Resumen

REQUENA-LARA, G. N. et al. Distribution and ecogeographic conditions of relict Abies forest at mountainous zones of Tamaulipas. Polibotánica [online]. 2020, n.49, pp.50-73.  Epub 20-Jun-2020. ISSN 1405-2768.  https://doi.org/10.18387/polibotanica.49.4.

In the northeast of Mexico, the genus Abies forms forests considered relicts, with distribution only recognized by governmental instances for the state of Nuevo León. There are four species of Abies known within the state of Tamaulipas, which are listed by IUCN, but only two of them (A. vejarii and A. guatemalensis) form forests, being those found in Mexican protection categories. The use of free visualization tools and geospatial modeling allowed us to study the relict distribution of these Tamaulipan forests. We recorded ecogeographic factors from three sites in this forest, at the Field Control Points (PCC), which allowed to establish optical characteristics on satellite images of the Google Earth ™ viewer. With the values of altitude, slope and exposure, we obtained a first model (approximation model), using Boolean algebra with the Spatial Analyst module for ArcView 3.2 of ESRI ™, which was superimposed on the images of the visualizer, to adjust it and obtain a model principal. We added other points on the viewer in places where the INEGI records the presence of the forest in Nuevo León. Subsequently, the values for each of the WordlClim variables of the ten points obtained were extracted, establishing ranges that we processed through Boolean algebra; also, a cluster analysis was applied to obtain the bioclimatic similarity between the sites. The potential distribution was also superimposed on Google Earth ™ to repeat the adjustment process of the model and get the real distribution of the Tamaulipan forest. In this way, we obtained a potential area of 165.9 km2, but the actual distribution is only 3.68 km2, which represents less than 1% of the state territory. In the PCCs there are conditions of humidity and temperate temperature throughout the year, which are the product of the exposure and slope of the hillside; there, humidity depends on the altitude at the sites of the Sierra Madre Oriental, and on the proximity to the Gulf of Mexico in the forest of the Sierra de San Carlos. Which is the main differentiation variable between both sites. In addition to these conditions, other factors have allowed the prevalence of forests in Tamaulipas: they are not harvested commercially, mainly to their isolation and difficult access. Some sites of the potential distribution are occupied primarily by pine forests, but a large part of the surface has been affected mainly by fires, which means that there are chaparrals, shrubs, or induced grasslands. Because it is an isolated and relictual ecosystem, formed of species at risk and that also does not have legal protection, it can present significant levels of fragility and vulnerability, especially in the face of changing global climate conditions. Knowing their distribution provides the basis for more in-depth studies and conservation strategies appropriate to these forests. Finally, and despite the limitation of digital cartography in great detail, the geospatial tools and the method used were adequate to model the real distribution of the Abies forest in Tamaulipas, being more appropriate than the use of ecological niche algorithms, mainly due to which they depend on a high number of records.

Palabras llave : Abies relictual forest; Tamaulipas, México; Geographic Information Systems; Google Earth™.

        · resumen en Español     · texto en Español     · Español ( pdf )