jean-luc Maeght

Institute of Research for Development | IRD · IRD 123 BotAnique et Modélisation de l'Architecture des Plantes et Végétations - Institue of Ecology and Environment de Paris iEES Paris

Vessel traits contribute to plant water transport from roots to leaves and thereby influence how plants respond to soil water availability, but the sources of variation in fine roots anatomical traits remain poorly understood. Here, we explore the variations of fine root vessel traits along topological orders within and across tropical tree species...

Non‐structural carbohydrates (NSC) are considered as indicators of the balance between tree carbon sources and sinks and reflect functional strategies throughout different biomes. However, little is known about the contribution of NSC to tree economics, and in particular, whether leaf, stem and coarse root traits co‐ordinate together into a whole‐t...

Wood performs several functions to ensure tree survival and carbon allocation to a finite stem volume leads to trade‐offs among cell types. It is not known to what extent these trade‐offs modify functional trade‐offs and if they are consistent across climates and evolutionary lineages. Twelve wood traits were measured in stems and coarse roots acro...

Context Farmland on steep slopes is increasingly abandoned because it is unsuitable for most forms of modern agriculture. Succession back to forest is often slow or inexistent due to over-exploitation. Observations and measurements in Dong Cao catchment 47.9 ha Vietnam, started under farming and continued after abandonment: 20 years of uninterrupte...

Objectives Carbon fixed during photosynthesis is exported from leaves towards sink organs as non-structural carbohydrates (NSC), that are a key energy source for metabolic processes in trees. In xylem, NSC are mostly stored as soluble sugars and starch in radial and axial parenchyma. The multi-functional nature of xylem means that cells possess sev...

Termites are key soil bioturbators in tropical ecosystems. Apart from mound nests constructed by some advanced lineages, most of the species use their faeces, oral secretions, debris, or soil aggregates to protect themselves from predators and desiccation when they go out to forage. Although this soil ‘sheeting’ is considered to play a key role in...

Vegetation processes are fundamentally limited by nutrient and water availability, the uptake of which is mediated by plant roots in terrestrial ecosystems. While tropical forests play a central role in global water, carbon, and nutrient cycling, we know very little about tradeoffs and synergies in root traits that respond to resource scarcity. Fro...

Vegetation processes are fundamentally limited by nutrient and water availability, the uptake of which is mediated by plant roots in terrestrial ecosystems. While tropical forests play a central role in global water, carbon, and nutrient cycling, we know very little about tradeoffs and synergies in root traits that respond to resource scarcity. Fro...

De plus en plus de voix appellent à résoudre simultanément la crise du climat et celle de la biodiversité. Cela est justifié par de nombreux arguments. Ainsi, les mêmes mécanismes liés à la surexploitation des ressources et des écosystèmes par les sociétés humaines conduisent conjointement à ces deux crises. On peut donc probablement résoudre les d...

This study is aimed at studying the influence of organic fertilization on coffee growth and its resistance to drought. The experiment was carried out on young coffee plantlets in a greenhouse in Viet Nam and compared three varieties (Arabica L, Robusta TR9, and Robusta M38) and two types of organic amendments (compost or vermicompost). This study s...

Soil macroporosity is a highly dynamic feature driven by numerous physical and biological processes, of which bioturbation, the movement of water in soil and swelling and shrinking cycles are the main processes. To date, the interaction between these factors, especially how galleries produced by soil fauna respond to rainwater percolation and wetti...

By ingesting soil and organic matter in different soil horizons and depositing casts on soil surface, anecic earthworms have large influence on soil ecological processes. However, we still have a limited understanding of the consequences of earthworm casting activity on nematode communities, and the role played by the land use in this relationship....

Mountain regions of the humid tropics are characterized by steep slopes and heavy rains. These regions are thus prone to both high surface runoff and soil erosion. In Southeast Asia, uplands are also subject to rapid land-use change, predominantly as a result of increased population pressure and market forces. Since 1998, the Houay Pano site, locat...

Soil is considered as a non-renewable resource, which may be lost in sloping land more rapidly than it is formed thus leading to loss of fertility and ecosystem deterioration. We hypothesized that earthworms could counteract this process due to their cast forming activity. To test this hypothesis, we quantified the production of casts in small plot...

