Impacts of land management and climate change in a developing and socioenvironmental challenging transboundary region

Land-use/cover change is the major cause of terrestrial ecosystem degradation. However, its impacts will be exacerbated due to climate change and population growth, driving agricultural expansion because of higher demand of food and lower agricultural yields in some tropical areas. International strategies aimed to mitigate impacts of climate change and land use-cover change are challenging in developing regions. This study aims to evaluate alternatives to minimize the impacts of these threats under socioeconomic trajectories, in one of the biologically richest regions in Guatemala and Mexico. This study is located at the Usumacinta watershed, a transboundary region that shares a common history, with similar biophysical properties and economic constraints which have led to large land use/cover changes. To understand the impacts on deforestation and carbon emissions of different land-management practices, we developed three scenarios (1): business as usual (BAU), (2) a reducing emissions scenario aimed to reduce deforestation and degradation (REDD+), and (3) zero-deforestation from 2030 onwards based on the international commitments. Our results suggest that by 2050, natural land cover might reduce 22.3 and 12.2% of its extent under the BAU and REDD + scenarios, respectively in comparison with 2012. However, the zero-deforestation scenario shows that by 2050, it would be possible to avoid losing 22.4% of the forested watershed (1.7 million ha) and recover 5.9% (0.4 million hectares) of it. In terms of carbon sequestration, REDD + projects can reduce the carbon losses in natural vegetation, but a zero-deforestation policy can double the carbon sequestration produced by REDD + projects only. This study shows that to reduce the pressures on ecosystems, particularly in regions highly marginalized with significant migration, it is necessary to implement transboundary land-management policies that also integrate poverty alleviation strategies

Characterization of Corrosion Behavior of Painted Galvanized Steel under Accelerated Conditions

In the present study three systems of carbon steel (1008) are evaluated, which were provide of two corrosion control methods, barrier and cathodic protection (painted and galvanized respectively) commonly used in the construction industry. They were evaluated under accelerated conditions exposed in fog chamber, according to ASTM B-117, which specifies continues exposition of sodium chloride at 5% and 35 °C. The main aim of the research was to characterize the corrosion resistance and to determine the degradation mechanism under test’s conditions. The results after 1080 and 3500 hours of exposure are presented, with adhesion measure (ASTM D-3359) and scratch resistance measure (D-1654) for each exposure time, as well as the characterization of corrosion attack through the mapping analysis of Scanning Electron Microscope / Energy Dispersive X-ray. According to the results it is proposed that the corrosion of the systems under study begins at galvanized – metal base interface. Later advances due to formation of porous layer of zinc hydroxi-chloride, which it’s characteristic of environments with chloride ions, forming zinc’s corrosion products like zinc oxide and zinc hydroxide on the porous layer until iron starts to dissolve, producing iron oxide and iron oxy-hydroxide on the zinc’s corrosion products and porous layer

Estimación de las concentraciones relativas de clorofila en foliolos de papa (solanum tuberosum l.) utilizando técnicas de reflectancia de la vegetación

La cantidad de energía solar absorbida por una hoja es en gran parte función de la concentración foliar de los pigmentos fotosintéticos. Por lo tanto, bajas concentraciones de clorofila pueden limitar el potencial fotosintético y por consiguiente la síntesis de compuestos primarios de una planta. En este trabajo se describe un método no destructivo para estimar las concentraciones de clorofila de foliolos de los cultivares de papa: SA–2563, Pumamaqui y Purranca, basada en la interacción entre la luz y la vegetación, que utiliza la primera derivada de sus respectivos espectros de reflectancia. Como referencia, se utilizaron las unidades SPAD adquiridas por un medidor de clorofila SPAD–502 que fue previamente validado. Correlaciones mayores al 90% entre las amplitudes de las señales obtenidas de derivar los espectros de reflectancia de foliolos en longitudes de onda alrededor de 720 nm y las concentraciones de clorofila medidas con un SPAD–502, evidencian el potencial del método basado en reflectancia de la vegetación como indicador seguro para estimar parámetros bioquímico–fisiológicos de las plantas