Leaf litter decomposition of the most abundant native and exotic woody species in the piedmont of Yungas forest, Tucumán, Argentina

Las especies exóticas pueden impactar en el proceso de descomposición, ya sea de manera directa (diferencias en calidad y/o cantidad de hojarasca) o de manera indirecta (modificando las condiciones micro ambientales y la abundancia y/o actividad de descomponedores). Los objetivos de este trabajo fueron: I) comparar la descomponibilidad de las especies exóticas y nativas más abundantes de los bosques secundarios del pedemonte de la Sierra de San Javier, Tucumán, II) analizar el efecto de las condiciones micro ambientales sobre la tasa de descomposición de un sustrato común y III) evaluar el efecto del tamaño de malla de las bolsas de descomposición en la descomposición de hojarasca. Para ello incubamos hojarasca de 7 especies nativas y 7 exóticas bajo condiciones estándares durante un año y hojarasca de Populus deltoides (sustrato común) en parches de bosques secundarios nativos e invadidos por Ligustrum lucidum en bolsas con dos tamaños de malla. La pérdida de peso no fue diferente entre el conjunto de especies nativas y exóticas pero si se encontraron diferencias interespecíficas. La constante de descomposición del sustrato común fue menor en los bosques invadidos por lo que L. lucidum modificaría la composición y/o actividad de organismos descomponedores y generaría cambios en las condiciones micro ambientales que determinan la descomposición. Por otra parte, la descomposición fue mayor en bolsas con malla grande, lo cual podría deberse al acceso de macro invertebrados. Nuestros resultados sugieren la ausencia de un patrón de descomposición en el conjunto de especies nativas y exóticas y la potencial influencia que tendría L. lucidum en los factores que controlan la descomposición.Exotic species may influence the process of decomposition, either directly (through differences in the quality and/or quantity of leaf-litter) or indirectly (by altering microclimatic conditions and the abundance and/or activity of decomposers). The aims of our study were: I) to compare the decomposability of the most abundant exotic and native species in secondary forests of the Sierra de San Javier, Tucumán, II) to assess the effect of microenvironemtal conditions on the rate of decomposition of an homogeneous substrate and III) to evaluate the effect of the litterbags mesh size on the decomposition process. To do this, we incubated leaf-litter of 7 native and 7 exotic species under standard conditions for one year and also leaf-litter of Populus deltoides (homogeneous substrate) in native and invaded by Ligustrum lucidum secondary forest patches in bags with two mesh sizes. Native and exotic species did not differ in their weight loss rates, but there were interspecific differences. The decay constant of the homogeneous substrate was lower in invaded patches so it is possible that L. lucidum modify the composition and /or activity of decomposing organisms and generate changes in micro-environmental conditions. In addition, decomposition was higher in bags with larger mesh size. This pattern may be explained by the differential access of macro invertebrates. Our results suggest the absence of a pattern of decay in native and exotic species as groups, and the potential influence that L. lucidum would have over the factors controlling littler decomposition.Fil: Fernandez, Romina Daiana. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales E Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Aragón, Roxana. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales E Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Spatial structure of remnants of native forest in the Dry Chaco and the Espinal

