Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Semiosis processes originated by the SARS-CoV-2 pandemic are explored. The aim is, first, to show the potential of social semiotics (as part of an interdisciplinary proposal) to understand contemporary communication and its incessant creation of complex, multifactorial and multimodal discourses. Second, reflect on the changes that the unusual health emergency has provoked on daily life. Analyzed material comes from memes about the pandemic, as well as official semiotic reconversion strategies amidst the “new normality".

In this paper, the trend on the issues that are visible in the alternative media in Medellín is stated. Although the data correspond to a random, non-systematic review of a sample selected at the convenience of the author; it is important to point out that it is the first observation of this agenda, which in the future could promote  lines of research in this regard, and the creation of an observatory of these media, which allows its study and ongoing support for the construction of. By drawing attention to the alternative media agenda, perhaps a third level is being reached in the analysis of these, after their characterization and construction of a public policy that seeks the creation and strengthening of media networks, training, visibility and access of communities to such media alternatives.   It is evident that alternative media are spaces that support, from the local and regional level, citizen awareness, human rights, address and problematize issues of social importance such as drug addiction, inclusion, old age, security, employment, social organization, etc.  Beyond the agenda, there are questions that would enrich studies of this type. Who manage the agendas of the alternative media? Does the agenda of these media coincide with that of the communities in which they are located? Does the agenda of these media have any kind of involvement in other media, governmental instances, community actions, generate public opinion, changes, among others?

The movie El castillo de la pureza, by Arturo Ripstein (1972), is based on a real event that took place in Mexico City in 1959. The objective of the article is to describe the context of the event, inscribed in the police annals of the Mexican Capital and how such a sordid story (according to our perspective) could be adapted to the screen as a “love story”, highlighting the work of the screenwriter José Emilio Pacheco (JEP). A first reading of the film shows us the confinement of a family (forced by the father) and that the isolation from the outside world is accepted by the wife as an almost divine plan of the one who loves and respects blindly. Our intention is to deepen this view by offering an analysis of the information from the press of the time,from excerpts from the script, as well as scenes from the film and the frames corresponding to the chosen sequence that I have named “Preamble to the crisis. The tranquility in the castle begins to crack”.

Los bosques mesófilos de montaña (BMM) se presentan entre 0.5% y 1% del territorio mexicano y están seriamente amenazados debido a la alta tasa de deforestación. Para contribuir a la conservación de especies arbóreas de BMM, se realizó el presente estudio con los objetivos de (1) determinar la diversidad de árboles en el bosque urbano El Cerrito de San Cristóbal, Chiapas, México, (2) enriquecer florísticamente el bosque urbano El Cerrito de San Cristóbal con la plantación de especies nativas del BMM de Chiapas y (3) describir la diversidad genética introducida mediante el enriquecimiento florístico. A través de un muestreo en parcelas circulares de 1000 m2, se registró la estructura y composición de la comunidad de árboles y, por recorridos, se registraron las especies de herbáceas. Se plantaron 14 especies nativas del BMM para enriquecimiento de El Cerrito y, mediante la técnica PCR-RFLPs de ADN de cloroplasto (tRNL), se determinó la diversidad genética introducida. Se detectó una composición de árboles dominada por especies introducidas hace 40 años (Cupressus lusitánica, Eucalyptus camaldulensis y Pinus pseudostrobus). No se observó reclutamiento de plántulas y juveniles de árboles del dosel y se identificaron algunos individuos de especies nativas establecidos naturalmente. La diversidad genética introducida fue baja por especie, pero en conjunto fue moderada. La baja diversidad por especie se atribuye a que el marcador utilizado es conservador. Los bosques urbanos pueden constituir un sistema de conservación de especies de árboles nativos y de su diversidad genética, al mismo tiempo que se promueve la regeneración y diversificación de bosque urbanos. Este estudio contribuye con la conservación y conocimiento genético de especies arbóreas de bosques de montaña de México.

The leaf litter from trees is the main route of entry of organic matter and its subsequent decomposition allows the flow of nutrients in the ecosystem. The study of these processes in ecosystems under rehabilitation is of vital importance to determine how such actions are influencing their recovery. This study was carried out to determine the effect of reforestations on litter production and decomposition at El Porvenir, Hidalgo State, México. We selected four different conditions: three correspond to areas with different reforestation ages, 5, 12 and 14-year-old (R5, R12 and R14) while the fourth is a reference site (SR) with remnants of natural vegetation. For each condition, 10 sampling points were selected in which litter traps were placed to quantify the litter production for one year. In 4 sampling points per condition we placed litter bags to measure the rate of decomposition for a 12-month period. The reforestation age showed a positive effect of litter production. The largest litter production was recorded in R14 (0.3099 kg m-2 year-1) while the lowest was for R5 (0.0436 kg m-2 yr-1). The highest and lowest decomposition rates correspond to SR (k= 0.676) and R14 (k = 0.229). On the other hand, the increased release of C was presented in SR and the lowest in R12. For its part, the release of more N at the end of the incubation period was recorded in SR and the lowest in R14.

