Action versus Result-Oriented Schemes in a Grassland Agroecosystem: A Dynamic Modelling Approach

Effects of agri-environment schemes (AES) on biodiversity remain controversial. While most AES are action-oriented, result-oriented and habitat-oriented schemes have recently been proposed as a solution to improve AES efficiency. The objective of this study was to compare action-oriented, habitat-oriented and result-oriented schemes in terms of ecological and productive performance as well as in terms of management flexibility. We developed a dynamic modelling approach based on the viable control framework to carry out a long term assessment of the three schemes in a grassland agroecosystem. The model explicitly links grazed grassland dynamics to bird population dynamics. It is applied to lapwing conservation in wet grasslands in France. We ran the model to assess the three AES scenarios. The model revealed the grazing strategies respecting ecological and productive constraints specific to each scheme. Grazing strategies were assessed by both their ecological and productive performance. The viable control approach made it possible to obtain the whole set of viable grazing strategies and therefore to quantify the management flexibility of the grassland agroecosystem. Our results showed that habitat and result-oriented scenarios led to much higher ecological performance than the action-oriented one. Differences in both ecological and productive performance between the habitat and result-oriented scenarios were limited. Flexibility of the grassland agroecosystem in the result-oriented scenario was much higher than in that of habitat-oriented scenario. Our model confirms the higher flexibility as well as the better ecological and productive performance of result-oriented schemes. A larger use of result-oriented schemes in conservation may also allow farmers to adapt their management to local conditions and to climatic variations

Tendencias y equitatividad de los principales cultivos extensivos en el centro de la provincia de Buenos Aires

Los procesos de expansión agrícola y pérdida de diversidad productiva han sido vinculados con un aumento de costos ambientales en términos de degradación del suelo, contaminación de agua y aire, pérdida de biodiversidad y deterioro de servicios ecológicos esenciales. El presente trabajo plantea como objetivo analizar tales procesos en un sector del centro de la provincia de Buenos Aires dominado por el sistema orográfico de Tandilia. El área de estudio, integrada por los partidos de Azul, Benito Juárez, Olavarría y Tandil, contiene terrenos ondulados periserranos y planicies interserranas que concentran la mayor parte de la actividad agrícola, rodeados por ambientes con limitaciones para la agricultura correspondientes a la Pampa deprimida. El estudio se basó en datos de siembra de los principales cultivos de la región aportados por el Sistema Integrado de Información Agropecuaria del Ministerio de Agroindustria de la Nación. Los cultivos seleccionados fueron trigo, maíz, girasol, soja, cebada cervecera y avena. Se analizaron 20 campañas a partir de mediados de los 90, momento en que el lanzamiento de la soja transgénica aceleró notablemente la expansión agrícola en el país. Las principales variables analizadas fueron la superficie destinada a los diferentes cultivos en cada campaña y la diversidad productiva asociada al número y superficie relativa de estos últimos. Dado que el número de cultivos fue establecido previamente en virtud de su relevancia regional, la diversidad productiva fue estimada por el índice de equitatividad de Shannon (J´) a fin de evaluar exclusivamente el grado de uniformidad entre las superficies relativas de los cultivos analizados. La superficie conjunta de estos últimos registró un incremento de 93% durante el periodo de estudio. Este incremento fue acompañado por diferentes dinámicas entre los cultivos analizados, destacándose el reemplazo de trigo por soja como cultivo dominante. A pesar de estos cambios, la equitatividad se mostró como una variable relativamente estable con valores elevados que oscilaron entre J´= 0,76 y J´= 0,86. Estos resultados y su discusión en términos de las relaciones entre heterogeneidad ambiental, biodiversidad y sustentabilidad fundamentan la conveniencia de conservar y de ser posible elevar aún más los niveles de equitatividad registrados para el área de estudio. Esto último podría lograse a partir de una mayor participación relativa de cultivos no dominantes, recomendándose especialmente aquellos que como maíz y trigo presentan mejores balances de carbono en el suelo con respecto a la soja

Evaluation of structural chemistry and isotopic signatures of refractory soil organic carbon fraction isolated by wet oxidation methods

