Resumen El Bosque seco Tropical (BsT) es uno de los ecosistemas más amenazados del planeta dada la pérdida de cobertura vegetal causada por actividades antropogénicas. Entender cómo se dan las interacciones planta-animal en este tipo de ecosistemas es particularmente importante porque promueven su mantenimiento y funcionamiento. Nuestro objetivo fue identificar las interacciones entre murciélagos frugívoros y plantas a través de redes de interacción mutualistas en diez remanentes de BsT del Valle del Cauca. Para esto se caracterizó el ensamblaje de murciélagos y las semillas encontradas en sus heces y se evaluaron las propiedades estructurales de redes (anidamiento, modularidad y robustez). Se encontraron 36 especies de murciélagos y 1142 individuos; adicionalmente, se identificaron 19 669 semillas y 85 interacciones entre 18 especies de murciélagos y 19 especies de plantas. La red de interacción resultante presentó una estructura anidada, modular y robusta a la pérdida de especies especialistas pero susceptible a la pérdida de especies generalistas. Estos resultados dejan en evidencia la importancia de los murciélagos para el análisis de las interacciones planta-animal y a su vez los propone como un grupo clave para ser incluidos en planes de conservación y restauración de ecosistemas altamente perturbados como el BsT del Valle del Cauca.

Abstract The Tropical Dry Forest is one of the most threatened ecosystems due to the loss of vegetation cover caused by anthropogenic activities. Understanding how plant-animal interactions occur in this type of ecosystem is particularly important because these interactions promote the maintenance and functioning of the ecosystems. Therefore, the objective of this study was to identify interactions between fruit bats and plants through mutualistic interaction networks in ten tropical dry forest fragments in Valle del Cauca, Colombia. For this purpose, we characterized the bat community, as well as the seeds found in their feces; with the data obtained, the structural properties of the network (nestedness, modularity and robustness) were evaluated. Our results show 36 species and 1142 individuals of bats, where we identified 19 669 seeds grouped in 85 interactions between 18 bat species and 19 plant species. Moreover, the resulting interaction network presented a nestedness, modular structure, robust to the loss of specialist species but susceptible to the loss of generalist species. These results demonstrate the importance of bats for the analysis of plant-animal interactions and highlight them as a key group to be considered in conservation and restoration plans in highly disturbed ecosystems such as the Tropical Dry Forest of Valle del Cauca.

Resumen Este artículo describe de forma comparativa las redes de participación social en tres áreas silvestres protegidas del Pacífico Central de Costa Rica. Estas áreas representan distintas categorías de manejo, es decir, distintas posibilidades de aprovechamiento de los recursos naturales. La metodología utilizó un enfoque mixto para ampliar las formas de entender los procesos socioambientales en estas áreas. Las herramientas de análisis incluyeron: la teoría de grafos, el análisis de redes sociales y los mapas de calor con variables atributivas e indicadores globales y posicionales de las redes. Los elementos de estudio consideraron 40 grupos organizados en los años 2009-2010, y 40 en los años 2019-2020, todos vinculados al desarrollo local y al medio ambiente. Las unidades de análisis fueron las interacciones que se dan entre ellos. Los resultados muestran que a mayor centralidad en las redes y menor el poder de los grupos locales y multisectoriales, mayor es la desvinculación de los temas que atañen a la sostenibilidad de las áreas silvestres protegidas y mayor es la vulnerabilidad ante cambios estructurales y externos. Entre las conclusiones destaca que, desde la dimensión estructural, las redes de participación sí están influenciadas por las categorías de manejo debido a que condicionan el acceso que se tenga a los servicios ecosistémicos que estas protegen. Desde la dimensión funcional, la capacidad de las redes para transformar esos servicios ecosistémicos en oportunidades de desarrollo es independiente de las categorías de manejo, pero sí está relacionada con otros aspectos sociales.

