Abstract

This study investigated two transition zones (matrix-forest edge-interior gradient) associated to forest fragments with different degrees of intervention, in an Andean paramo ecosystem located in Puracé National Park (Colombia). The relationship between the structures of vegetation and the spatial dynamics associated with microclimatic variation in each patch of woodland was determined in order to establish the Depth of Edge Influence (DEI). In each fragment, the vegetation was evaluated using transects of 80 x 2 m perpendicular to the margin, corresponding to 30 m of the matrix and 50 m into the woodland. All woody plants were identified, the heights and dominance was the most relevant features to determining the structure of the forest edge. Microclimatic data (humidity, sunlight exposure, air and soil temperature) were measured in transects and mapped using interpolation for determining the spatial dynamics in each gradient and the behavior of the variables associated with the DEI. The results obtained indicate that the change of microclimatic variables was significant in the margin-forest edge-interior gradient when comparing the forest fragments. The differences are related to the degree of human intervention, since the pressure exerted on certain plant species determined the spatial arrangement of these plants in the gradient. On mapping the dynamics of the microclimatic variables and their relationship to the distance in the gradient, a depth of edge influence was identified of 10 m for the fragment with less intervention (Woodland 2) and 20 m for the one with most intervention (Woodland 1).

Key words: Paramo, ecotone, edge effect, gradient, microclimate.