Intensive coffee production is accompanied by several environmental issues, including soil degradation, biodiversity loss, and pollution due to the wide use of agrochemical inputs and waste generated by processing. In addition, climate change is expected to decrease the suitability of cultivated areas while potentially increasing the distribution a...

Understanding the variables explaining earthworm cast properties remains a key challenge in soil ecology. For this purpose, this study aimed to determine the relationships between the physical and chemical properties of earthworm casts and those of their surrounding soil environment. Surface earthworm casts (recently emitted or degraded) produced b...

By creating vertical and continuous burrows, anecic earthworms accelerate the transfer of water in soils. However, the degradation mechanisms and lifespan of burrows and the consequence of changes in burrow characteristics for water infiltration remain poorly known. In this study, the dynamics of the degradation and hydraulic properties of burrows...

Key message In this study, deep roots of teak tree seem to have acted as a “safety net”, allowing trees to maintain their canopy cover longer, thus coping with inter- and intra-seasonal drought. Abstract Most deciduous species of dry monsoon forest, such as teak tree (Tectona grandis Linn F.), establish new foliage slightly before, or at the onset...

This study suggests that fine roots play an important role in the interaction with microbial communities all along the soil profile. The presence of roots deep in the soil profile, in agroforest systems and natural vegetation, should be taken into account as a significant contributor to belowground ecosystem services and long-term carbon storage.

In agroforests, if the role of tree lines as physical barriers to runoffs is easily understanding, processes involving rooting systems and soil erodilbility are still unknown.

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.

Researches axes on Environmental impacts of land use change ans soil ecosystem engineers in Vietnam.

The expansion of rubber cultivation into drought prone areas calls for innovative management to increase the drought resistance of the trees. The competition for water exerted by an intercrop in the upper soil layers will likely stimulate the growth of young rubber tree roots into deeper soil layers where water availability is more stable. This stu...

In many tropical regions, such as New Caledonia, soil erosion from anthropogenic activities and subsequent ecological restoration are major issues that require detailed soil and vegetation data for the production of management plans. To determine if some plant species are more useful for stabilizing soil aggregates and thus reducing erodibility, we...

Melioidosis, a severe infection with the environmental bacterium Burkholderia pseudomallei, is being recognised increasingly frequently. What determines its uneven distribution within endemic areas is poorly understood. We cultured soil from a rice field in Laos for B. pseudomallei at different depths on 4 occasions over a 13-month period. We also...

Study roots from wells and scanner technics Maeght Jean-Luc, Clément Corentin, Gonkhamdee Santimaitree, Isarangkool Na Ayutthaya Supat, Stokes Alexia, Pierret Alain .Seasonal patterns of fine root production and turnover in a mature rubber tree (Hevea brasiliensis Müll. Arg.) stand - differentiation with soil depth and implications for soil carbon...

Although vegetation is increasingly used to mitigate landslide risks, how vegetation affects the temporal variability of slope stability is poorly understood, especially in earthquake-prone regions. We combined 3-year long soil moisture monitoring, measurements of soil physical properties and plant functional traits, and numerical modeling to compa...

Background Belowground processes play an essential role in ecosystem nutrient cycling and the global carbon budget cycle. Quantifying fine root growth is crucial to the understanding of ecosystem structure and function and in predicting how ecosystems respond to climate variability. A better understanding of root system growth is necessary, but cho...

Although vegetation is increasingly used to mitigate landslide risks, how vegetation affects the temporal variability of slope stability is poorly understood, especially in earthquake-prone regions. We combined 3-year long soil moisture monitoring, measurements of soil physical properties and plant functional traits, and numerical modeling to compa...

In Northeastern Thailand, dipterocarp forest has been cut massively in recent decades to be gradually replaced by cash crops. The aerial parts of the vegetation were sold or burned while underground parts have been degraded with time on site by microbial activity that converts the plant tissues in organic matter more or less mineralized (humus). A...

