Auteurs, date et publication :
Auteurs M Disney , A Burt , Kim Calders , C Schaaf , A Stovall
Publication : Surveys in Geophysics
Date : 2025
Volume : 40
Issue : 4
Pages : 937-958
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Over the centuries, specific farming practices shaped permanent grasslands in mountains. With socioeconomic change, farming practices have changed and with them the landscape. Over time, food production has been increasingly decoupled from the preservation of permanent grassland, endangering the delivery of crucial ecosystem services. This contribution looks into the role of institutions – including normative, regulative and cultural-cognitive elements – in preserving current bundles of ecosystem services provided by mountain grasslands. In particular, we investigate how such institutions affect farmers’ management choices. Based on a review of scientific literature and empirical data from three case studies, we compare institutions in Austria, France and Norway. The cases represent different modes of multi-level governance (EU and non-EU), different grassland management practices, linked to different farming systems (dairy, breeding, rearing of heifers, suckler cow and sheep production) and different socio-economic conditions. The results underpin that ecological insights into the impact of farming practices on the ecology of grassland need to be combined with an understanding of the complex institutional interactions that affect farming practices, to ensure the resilience of mountain grasslands. If the design of regulatory measures considers both changing dynamics, it may enable farms to adapt and transform while maintaining traditional grassland management practices © 2015 Elsevier Ltd. All rights reserved.
Auteurs, date et publication :
Auteurs Markus Schermer , Ika Darnhofer , Karoline Daugstad , Marine Gabillet , Sandra Lavorel , Melanie Steinbacher
Publication : Land Use Policy
Date : 2025
Volume : 52
Pages : 382-391
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs LoïC Harrault , Beatrice Allard , Michael Danger , Florence Maunoury-Danger , Alexis Guilpart , Gerard Lacroix
Publication : Freshwater Biology
Date : 2025
Volume : 57
Issue : 11
Pages : 2390-2400
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
LiDAR technology has been widely used to characterize structural parameters of forest ecosystems, which in turn are valuable information for forest monitoring. GEDI is a spaceborne LiDAR system specifically designed to measure vegetation’s vertical structure, and it has been acquiring waveforms on a global scale since April 2019. In particular, canopy height is an important descriptor of forest ecosystems, as it allows for quantifying biomass and other inventory information. This paper analyzes the accuracy of canopy height estimates from GEDI data over tropical forests in French Guiana and Gabon. The influence of various signal acquisition and processing parameters is assessed to highlight how they impact the estimation of canopy heights. Canopy height models derived from airborne LiDAR data are used as reference heights. Several linear and non-linear approaches are tested given the richness of the available GEDI information. The results show that the use of regression models built on multiple GEDI metrics allows for reaching improved accuracies compared to a direct estimation from a single GEDI height metric. In a notable way, random forest improves the canopy height estimation accuracy by almost 80% (in terms of RMSE) compared to the use of rh_95 as a direct proxy of canopy height. Additionally, convolutional neural networks calibrated on GEDI waveforms exhibit similar results to the ones of other regression models. Beam type as well as beam sensitivity, which are related to laser penetration, appear as parameters of major influence on the data derived from GEDI waveforms and used as input for canopy height estimation. Therefore, we recommend the use of only power and high-sensitivity beams when sufficient data are available. Finally, we note that regression models trained on reference data can be transferred across study sites that share identical environmental conditions.
Auteurs, date et publication :
Auteurs Kamel Lahssini , Nicolas Baghdadi , Guerric le Maire , Ibrahim Fayad
Publication : Remote Sensing
Date : 2022
Volume : 14
Issue : 24
Pages : 6264
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
Climate change and habitat fragmentation exert considerable pressures on biodiversity. The spatial distribution of microclimatic refuges in the landscape can influence species responses to warming climates.
Auteurs, date et publication :
Auteurs Laurane Winandy , Félix Pellerin , Lucie Di Gesu , Delphine Legrand , Julien Cote
Publication : Landscape Ecology
Date : 2023
Catégorie(s)
#CNRS #Metatron terrestreRésumé
Abstract. Light-absorbing particles (LAPs) such as black carbon or mineral dust are some of the main drivers of snow radiative transfer. Small amounts of LAPs significantly increase snowpack absorption in the visible wavelengths where ice absorption is particularly weak, impacting the surface energy budget of snow-covered areas. However, linking measurements of LAP concentration in snow to their actual radiative impact is a challenging issue which is not fully resolved. In the present paper, we point out a new method based on spectral irradiance profile (SIP) measurements which makes it possible to identify the radiative impact of LAPs on visible light extinction in homogeneous layers of the snowpack. From this impact on light extinction it is possible to infer LAP concentrations present in each layer using radiative transfer theory. This study relies on a unique dataset composed of 26 spectral irradiance profile measurements in the wavelength range 350–950 nm with concomitant profile measurements of snow physical properties and LAP concentrations, collected in the Alps over two snow seasons in winter and spring conditions. For 55 homogeneous snow layers identified in our dataset, the concentrations retrieved from SIP measurements are compared to chemical measurements of LAP concentrations. A good correlation is observed for measured concentrations higher than 5 ng g−1 (r2=0.81) despite a clear positive bias. The potential causes of this bias are discussed, underlining a strong sensitivity of our method to LAP optical properties and to the relationship between snow microstructure and snow optical properties used in the theory. Additional uncertainties such as artefacts in the measurement technique for SIP and chemical contents along with LAP absorption efficiency may explain part of this bias. In addition, spectral information on LAP absorption can be retrieved from SIP measurements. We show that for layers containing a unique absorber, this absorber can be identified in some cases (e.g. mineral dust vs. black carbon). We also observe an enhancement of light absorption between 350 and 650 nm in the presence of liquid water in the snowpack, which is discussed but not fully elucidated. A single SIP acquisition lasts approximately 1 min and is hence much faster than collecting a profile of chemical measurements. With the recent advances in modelling LAP–snow interactions, our method could become an attractive alternative to estimate vertical profiles of LAP concentrations in snow.