El vasto territorio del Chaco Seco y el Espinal se consolida como uno de los centros globales de producción de granos y carne. Tanto por distintas normas legales, limitaciones productivas, o causas culturales, el bosque nativo se preserva en grandes porciones y numerosos pequeños fragmentos inmersos en la matriz agrícola (en lo subsiguiente, "remanentes"). Estos remanentes suelen pasar desapercibidos para la comunidad científica y los tomadores de decisiones, quedando al margen de la planificación territorial y de acciones de conservación. En este trabajo describimos la estructura espacial de los remanentes, y generamos un esquema de clasificación que permite identificar distintos tipos según sus propiedades espaciales. Siguiendo una estrategia de clasificación basada en objetos, cartografiamos ~22,000 remanentes en ocho áreas focales (AF) dispersas en el territorio usando imágenes satelitales CBERS-2B. Mediante índices espaciales, estos remanentes de tamaños, formas, y niveles de aislamiento variables, fueron categorizados en cinco clases, desde "isletas" hasta "bloques compactos". La superficie de remanentes resultó mayor en el Chaco Seco que en el Espinal (entre 10.1% y 19.4% en la primera región, y entre 3.1% y 7.3% en la segunda). Las diferencias en el nivel de fragmentación se amplificaron entre AF, dependiendo tanto de la superficie total de remanentes, como de la ocurrencia relativa de distintos tipos. Así, en AF San Luis la fragmentación resultó 70 superior que en AF de Anta (Salta). En este trabajo brindamos herramientas para la identificación y el monitoreo de estos remanentes, las cuales podrán ser consideradas tanto con fines productivos como de conservación. Finalmente, las acciones de manejo y conservación deben reconocer la existencia de estos fragmentos de bosques en paisajes altamente transformados por la actividad agropecuaria.The vast territory of the Dry Chaco and the Espinal became one of the global centers for the production of grains and meat. Due to different legal norms, productive limitations or cultural causes, the native forest is preserved on extensive patches as well as on numerous small fragments within the agricultural matrix. These remnants are seldom considered by the scientific community and decision-makers, and are left out of territorial planning and conservation actions. In this paper, we describe the spatial structure of the remnants and generate a classification scheme that allows identifying different types according to their spatial properties. Following an object-based classification strategy, we mapped ~22000 remnants in eight foci areas (FA) scattered throughout the territory using CBERS-2B satellite images. By means of spatial metrics, these remnants of variable sizes, shapes and isolation levels were categorized into five classes, from “islets” to “compact blocks”. The surface of remnants was higher in the Dry Chaco than in the Espinal (between 10.1% and 19.4% in the first region, and between 3.1% and 7.3% in the second). Differences in the level of fragmentation were amplified between FA, depending both on the total surface of remnants and on the relative occurrence of different types. Thus, in the FA of San Luis the fragmentation was 70 times higher than in the FA of Anta (Salta). In this work, we provide tools for the identification and monitoring of these remnants, which may be considered for both productive and conservation purposes. Finally, management and conservation actions must recognize the existence of these pieces of forest in landscapes highly transformed by agricultural activity.Fil: Muñoz Garachana, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Aragón, Myriam Roxana. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Baldi, Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; Argentin

Soil enzymes associated with carbon and nitrogen cycling in invaded and native secondary forests of northwestern Argentina

Background and aims: Alien success has frequently been associated with changes in the concentrations of soil nutrients. We aim to investigate the effects of plant invasion on soil nutrients, potential enzyme activity and litter elemental composition and stoichiometry - Methods: We compared stands of secondary forest invaded by Ligustrum lucidum and those dominated by natives, and performed litter chemical analyses on 3 native and 2 exotic tree species - Results: Soils of invaded sites had 20 and 30 % increase in β-glucosidase and alkaline phosphatase activity, higher Olsen-phosphorus (P) and potassium (K) concentrations and lower nitrogen (N) concentration and N:P, N:K and ammonium:Olsen-P ratios. Invaded and non-invaded sites differed in their overall nutrient composition and enzyme activity. Natives and exotics differed in nine of the 16 litter elemental composition and stoichiometry variables analyzed - Conclusions: The low N:P ratio in litter, the decrease in soil N in invaded stands and the low N concentration of exotics suggest that N is the limiting nutrient and that exotic success is related to higher N uptake and use efficiency. The higher investment in the acquisition of soil resources, higher nutrient uptake and use efficiency of limiting nutrients contribute to the success of exotics in this subtropical forest

Second record of <i>Colibri thalassinus</i> for Argentina

A Green Violetear <i>Colibri thalassinus</i> was mistnetted in <i>Alnus acuminata</i> forest at Catamarca province, northwestem Argentina. The previous record for this hummingbird was Olrog (1963) for Tucumán province. The individual captured was an adult, with neither molt nor brood patch

Factores asociados a Diabetes Gestacional en mujeres atendidas en el Servicio de ARO del Hospital Victoria Motta Jinotega Abril 2019 a Marzo 2020

