Effect of native forest replacement by pine plantations on plant communities of riverine habitats in the south of Chile
Native forest replacement by forestry plantations of exotic species may produce not only loss of biodiversity in replaced areas, but also collateral effects on biodiversity of remnant fragments. In many countries, replacement of native forest by forestry plantations is restricted to the slopes of basins, and riverine habitats remain without replacement in order to preserve their biodiversity and water flows. However, these remnant riverine fragments may be affected by factors related to the management of the plantations that surround them. Although many works have evaluated the effects of forest replacement and fragmentation, few studies have examined the effects of replacement of native forests by plantations in slopes, on biodiversity of remnant fragments of riverine habitats. In this study we evaluated the collateral effects of the replacement of native forest by plantations of the exotic species Pinus radiata on plant communities of riverine habitats in basins of south-central Chile. We compared vegetation structure and composition of riverine forests between basins with and without replacement within the region of Deciduous Temperate Forests. In each basin we sampled different vegetation variables in ten 40 m2 plots located along riverine forests in five replaced and six unreplaced basins distributed between 35° and 39° S.
We found that density of trees with higher stem diameter, canopy cover > 5m height, and density (but not richness) of woody regeneration were greater in riverine forests of basins without replacement. Furthermore, riverine forests of replaced basins presented higher richness and abundance of exotic species, and richness of liana species was higher in unreplaced basins. However, species richness of other life forms did not vary between basins with and without replacement of native forest. Our results suggest that the management of Pine plantations indirectly affect plant communities of remnant riverine fragments. Therefore, restricting replacement of native forest on slopes do not necessarily guarantee perfect conservation of remnant riverine forests. Nevertheless, these remnant fragments effectively allow to preserve an important proportion of plant biodiversity in basins replaced by forestry plantations. Hence, these fragments should receive more attention to include them in conservation programmes.
Conicyt project USA 2012-011.