The effect of native forest replacement by Pinus radiata plantations on riparian plant communities in Chile

Background: As riparian habitats are legally protected, they have been maintained even in areas where extensive reforestation by exotic species occurred in areas surrounding riparian environments. However, the extent to which the riparian plant communities have been affected by the replacement of native forest on slopes has rarely been investigated.Aims: In this study, we evaluated the effects of replacement of native forest by Pinus radiata plantations, on the diversity and structure of plant communities of remnant forests preserved in riparian habitats.Methods: We selected five watersheds with native forest and five watersheds where the native forest had been replaced by pine plantations preserving riparian forests and compared composition, diversity and structure of riparian vegetation.Results: In watersheds with pine plantation, riparian forests had lower adult tree density, tree cover, diversity and regeneration and higher shrub cover, diversity of herb species and diversity and richness of exotic species than riparian forests with abutting native forest.Conclusions: The results suggest that the replacement of native forest by pine plantations negatively affects the diversity and structure of riparian forest. However, in other respects (e.g. shrub and climber richness), these habitats are not affected and they contribute significantly to the biodiversity conservation.