Resumo Este artigo descreve de forma comparativa as redes de participação social em três áreas naturais protegidas do Pacífico Central da Costa Rica. Essas áreas representam diferentes categorias de gestão, ou seja, diferentes possibilidades de uso dos recursos naturais. A metodologia utilizou uma abordagem mista para ampliar as formas de compreensão dos processos socioambientais nessas áreas. As ferramentas de análise incluíram: teoria dos grafos, análise de redes sociais e mapas de calor com variáveis atributivas e indicadores globais e posicionais das redes. Os elementos do estudo consideraram 40 grupos organizados nos anos 2009-2010, e 40 nos anos 2019-2020, todos vinculados ao desenvolvimento local e ao meio ambiente. As unidades de análise foram as interações que ocorrem entre elas. Os resultados mostram que quanto maior a centralidade das redes e menor o poder dos grupos locais e multissetoriais, maior a desvinculação de questões relacionadas à sustentabilidade das áreas naturais protegidas e maior a vulnerabilidade às mudanças estruturais e externas. Entre as conclusões destaca-se que, a partir da dimensão estrutural, as redes de participação são influenciadas pelas categorias de gestão, pois condicionam o acesso aos serviços ecossistêmicos que protegem. A partir da dimensão funcional, a capacidade das redes de transformar esses serviços ecossistêmicos em oportunidades de desenvolvimento é independente das categorias de gestão, mas está relacionada a outros aspectos sociais.

Abstract This article compares social participation networks in three wildlife protected areas in the Central Pacific of Costa Rica. These areas represent different management categories, which means different approaches to the use of natural resources. A mixed approach methodology was used to have a wider understanding of the socio-environmental processes in these areas. Analyses used included graph theory, social network analysis, and heat maps with attribute variables and global and positional network indicators. The elements of analysis included 40 civil society groups related to local development and environment conservation organized between 2009-2010 and 40 between 2019-2020. The analysis units were the interactions among the groups. Results show that the more centralized the social networks and the less power of local and multisectoral groups, the greater the dissociation of the topics related to sustainability of wildlife protected areas and the more vulnerable to structural and external changes. It is concluded that, from the structural dimension, participation networks are influenced by the management categories, since they condition the access to their ecosystem services. From the functional dimension, the capability of participation networks to transform ecosystem services into development opportunities is irrespective of the management categories, although it is related to other social aspects.

Assessment of social relations, including social network analysis, is central to understanding collaborative processes for environmental decision-making and action. The capacity of network role players to learn and adapt appropriately to uncertainty and change is a critical determinant of the resilience of social-ecological systems. Poor social network structure can predispose failure. In this study, we used social network analysis to explore learning capacity and network resilience in a multi-authority conservation initiative on the West Coast of South Africa (Dassenberg Coastal Catchment Partnership). Our analysis focused on structural variables for network learning and resilience, namely connectivity, heterogeneity, and centrality. The governance network was found to be structurally connected, with the interaction between heterogeneous organisations and sectors, and centralised around a core group of actors. The network had good structural features to enable learning. However, the high level of centrality, and dependence on a small number of core actors, rendered the network potentially vulnerable to dealing with complex challenges. We recommend that core actors (1) reflect on their core functions and whether the network can absorb these functions if they were to leave and (2) tap into the knowledge potential of actors on the network periphery or invite new actors to the network when dealing with complex challenges. This may require the network to diverge into decentralised subgroups to deal with complex issues. We further suggest that the Dassenberg Coastal Catchment Partnership network incorporate social network research with qualitative monitoring into a long-term plan to monitor the movement and influence of actors as the initiative evolves. SIGNIFICANCE: •This study illustrates how social network analysis can help researchers, public-sector organisations, and donor agencies to monitor the structural features of governance networks that enable or disable learning and resilience within landscape-scale conservation initiatives. •Our results illustrate how social network analysis can assist public-sector actors to reflect on their roles and whether there is redundant competency within the network to maintain its resilience

