Monitoreo de servicios ecosistémicos en un observatorio de cafetales agroforestales. Recomendaciones para el sector cafetalero

Ocho años de estudio de la ecofisiología del café, a través de experimentación y de modelación y el monitoreo de los servicios del ecosistema (SE) en una gran finca cafetalera en Costa Rica, revelaron varias recomendaciones prácticas para los agricultores y los formuladores de políticas. El sistema de cultivo estudiado dentro de nuestro observatorio colaborativo (Coffee-Flux), corresponde a un sistema agroforestal (SAF) a base de café bajo la sombra de grandes árboles de Erythrina poeppigiana (16% de la cubierta del dosel). Una gran cantidad de SE y limitantes dependen de las propiedades locales del suelo (en este caso Andisoles), especialmente de la erosión/infiltración, el agua/carbono y la capacidad de almacenamiento de nutrientes. Por lo tanto, para la evaluación de SE, el tipo de suelo es crucial. Una densidad adecuada de árboles de sombra (bastante baja aquí por la condición de libre crecimiento), redujo la severidad de las enfermedades de las hojas con la posibilidad de reducir el uso de plaguicidas y fungicidas. Un inventario simple del área basal en el collar de las plantas de café permitió estimar la biomasa subterránea y la edad promedio de la plantación, para juzgar su valor de mercado y decidir cuándo reemplazarla. Las fincas de café probablemente estén mucho más cerca de la neutralidad de C que lo indicado en el protocolo actual de C-neutralidad, que solo considera árboles de sombra, no los cafetos ni el suelo. Se proponen evaluaciones más completas, que ncluyen árboles, café, hojarasca, suelo y raíces en el balance C del SAF. Los árboles de sombra ofrecen muchos SE si se gestionan adecuadamente en el contexto local. En comparación con las condiciones a pleno sol, los árboles de sombra pueden (i) reducir la erosión laminar en un factor de 2; (ii) aumentar la fijación de N y el % de N reciclado en el sistema, reduciendo así los requisitos de fertilizantes; (iii) reducir la severidad de enfermedades de las hojas; (iv) aumentar el secuestro de C; (v) mejorar el microclima y (vi) reducir sustancialmente los efectos del cambio climático. En nuestro estudio de caso, no se encontró ningún efecto negativo sobre el rendimiento del café

Agroforesterie et services écosystémiques en zone tropicale

Respectueux de l’environnement et garantissant une sécurité alimentaire soutenue par la diversification des productions et des revenus qu’ils procurent, les systèmes agroforestiers apparaissent comme un modèle prometteur d’agriculture durable dans les pays du Sud les plus vulnérables aux changements globaux. Cependant, ces systèmes agroforestiers ne peuvent être optimisés qu’à condition de mieux comprendre et de mieux maîtriser les facteurs de leurs productions. L’ouvrage présente un ensemble de connaissances récentes sur les mécanismes biophysiques et socio-économiques qui sous-tendent le fonctionnement et la dynamique des systèmes agroforestiers. Il concerne, d’une part les systèmes agroforestiers à base de cultures pérennes, telles que cacaoyers et caféiers, de régions tropicales humides en Amérique du Sud, en Afrique de l’Est et du Centre, d’autre part les parcs arborés et arbustifs à base de cultures vivrières, principalement de céréales, de la région semi-aride subsaharienne d’Afrique de l’Ouest. Il synthétise les dernières avancées acquises grâce à plusieurs projets associant le Cirad, l’IRD et leurs partenaires du Sud qui ont été conduits entre 2012 et 2016 dans ces régions. L’ensemble de ces projets s’articulent autour des dynamiques des systèmes agroforestiers et des compromis entre les services de production et les autres services socio-écosystémiques que ces systèmes fournissent

Il male dal prisma del Kulturarbeit. Sull'opera di Nathalie Zaltzman

Poco conosciuta in Italia, Nathalie Zaltzman (1933-2009) è stata una figura di rilievo nel panorama psicoanalitico contemporaneo di recente scomparsa. Con Piera Aulagnier ha segnato la vitalità scientifica del Quatrième Groupe, tra le più interessanti società psicoanalitiche francesi. Ricercatrice originale, ha rinvigorito il legame tra individuale e collettivo, incardinandolo solidamente nella clinica psicoanalitica. Nella convinzione che la psicoanalisi vada intesa come strumento del lavoro di civiltà (Kulturarbeit), Nathalie Zaltzman ha posto questioni coraggiose sul rapporto tra Kulturarbeit e male estremo: le potenzialità e le impasses del lavoro di civiltà; la resistenza dell’uomo di fronte alla barbarie; l’inumano nell’umano; il totalitarismo di Eros e la funzione vitale di Thanatos in situazioni estreme. Riferimento, quest’ultimo, al suo concetto di pulsione anarchica che percorre carsicamente l’intera produzione scientifica. Questo volume è frutto di una collaborazione internazionale e propone un confronto scientifico tra autorevoli esponenti del Quatrième Groupe e componenti del gruppo di ricerca interdisciplinare universitario ed extrauniversitario "Rileggere il disagio" da tempo impegnato sul tema del disagio della civiltà e delle sue variazioni nell’orizzonte contemporaneo. A partire dal contributo di Nathalie Zaltzman, il fil rouge dei contributi qui presentati è la questione del male, analizzata fuori e dentro le mura della clinica psicoanalitica: dalla figura prometeica del Don Giovanni di Molière, all’inquietante fenomeno delle Mara, efferate organizzazioni criminali giovanili che oggi funestano l’America latina; fino ad una ‘clinica dell’estremo’, quella del reale di una violenza catastrofica divenuta eredità muta che pone lo psicoanalista a confronto con le impasses e gli aggiustamenti della sua tecnica