Accurate quantification of different soil organic carbon (SOC) fractions is needed to understand their relative importance in the global C cycle. Among the chemical methods of SOC fractionation, oxidative degradation is considered more promising because of its ability to mimic the natural microbial oxidative processes in soil. This study focuses on detailed understanding of changes in structural chemistry and isotopic signatures of SOC upon different oxidative treatments for assessing the ability of these chemicals to selectively isolate a refractory fraction of SOC. Replicated sampling (to ~1 m depth) of pedons classified as Typic Fragiudalf was conducted under four land uses (woodlot, grassland, no-till and conventional-till continuous corn [Zea mays L.]) at Wooster, OH. Soil samples (<2 mm) were treated with three oxidizing agents (hydrogen peroxide (H2O2), disodium peroxodisulfate (Na2S2O8) and sodium hypochlorite (NaOCl)). Oxidation resistant residues and the bulk soil from A1/Ap1 horizons of each land use were further analyzed by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and accelerator mass spectrometry to determine structural chemistry and 14C activity, respectively. Results indicated that, oxidation with NaOCl removed significantly less SOC compared to Na2S2O8 and H2O2. The NMR spectra revealed that NaOCl oxidation preferentially removed lignin-derived compounds at 56 ppm and at 110-160 ppm. On the other hand, the SOC resistant to Na2S2O8 and H2O2 oxidation were enriched with alkyl C groups, which dominate in recalcitrant macromolecules. This finding was corroborated by the 14C activity of residual material, which ranged from -542 to -259‰ for Na2S2O8 resistant SOC and -475 to -182‰ for H2O2 resistant SOC as compared to relatively greater 14C activity of NaOCl resistant residues (-47 to 61‰). Additionally, H2O2 treatment on soils after light fraction removal was more effective in isolating the oldest (14C activity of -725 to -469‰) SOC fraction. The Δ14C signature of SOC removed by different oxidizing agents, calculated by mass balance, was more or less similar irrespective of the difference in labile SOC removal efficiency. This suggests that SOC isolated by many fractionation methods is still a mixture of much younger and older material and therefore it is very important that the labile SOC should be completely removed before measuring the turnover time of stable and refractory pools of SOC. © 2009 Springer Science+Business Media B.V

Evaluation of structural chemistry and isotopic signatures of refractory soil organic carbon fraction isolated by wet oxidation methods

Accurate quantification of different soil organic carbon (SOC) fractions is needed to understand their relative importance in the global C cycle. Among the chemical methods of SOC fractionation, oxidative degradation is considered more promising because of its ability to mimic the natural microbial oxidative processes in soil. This study focuses on detailed understanding of changes in structural chemistry and isotopic signatures of SOC upon different oxidative treatments for assessing the ability of these chemicals to selectively isolate a refractory fraction of SOC. Replicated sampling (to similar to 1 m depth) of pedons classified as Typic Fragiudalf was conducted under four land uses (woodlot, grassland, no-till and conventional-till continuous corn [Zea mays L.]) at Wooster, OH. Soil samples (< 2 mm) were treated with three oxidizing agents (hydrogen peroxide (H₂O₂), disodium peroxodisulfate (Na2S2O8) and sodium hypochlorite (NaOCl)). Oxidation resistant residues and the bulk soil from A1/Ap1 horizons of each land use were further analyzed by solid-state C-13 nuclear magnetic resonance (NMR) spectroscopy and accelerator mass spectrometry to determine structural chemistry and C-14 activity, respectively. Results indicated that, oxidation with NaOCl removed significantly less SOC compared to Na2S2O8 and H₂O₂. The NMR spectra revealed that NaOCl oxidation preferentially removed lignin-derived compounds at 56 ppm and at 110-160 ppm. On the other hand, the SOC resistant to Na2S2O8 and H₂O₂ oxidation were enriched with alkyl C groups, which dominate in recalcitrant macromolecules. This finding was corroborated by the C-14 activity of residual material, which ranged from -542 to -259aEuro degrees for Na2S2O8 resistant SOC and -475 to -182aEuro degrees for H₂O₂ resistant SOC as compared to relatively greater C-14 activity of NaOCl resistant residues (-47 to 61aEuro degrees). Additionally, H₂O₂ treatment on soils after light fraction removal was more effective in isolating the oldest (C-14 activity of -725 to -469aEuro degrees) SOC fraction. The Delta C-14 signature of SOC removed by different oxidizing agents, calculated by mass balance, was more or less similar irrespective of the difference in labile SOC removal efficiency. This suggests that SOC isolated by many fractionation methods is still a mixture of much younger and older material and therefore it is very important that the labile SOC should be completely removed before measuring the turnover time of stable and refractory pools of SOC

Conception et appropriation de MAE à obligation de résultat sur les surfaces herbagères : comment concilier pertinence écologique et agricole dans l'action publique en faveur de la biodiversité ? (acronyme DIVA2 : MAE Résultat)

Two agri-environmental measures (MAE) tied to an obligation of result aimed at pastureland management (Herbe_09) and preserving species-rich grassland (Herbe_07) were studied: genesis of these measures in Europe and in France, conditions of implementation in different areas and agroecological relevance. This type of MAE restores a sense of responsibility to farmers. Implementing these measures may generate a positive territorial dynamic in the sometimes contradictory debate over the best interests of farmers vs. ecological biodiversity conservation measures. Results show that their positive impact in terms of social, ecological and agricultural benefits supports the idea that they ought to be implemented on a wider scale, along with improved regulations, a better dialogue between farmers and environmental activists, and progress in technical and scientific knowledge.Les mesures agri-environnementales (MAE) visant la gestion pastorale (Herbe_09) et le maintien de prairies à forte richesse spécifique (Herbe_07) sont analysées : genèse de ces mesures en Europe et en France, conditions de leur mise en oeuvre dans plusieurs territoires et pertinence agri-écologique. Ce type de MAE est susceptible de redonner aux éleveurs une responsabilité valorisante ; leur mise en oeuvre peut entraîner une dynamique territoriale positive dans le débat parfois contradictoire entre agriculture et conservation de la biodiversité ; enfin, elles permettent de concilier production et biodiversité, mais sont peu propices à d’autres fonctions écologiques (pollinisation, séquestration du carbone...). Au final, leur bilan social, écologique et agricole, positif, incite à les généraliser mais en faisant progresser réglementation, concertation entre acteurs agricoles et environnementaux, et connaissances techniques et scientifiques