Resumo A colaboração inclusiva e equitativa dos atores tem sido cada vez mais reconhecida como elemento essencial para o sucesso da governança na conservação da biodiversidade em larga escala. No entanto, as evidências empíricas sobre o papel dos arranjos de colaboração no estabelecimento e manutenção da governança são ainda limitadas, especialmente em paisagens tropicais megadiversas. Aplicou-se a análise de redes sociais para mapear a rede colaborativa entre os atores envolvidos na governança de um mosaico de áreas protegidas no Brasil e testar se a rede apresentava padrões relacionais favoráveis à boa governança. A rede é densa e diversificada, contendo variedade de atores e arranjos de colaboração horizontal entre os grupos. Esses aspectos estruturais são consistentes com uma rede que promove o engajamento inclusivo e equitativo. A análise também identificou alguns riscos e desafios que oferecem informações úteis para melhorar a eficácia da governança.

Abstract Inclusive and equitable collaboration of actors has increasingly been recognized as an essential element for successful governance in large-scale biodiversity conservation. However, there is still limited empirical evidence of the role of collaboration arrangements in establishing and maintaining governance, especially in megadiverse tropical landscapes. Social network analysis was applied to map the collaborative network between the actors involved in the governance of a mosaic of protected areas in Brazil and test whether the network displayed relational patterns favorable to good governance. The network is dense and diversified, containing a variety of actors and horizontal collaboration arrangements between groups. These structural aspects are consistent with a network promoting inclusive and equitable engagement. The analysis also identified some risks and challenges that provide useful information to improve governance effectiveness.

Resumen La colaboración inclusiva y equitativa de los actores está siendo cada vez más reconocida como elemento esencial para el éxito de la gobernanza en la conservación de la biodiversidad a gran escala. Sin embargo, las evidencias empíricas sobre el papel de los arreglos colaborativos en el establecimiento y mantenimiento de la gobernanza son aún limitadas, especialmente en paisajes tropicales megadiversos. Se aplicó el análisis de redes sociales para mapear la red colaborativa entre los actores involucrados en la gobernanza de un mosaico de áreas protegidas en Brasil y probar si la red presentaba patrones relacionales favorables a la buena gobernanza. La red es densa y diversificada, englobando diferentes actores y arreglos de colaboración horizontal entre grupos. Estos aspectos estructurales son consistentes con una red que promueve la participación inclusiva y equitativa. El análisis también identificó algunos riesgos y desafíos que ofrecen informaciones útiles para mejorar la eficacia de la gobernanza.

RESUMO O conceito de conservação de precisão pode ser definido como um conjunto de tecnologias espaciais e outros procedimentos ligados as variáveis ambientais mapeáveis, que podem ser utilizadas para programar práticas de gestão da conservação recursos naturais que levam em consideração a variabilidade dessas variáveis no espaço e tempo dentro de sistemas naturais ou agrícolas. Nesse contexto, considera-se a perda estrutural do solo por meio de atividades antrópicas, como com um processo com variação espacial e temporal. A gestão da condição de agregação do solo pode contribuir para processos agrícolas mais regenerativos e sustentáveis, pois permite a utilização das tecnologias de análise espacial, por meio de indicadores visuais georreferenciados ou mesmo a utilização de sistemas com aprendizado automático, conhecidos como deep learning. Nesse sentido, foi desenvolvido um método visual justaposto com uma análise de lógica fuzzy para a classificação dos agregados quanto à forma, rugosidade superficial e estruturas biogênicas. Assim, numa segunda etapa foi desenvolvido um modelo de rede neural artificial capaz de detectar e classificar diferentes formas de agregados do solo, permitindo dessa maneira, uma breve discussão da temática e seu potencial de aplicação na gestão conservacionista por meio da análise de agregados via sistemas automáticos de classificação. Dessa maneira, são apresentados elementos para a motivação de pesquisas e desenvolvimento em tecnologias adaptativas, no apoio à decisão que possam auxiliar a integração de informações dinâmicas e espaciais no entendimento da condição estrutural do solo com a finalidade de uma conservação dos solos com mais precisão.

