Résumé
The soil microbial activity is a key parameter in numerous studies aiming to assess soil quality in agricultural plots. Basal Soil Respiration (BSR) has been extensively used as an indicator of this soil microbial activity. However, available methods to measure BSR remain time- and labor- consuming and must be performed in the laboratory which may lead to result distortion due to the needed soil pre-treatments. The SituResp® method was developed to assess BSR in a time- and cost-effective way. This method was adapted from a laboratory methodology, the MicroResp™ method, in order to be implemented in the field on fresh soil samples. It is based on the color change of a pH-sensitive gel in reaction to the CO2 concentration change in the headspace of a soil sample over the 24-h incubation. This study presents the calibration and validation of the SituResp® method in laboratory conditions, and a comparison in the field with the Solvita® tool, a comparable method used by agricultural scientists and advisors. The results of the calibration showed a high correlation between the air CO2 concentration and the absorbance variation of the gel at 570 nm (R2 = 0.95). The validation against the titration alkali-trap method, on 21 soil samples, showed a strong correlation between the two methods (R2 = 0.90). In the field test on 9 agricultural-plots, the SituResp® method yielded similar results to the Solvita® tool. The SituResp® method is therefore a reliable method for performing a cheap, rapid but efficient assessment of soil microbial activity in the field which could be included in soil quality monitoring.
Auteurs, date et publication :
Auteurs Alexis Thoumazeau , Frédéric Gay , Pascal Alonso , Nopmanee Suvannang , Audjima Phongjinda , Phantip Panklang , Tiphaine Chevallier , Cécile Bessou , Alain Brauman
Publication : Applied Soil Ecology
Date : 2025
Volume : 121
Pages : 223-230
Catégorie(s)
#CIRAD #FORET Itatinga #FORET RubberfluxAuteurs, date et publication :
Auteurs Odhran S. O'sullivan , Mary A. Heskel , Peter B. Reich , Mark G. Tjoelker , Lasantha K. Weerasinghe , Aurore Penillard , Lingling Zhu , John J. G. Egerton , Keith J. Bloomfield , Danielle Creek , Nur H. A. Bahar , Kevin L. Griffin , Vaughan Hurry , Patrick Meir , Matthew H. Turnbull , Owen K. Atkin
Publication : Global Change Biology
Date : 2017
Volume : 23
Issue : 1
Pages : 209–223
Catégorie(s)
#CIRAD #FORET ParacouRésumé
The influence of vegetation on slope stability is well understood at the slope level but scaling up to the catchment level is still a challenge, partially because of a lack of suitable data to validate models. We tested the physical landslide model, LAPSUS_LS, which models slope stability at the catchment scale. LAPSUS_LS combines a hydrological model with a Limit Equilibrium Method model, and calculates the factor of safety of individual cells based on their hydrological and geomorphological characteristics. We tested two types of vegetation on slope stability: (i) coffee monoculture (Coffea arabica) and (ii) a mixed plantation of coffee and deep rooting Erythrina (Erythrina poeppigiana) trees. Using soil and root data from Costa Rica, we performed simulations to test the response of LAPSUS_LS to root reinforcement, soil bulk density, transmissivity, internal friction angle and depth of shear plane. Furthermore, we modified the model to include biomass surcharge effect in the calculations. Results show that LAPSUS_LS was most sensitive to changes in additional cohesion from roots. When the depth of the shear plane was fixed at 1.0 m, slopes were not unstable. However, when the shear plane was fixed to 1.5 m, the mixed plantation of coffee and trees stabilized slopes, but the coffee monoculture was highly unstable, because root reinforcement was low at a depth of 1.5 m. Soil transmissivity had a limited impact on the results compared to bulk density and internal friction angle. Biomass surcharge did not have any significant effect on the simulations. In conclusion, LAPSUS_LS responded well to the soil and vegetation input data, and is a suitable candidate for modeling the stability of vegetated slopes at the catchment level.
Auteurs, date et publication :
Auteurs L.M.W. Rossi , B. Rapidel , O. Roupsard , M. Villatoro-sánchez , Z. Mao , J. Nespoulous , J. Perez , I. Prieto , C. Roumet , K. Metselaar , J.M. Schoorl , L. Claessens , A. Stokes
Publication : Ecological Engineering
Date : 2025
Volume : 109
Pages : 249-255
Catégorie(s)
#CIRAD #FORET CoffeeFluxAuteurs, date et publication :
Auteurs Talie Musavi , Mirco Migliavacca , Markus Reichstein , Jens Kattge , Christian Wirth , T. Andrew Black , Ivan Janssens , Alexander Knohl , Denis Loustau , Olivier Roupsard , Andrej Varlagin , Serge Rambal , Alessandro Cescatti , Damiano Gianelle , Hiroaki Kondo , Rijan Tamrakar , Miguel D. Mahecha
Publication : Nature Ecology & Evolution
Date : 2017
Volume : 1
Issue : 2
Pages : 0048
Catégorie(s)
#CIRAD #CNRS #FORET CoffeeFlux #FORET PuechabonRésumé
Upscaling instantaneous evapotranspiration retrieved at any specific time-of-day (ETi) to daily evapotranspiration (ETd) is a key challenge in mapping regional ET using polar orbiting sensors. Various studies have unanimously cited the shortwave incoming radiation (RS) to be the most robust reference variable explaining the ratio between ETd and ETi. This study aims to contribute in ETi upscaling for global studies using the ratio between daily and instantaneous incoming shortwave radiation (RSd / RSi) as a factor for converting ETi to ETd.