Les espaces scolaires

Comment l’espace scolaire peut-il contribuer à l’épanouissement des élèves et à la qualité des apprentissages ? La qualité de ces espaces se définit-elle seulement par l’architecture des bâtiments ? Quels liens entre l’école et son environnement peut-on déduire de la façon dont sont conçus les espaces et les bâtiments scolaires ? Quelles sont les tendances observables aujourd’hui dans le monde et que nous disent-elles de l’évolution des attentes et des besoins éducatifs, voire de la forme scolaire au XXIe siècle ? Dans ce numéro 64 de la Revue internationale d’éducation de Sèvres, des architectes confirmés, de jeunes chercheurs, des sociologues, des proviseurs, des responsables de la construction scolaire dans les collectivités territoriales, sont invités à répondre à ces questions rarement abordées, en s’appuyant sur des recherches récentes et sur des exemples pris dans plusieurs pays : Italie, Danemark, France, Australie, Belgique (Flandres), Israël, Canada (Québec), Chili, Suisse, ainsi que sur une analyse comparée à l’échelle mondiale. Cette variété des approches et des analyses recueillies se révèle riche d'enseignements. Selon les contextes, les architectures innovantes portent les évolutions pédagogiques ou l'inverse. De nouveaux modes de configuration des espaces à l’école sont en train d’apparaître, en particulier dans certains pays comme l’Australie. Partout, il semble que la communauté éducative et les responsables politiques s’emparent de ces questions. L’enjeu est de taille : les espaces scolaires sont essentiels pour accompagner et faciliter les évolutions éducatives, mais aussi pour favoriser des relations apaisées entre les personnes. How can the school space contribute to pupils’ fulfilment and learning quality? Is the quality of such spaces determined solely by the architecture of the buildings in question? What links between the school and its environment can we deduce from the way in which school spaces and buildings are designed? What trends are we currently seeing around the world and what do they tell us about changes in education-related needs and expectations, or even the school format in the 21st century? In this issue 64 of the Revue Internationale d’Education de Sèvres, experienced architects, young researchers, sociologists, heads and those responsible for the construction of schools within regional authorities are invited to respond to such rarely raised questions, drawing on recent research and examples taken from various countries, including Italy, Denmark, France, Australia, Belgium (Flanders), Israel, Canada (Quebec), Chile and Switzerland, as well as a global comparative analysis. This variety of approaches and analyses gathered proves rich in lessons to be learned. Innovative architecture can result in educational development or indeed the opposite, depending on the context. New ways of configuring school spaces are emerging, particularly in certain countries such as Australia. It would appear that the educational community and policy-makers everywhere are tackling these questions. The issue is a sizeable one, since school spaces are essential to supporting and facilitating educational development, as well as to encouraging peaceful relations between people. ¿Cómo puede el espacio escolar contribuir al desarrollo de los alumnos y a la calidad de los aprendizajes ? ¿Se define la calidad de los espacios únicamente por la arquitectura de los edificios ? ¿Qué vínculos entre la escuela y su entorno podemos deducir de la manera con la cual se conciben los espacios y los edificios escolares ? ¿Cuáles son las tendencias que se pueden observar hoy en día en el mundo y qué nos dicen acerca de la evolución de las expectativas y de las necesidades educativas, e incluso a propósito de la forma escolar en el siglo XXI ? En este número 64 de la Revue internationale d’éducation de Sèvres, tanto arquitectos confirmados, como jóvenes investigadores, sociólogos, directores de institutos, responsables de la construcción escolar en las colectividades territoriales fueron invitados a contestar a estas preguntas raras veces tratadas, apoyándose en los estudios recientes y en ejemplos que proceden de varios países —Italia, Dinamarca, Francia, Australia, Bélgica (Flandes), Israel, Canadá (Quebec), Chile, Suiza— así como en el análisis comparado a nivel mundial. Esta variedad de las aproximaciones y de los análisis recogidos en el presente número conlleva no pocas enseñanzas. Según los contextos, las arquitecturas innovadoras dan vida a las evoluciones pedagógicas o recíprocamente. Nuevos modos de configuración de los espacios en la escuela van apareciendo, en particular en algunos países como Australia. Por todas partes, parece que la comunidad educativa y los responsables políticos se apoderan de este tema