ABSTRACT The concept of precision conservation can be defined as a set of space technologies and other procedures linked to mappable environmental variables, which can be used to program conservation management practices for natural resources that consider the variability of these variables in space and time within of natural or agricultural systems. In this context, structural loss of soil through human activities is considered, as with a process with a spatial and temporal variation. The management of soil aggregation conditions can contribute to more regenerative and sustainable agricultural processes. It allows spatial analysis technologies through georeferenced visual indicators or even the use of systems with automatic learning, known as deep learning. In this sense, a fair visual method was developed with an analysis of fuzzy logic to classify aggregates in terms of shape, surface roughness, and biogenic structures. Thus, in a second stage, a model of the artificial neural network was developed, capable of detecting and classifying different forms of soil aggregates, thus allowing a brief discussion of the theme and its potential for application in conservation management through the analysis of aggregates via systems automatic sorting. In this way, elements are presented for the motivation of research and development in adaptive technologies in supporting decision-making that can help integrate dynamic and spatial information in the understanding of the soil’s structural condition to preserve the soil more precisely.

Abstract The knowledge of species diversity, the associated ecosystem functions, and the network of community structure are key for effective decision-making for conservation legislation. In Mendoza Province, the study of mammals has been relevant for the development of theoretical models, but such information is scattered and patchy. In this paper, we evaluate the pattern of organization and the conservation status of the diversity of mammals in the Monte desert of Mendoza, integrating these data into two Provincial Conservation Strategies (PCS): Protected Areas and Native Forest Management Law. We found that both specific and functional richness were equal inside and outside the PCS locations. However, these variables are more strongly correlated within the PCS. In addition, rarefied richness and species of outstanding value were higher in localities within the PCS. Finally, the modular structure of the regional system, together with the presence of a large number of locations forming connections within the PCS network, indicate that the PCS is currently effective in protecting not only mammalian biodiversity, but also the connectivity of the regional system. This large number of corridors strengthens the structural continuity of mammalian biodiversity throughout the environmental gradient of Monte, within Mendoza Province.

Resumen El conocimiento de la diversidad de especies, las funciones que ellas cumplen en el ecosistema y la red de organización comunitaria es clave para la toma de decisiones en conservación. En la Provincia de Mendoza, el estudio de la fauna de mamíferos ha sido relevante en el desarrollo de modelos teóricos, pero dicha información se encuentra dispersa y parchada. En este trabajo evaluamos el patrón de organización y el estado de conservación de la diversidad de mamíferos del Monte mendocino integrando localidades pertenecientes a dos Estrategias Provinciales de Conservación (ECP): Áreas protegidas y Ley de Presupuestos Mínimos de Protección Ambiental de los Bosques Nativos. Encontramos que la riqueza específica y la funcional fueron iguales dentro y fuera de las localidades de la ECP aunque se correlacionaron más fuertemente dentro de la ECP. Además, la riqueza rarefaccionada y el número de especies de valor sobresaliente fue mayor en localidades dentro de la ECP. Por último, la organización modular del sistema regional, junto con la presencia de un gran número de localidades conectoras en la red espacial de la ECP, indicarían que la ECP está actualmente siendo eficaz en conservar no sólo la biodiversidad de mamíferos, sino también la conectividad del sistema regional, ya que el gran número de localidades conectoras reaseguran la continuidad estructural de la biodiversidad de mamíferos a través del gradiente ambiental del Monte dentro de la provincia de Mendoza.

