Ravine forests of the of the Maule coast: spatial and vegetational evaluation in a context of anthropic impacts

Abstract

In the coastal mountain range of the Maule region, 23 ravine rain forests dominated by canelo (Drimys winteri) and various native myrtaceae species were described in phytosociological terms in a study published in 1988. In this study, 20 of these forests were located again thirty years later to document their current situation in a context of successive anthropogenic impacts and climate change. The objectives of this study are to characterize changes in plant composition using the modified Braun-Blanquet phytosociological method, evaluate changes in soil occupation through comparative analysis of Landsat images from 1987, 2003 and 2017, and examine the natural regeneration of woody species inside and outside ravine forests. The results showed that between 1987 and 2017, the area occupied by native forest in the study area was reduced by 72 %. The importance and presence of representative species, such as Drimys winteri and Blechnum chilense reported in the original inventories, decreased, and sclerophyllous species, like Lithrea caustica and Cryptocarya alba, entered, along with introduced species, like Pinus radiata and Teline monspessulana. The regeneration of native trees and native creeping and climbing species was higher inside the ravine forests, while the germination of native shrubs was higher at their edges. The modification of the surrounding matrix of forests due to increased anthropic pressure and an advance of stressful conditions explains the observed changes.