Root biomass, turnover and net primary productivity of a coffee agroforestry system in Costa Rica: effects of soil depth, shade trees, distance to row and coffee age.

In Costa Rica, coffee (Coffea arabica) plants are often grown in agroforests. However, it is not known if shade-inducing trees reduce coffee plant biomass through root competition, and hence alter overall net primary productivity (NPP). We estimated biomass and NPP at the stand level, taking into account deep roots and the position of plants with regard to trees.Stem growth and root biomass, turnover and decomposition were measured in mixed coffee/tree (Erythrina poeppigiana) plantations. Growth ring width and number at the stem base were estimated along with stem basal area on a range of plant sizes. Root biomass and fine root density were measured in trenches to a depth of 4 m. To take into account the below-ground heterogeneity of the agroforestry system, fine root turnover was measured by sequential soil coring (to a depth of 30 cm) over 1 year and at different locations (in full sun or under trees and in rows/inter-rows). Allometric relationships were used to calculate NPP of perennial components, which was then scaled up to the stand level.Annual ring width at the stem base increased up to 2·5 mm yr(-1) with plant age (over a 44-year period). Nearly all (92 %) coffee root biomass was located in the top 1·5 m, and only 8 % from 1·5 m to a depth of 4 m. Perennial woody root biomass was 16 t ha(-1) and NPP of perennial roots was 1·3 t ha(-1) yr(-1) Fine root biomass (0-30 cm) was two-fold higher in the row compared with between rows. Fine root biomass was 2·29 t ha(-1) (12 % of total root biomass) and NPP of fine roots was 2·96 t ha(-1) yr(-1) (69 % of total root NPP). Fine root turnover was 1·3 yr(-1) and lifespan was 0·8 years.Conclusions Coffee root systems comprised 49 % of the total plant biomass; such a high ratio is possibly a consequence of shoot pruning. There was no significant effect of trees on coffee fine root biomass, suggesting that coffee root systems are very competitive in the topsoil

Increased light-use efficiency sustains net primary productivity of shaded coffee plants in agroforestry system

In agroforestry systems, shade trees strongly affect the physiology of the undergrown crop. However, a major paradigm is that the reduction in absorbed photosynthetically active radiation is, to a certain extent, compensated by an increase in light-use efficiency, thereby reducing the difference in net primary productivity between shaded and non-shaded plants. Due to the large spatial heterogeneity in agroforestry systems and the lack of appropriate tools, the combined effects of such variables have seldom been analysed, even though they may help understand physiological processes underlying yield dynamics. In this study, we monitored net primary productivity, during two years, on scales ranging from individual coffee plants to the entire plot. Absorbed radiation was mapped with a 3D model (MAESPA). Light-use efficiency and net assimilation rate were derived for each coffee plant individually. We found that although irradiance was reduced by 60% below crowns of shade trees, coffee light-use efficiency increased by 50%, leaving net primary productivity fairly stable across all shade levels. Variability of aboveground net primary productivity of coffee plants was caused primarily by the age of the plants and by intraspecific competition among them (drivers usually overlooked in the agroforestry literature) rather than by the presence of shade trees

The "Coffee-flux collaborative observatory": measuring and modeling carbon, nutrients, water and sediment Ecosystem services in a coffee agroforestry watershed (Costa Rica)

il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : REPORTCoffee-flux is a platform where collaborative research on coffee agroforestry is promoted: data are being shared between collaborators and positive interactions are enhanced. The philosophy is to concentrate several investigations on one specific site and for several years, to share a useful common experimental database, to develop modelling and to publish results in highly-ranked scientific journals. Applied research is also highly encouraged (e.g. C-Neutral certification, NAMA, Agronomy, etc.). Coffee-Flux benefits from infrastructure, easy access from CATIE and very good security, ready to welcome complementary scientific investigations and collaborations. The project is wide open to complementary projects, scientists and of course to students. The core data base is for sharing. The aim of Coffee-Flux is to assess carbon, nutrients, water and sediment Ecosystem Services (ES) at the scale of a coffee agroforestry watershed. Observation, experimentation, modelling and remote-sensing are combined, collecting data and calibrating models locally, then upscaling to larger regions. The project has been running continuously since 2009, in order to encompass seasonal and inter-annual fluctuations of coffee productivity and ecosystem services