Abstract Identifying factors that influence the importance of species for mutualistic interactions is crucial for designing management and conservation strategies that aim to conserve ecosystem functions. Even though bats are key seed-dispersers, factors that influence their importance for structural properties of seed-dispersal networks are poorly studied. We evaluated the influence of cranial morphology, phylogenetic legacy and abundance of frugivorous bats on the structural properties of an interaction network in a tropical dry forest. Consequently, we captured bats and identified interactions with plants by collecting and identifying seeds from fecal samples. Then, we described network structure by using network-level indexes and assessed the contribution of bats to network structure by using species-level indexes. Analysis of the mutualistic network indicated that: (1) there are few species with high number of interactions, (2) the structure was more compartmentalized and less nested than expected, (3) there are subgroups of bats and plants that are highly connected among them, and (4) network would collapse promptly with the loss of bats with most interactions (generalist). Furthermore, bats that contribute the most to network structure tended to have short rostrum and wide cranium and/or were abundant, with Artibeus lituratus being the most important bat; however, contribution to network structure did not have phylogenetic signal. According to the interaction neutrality hypothesis, species’ abundances drive the chances of individuals encountering and interacting with other species. However, our results suggest that frugivores bats are not functionally equivalent since contribution of species to network’s structure was associated with both cranial morphologically and abundance.

RESUMEN La fragmentación de bosques y la potencial pérdida de calidad de hábitat asociada es una de las principales causas de pérdida de biodiversidad. Una de las estrategias para fomentar el mantenimiento de la misma a nivel de paisaje es el establecimiento de corredores biológicos que faciliten la conectividad estructural y funcional de los elementos bióticos. Sin embargo, la aplicabilidad y funcionalidad de esta herramienta está limitada por la falta de planeación al momento del diseño y establecimiento de corredores o redes de conectividad que obedezcan a métodos detallados y rigurosos. En esta investigación desarrollamos una propuesta teórica de conectividad ecológica para el corregimiento de Santa Elena, municipio de Medellín, Colombia, empleando herramientas de la ecología del paisaje. Inicialmente, se seleccionaron 21 fragmentos de bosque o núcleos a conectar a partir de su tamaño mínimo (mayores a 5 ha), área de interior (mayor a 1 ha) y sus índices de forma (redondeados o casi redondeados). Seguidamente, a partir de la creación de una matriz de fricción al desplazamiento, diseñamos una red potencial que permitiría conectar 1356,35 ha de nodos de bosques remanentes a través de 31 corredores ecológicos de 100 m de ancho con una extensión total de 208,33 ha. Finalmente, discutimos la importancia de fomentar este tipo de herramientas de planeación con herramientas de la ecología del paisaje que promueven la conservación de hábitats y la conectividad del paisaje en áreas cercanas a grandes urbes latinoamericanas.

ABSTRACT Forest fragmentation and the associated potential habitat loss is one of the main causes of biodiversity loss. One strategy that promotes its maintenance at a landscape scale is the establishment of biological corridors that enhance structural and functional connectivity of the biotic components. However, the applicability and functionality of this tool is limited due to the lack of planning at the moment of the design and establishment of corridors or connectivity networks that are guided by detailed and rigorous methods. In this research, we developed a theoretical proposal of ecological connectivity for the Santa Elena village, Medellin municipality, Colombia, using tools from landscape ecology. Initially, 21 forest fragments or nucleus were selected based on their minimum size (larger than 5 ha), core area (larger than 1 ha), and shape index (rounded or nearly rounded). Then, based on a friction matrix, we designed a potential network that would allow to connect 1356.35 ha of remnants forests through 31 ecological corridors of 100 m wide, comprising 208.33 ha in total. Finally, we discussed the importance of promoting this kind of strategies based on landscape ecology that enhance both habitat conservation and landscape connectivity in areas near large Latin-American cities.

