Mass mortality and biomass of mangrove trees are related to soil factors in the Caribbean Coast of Colombia. Soil properties measured were particle size distribution, bulk density, organic matter, total nitrogen, total phosphorus, pH, redox potential, salinity, and extractable nitrogen (NO2, NO3, NH4) and phosphorus (PO4). Sampling was performed at three locations along two 50 m transects at each site. Soil nutrient concentrations of either exchangeable nitrogen or phosphorus were comparable to other reported values. Redox potentials (Eh) were variable probably due to microtopographic conditions and to the amount of water and organic matter present in the soil. Hydrogen potentials (pH) are within the range reported as normal for mangrove soils. Locations with highest biomass had an average soil salinity of 35 with a range of 20 to 53. Sites with dead or dwarfed vegetation had an average soil salinity of 74 and minimum and maximum values observed were 52 and 100 respectively. Statistical analysis exhibited temporal and spatial differences in soil salinity and suggest that this parameter is most correlated to the development and distribution of mangrove vegetation in the area indicating that basal area and biomass volume are inversely correlated with soil salinity.

Uno de los métodos utilizados para analizar impactos ambientales ocurridos a través del tiempo, es conocer la evolución de los ecosistemas mediante Sistemas de Información Geográfica-SIG; así que en este artículo, se presenta un análisis multitemporal de una zona con influencia de dos sistemas productivos principalmente: la ganadería y la minería y sobre la cual se presentan impactos ambientales significativos. La metodología partió de la utilización y digitalización de fotografías aéreas de los años 1998 y 2010 y una imagen tomada de Google Earth del año 2015 debidamente georreferenciada, se trabajó con una escala 1:25000; así mismo, se utilizó el programa ArcGIS para el procesamiento de la información. En el análisis se estableció como han sido las variaciones en las coberturas vegetales en el tiempo, la influencia de los sistemas productivos sobre las áreas boscosas, las áreas que han tenido procesos de recuperación y otras que con el tiempo han ido desapareciendo.

With the main purpose of providing a baseline for future evaluations of ecosystem changes as a consequence of the reopening of freshwater canals from the Magdalena River, the structure of mangrove forests of the Exterior Delta of the Magdalena River-Ciénaga Grande de Santa Marta (DERM-CGSM land several soil properties were quantified. Mangrove forests surrounding the lagoonal complex exhibit from low and almost null structural development (completely dead) to complex structures. Best structural development was found on Caño El Jobo (JOB) and Ciénaga de la Aguja (AGU) in the southwestern part of the study area. JOB showed only two mangrove species but individual trees exhibited large sizes. In ARA, on the eastern side of Ciénaga Grande, the three species were present and structural development can be considered intermediate with several individuals of large size. These three stations (JOB, AGU, ARA) still receive fresh water flow from either the Magdalena River or from rivers of the Sierra Nevada de Santa Marta. The areas most isolated from freshwater flow (stations on Ciénaga de Pajaral and on the western end of Caño Clarín) showed the lowest structural development of the vegetation and a large part of it completely dead. It is concluded \Y\a\ Avicenniagerminans is the dominant species in the study area. In general, Rhizophoramangle was only found on the edges of canals or lagoons and towards the western side this species was almost all dead. An inverse relationship was demonstrated between soil salinity and basal area, height and foliar area and a direct one between redox potentials and the same attributes. The low foliar area values of A. germinans in the stations with highest soil salinities reflect in part the "aggressiveness"of the environment in which the species lives and specially its response to the stress imposed by the difficulty of obtaining water from the soil.

This article is part of the results of a research project whose objective was to formulate a strategy for environmental awareness for children and adolescents of the Fundación Niños de Los Andes (Children of the Andes Foundation) in the city of Manizales, Colombia. The methodological process was a quantitative and descriptive approach, using the survey as a tool for information gathering and the SPSS tool for systematization. A later discussion of the results was performed, and it determined the best way to approach the environmental education in children. The main conclusion was that the best strategy for acceptance of environmental education in children is to develop practical workshops that enable them to know, through real cases, environmental issues and ways of approach to prevent these issues, mitigate them, and control them.