Influencia Del Borde Sobre El Contenido De Humedad En Relictos De Bosque Húmedo Tropical Del Municipio El Retorno (Guaviare)

Abstract

The edges in the fragmented landscapes generate a series of direct effects, being the loss of humidity, the most notable change affecting the forests. To evaluate the influence of the edge on the humidity in forest fragments with two types of adjacent coverings (Pastures and Rubber Plantations), a multitemporal analysis of land use changes and canopy desiccation in the period 1990 - 2016 was carried out. Established transects from the edge into the forest for the measurement of temperature, relative humidity, composition and vegetation structure. A loss of 56.34% of the areas of natural forest was identified, as well as an increase in the number of patches, the reduction of its area and an increase in the distance between relics, evidencing fragmentation processes. In contrast, pasture areas increased their occupation from 15.8% of the area in 1990 to 50.27% of the area in 2016, being the dominant coverage. In the sampled forests the dominance of heliophite species generalist of disturbed ecosystems was recorded and a structure in which no strata and dominated lower diametric classes. Regarding the influence of the edge in the loss of atmospheric humidity, it was found that it reaches 50 m when the adjacent cover is grass, whereas there is no significant difference between the values of humidity in the edge compared to the interior of the forest when the Adjacent cover is rubber; However, according to the Normalized Difference Humidity Index (NDMI) and the Water Stress Index (SIWSI) values, the influence of the edge can extend more than 100 m in the interior, whereby fragments consisting of fringes of vegetation less than 100 m have in their entirety edge conditions and do not present core area It is considered that what has been found has great implications for the conservation of the forests, since forest degradation processes are evidenced, as well as the national distances established for the protection of water rounds, since the edge influence distances are not sufficient to maintain the functionality of the forest ecosystem