Las dinámicas de la organización y la participación social son un aspecto fundamental en el logro de las metas de la conservación de los bosques. Partiendo del estudio de los vínculos observados entre 31 actores institucionales y comunitarios, en torno a la conservación del bosque de robles, en los municipios de Paipa y Duitama del corredor de robles Guantiva – la Rusia – Iguaque en Co lombia, este artículo cuestiona sobre las dinámicas organizativas cooperantes para la conservación del bosque de robles en el período que comprende los años 2004–2008 y sus aportes a la conservación de éstos, aplicando la perspectiva del Análisis de Redes Sociales. Esta investigación se pregunta so bre cómo se ha venido incluyendo la participación social en la conservación de los bosques y cuál ha sido su impacto en estas dinámicas de las organizaciones a nivel local. Con estos objetivos, después de haber situado el contexto de los vínculos sociales y la coparticipación de estos actores en torno a la conservación del bosque de robles de Paipa y Duitama, se presenta un análisis de los vínculos entre las organizaciones, lo que permite examinar las formas de participación y vinculación de estos actores sociales en los procesos de organización social para la conservación del bosque durante este período de tiempo en el territorio de estudio, teniendo en cuenta las relaciones de poder entre ellos y su impacto sobre la conservación del bosque.

Social dynamics within social participation is a crucial issue for the accomplishment of forest conservation. In order to contribute to this field, a study of 31 institutional and community organized actors’ cooperative practices, within forest conservation processes in Paipa and Duitama, located at the oak forests conservation corridor Guantiva, La Rusia, Iguaque in Colombia, was made, applying Social Network Analysis (SNA). Particularly, this article inquiry is about models of participation of these actors within the period of 2004-2008, looking at their projects and actions as management practices of forest conservation. The research questions were how social participation is included and understood in the conservation of these oak forests, observing cooperative practices amongst this set of actors, at local level. The results are related with the structural patterns of co-participation established amongst these actors within each other’s projects and actions and the impact of those in the aim of forest conservation at local level, regarding power relations and its impact on forest conservation.

As dinámicas da organização e a participação social são um aspecto fundamental no alcance das metas de conservação dos bosques. Partindo de um estudo dos vínvulos observados entre 31 atores institucionais e comunitarios, em torno à conservação do bosque de robles, nos municipios de Paipa e Duitama do corredor de robles Guantiva – a Rusia – Iguaque na Colômbia, este artigo questiona as dinâmicas organizativas cooperantes para a conservação do bosque de robles no período que compreende os anos de 2004 a 2008 e seus aportes à conservação destes, aplicando a perspectiva da Análise das Redes Sociais. Esta investigação pergunta como se incluiu a participação social na conservação dos bosques e qual foi seu impacto nas dinâmicas das organizações a nível local. Com estes objetivos, depois de haver situado o contexto dos vínculos sociais e a cooparticipação destes atores em torno à conservação do bosque de robles de Paipa e Duitama, se apresenta uma análises dos vínculos entre as organizações, que permitem examinar as formas de participação e a vinculação destes atores sociais nos processos de organização social para a conservação do bosque durante este período de tiempo no campo de estudo, tendo em conta as relações de poder entre eles e seu impacto sobre a conservação do bosque.

Sustainable land use implies the conservation of soil properties associated both to fertility and tillage. Soil alterations induced by management may affect crop production since management practices influence organic matter distribution and nutrient dynamics, and also soil aggregation and porosity. The Argentinean Northern Pampa is one of the region of the world where soils have been subjected to an intensive agricultural use during the last decades, and where direct drilling has been increasingly adopted. The aim of the present work was to evaluate soil physical quality parameters from agricultural systems under no tillage, in soils representative of the Northern Pampa Region, and to compare them with the same soil type but under pristine condition. A soil physical characterization of plots under cropping was carried out on eleven fields included in the Nutrition Network of CREA Southern Santa Fe, with trials located in Santa Fe, Córdoba and Buenos Aires Provinces. Also, a sampling in an adjacent undisturbed sector with the same soil type was carried out. Soil composite samples were collected at two depths (0-0.08 m and 0.08 m to the lower limit of the Ap horizon). Water and ethanol stable aggregate percentage (Ea and Ee, respectively), total organic carbon (COT), bulk density (DA) and maximum soil density were determined (DMAX). Mechanical resistance (RM) was measured at 0.05 m increments from the soil surface to 0.35 m depth. Soils were clustered in two groups according to their texture: Group I (surface clay content between 215 and 265 g kg-1) and Group II (surface clay content between 98 and 170 g kg-1). Higher values of Ea, Ee and COT were found in both surface and deep layers in the undisturbed soil with respect to cropped soil (p < 0.05). Soils from Group I showed higher Ea, Ee and COT with respect to those from the Group II. Total organic carbon decrease because of management was between 10 and 44%. Direct relationships were found between Ea and COT, and Ee-COT, respectively. Soils from the Group I showed higher levels of Ea than soils from Group II at similar COT contents. Bulk density and DMAX were higher in soils from cropped plots than in the reference undisturbed soils. Soils from the Group I showed, in general, lower DA and DMAX values, at both sampling depths, than those from the Group II. An inverse relationship was found between DMAX and COT. The loss of COT and the structural instability increase soil susceptibility to compaction. The RM from the cropped plots was higher to that from the undisturbed soils, and reached values greater than the limit of 2.0 MPa, at which root growth and fluids supply are affected. Soil indicators of physical fertility that were more sensitive or more informative in this study were Ea and Ee. The analysis of soil structure contributes to understand the effect of external factors on the soil, particularly the anthropogenic ones.