Auteurs, date et publication :
Auteurs Francois Tuzet , Marie Dumont , Laurent Arnaud , Didier Voisin , Maxim Lamare , Fanny Larue , Jesus Revuelto , Ghislain Picard
Publication : The Cryosphere
Date : 2019
Volume : 13
Issue : 8
Pages : 2169-2187
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Although it is known that multiple interactions among plant functional traits, microbial properties, and abiotic soil parameters influence the nutrient turnover, the relative contribution of each of these groups of variables is poorly understood. We manipulated grassland plant functional composition and soil nitrogen (N) availability in a multisite mesocosm experiment to quantify their relative effects on soil N turnover. Overall, root traits, arbuscular mycorrhizal colonization, denitrification potential, as well as N availability and water availability, best explained the variation in measured ecosystem properties, especially the trade-off between nutrient sequestration and plant biomass production. Their relative contributions varied with soil N availability. In relatively N-p oor soils (10–20 μg·N·g−1 soil), N turnover was mainly controlled by microbial properties and abiotic soil parameters, whereas in the relatively N-rich soils (110–120 μg·N·g−1 soil), N turnover was mainly controlled by plant traits and microbial properties. This experiment is a strong demonstration of the importance of functional characteristics of both plants and soil microbes, and their interplay with soil N availability, for N turnover in grassland soils.
Auteurs, date et publication :
Auteurs Nicolas Legay , Sandra Lavorel , Catherine Baxendale , Ute Krainer , Michael Bahn , Marie-Noëlle Binet , Amélie A. M. Cantarel , Marie-Pascale Colace , Arnaud Foulquier , Eva-Maria Kastl , Karl Grigulis , Bello Mouhamadou , Franck Poly , Thomas Pommier , Michael Schloter , Jean-Christophe Clément , Richard D. Bardgett
Publication : Ecosphere
Date : 2025
Volume : 7
Issue : 11
Pages : e01448
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Loïc Tudesque , Gaël Grenouillet , Muriel Gevrey , Kamran Khazraie , Sébastien Brosse
Publication : Ecological Indicators
Date : 2025
Volume : 14
Issue : 1
Pages : 100-106
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Loïc Harrault , Béatrice Allard , Jacques Mériguet , David Carmignac , Samuel Perret , Sylvain Huon , Eric Edeline , Gérard Lacroix
Date : 2025
Volume : 15
Catégorie(s)
#⛔ No DOI found #CNRS #ENS #PLANAQUARésumé
In the subsurface, water content, gas solubility, organic mater
degradation as well as plant and microorganism respiration control
gas fluxes between soil and the atmosphere. Indeed, all of this
controls the partial pressures of major gas species, such as O2 and
CO2 , which controls in turn the advective and diffusive transport of
all the gaseous species, including the inert gases. Because these
processes vary in intensity with time and space, it is very
challenging to define where, when and how to measure gas fluxes
between soil and the atmosphere. This is equaly important for
detection of anomalous fluxes as well as for the calculation of
relevant mass budgets. We focus here on inert gases because of their
relevance as tracers for a large variety of processes. An
experimental setup was developed and validated at the ECOTRON
IleDeFrance research center. It is composed of a 60-cm high and 40-cm
diameter sand column placed under controlled conditions (water
content, temperature, pressure, light) in a climatic chamber. Plants
are grown at the top of the column. An inert gas (SF6) is injected at
the bottom and its flux is continuously monitored at the surface. A
similar experimental setup is run without plants. Effects of
watering, daytime/nighttime plant activity, cut out of leaves, plant
destruction as well as of other solicitations are determined and
discussed. First-order models are proposed and their results are
compared to the experimental data. These models are based on
consumption of O2 , production of CO2 with a higher solubility in
water and their effects on inert gas advection-dispersion.
Auteurs, date et publication :
Auteurs Clément Alibert , Eric Pili , Pierre Barré , Florent Massol
Date : 2018
Volume : 20
Pages : 2177