Soil organic matter and ecosystem services

The soil organic matter (SOM) plays an important role determining physical (structure, water retention), chemical (nutrient availability, buffer effect), and biological (microbial diversity, biologically active compounds) properties.

There is a generalized problem of organic matter loss in Mediterranean soils, and one of the solutions is to add compost from organic residues, as part of the circular economy.

Soils improved with compost provide with ecosystem services of provision (increasing food production) and regulation (nutrient cycling, carbon sequestration), thus contributing to human wellbeing.

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In the Guadiamar Green Corridor (Sevilla, Spain), we are evaluating the effectiveness of combined measures of amendment addition and tree plantation, for two ecosytem services: stabilization of trace elements, and storage of soil carbon.

The IRNAS researchers Teodoro Marañón and Engracia Madejón presented the opening lecture entitled “Soil functions and ecosystem services: the importance of organic matter” (in Spanish), within the V Jornadas de la Red Española de Compostaje, held at Sevilla, Spain, on November 16-18, 2016.

A pdf copy of the slides can be consulted in Digital CSIC repository.

The value of the forests

Forests have multiple values for human wellbeing. They provide with raw materials (timber, wood, cork) and food (nuts, fruits, mushrooms, cattle, game animals). These ecosystem services of provisioning have economic value recognized by the society and the market.

Other values are intangibles, like improving the quality of water and air, soil formation and protection against erosion, or the mitigation of climate change by carbon sequestration. These ecosystem services of regulation benefit all us, but society not always recognize and value.

Finally the forests have cultural services contributing to our physical and mental health. They are favourable spaces for outdoor recreation, give us aesthetic pleasure and spiritual comfort, have landscape values, and for many people represent identity and links with local culture.

maranon_ep2016The IRNAS researcher Teodoro Marañón has been interviewed in the report “Values of Andalusian forests” showed in “Espacio Protegido” by Canal Sur on November 2nd 2016.

The interview can be seen at Canal Sur online or the video in the Youtube platform.

The role of soil in the facilitation effect by the retama shrub

foto_retamasShrubs are considered to be hotspots of soil fertility and biological activity in dry ecosystems. The use of shrubs, like “retama” (Retama sphaerocarpa (L.) Boiss.), as nurse plants to facilitate woody plant recruitment has been proved to be particularly useful for the revegetation of highly disturbed environments, such as contaminated lands.

Researchers from IRNAS-CSIC, led by MT Domínguez, have studied the usefulness of the nurse effect for the revegetation of contaminated Mediterranean soils with Holm oak (Quercus ilex subsp. ballota). In particular, they have assessed whether the nurse effect is related to increases in soil fertility and microbial extracellular enzyme activities underneath the shrub plant, using the retama-Holm oak association as a model system. The study was conducted along a gradient of soil contamination in the Guadiamar River Valley, where afforestation with retama shrubs was conducted following a contamination episode.  Along this gradient, soil fertility and microbial activity from different microsites (bare soil, retama cover, Holm oak cover and retama + Holm oak cover) was analysed.

Thirteen years after the start of the remediation activities in the area, soil organic matter and nutrient content were scarcely influenced by the development of the vegetation, being similar across microsite types. Likewise, soil enzyme activities were more influenced by the background soil conditions (pH, and organic matter content, modified by the addition of soil amendment during soil remediation) than by the development of the vegetation. In the soils under the cover of the retama-oak association, intense acidification (pH <4) was observed in the most contaminated sites, which resulted in a higher solubility of toxic trace elements and lower enzyme activities (five times lower dehydrogenase and b-glucosidase activities, in comparison to neutral soils).

The results confirms previous evidence that in these systems the facilitation effect of the retama shrubs is more related to the improvement of abiotic conditions (light and extreme temperatures) than to soil biotic factors. They also suggest that improving soil conditions before plantation through amendment application is critical to ensure the improvement of microbial activity at the long-term in such degraded sites.

The study has been published in Ecological Engineering (available online 18 October 2016).

Reference:

Domínguez, M.T., Madejón E., López-Garrido, R., Marañón, T., Murillo, J.M. 2016. Shrubs for the remediation of contaminated Mediterranean areas: is the nurse effect mediated by increases in soil enzyme activities? Ecological Engineering, 97: 577-581.

 

Helping nature to help us

Changes in the natural capital’s properties influence soil processes, which support the provision of ecosystem services. The benefits produced by these ecosystem services are explicitly or implicitly valued by individuals and society. This can influence decision- and policy making at different scales, potentially leading to a societal response, such as improved land management.