El uso sustentable de las tierras requiere conservar propiedades edáficas que son importantes desde el punto de vista de la fertilidad y el laboreo del suelo. La alteración de las condiciones del suelo por el manejo puede afectar la producción de los cultivos debido a que influye en la distribución de la materia orgánica y dinámica de nutrientes; como así también sobre la agregación y porosidad del suelo. Una de las regiones del mundo donde los suelos han sido sujetos a un intenso uso agrícola durante las últimas décadas es la Región Pampeana Norte. En los últimos años los productores han adoptado la siembra directa en forma creciente. El objetivo de este trabajo fue evaluar, en suelos representativos de esta región, parámetros de calidad física del suelo en sistemas agrícolas bajo siembra directa en comparación con el mismo tipo de suelo en su condición quasi-prístina. Se realizó la caracterización física de suelos cultivados de once establecimientos correspondientes a ensayos de la Red de Nutrición de la Región CREA Sur de Santa Fe ubicados en las provincias de Santa Fe, Córdoba y Buenos Aires. Se realizó además un muestreo en un sector adyacente sobre el mismo tipo de suelo en su condición quasi-prístina. Se extrajeron muestras compuestas de suelo a dos profundidades: 0-0,08 m y 0,08 m al límite inferior del horizonte Ap y se evaluó el porcentaje de agregados estables al agua (Ea) y al etanol (Ee), el carbono orgánico total (COT), la densidad aparente (DA) y la densidad del suelo máxima (DMAX). La resistencia mecánica (RM) se midió a intervalos de 0,05 m desde superficie hasta 0,35 m de profundidad. Se constituyeron dos grupos de suelos en función de la textura: el Grupo I (con un contenido de arcilla en superficie que oscila entre 215 y 265 g kg-1) y el Grupo II (suelos que poseen entre 98 y 170 g kg-1 de arcilla en superficie). Los valores de Ea, Ee y COT fueron mayores (p < 0,05) en los suelos no perturbados o quasi-prístinos en comparación con los suelos adyacentes cultivados, tanto en superficie como en profundidad. Los suelos del Grupo I presentaron mayor Ea, Ee y COT con respecto a los del Grupo II. La reducción de COT que se produjo por el manejo fluctuó entre 10 y 44%. Se hallaron relaciones directas entre COT y Ea y Ee, respectivamente. A similar concentración de COT, se hallaron mayores valores de Ee en los suelos del Grupo I. La DA y DMAX fueron mayores en el suelo cultivado con respecto a la situación quasi-prístina. Los suelos del Grupo I, en general, presentaron valores más bajos de DA y DMAX en ambas profundidades de muestreo, con respecto al Grupo II. Se halló una relación inversa entre DMAX y COT. Las pérdidas de COT y la inestabilidad estructural resultante aumentaron la susceptibilidad de los suelos a la compactación. La RM fue superior en los suelos cultivados que en los quasi-prístinos, alcanzando valores que superaron el límite crítico de 2,0 MPa, donde se ve afectado el crecimiento de las raíces y el abastecimiento de fluidos. De la información obtenida se desprende que los indicadores de fertilidad física más sensibles o los que aportaron más información en este relevamiento, fueron Ea y Ee. El estudio de la estructura contribuyó a comprender el efecto de los factores externos sobre el suelo, en particular los antrópicos.

