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Context[br/] Parasites can induce strong effects on their host’s growth, not only as a result of host resource exploitation (growth loss) but also with a potential adaptive value for host (tolerance response) and themselves (increased transmission).[br/] [br/] Aims[br/] We assessed these three types of phenotypic changes in oak seedlings infected by powdery mildew.[br/] [br/] Methods[br/] A manipulative field experiment with three levels of parasite inoculum was designed in order to tease apart infection from genetic effects on oak growth. Seedlings were monitored during 3 years for height growth, phenology and infection.[br/] [br/] Results[br/] Powdery mildew infection induced both significant growth loss and qualitative changes in plant architecture. The most striking and unexpected change was increased growth polycyclism in infected seedlings. This benefitted both the host as a form of compensation for infection-caused height loss, and the pathogen, by increasing sporulation.[br/] [br/] Conclusion[br/] The study highlights the effect of parasites in the expression of plant phenotypic traits, such as phenology and ultimately tree architecture. Both host tolerance and parasitic manipulation may be involved in the observed changes in growth patterns. These results suggest a complex interplay between development and defence in trees and emphasize the need to better assess tolerance mechanisms when considering the defence strategies of trees against pathogens.

The limited availability of soil information has been recognized as a main limiting factor in digital soil mapping (DSM) studies. It is therefore important to optimize the joint use of the three sources of soil data that can be used as inputs of DSM models, namely spatial sets of measured sites, soil maps and soil sensing products.In this paper, we propose to combine these three inputs, through a cokriging with a categorical external drift (CKCED). This new interpolation technique was applied for mapping seven soil properties over a 24.6 km2 area located in the vineyard plain of Languedoc (Southern France), using an hyperspectral imagery product as example of a soil sensing data. Cross-validation results of CKCED were compared with those of five spatial and non-spatial techniques using one of these inputs or a combination of two of them.The results obtained in the La Peyne Catchment showed i) the utility of soil map and hyperspectral imagery products as auxiliary data for improving soil property predictions ii) the greater added-value of the latter against the former in most situations and iii) the feasibility and the interest of CKCED in a limited number of soil properties and data configurations. Testing CKCED in case study with soil maps of better quality and soil sensing techniques covering more area and depths should be necessary to better evaluate the benefits of this new technique. International audience

Abstract This article discusses the land use dynamics in the urban fringe of Onitsha—one of the fastest growing towns in Nigeria. It analyses the land conversion process In the city's rurban fringe and looks at the characteristic features of such a fringe environment, namely the loss of prime agricultural land in the urban fringe areas, the dysfunctional use of land in the zone and a confused administrative set-up to handle these problems. The land use planning implications associated with these characteristics are looked at.

Variations du coût de construction associées au renouvellement de la surface foliaire chez de jeunes plants de deux espèces sympatriques de forêt tempérée (Acer platanoides L. et Fraxinus excelsior L.) le long d'un gradient de lumière. Le renouvellement des feuilles et des structures nécessaires à leur maintien (l'ensemble correspondant à la tige feuillée) représente chaque année un coût pour les plants. La contribution de la composition biochimique (coût de construction des tissus, CC) et des caractéristiques morphologiques (répartition de la biomasse, masse des feuilles par unité de surface, LMA) aux changements du coût associé à l'étalement des feuilles (coût de construction de la tige feuillée, par unité de surface foliaire, CCA) a été étudiée chez de jeunes plants de Acer platanoides L. et Fraxinus excelsior L. croissant dans un gradient naturel de lumière sous un couvert forestier. Une diminution de LMA avec l'ombrage et des modifications de répartition de biomasse au profit des feuilles et des pétioles et au détriment de la tige expliquent la forte diminution de la masse de la tige feuillée de l'année par unité de surface foliaire (SMA), et l'essentiel de la plasticité observée pour CCA de la tige feuillée chez les deux espèces. En plus, une diminution du coût de construction des feuilles chez A. platanoides contribue également à la diminution de CCA de la tige feuillée avec l'ombrage chez cette espèce. Le coût de construction des feuilles est positivement corrélé à LMA chez F. excelsior, positivement corrélé à LMA et à l'absorbance de l'épiderme dans l'UV (AUV) chez A. platanoides. CC des feuilles est négativement corrélé au contenu en cendre chez les deux espèces. La forte corrélation négative entre AUV et le contenu en azote pourrait tamponner les variations de CC des feuilles chez F. excelsior. The yearly renewal of leaves and their holding organs (the leafy shoot) represent an energetic cost for saplings. The contribution of both biochemical (tissue construction cost, CC) and morphological traits (biomass partitioning and leaf mass per unit area, LMA) to the cost associated with leaf area renewal (construction cost of the leafy shoot per unit leaf area, shoot CCA) was studied in saplings of Acer platanoides L. and Fraxinus excelsior L. growing in a natural light gradient below forest canopy. Decrease in LMA with shade and change in biomass partitioning from stems towards leaves and petioles accounted for the strong decrease in mass per unit area of the leafy shoot (SMA) with shade and for most of the plasticity of shoot CCA in both species. In addition, a decrease in leaf CC in A. platanoides also contributed to the overall decrease of shoot CCA with shade in this species. Leaf CC was positively correlated with LMA in F. excelsior, positively correlated with both LMA and epidermal absorbance of UV (AUV) in A. platanoides. Leaf CC was negatively correlated with ash content in both species. The strong negative correlation between AUV and nitrogen content might have damped variations in leaf CC in F. excelsior.

