Conservation status of remnant caducifolius valley-forest of South-Central Chile [2010]

The Southern Deciduous Forest (SDF) is mainly located in the valley areas of the Araucanía, Los Ríos, and Los Lagos regions. It is characterized by the dominance of the tree species Nothofagus obliqua and Laurelia sempervirens. This vegetation formation, although it has experienced a high level of deforestation, has potential to be conserved and restored based on the forest fragments that still remain. The objective of this study was to evaluate the general condition of SDF patches present in the Los Ríos Region. In particular, the current extent and distribution of the remnants and their status in a spatial and regional context (conservation status at the landscape scale), and the evaluation of their conservation status at the patch scale, through field sampling of vascular vegetation in eight of the largest patches in the Los Ríos Region.Remote sensing was used to generate updated cartography for the year 2008. Subsequently, spatial structure was quantified using landscape indices, and the level of protection of the current remnants was assessed in relation to areas protected by the State and by private owners. The results show that only approximately 8.5% of this forest remains relative to its potential distribution area, embedded within a matrix where the predominant land use is represented by grasslands. This remnant is composed of 25,512 forest fragments; only 79 fragments have areas larger than 200 ha, and 22 fragments are larger than 500 ha. The total remnant of this forest association is distributed in a highly patchy and clustered manner.The municipalities of Loncoche, Fresia, Vilcún, Purranque, Los Lagos, and Lanco contain 40% of the total current SDF and 15 of the 20 largest patches, making these the areas that present the highest concentration of the current remnant. The distribution of small-sized patches is fundamental for providing structural connectivity to the remnant SDF landscape. In the absence of patches smaller than 120 ha, the level of isolation increases markedly and the distribution pattern changes from clustered to random.The eight sampled patches showed high levels of degradation due to anthropogenic disturbances. We found no differences between the number of introduced plant species in the interior and at the edge of the patches, which indicates a high penetration of species from the matrix into the interior of the remnants. A low tree density was found in some of the analyzed patches, evidencing the condition of open remnants with a strong dominance of C. quila in some of them. The absence of Nothofagus obliqua in the upper canopy of patches with a low number of trees per hectare was observed. Since open forests represent an ideal condition for the establishment of this species, its absence may be the effect of selective logging.Finally, due to the small current area of SDF and the high level of degradation of these remnants, it is essential to generate protection measures for this forest formation. These protection measures should consider the safeguarding of large patches, as these should be capable of hosting the greatest possible species richness. The protection of large patches should be complemented by the protection of small patches, which would provide a higher level of connectivity both among patches and at the scale of the remnant SDF landscape as a whole.