Background Deep roots are a common trait among a wide range of plant species and biomes, and are pivotal to the very existence of ecosystem services such as pedogenesis, groundwater and streamflow regulation, soil carbon sequestration and moisture content in the lower troposphere. Notwithstanding the growing realization of the functional significan...

Fine root dynamics is a main driver of soil carbon stocks, particularly in tropical forests, yet major uncertainties still surround estimates of fine root production and turnover. This lack of knowledge is largely due to the fact that studying root dynamics in situ, particularly deep in the soil, remains highly challenging. We explored the interact...

Session 2 Integrated Soil Management and Conservation for Food Security POSTER Deep Root Biomass and Interfluve Aquifer: Case of a Watershed in Northeast Thailand

Storing more carbon in soils, particularly at depth, could be an effective and readily available means to mitigate climate change. Current estimates of soil organic carbon (SOC) are based on sampling the first 30 cm of soil. Deep soils abound worldwide, particularly in the tropics, and many plants are known to grow deep root systems. In addition, r...

Effet d’une sécheresse induite sur la physiologie du Teck. Une vidéo décrivant le site expérimental utilisé dans le cadre du projet ECOSFIX au Laos. Réalisé par A. Pierret et J.L.Maeght (Bioemco, IRD).

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

Soil erosion in farmlands is a major cause of water quality degradation and reduced crops production potential throughout the European countries. In agroforests, if the role of tree lines as physical barriers to runoffs is easily understanding, processes involving rooting systems and soil erodilbility are still unknown. Objectives-Do the presence o...

Le rôle méconnu des racines profondes

Aim This study aims to improve our understanding of temporal variations and controlling factors of soil respi-ration (R s) and its components (microbial respiration or R m and root respiration or R b) in an Asian tropical seasonal forest at diurnal, seasonal and annual timescales in relation to biotic and abiotic controls. Methods R s was studied b...

There is a fundamental trade-off between leaf traits associated with either resource acquisition or resource conservation. This gradient of trait variation, called the economics spectrum, also applies to fine roots, but whether it is consistent for coarse roots or at the plant community level remains untested. We measured a set of morphological and...

Melioidosis is a serious infectious tropical disease caused by a soil-dwelling bacterium, Burkholderia pseudomallei, transmitted from contaminated soil or surface water. Although endemic in Southeast Asia, it is considered an emerging disease in Lao PDR where it has only been recognised for 15 years, becoming one of the leading causes of community-...

For almost two decades, the French Institut de Recherche pour le Développement (IRD) has been working in partnership with the Soils and Fertilizer Research Institute (SFRI) to study soil erosion and land use change in the small catchment of Dong Cao, Tien Xuan, North Vietnam. This partnership forms one of the main pillars of the regional Multi - Sc...

Abstract: For almost two decades, the French Institut de Recherche pour le Développement (IRD) has been working in partnership with the Soils and Fertilizer Research Institute (SFRI) to study soil erosion and land use change in the small catchment of Dong Cao, Tien Xuan, North Vietnam. This partnership forms one of the main pillars of the regional...

Abstract: For almost two decades, the French Institut de Recherche pour le Développement (IRD) has been working in partnership with the Soils and Fertilizer Research Institute (SFRI) to study soil erosion and land use change in the small catchment of Dong Cao, Tien Xuan, North Vietnam. This partnership forms one of the main pillars of the regional...

There is a fundamental trade‐off between leaf traits associated with either resource acquisition or resource conservation. This gradient of trait variation, called the economics spectrum , also applies to fine roots, but whether it is consistent for coarse roots or at the plant community level remains untested. We measured a set of morphological an...

The root system is essential but essentially invisible. It is a vital link between the plant and the soil but remains largely unstudied as a whole. Plants are anchored to the soil through their root system; their adaptation and survival abilities are highly dependent on their ability to learn to take advantage of the space that surrounds them. Cert...

Le système racinaire, lien essentiel entre la plante et le sol quoi qu'essentiellement invisible, reste encore aujourd'hui peu étudié dans son ensemble. Les plantes étant ancrées au sol via leur système racinaire, leurs facultés d'adaptation et de survie sont donc très dépendantes de leurs capacités à savoir tirer profit de l'espace qui les entoure...