El objetivo principal del presente trabajo fue determinar los factores asociados a diabetes gestacional en mujeres atendidas en el servicio de ARO del Hospital Victoria Motta Jinotega abril 2019 a marzo 2020. Es un estudio descriptivo, retrospectivo de corte transversal donde la muestra fueron 70 pacientes, que fueron diagnosticadas con diabetes gestacional durante el período de estudio, atendidas en el Hospital Victoria Motta Jinotega, y que cumplieron con los criterios de inclusión. Entre los resultados se destacan, las características sociodemográficas de las embarazadas que predominan en el estudio son mujeres con edades comprendidas de 20-35 años, en unión estable con obesidad, la mayoría son originarias de los municipios en comparación con el área urbana, ama de casa con nivel académico de primaria, que en su mayoría tenían gestas previas con peso de bebes de embarazos anteriores en grupo de 2500-3999 gramos. Al estudiar comorbilidades en las pacientes en estudios se encontró que el principal factor asociado con la diabetes gestacional corresponde a la presencia de obesidad materna pregestacional y en menor asociación con la dislipidemia e hipertensión arterial crónic

Co-production of sustainability indicators in a vulnerable South American agricultural frontier

Deforestation linked to agricultural activities is a major sustainability concern. Planning towards sustainable agricultural landscapes in the (sub-)tropics requires indicators that capture the many aspects of social-ecological cost and benefit of agriculture. Agricultural production strategies are developed using the best available data and knowledge such as high-yield locations, distance to storage facilities, or certification bonuses. However, there is often a divide between sustainable production data generated by the scientific community and current data that are of interest to actors, such as those in the agribusiness sector. Here, we describe how the harmonization of crop production, conservation, and social data used by scientists and agribusiness is possible using a participatory exercise based on knowledge co-production (i.e., generation of knowledge in a collaborative way) of socio-economic and environmental indicators (such as agricultural production, logistics, or the location of indigenous communities). This was made available through an online decision support platform that facilitated the generation of sustainable entrepreneurial strategies. We tested this exercise for the social-environmentally vulnerable Argentine Chaco dry forest, subject to some of the highest rates of deforestation globally, mainly due to soybean production. The cooperation between participants of this exercise built a knowledge exchange network that was key for informing decision-makers and highlighted information gaps including agricultural productivity, accessibility of regions, and the vulnerability of rural communities. Our exercise may be applicable to other agricultural commodity frontiers and showcases the value of including actors’ priorities in the design of indicators to ensure their policy impact and to achieve food systems’ sustainability

Changes in community functional structure and ecosystem properties along an invasion gradient by 'Ligustrum lucidum'

13 p.Questions It is well documented that invasive alien plants can reduce species richness and diversity and modify the composition of invaded communities. However, our knowledge on the impacts of invasive alien plants on the community functional structure and ecosystem properties and the mechanisms underlying these changes is more limited. We evaluated how the community functional structure and ecosystem properties change along a gradient of Ligustrum lucidum abundance. Location Subtropical mountain forest in NW Argentina. Methods We conducted tree vegetation sampling in 164 plots distributed along a gradient of L. lucidum abundance. For L. lucidum and for the most abundant tree species in these plots we estimated six functional traits (specific leaf area, leaf tensile strength, leaf nitrogen concentration, leaf water potential, wood density and maximum plant height), as well as their relative growth rates. Then, we calculated indices of community functional structure (community-weighted means for each trait; richness, evenness, divergence and dispersion). We explored the extent to which the invasive success of L. lucidum and its impact may be attributed to niche differentiation or to fitness superiority. Finally, we explored how L. lucidum abundance alters ecosystem properties. Results Some indicators of community functional structure changed linearly while others tended to saturate along the invasion gradient. L. lucidum has a higher growth rate than resident species and it lays close to the periphery, but within the limits of the functional space defined by resident trees. L. lucidum tends to displace more functionally similar resident species. Soil moisture and N content declined, while soil C:N increased with L. lucidum abundance. Conclusions Our findings suggest that both niche differentiation and fitness superiority contribute to explain the invasion success of L. lucidum and the changes in functional structure of the community along the gradient of L. lucidum abundance with evident impacts on ecosystem properties.Universidad de AlcaláMinisterio de Ciencia e InnovaciónFondo Europeo de Desarrollo Regional (FEDER)Comunidad de Madri

