The RESTECO researcher María T. Domínguez has given the conference “Soil contamination and provision of ecosystem services in the Guadiamar River Basin”, within the Open Classroom program of the University of Córdoba, Spain, on May 9th 2017.
In the conference, the main concepts relative to the role of soil provisioning ecosystem services were introduced. The Guadiamar River Valley was presented as a case study, where many works focused on the impact of soil contamination on the provision of ecosystem services have been carried out.
The functional diversity of a community is a key factor for its stability against climatic change.
Researchers from RESTECO project, in collaboration with University of Córdoba, Autonomous University of Barcelona and EBD-CSIC, have studied the role of functional diversity and soil conditions as main drivers of the stability of woody plant communities in Doñana (south Spain).
The community stability has been assessed as changes in cover, species composition and diversity, in 19 experimental plots during 9 years. The functional diversity was calculated using eight traits (of leaves, stems and roots) for the 16 species comprising the different communities.
Results have proved that shrubland communities were strongly sensitive to inter-annual variability in climate. During colder and drier conditions, total plant cover decreased remarkably, but functional diversity increased; likely because of the expansion of functionally dissimilar species in the new open microsites.
The most functionally diverse communities, and those inhabiting resource-limited environments were the most stable over time in terms of species diversity. This could be explained because they were mainly constituted by a large diversity of slow-growth, stress-tolerant species that are potentially better adapted to harsh climatic conditions.
We could infer that the increased frequency of extreme climatic events (predicted by climatic models) will alter the functional structure of shrubland communities, with potential repercussions for ecosystem functioning.
This study has been published in the Journal of Ecology (on line since February 28, 2017).
On March 24th, the students of the subject “Ecology of Global Change: Current Transition of the Biosphere” visited the Guadiamar River basin. The subject belongs to the Biology degree of the University of Seville (US).
The objective of the excursion was to carry out an ecological and environmental analysis of the landscape and ecosystem transformations produced by the anthropic action during centuries in the outskirts of the city of Seville. The Guadiamar River, because of its ancestral importance as a source of water and resources, is a good example of these transformations that can be observed from its birth in the Sierra Norte until its mouth in the Guadalquivir River, in the marshes of the Doñana Park.
The professors María Cruz Díaz Antúnez-Barradas (US) and María José Leiva Morales (US) described the different ecosystems where the Guadiamar River flows. In its high part, in the mountain range, the Guadiamar River crosses forests and plantations of eucalyptus trees. In the middle section, the amplitude of the fluvial valley appears increasing riverside vegetation in the borders and meadows in the high zones. Further down, the river enters the Protected Landscape of the Guadiamar Green Corridor where the forest of the alluvial plains was reforested with Mediterranean shrubs and trees (oaks, olive trees, brooms, etc.), while the forest gallery shows poplars, ash trees and willows. Finally, in the low section, it ends in the marshes of Doñana, where crops of rice and brackish pastures appear.
At the Doblas stop (Sanlúcar la Mayor), Marta Gil Martínez (IRNAS-CSIC) was invited to talk about the consequences and restoration measures after the Aznalcóllar mine spill to the Guadiamar River, as well as the results of the investigations which is carried out by IRNAS-CSIC researchers in the Green Corridor (RECARE and RESTECO projects). Soil contamination by heavy metals, such as lead, zinc, cadmium and copper, affects the growth and health of plants, soil organisms and, in general, the ecosystem food web. Soil-plant-microorganism interaction is being investigated in soils with different levels of contamination. The ability of plants and their associated microbes to stabilize heavy metals in the soil (a technique known as phytostabilization) and thus reduce the risk of toxicity in the ecosystem is studied.