ES1406 COST Action: Soil fauna: Key to Soil Organic Matter Dynamics and Fertility. How far have we got?

Soil organic matter (SOM) is key to soil fertility, climate change mitigation, combatting land degradation, and the conservation of above- and below-ground biodiversity and associated ecosystem services like decomposition, nutrient cycling, carbon sequestration, detoxification and maintenance of soil physico-chemical properties. SOM dynamics represent the balance between the input of plant material (residues, root-derived materials) and the output through decomposition (OM mineralization) by organisms, erosion and leaching. Approximately 20% of global CO2 emissions, one third of global CH4 emissions and two thirds of N2O emissions originate from soils. In many soils, most of the macro-aggregate structure is formed by the activities of soil invertebrates and roots, with important consequences for soil organic matter dynamics, carbon sequestration and water infiltration at several spatial and temporal scales. Current models of SOM dynamics are defined in terms of plant residues input and microbial decomposition, overlooking the important contribution of soil fauna. The composition and activity of soil fauna greatly vary with respect to climate and land use. SOM modelling has thus far largely ignored soil fauna due to various reasons: i) hardly existing communication between [C flow centered] biogeochemistry and [organism-centered] soil ecology, ii) lack of [awareness of] data on soil animals (both in the field and from labora-tory experiments) and, iii) two different visions by soil ecologists: foodweb vs. self-organization. An international interdisciplinary approach (COST Action ES1406) is the proper platform for both experimentalists and modellers to discuss and provide solutions. This Action has fostered networking and collaboration for improved SOM mod-els by implementing the role of the soil fauna as a basis for sustainable soil management. Key challenges in SOM management, soil fauna and modelling will be addressed and how far have we got thus far to meet the objectives of this Action

Genotypic variability enhances the reproducibility of an ecological study

Many scientific disciplines are currently experiencing a “reproducibility crisis” because numerous scientific findings cannot be repeated consistently. A novel but controversial hypothesis postulates that stringent levels of environmental and biotic standardization in experimental studies reduces reproducibility by amplifying impacts of lab-specific environmental factors not accounted for in study designs. A corollary to this hypothesis is that a deliberate introduction of controlled systematic variability (CSV) in experimental designs may lead to increased reproducibility. We tested this hypothesis using a multi-laboratory microcosm study in which the same ecological experiment was repeated in 14 laboratories across Europe. Each laboratory introduced environmental and genotypic CSV within and among replicated microcosms established in either growth chambers (with stringent control of environmental conditions) or glasshouses (with more variable environmental conditions). The introduction of genotypic CSV led to lower among-laboratory variability in growth chambers, indicating increased reproducibility, but had no significant effect in glasshouses where reproducibility was generally lower. Environmental CSV had little effect on reproducibility. Although there are multiple causes for the “reproducibility crisis”, deliberately including genetic variation may be a simple solution for increasing the reproducibility of ecological studies performed in controlled environments

Earthworms promote greater richness and abundance in the emergence of plant species across a grassland-forest ecotone

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CARBON AND NUTRIENT LOSSES THROUGH BIOMASS BURNING, AND LINKS WITH SOIL FERTILITY AND YAM ( DIOSCOREA ALATA ) PRODUCTION

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The dynamics of hollowing in annually burnt savanna trees and its effect on adult tree mortality

Savanna trees often display significant hollows due to the combined action of fire and termites (N'Dri et al., J Trop Ecol 27:269-278, 2011). Observations have shown that internal cavities caused by termites in tree stems often result in external hollow

The Demographic Response of Grass Species to Fire Treatments in a Guinean Savanna

International audienceFighting tree encroachment using fire promotes C4 perennial grasses but likely affects their demography according to the fire date during the dry season. We analyzed the impact of four fire treatments (early, middle, late and no fire) on the demography of the four dominant perennial grasses (Andropogon canaliculatus, Andropogon schirensis, Hyparrhenia diplandra and Loudetia simplex) in a Guinean savanna of West Africa (Lamto, Côte d'Ivoire). We carried out a yearly demographic monitoring of each grass individual during five years (2015\textendash 2019) on three plots by treatment and parametrized a size-classified matrix model with five circumference classes. The results showed that A. schirensis, H. diplandra and L. simplex declined (λ < 1.0) under late fire and will disappear after 10 years, as did L. simplex under the middle fire. Stasis influenced the most λ values and stable class distribution was nearly achieved in all species under all treatments. The size of L. simplex should increase under early and late fires. Our results suggest that late fire is the most detrimental fire regime for grasses in this Guinean area, contrary to early and middle fires, which could be recommended to savanna managers

Unfolding the link between multiple ecosystem services and bundles of functional traits to design multifunctional crop variety mixtures

Abstract In face of the current environmental challenges, developing multifunctional cropping systems is increasingly needed, and crop variety mixtures are particularly interesting since they can deliver diverse services including grain production, yield stability, N 2 O production regulation, disease control, and reduction of N-fertilizer losses. However, the relationships between intraspecific diversity and ecosystem multifunctionality are poorly understood so far, and practitioners lack science-based guidance to design mixtures. We used a pool of 16 bread wheat varieties classified into 4 functional groups based on 26 below- and aboveground functional traits, to conduct a field trial (88 large plots cultivated with single varieties or mixtures of 2, 4, or 8 varieties), quantifying 15 provisioning and regulating services for each plot. To assess yield stability between local conditions and years, the trial was replicated at 4 other locations and for 2 years, using 2 managements each time. We analyzed how variety number and functional groups predicted the variance in services, and applied in an innovative manner the RLQ co-inertia analysis to relate the (variety × traits) matrix Q to a (plot × services) matrix R , using a (plot × variety) composition matrix L as a link. Our results show that using variety mixtures allowed delivery of baskets of services not reachable when cultivating single varieties, and that mixtures mitigated tradeoffs between different pairs of services. Variety number or functional groups poorly predicted the variance in services, but the RLQ approach allowed the identification of groups of plots delivering consistent baskets of services. Moreover, we demonstrated for the first-time significant relationships between specific baskets of services and bundles of variety traits. We discuss how our results increase our understanding of intraspecific diversity–agroecosystem multifunctionality relationships, and propose the next steps using our new approach to support practitioners for designing variety mixtures that provide particular baskets of services