Onset of deep drainage and salt mobilization following forest clearing and cultivation in the Chaco plains (Argentina)

Semiarid sedimentary plains occupied by dry forest ecosystems often display low groundwater recharge rates and accumulation of salts in the soil profile. The transformation of these natural systems to rain‐fed agriculture has led to raising water tables and a slow, but steady, process of groundwater and soil salinization in vast areas of Australia. In the semiarid plains of Chaco (central South America), unprecedented deforestation rates are taken place. Based on deep soil sampling (0–6 m) in seven paired stands under natural dry forest, rain‐fed agriculture and pasture, with different age of clearance (>30 years, 20 and 3 years) in Salta, Argentina, we provide evidence of groundwater recharge increase and onset of salt mobilization in areas where forests were replaced by annual croplands. Soils with higher water and lower chloride content are evidence of deep percolation and salt leaching. In Salta, stands subject to 30 years of rain‐fed cultivation had profiles with 30–46% higher moisture content and 94% lower chloride stocks compared to dry forest (0.05 ± 0.04 kg/m2 versus 0.77 ± 0.4 kg/m2). Estimates of groundwater recharge based on the displacement of chloride peaks suggested values of 27–87 mm yr−1 for agricultural soybean stands, and 10.4 mm yr−1 for pastures. While hydrological shifts in the regional groundwater system are poorly monitored and understood, our findings show that it is potentially sensitive to land use changes and to salinization processes.EEA SaltaFil: Amdam, M. Laura. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Aragón, Myriam Roxana. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Jobbagy Gampel, Esteban Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Volante, Jose Norberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; ArgentinaFil: Paruelo, José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentin

Imperfect Vertical Transmission of the Endophyte Neotyphodium in Exotic Grasses in Grasslands of the Flooding Pampa

Fil: Gundel, Pedro E. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas vinculadas a la Agricultura; Argentina.Fil: Garibaldi, Lucas Alejandro. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio Ecotono; Argentina.Fil: Tognetti, Pedro M. Universidad de Buenos Aires (UBA). Facultad de Agronomía; Argentina.Fil: Aragón, Roxana. Universidad de Buenos Aires (UBA). Facultad de Agronomía; Argentina.Fil: Ghersa, Claudio M. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas vinculadas a la Agricultura; Argentina.Fil: Omacini, Marina. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas vinculadas a la Agricultura; Argentina.Fil: Gundel, Pedro E. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Garibaldi, Lucas Alejandro. Universidad de Buenos Aires (UBA). Facultad de Agronomía; Argentina.Fil: Ghersa, Claudio M. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Omacini, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Cool-season grasses establish symbioses with vertically transmitted Neotyphodium endophytes widespread in nature. The frequency of endophyte-infected plants in closed populations (i.e., without migrations) depends on both the differential fitness between infected and non-infected plants, and the endophyte-transmission efficiency. Most studies have been focused on the first mechanism ignoring the second. Infection frequency and endophyte transmission from vegetative tissues to seeds were surveyed in two grasses growing in vegetation units that differ in flood and grazing regimes, and soil salinity. Transmission efficiency and infection frequency for tall fescue did not vary significantly and were 0.98 and 1.00, respectively. For Italian ryegrass, transmission efficiency and infection frequency were 0.88 and 0.57 in humid prairies, and 0.96 and 0.96 in the other vegetation units. Only in humid mesophytic meadows, the observed pattern was irrespective of the presence or absence of grazers. Our results suggest that selection forces for endophyte infection are different for both species. Imperfect transmission was only compensated in tall fescue through an increased fitness of infected plants. Interpreting variations of infection frequency only in terms of differential fitness can be misleading, considering that endophyte transmission can be imperfect and variable in nature. Therefore, this study highlights the importance of measuring transmission efficiency