Este artículo pretende estudiar en detalle el estado y los daños típicos de los puentes en acero y en estructura mixta (acero y concreto) de la red vial de Colombia, sin incluir su evaluación desde el punto de vista sísmico. Basados en la evaluación del inventario y las inspecciones realizadas por el Instituto Nacional de Vías de Colombia (Invias) desde el año de 1996, a través del Sistema de Administración de Puentes de Colombia (Sipucol). El artículo se divide en dos (2) partes: en la primera se presenta una descripción de las diferentes tipologías de los puentes en acero basados en el módulo de inventario del Sipucol y en la segunda el estado y los daños típicos de los componentes principales. De los doscientos cuarenta y cuatro (244) puentes en acero que hacen parte de la Red Vial Nacional, se encontraron deficiencias estructurales, corrosión generalizada y parcial, infiltración, detallado no adecuado de las uniones, identificación de problemas de fatiga en uniones y regular calidad de las uniones soldadas. Este documento se constituye en la base para una futura y más completa investigación de estructuras vitales en la infraestructura vial como son los puentes, con el objeto de avanzar en el tema de la inspección detallada incluida la condición sismorresistente y la conservación de puentes de acero.

This paper studies in detail the state evaluation and typical damages of Steel and composite structures(concrete plus steel) of the National Roadway Network , without include seismic evaluation. The studies is based in the inventory and the inspections made by the Colombian Government’s Roads Institute (Invias) since 1996, throughout the Colombian Bridge Management System (Sipucol). This paper is divided in two parts: the first one presents a brief description of the different types of steel bridges and composite structures based on the Sipucol inventory module and the second one presents the state and typical damages of the main components. Of the 244 steel and composite structures bridges of the National Roadway Network, they presents structural deficiencies, widespread and partial corrosion, infiltration, not appropriate unions details, presence of fatigue problems in the unions and poor quality in welded unions. It is considered that this paper will be the base for a further and more comprehensive investigation of structures that are vital in the road infrastructure like the bridges, in order to advance in the detailed inspection including seismic vulnerability analysis, and conservation of steel bridges topics.

Plants and some other organisms including protists possess a complex branched respiratory network in their mitochondria. Some pathways of this network are not energy-conserving and allow sites of energy conservation to be bypassed, leading to a decrease of the energy yield in the cells. It is a challenge to understand the regulation of the partitioning of electrons between the various energy-dissipating and -conserving pathways. This review is focused on the oxidase side of the respiratory chain that presents a cyanide-resistant energy-dissipating alternative oxidase (AOX) besides the cytochrome pathway. The known structural properties of AOX are described including transmembrane topology, dimerization, and active sites. Regulation of the alternative oxidase activity is presented in detail because of its complexity. The alternative oxidase activity is dependent on substrate availability: total ubiquinone concentration and its redox state in the membrane and O2 concentration in the cell. The alternative oxidase activity can be long-term regulated (gene expression) or short-term (post-translational modification, allosteric activation) regulated. Electron distribution (partitioning) between the alternative and cytochrome pathways during steady-state respiration is a crucial measurement to quantitatively analyze the effects of the various levels of regulation of the alternative oxidase. Three approaches are described with their specific domain of application and limitations: kinetic approach, oxygen isotope differential discrimination, and ADP/O method (thermokinetic approach). Lastly, the role of the alternative oxidase in non-thermogenic tissues is discussed in relation to the energy metabolism balance of the cell (supply in reducing equivalents/demand in energy and carbon) and with harmful reactive oxygen species formation.