Amandine Erktan

Institute of Research for Development | IRD · 210 - Functional Ecology and Biochemistry of Soils and Agroecosystems (Eco&Sols)

Soil biodiversity is pivotal for ecological intensification of agriculture by enhancing soil functions, sustainable crop production and resilience to environmental shocks and disturbances. However, a detailed understanding of mechanisms in field conditions to inform ecological intensification strategies based on the beneficial effects of soil biodi...

Soil structure and aggregation are crucial for soil functionality, particularly under drought conditions. Saprobic soil fungi, known for their resilience in low moisture conditions, are recognized for their influence on soil aggregate dynamics. In this study, we explored the potential of fungal amendments to enhance soil aggregation and hydrologica...

Evolution optimizes the performance of living organisms through budgeting of limited resources, leading to life-history trade-offs. Many life-history traits are related to body size with larger species typically exhibiting a slower pace of life and lower fecundity. However, soil-living organisms may exhibit size-independent life-history strategies...

Trophic interactions between soil-living organisms occur largely in soil pores and are essential for soil functioning. As soil is a three-dimensional environment where resources are distributed in pores of contrasting size, and higher trophic level consumers (grazers) are typically larger than their microbial food sources, the location of microbial...

Les espèces exotiques envahissantes représentent une menace pour la biodiversité à l’échelle mondiale. Parmi les plantes problématiques en France et en Europe, les renouées asiatiques (Reynoutria spp.) posent un véritable défi, leur gestion étant coûteuse et d’efficacité aléatoire. Premièrement, les gestionnaires doivent choisir d’agir ou de ne pas...

Purpose Interactions between plants and soil biota play an important role in maintaining the productivity and sustainability of agro-ecosystems, but mechanisms responsible for these interactions still are little understood. We investigated the growth of different faba bean genotypes in response to soil decomposer animals in monoculture and mixed cr...

Mixed cropping, crop breeding and soil biodiversity all serve as promising strategies for the management of agroecosystems, but empirical evidence for their synergies and trade-offs remains little explored. Here, we studied the effects of two main soil decomposers, collembolans and earthworms, on ¹⁵N uptake from organic residues, crop production, r...

Les sols hébergent une importante biodiversité. Ils sont essentiels pour nourrir l'humanité et jouent un rôle fondamental dans les cycles biogéochimiques de la planète. Alors qu'à l'échelle du globe, un tiers des sols sont dégradés, comprendre les processus écologiques qui s'y déroulent pour mieux les préserver et les restaurer est un enjeu majeur....

Classifying organisms has a wide use and a long history in ecology. However, the meaning of a 'group of or-ganisms' and how to group organisms is still the subject of much theoretical and empirical work. Achieving this long quest requires simplifying the complexity of species niches for which relevant morphological, behavioural, biochemical or life...

Les sols hébergent une importante biodiversité. Ils sont essentiels pour nourrir l'humanité et jouent un rôle fondamental dans les cycles biogéochimiques de la planète. Alors qu'à l'échelle du globe, un tiers des sols sont dégradés, comprendre les processus écologiques qui s'y déroulent pour mieux les préserver et les restaurer est un enjeu majeur....

Heteroblastic variations among leaf traits is a well-known process, especially in bromeliad species that show abrupt changes, but little effort was directed to test whether comparable ontogenetic variation occurs among root traits and their fungal partners. Usually considered for their mechanical role, roots of bromeliads may also play a role in re...

Characterizing plant functional diversity is essential to decipher community assembly rules and ecosystem functioning. Most studies focused on above-ground traits whereas the analysis of root diversity lags far behind. We analyzed the structure of fine root (< 2mm) diameter distribution at the community level as an indicator of root morphological d...

Did you ever notice that dead leaves never accumulate in forests? For that service, we can thank a cleaning team of tiny recyclers living in the soil. Dead organisms are their food source, and they recycle them by just eating them. Knowing who eats what or whom in soils is essential to understand this recycling machinery. But that is hard to know,...

Microbes play an essential role in soil functioning including biogeochemical cycling and soil aggregate formation. Yet, a major challenge is to link microbes to higher trophic levels and assess consequences for soil functioning. Here, we aimed to assess how microbial consumers modify microbial community composition (PLFA markers), as well as C dyna...

Trophic interactions play a vital role in soil functioning and are increasingly considered as important drivers of the soil microbiome and biogeochemical cycles. In the last decade, novel tools to decipher the structure of soil foodweb has provided unprecedent advance in describing complex trophic interactions. Yet, the major challenge remains to u...

Abstract. The formation and stabilisation of soil macro-aggregates protects soils from erosion, a major worldwide threat on soils. While the role of bacteria and fungi in soil aggregation is well established, how predators feeding on microbes modify soil aggregation has hardly been tested. Here, we studied how predators modulate the effect of micro...

Biodiversity of ecosystems is an important driver for the supply of ecosystem services to people. Soils often have a larger biodiversity per unit surface area than what can be observed aboveground. Here, we present what is to our knowledge the most extensive literature-based key-word assessment of the existing information about the relationships be...

Les racines profondes des arbres peuvent ancrer les couches de sol « mou » dans la roche « dure », comme l’ancre d’un bateau empêche celui-ci de dériver.