Landscape approaches to integrated land management have recently gained considerable attention in the scientific literature and international fora. The approach is gaining increasing support at governmental and intergovernmental levels, as well as being embraced by a host of international research and development agencies. In an attempt to determine whether, and how, these approaches compare with previous conservation and development paradigms, we reviewed the implementation of integrated landscape approaches across the tropics. Within the scientific literature we fail to find a single applied example of the landscape approach in the tropics that adequately—that is with reliable, in depth collection and reporting of data—demonstrated the effective balancing of social and environmental trade-offs through multi-scale processes of negotiation for enhanced outcomes. However, we provide an assessment of 150 case studies from unpublished grey literature and 24 peer-reviewed studies that exhibit basic characteristics of landscape approaches. Our findings indicate that landscape approaches show potential as a framework to reconcile conservation and development and improve social capital, enhance community income and employment opportunities as well as reduce land degradation and conserve natural resources. However, comprehensive data on the social and environmental effects of these benefits remain elusive. We identify key contributing factors towards implementation, and progress, of landscape approaches and our findings suggest that multi-level, or polycentric, governance structures relate well with intervention success. We conclude that landscape approaches are a welcome departure from previous unsuccessful attempts at reconciling conservation and development in the tropics but, despite claims to the contrary, remain nascent in both their conceptualization and implementation.

Aim of study: The program "Typology of truffle stations in the Pyrenean Regions" aimed to define the ecological conditions and culture practices that favor Tuber melanosporum growth and fruiting in this area.Area of study: Navarra, Catalonia, Midi-Pyrénées and Languedoc-Roussillon.Material and methods: The program was based on the survey of 212 wild and cultivated truffle beds of evergreen oaks (Quercus ilex). The data collected in the field consisted of photographs, samples of soil, roots and mycorrhizae, and information on cultural practices followed by truffle growers.Main results: (i) truffle soils are alkaline, from neutral, dolomitic, to moderately or very calcareous soils; (ii) truffle soils are light, well-structured and stable to water immersion; (iii) mycelium that colonizes roots survives in suboptimal conditions, but it does not necessarily bear ascocarps. Finally our results suggest that T. melanosporum is a relatively ubiquitous fungus able to grow, or at least to persist, in a wide range of physical and chemical soil conditions. We propose a probabilistic model of the environment favorable for fruiting, built around a two-dimensional graph with an axis for the chemical conditions, like soil alkalinity, and another axis for the physical conditions, like soil structure. Research highlights: Soil alkalinity and structure allow to built a convenient representation of the ecological capacity of a place to be good T. melanosporum habitat, and thus of the probability for truffle growers to harvest truffles according to the environmental properties of their truffle orchards.Keywords: dolomite; limestone; mycorrhizae; Quercus ilex; field survey; Tuber melanosporum.