Testing environmentaly-friendly plant essential oils for their ability to protect non-durable wood against wood decay fungi is a research topic of current interest. In this study, wood preservative potential of extracts from the wood of the durable species, Tetraclinis articulata and Cedrus atlantica were assessed on non-durable maritime pine sapwood, Pinus pinaster var atlantica, after exposure to three wood decay fungi, according to the EN 113 Standard. Significant differences were observed between treatment effects of these extracts, between fungal decay levels and between oils concentrations. Overall, mean mass losses of treated wood specimens were above 8%. T. articulata root burl extract gave the best protection level for this type of wood against Gleophyllum trabeum and Rhodonia placenta but only at test concentrations above 0.1%v/v. However, efficacy levels of both extracts’ treatments, applied at the tested concentrations, were judged insufficient on the basis of the NF EN 113 standard used.

Dendroecology is a sub-discipline of dendrochronology, which refers to the study of ecological processes in a forest through the analysis of tree rings in a forest stand. This sub-discipline is useful for understanding the growth dynamics, in natural and managed conditions. The objective of this study was to review the application of dendroecology as a forest management tool. Seventy-eight papers were identified that involved 118 species. The countries where more dendroecological studies have been carried out are United States of America, Spain, and Argentina. The management practices that are mostly benefited from the use of dendroecological methods are the estimation of the rotation-time in the planning phase; thinning in the execution phase; and growth and performance assessments, as well as the impacts of pests and diseases on growth in the monitoring phase. Forest management research is mainly based on the monitoring of permanent sampling plots and can be supported by tree-ring analysis. Dendrochronological methods provide relevant information on forest structure, phytosanitary status, tree-species growth rates and their temporal variation. Dendroecological research experiences carried out in other countries can also be applied in Mexico, including the study of broadleaved species. The use of dendroecology as forest management tool would help to optimize timber production and promote the conservation of forest ecosystems in Mexico.

Los anillos de crecimiento de los árboles han sido útiles como indicadores para estimar la captura de carbono en los ecosistemas forestales. México es considerado un país megadiverso con un gran potencial para las dendrociencias dada su alta variabilidad ambiental. El objetivo del presente estudio es presentar la perspectiva que ofrecen los anillos de crecimiento de los árboles para estimar la captura potencial de carbono en México. Se realizó una revisión bibliográfica a escala mundial, considerando estudios que abarcan proxies dendroecológicos sobre el contenido de carbono almacenado. La revisión incluyó 74 estudios publicados entre 2004 y 2019. Las investigaciones dendroecológicas del contenido de carbono se realizaron principalmente a partir de 2012 en México. La mayoría de estos estudios se basaron en especies como Pinus sylvestris y Fagus sylvatica. Adoptando un enfoque dendroecológico, asociado con técnicas alométricas este estudio ofrece una gran oportunidad para promover el desarrollo del estudio de la dinámica del carbono almacenado en México.

Ante el impacto que representa el cambio de uso de suelo en la pérdida de biodiversidad y deterioro del medio ambiente, los sistemas agroforestales de cacao de sombra son una alternativa para la conservación de biodiversidad y almacén de carbono. El objetivo de este trabajo fue conocer el efecto de la edad de los sistemas agroforestales de cacao en la diversidad arbórea y almacenes de carbono de su vegetación de sombra. Se compararon 258 parcelas distribuidas en once sistemas agroforestales entre 10 años y 70 años, totalizando 7.87 ha. Dentro de cada parcela se midió el diámetro normal (DN) y altura total de todos los árboles >5 cm (DN) para estimar su biomasa aérea con una ecuación general y otra específica, y conocer la discrepancia de ambos métodos. Los sistemas agroforestales de 70 años presentaron en promedio más especies arbóreas por hectárea (23), índice de diversidad Shannon (2.0) y almacén de carbono (75 Mg ha-1) que los de 10 años (p < 0.01; 10 Mg ha-1, 1.1 Mg ha-1 y 36 Mg ha-1; respectivamente). La ecuación alométrica específica estimó 27.7% (p = 0.05) más biomasa aérea que la ecuación general, por lo que se considera de mayor precisión para estos sistemas agroforestales en particular, y se recomienda su uso para estos tipos de vegetación. Se concluye que, particularmente para México, conservar sistemas agroforestales de cacao de edad madura contribuye a la conservación de la biodiversidad arbórea y almacenes de carbono de la vegetación tropical, asemejando relictos de la vegetación original.

The estimation of accumulated aboveground biomass in a forest with management for timber harvesting is of importance to evaluate sustainability regarding the effect of the silvicultural system, and to understand the dynamics and functioning of forest ecosystems. Aboveground biomass accumulation reflects productivity at a given site. In this work we estimated the aboveground biomass and the carbon, in stands with and without forest management, in the Chincua, Senguio, Michoacán Ejido, through the generation of allometric equations for Abies religiosa (Kunth) Schltdl. & Cham and Pinus pseudostrobus Lindl, while for the broadleaf equations from other studies were used and, in addition, by means of inventory data for all species. The stand without management had a biomass of 323.23 Mg ha-1, while the stand with management 287.62 Mg ha-1, which, despite its variability, did not present significant differences (P = 0.96). The carbon content also did not present significant differences (P = 0.97), being 155.03 Mg ha-1 and 128.44 Mg ha-1 in the stands without and with management, respectively. The results indicate that with forest management, under the silvicultural selection system, the structure and composition of the managed stand were conserved, which allowed maintaining the biomass storage in an amount similar to that of a forest without management; Therefore, managed forests can be efficient carbon sinks, plus the amount of this element in the process of harvesting and processing of wood to long-term forest products, such as construction timber, furniture, railways ties, utility poles, among others, which allow their permanence for relatively long periods.