While soil erosion is reasonably well documented at the plot scale, data remain scarce at the catchment scale and predominantly stem from short-term studies. In this context, the “Management of Soil Erosion Consortium” network, which recently became the Multi-Scale Environmental Changes observatory (MSEC3, http://www.msec3.net/portal/), was establi...

De nombreux petits agriculteurs du sud-est asiatique développent actuellement des plantations d'hévéa (Hevea brasiliensis Muell. Arg.) dans des régions peu propices à cet arbre du point de vue pédoclimatique. Ceci se traduit par des délais importants d'entrée en production des arbres et des risques d'érosion des sols. L'introduction de plantes de c...

Background and aims This paper provides an overview of the measuring capabilities of IJ_Rhizo, an ImageJ macro that measures scanned images of washed root samples. IJ_Rhizo is open-source, platform-independent and offers a simple graphic user interface (GUI) for a main audience of non-programmer scientists. Being open-source based, it is also fully...

The factors determining the distribution of Burkholderia pseudomallei in the environment are poorly understood. We intensively studied a rice paddy in Vientiane Province, Lao PDR, over a 12-month period. Soil samples were collected at the end of the dry season, just after the onset of the rainy season, at the end of the rainy season and at the end...

The drivers underlying the development of deep root systems, whether genetic or environmental, are poorly understood but evidence has accumulated that deep rooting could be a more widespread and important trait among plants than commonly anticipated from their share of root biomass. Even though a distinct classification of “deep roots” is missing t...

Water flow and solute transport in soils forms an essential part in many groundwater hydrology studies. This is especially true for Northeast Thailand, where the agricultural land is affected by the soil salinity, which is a widespread and an increasing phenomenon affecting 25% of the agricultural land. Salinization appears as scattered discrete pa...

The aim of this paper is to summarize the successive biological, pedological, hydrodynamic, geomorphological and geochemical processes that have occurred in the Senegal valley, and to describe how their interactions during the late Holocene conditioned soil cover formation and landscape evolution. Potential acidity accumulated as pyrite in the floo...

Soil biomass comprises a tiny proportion of the total soil mass, and plays a dominant role in delivering the wide range of ecosystem services provided by soil systems. The soil biota create physical structure within their habitat, affect the resultant dynamics of many soil processes and are themselves affected by such structure. This interplay betw...

Effects of soil and atmospheric drought on whole-tree transpiration (E(T)), leaf water potential (Ψ(L)) and whole-tree hydraulic conductance (K(T)) were investigated in mature rubber trees (Hevea brasiliensis, clone RRIM 600) during the full canopy stage in the rainy season in a drought-prone area of northeast Thailand. Under well-watered soil cond...

Trunk phloem necrosis (TPN) is a major constraint in rubber (Hevea brasiliensis) plantations. Current knowledge supports a scenario of a multi-factor physiological ‘disease’ caused by an accumulation of endogenous and exogenous stresses. Without evidence of a pathogen, the apparent spread of the syndrome from tree to tree along the planting line, s...

Biotic regulation: Plants

This study focused on the variability of rice yield under water and soil salinity risks in farmers’ fields in northeast Thailand. A rice plot was monitored in 24, 16 and 11 farmers’ fields during the rice seasons 2005, 2006 and 2007, respectively. The results emphasized that few plots were continuously submerged during the 2005 season,...

Understanding better the interactions between root systems in associated crops is significant for basic knowledge in plant science and to help designing cropping systems. Current research on inter-specific root interactions concentrates on static descriptions of the horizontal extension of root systems or on the dynamics of provoked root encounters...

This study focused on the variability of rice yield under water and soil salinity risks in farmers’ fields in northeast Thailand. A rice plot was monitored in 24, 16 and 11 farmers’ fields during the rice seasons 2005, 2006 and 2007, respectively. The results emphasized that few plots were continuously submerged during the 2005 season, when rai...

Nowadays, tree transpiration (ETree) limitation is investigated in several plant species especially the commercial trees such as the rubber tree. Exceptional tree physiology responds to droughts, the modeling for prediction of ETree is also interest. The aim of this investigation was to evaluate the environmental model for ETree estimation in all l...