1. Quantifying the variation in community-level fine root (<2mm) traits along ecological gradients or in response to disturbances is essential to unravel the mechanisms of plant community assembly, but available surveys are scarce. Whether fine root traits covary along a one-dimensional economic spectrum, as previously shown for leaves, is highly d...

Background: Roots play a pivotal role in defining plant ecological success and mediating terrestrial ecosystem functioning. However, roots are difficult to study as they are hidden in the soil matrix and express a plurality of forms and functions: nutrient acquisition, anchorage, nutrient and water transport. Scope: In this special issue, we gather...

Depuis le milieu du XX e siècle, du fait de la forte croissance démographique, les sols et la végétation des zones tropicales et méditerranéennes subissent d'importantes dégradations. Actuellement, plus de 20 % des terres cultivées sont dégradées chimiquement, physiquement et biologiquement. En effet, malgré la mise en oeuvre de grands projets tels...

Soil aggregate stability is a major component of soil functioning. This research aimed at tracking variations of soil aggregate stability along succession and to unravel how root characteristics contribute to drive these variations. Forty-eight plant communities on embankments along roadsides were selected in the French Mediterranean region, aged f...

Fine roots (<2 mm) have historically been considered as a single pool with a main role in nutrient and water absorption. Recent studies highlighted a strong heterogeneity within this pool, with roots from various orders and functions (absorptive & transport), associated with contrasted morphologies. Exploring this heterogeneity could provide unique...

Disturbances of biogeochemical cycles as a result of human activities can lead to dramatic consequences for ecosystems. The enrichment of traffic related trace elements (TE) in roadside environments has been a focus of concern for more than 50 years. The duration of exposition is a key factor for TE accumulation in the topsoil and plants. The purpo...

Background and aims Our objectives were to evaluate changes in soil aggregate stability along a successional gradient, located in severely eroded Mediterranean gully bed ecosystems and to identify predictors of soil aggregate stability variations among several soil, root traits and plant community characteristics. Methods We selected 75 plots in gu...

Correlation matrix between soil, plant community and roots characteristics along the successional gradient (n = 75). Data are correlation coefficient r and significance levels according to Pearson correlation test (n.s non significant; * P < 0.05; ** P < 0.01; *** P < 0.001). The grey shaded parts represent the plant related parameters.

Replacement of species, with contrasting ecological strategies for resource use, occurs along successional gradients and with disturbance. Studying the variations of plant ecological strategies provides insightful information to better understand plant community dynamics and functioning. Shoot and root plant functional parameters (morphological, ph...

Pourquoi les sols peuvent être instables ? Quelles conséquences pour l'homme ? Quel rôle pour les racines ?

Soil erosion on marly terrains is a frequent problem in the mountain and Mediterranean areas in the Durance catchment in the French Southern Alps. One of the consequences of this erosion is high yields of fine sediment at the exit of catchments, which can cause economic, social and ecological damages downstream. To avoid these sediment transports,...

Plant traits vary along secondary successions and with perturbations. While some traits have been intensively studied, modifications of root traits remain poorly investigated. We aim at understanding how changes in root traits along secondary successions contribute to the dynamic of Mediterranean plant communities and how perturbations modify these...

In the French Southern Alps, severe erosion in marly badlands shows negative consequencesfor human populations, who worked to restore these terrains since the XIXth century. For adecade, an ecological engineering strategy is developed and focuses on gully beds, cornerstonesof their restoration. The operational question at the root of this PhD proje...

Aims Sediment retention by plant barriers initiates common strategies to conserve soil fertility or restore degraded terrains, including gullied ones. Differences in species performance for sediment retention have been studied but little is known about plant performance in retention when upscaling to plurispecific barriers. We investigated the role...

Marly badlands, showing active eroded gullies and low soil fertility, are found in the French Southern Alps for around 250 years. Negative ecological, social and and economical consequences of such intense erosion historically promoted the ecological restoration of these terrains. In a small catchment of 390 ha (Saignon catchment, France), a first...

Aims: Sediment retention by plant barriers initiates common strategies to conserve soil fertility or restore degraded terrains, including gullied ones. Differences in species performance for sediment retention have been studied but little is known about plant performance in retention when upscaling to plurispecific barriers. We investigated the rol...

L’activité érosive des badlands marneux des Alpes du Sud présente des conséquences négatives pour l’homme qui a ainsi cherché à restaurer ces terrains dès le XIXème siècle. Depuis une dizaine d’années, une stratégie d’ingénierie écologique y est développée et se concentre sur les lits de ravines, pierres angulaires de leur restauration. La question...

In the southern French Alps, the brittleness of the black marls, combined to the erosivity of the rain and the scarce vegetative cover, has led to high sediment yields at the exit of gullies. From the observation that gullies, with a 20% vegetative cover located in the lower gully bed, can shut down gully exit activity through sediment trapping, a...

Dans les terrains marneux très érodables du bassin versant de la Durance, dans les Alpes du Sud, l’érosion torrentielle produit des matériaux fins qui provoquent l’envasement des barrages hydroélectriques et de l’étang de Berre, l’accroissement des risques d’inondations ainsi que le colmatage des frayères à poissons. Pour y remédier, le génie biolo...