• Rural Digital Europe
• Research Collection close
• ProdInra close

Over the past 25 years, the study of driving forces of landscape change has developed into a central theme in land change science by contributing to theory development, promoting the analysis of causation of change and gaining insights into how landscape development could be steered into a societally more desirable direction. Based on this progress, we designate important research avenues, reviewing critical challenges forming the base for advancing the study of driving forces of landscape change and addressing the question on how the study of driving forces can contribute to system transformative research. For each of the research avenues, we describe the current dominant approach and provide some specific ways of advancing both the conceptualization and the research methods. Together, advancing on these research avenues will promote a more social-ecological systems perspective to the study of driving forces of landscape change. Journal of Land Use Science, 17 (1) ISSN:1747-4248 ISSN:1747-423X

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

Gross primary production (GPP) by boreal forests is highly sensitive to environmental changes. However, GPP simulated by land surface models (LSMs) remains highly uncertain due to the lack of direct photosynthesis observations at large scales. Carbonyl sulfide (COS) has emerged as a promising proxy to improve the representation of GPP in LSMs. Because COS is absorbed by vegetation following the same diffusion pathway as CO2 during photosynthesis and not emitted back to the atmosphere, incorporating a mechanistic representation of vegetation COS uptake in LSMs allows using COS observations to refine GPP representation. Here, we perform ecosystem COS flux and GPP data assimilations to constrain the COS- and GPP-related parameters in the ORCHIDEE LSM for boreal evergreen needleleaf forests (BorENF). Assimilating ecosystem COS fluxes at Hyytiälä forest increases the simulated net ecosystem COS uptake by 14%. This increase largely results from changes in the internal conductance to COS, highlighting the need to improve the representation of COS internal diffusion and consumption. Moreover, joint assimilation of ecosystem COS flux and GPP at Hyytiälä improves the simulated latent heat flux, contrary to the GPP-only data assimilation, which fails to do so. Finally, we scaled this assimilation framework up to the boreal region and find that the joint assimilation of COS at Hyytiälä and GPP fluxes at 10 BorENF sites increases the modeled vegetation COS uptake up to 18%, but not GPP. Therefore, this study encourages the use of COS flux observations to inform GPP and latent heat flux representations in LSMs. Journal of Geophysical Research: Biogeosciences, 128 (7) ISSN:2169-8961 ISSN:0148-0227 ISSN:2169-8953

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.