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The growing processes of urban expansion have led to changes in the biochemical and physical properties of the hydrological systems in watersheds, not only by altering the hydrological conditions of the territory, but also by introducing pollutants into water bodies. Thus, diffuse pollution from stormwater runoff is considered one of the main causes of water quality degradation in receiving waters in urban areas, especially in rainy regions such as the South American tropics, where urban development and management processes are generally poorly planned. This article presents the results of an evaluation of the relationship between land use and runoff water quality, taking into account different rainfall characteristics. Sampling was carried out in Medellín, Colombia, in areas with different land uses. Basic water quality parameters and some sources of urban pollution were studied. The results showed that parameters such as total suspended solids have a high variability, especially in the residential area, which makes it difficult to control the activities carried out there. The highest levels of pollution were found in the industrial area, where the presence of covers with very low or no permeability and the increase in anthropic activity cause a strong alteration in the quality of runoff water. These results open the door to question the impact of land use on the chemical composition of rainwater and promote a better understanding of surface runoff water pollution processes, thus providing a complete vision of the interactions in an urban ecosystem, establishing a key tool for water management in urban watersheds., Los crecientes procesos de expansión urbana han generado diversas alteraciones en las propiedades bioquímicas y físicas de los sistemas hidrológicos en las cuencas, puesto que además de modificar las condiciones hidrológicas del territorio, incorporan múltiples contaminantes a los cuerpos de agua. De esta manera, la contaminación difusa resultante de la escorrentía de aguas pluviales, es considerada como una de las principales causas de la degradación de la calidad del agua en las fuentes receptoras en zonas urbanas, lo cual es particularmente relevante en regiones lluviosas como el trópico suramericano donde los procesos de desarrollo y gestión urbana son poco planificados. Este artículo presenta los resultados de la evaluación de la relación entre el uso del suelo y la calidad de las aguas de escorrentía, considerando además diferentes características de la lluvia. Los muestreos se realizaron en la ciudad de Medellín, Colombia en zonas con diferente uso del suelo. Se estudiaron parámetros básicos de calidad del agua, además de algunas fuentes de contaminación urbana. Los resultados mostraron que parámetros como los sólidos suspendidos totales presentaron alta variabilidad, especialmente en la zona residencial, ocasionando así una complejidad en el control de las actividades que allí se desarrollan. Por otra parte, los mayores niveles de contaminación observados se encontraron en la zona industrial, donde la presencia de coberturas con muy baja o nula permeabilidad y el aumento de la actividad antrópica generan una fuerte alteración en la calidad de las aguas de escorrentía. Estos resultados abren la puerta a cuestionamientos en cuanto al impacto del uso del suelo en la composición química de las aguas pluviales y promueven una mejor comprensión de los procesos de contaminación del agua de escorrentía superficial y por ende una visión más completa de las interacciones que se presentan en un ecosistema urbano, estableciendo una herramienta clave para la gestión hídr

• Climate warming is causing compositional changes in Andean tropical montane forests (TMFs). These shifts are hypothesised to result from differential responses to warming of cold- and warm-affiliated species, with the former experiencing mortality and the latter migrating upslope. The thermal acclimation potential of Andean TMFs remains unknown. • Along a 2000m Andean altitudinal gradient, we planted individuals of cold- and warm-affiliated species (under common soil and irrigation), exposing them to the hot and cold extremes of their thermal niches, respectively. We measured the response of net photosynthesis (Anet), photosynthetic capacity and leaf dark respiration (Rdark) to warming/cooling, five months after planting. • In all species, Anet and photosynthetic capacity at 25°C were highest when growing at growth temperatures (Tg) closest to their thermal means, declining with warming and cooling in cold-affiliated and warm-affiliated species, respectively. When expressed at Tg, photosynthetic capacity and Rdark remained unchanged in cold-affiliated species, but the latter decreased in warm-affiliated counterparts. Rdark at 25°C increased with temperature in all species, but remained unchanged when expressed at Tg. • Both species groups acclimated to temperature, but only warm-affiliated species decreased Rdark to photosynthetic capacity ratio at Tg as temperature increased. This could confer them a competitive advantage under future warming.