A group of scientists within the RECARE project, including Teodoro Marañón (IRNAS, CSIC), has presented a comunication on soil-related ecosystem services at the session Strengthening Ecosystem Services Community of Practices, in the European Ecosystem Services Conference, with the motto “Helping Nature to help us”, that was held at Antwerpen, 19-23 September 2016.

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It was proposed an adapted framework for soil-related ecosystem services that is suited for practical application in the prevention and remediation of soil degradation across Europe. It will be applied in the 17 study sites included in the RECARE project.

Gudrun Schwilch, Simone Verzandvoort, Hedwig van Delden, Luuk Fleskens, Elias Giannakis, Teodoro Marañón, Jane Mills, Chris Short, Jannes Stolte (2016). Operationalizing ecosystem services for the mitigation of soil threats. En: European Ecosystem Services Conference, Antwerp, Bélgica, 19-23 septiembre 2016.

A copy of the presentation slides can be consulted here.

Presentation at 5th Ecosummit of Montpellier

ecos2016_300x250The 5th International Ecosummit, Ecological Sustainability, has been held at Montpellier, France, with more than 1,400 participants from 88 countries.

One of the scientific sessions was focused on Soil-plant interactions and soil ecosystem services delivery. In this session, researchers of IRNAS, CSIC have presented results on tree plantations in the Guadiamar Green Corridor (Seville, Spain) and their role in soil trace elements stabilization and carbon sequestration.

The importance of tree-soil interactions was remarked for the delivery of two ecosystem services: 1) improvement of soil quality by phytostabilization of contaminants, and 2) mitigation of climate change by carbon sequestration in biomass and soil.

Marañón, T., Domínguez, M. T., Navarro Fernández, C. M., Madejón, P., Burgos, P., Gil Martínez, M., & Murillo, J. M. (2016). Tree-soil interactions and the provision of ecosystem services in contaminated soils: trace elements phytostabilization and carbon sequestration. 5th International Ecosummit. Ecological sustainability. Engineering change. Montpellier, 29 August-1 September 2016.

Copy in pdf of the slides can be consulted in the CSIC repository.

Mycorrhization patterns along an environmental gradient

figura_micorrizasMycorrhizal symbiosis is a mutualist association between plants and fungi which may be critical under stressful environmental conditions, like in Mediterranean forests constrained by water stress and resource scarcity.

Researchers of the IRNAS-CSIC and the University of Córdoba have studied how the degrees of colonization by ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) fungi were related to other root and leaf traits, in woody plant communities of Sierra Morena (Córdoba) distributed along a gradient of soil resources.

The level of ECM colonization was positively related to the abundance of evergreen species and to tissue dry matter content (in leaves and roots), but negatively to specific root length and specific leaf area. The best abiotic predictor of ECM colonization was soil moisture, with higher ECM colonization in drier sites.

However, AM colonization was not related to any of the plant traits studied and was positively related to soil Cu and other physico-chemical soil properties.

Changes in community ECM mycorrhization were primarily due to plant species turnover, while in the case of AM colonization was more important the intraspecific variability.

The proposed mycorrhizal trait-based approach is novel and useful to understand the functioning of Mediterranean forests and shrublands.

The study has been published (on line since August 29 2016) in the Journal of Vegetation Science.

Navarro-Fernández CM, Pérez-Ramos IM, de la Riva EG, Vera JR, Roumet C, Villar R, Marañón T (2016). Functional responses of Mediterranean plant communities to soil resource heterogeneity: a mycorrhizal trait-based approach. Journal of Vegetation Science, DOI: 10.1111/jvs.12446.

Evaluation of forest ecosystem services in Andalusia (S Spain)

Castanea IstanForests are suppliers of important ecosystem services, provisioning (timber, foods, resins), regulating (improving air and water quality, soil protection, carbon sequestration) and cultural (recreation, aesthetic, spiritual) contributing to human well-being.

Researchers of the IRNAS, CSIC and EVENOR-TECH have evaluated the state and trends of ecosystem services provided by the forests of Andalusia (S Spain). In particular, changes during the last 50 years have been analysed for two main regulating services: soil protection from erosion and capacity of carbon storage.

In general Andalusian forests have increased their carbon storage by 3040 Gg C during the last 50 years, due to the plantations of conifers and eucalyptus. While the soil erosion risk has increased because the area of open spaces, deforested or burnt has tripled.

This study has been published in the August 2016 issue of the journal Ecosystem Services.

Anaya-Romero M, M Muñoz-Rojas, B Ibáñez y T. Marañón. Evaluation of forest ecosystem services in Mediterranean areas. Ecosystem Services 20: 82-90.