Auteurs, date et publication :
Auteurs Loise Wandera , Kaniska Mallick , Gerard Kiely , Olivier Roupsard , Matthias Peichl , Vincenzo Magliulo
Publication : Hydrology and Earth System Sciences
Date : 2017
Volume : 21
Issue : 1
Pages : 197-215
Catégorie(s)
#CIRAD #FORET CoffeeFluxRésumé
Modern measures of diversity satisfy reasonable axioms, are parameterized to produce diversity profiles, can be expressed as an effective number of species to simplify their interpretation, and come with estimators that allow one to apply them to real-world data. We introduce the generalized Simpson's entropy as a measure of diversity and investigate its properties. We show that it has many useful features and can be used as a measure of biodiversity. Moreover, unlike most commonly used diversity indices, it has unbiased estimators, which allow for sound estimation of the diversity of poorly sampled, rich communities.
Auteurs, date et publication :
Auteurs Michael Grabchak , Eric Marcon , Gabriel Lang , Zhiyi Zhang , Stefan J. Green
Publication : Plos One
Date : 2017
Volume : 12
Issue : 3
Pages : e0173305
Catégorie(s)
#CIRAD #FORET ParacouRésumé
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 compare slope stability under paired land uses with and without trees in tropical, subtropical, and temperate landslide- and earthquake-prone regions. Trees improved stability for 5–12 months per year from drawdown of soil moisture and resulted in less interannual variability in the duration of high-stability periods compared to slopes without trees. Our meta-analysis of published data also showed that slopes with woody vegetation were more stable and less sensitive to climate and soil factors than slopes with herbaceous vegetation. However, estimates of earthquake magnitude necessary to destabilize slopes at our sites suggest that large additional stabilization from trees is necessary for meaningful protection against external triggers.
Auteurs, date et publication :
Auteurs John H. Kim , Thierry Fourcaud , Christophe Jourdan , Jean-Luc Maeght , Zhun Mao , James Metayer , Louise Meylan , Alain Pierret , Bruno Rapidel , Olivier Roupsard , Anneke de Rouw , Mario Villatoro Sanchez , Yan Wang , Alexia Stokes
Publication : Geophysical Research Letters
Date : 2017
Volume : 44
Issue : 10
Pages : 4897-4907
Catégorie(s)
#CIRAD #FORET CoffeeFluxAuteurs, date et publication :
Auteurs Lucy Rowland , Joana Zaragoza-Castells , Keith J. Bloomfield , Matthew H. Turnbull , Damien Bonal , Benoit Burban , Norma Salinas , Eric Cosio , Daniel J. Metcalfe , Andrew Ford , Oliver L. Phillips , Owen K. Atkin , Patrick Meir
Publication : New Phytologist
Date : 2017
Volume : 214
Issue : 3
Pages : 1064–1077
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Florian Schnabel , Elias de Melo Virginio Filho , Su Xu , Ian D. Fisk , Olivier Roupsard , Jeremy Haggar
Publication : Agroforestry Systems
Date : 2017
Catégorie(s)
#CIRAD #FORET CoffeeFluxRésumé
Despite advances in Earth observation and modeling, estimating tropical biomass remains a challenge. Recent work suggests that integrating satellite measurements of canopy height within ecosystem models is a promising approach to infer biomass. We tested the feasibility of this approach to retrieve aboveground biomass (AGB) at three tropical forest sites by assimilating remotely sensed canopy height derived from a texture analysis algorithm applied to the high-resolution Pleiades imager in the Organizing Carbon and Hydrology in Dynamic Ecosystems Canopy (ORCHIDEE-CAN) ecosystem model. While mean AGB could be estimated within 10% of AGB derived from census data in average across sites, canopy height derived from Pleiades product was spatially too smooth, thus unable to accurately resolve large height (and biomass) variations within the site considered. The error budget was evaluated in details, and systematic errors related to the ORCHIDEE-CAN structure contribute as a secondary source of error and could be overcome by using improved allometric equations.
Auteurs, date et publication :
Auteurs E. Joetzjer , M. Pillet , P. Ciais , N. Barbier , J. Chave , M. Schlund , F. Maignan , J. Barichivich , S. Luyssaert , B. Herault , F. von Poncet , B. Poulter
Publication : GEOPHYSICAL RESEARCH LETTERS
Date : 2017
Volume : 44
Issue : 13
Pages : 6823-6832