Herbivory, pathogens, and epiphylls in Araucaria Forest and ecologically-managed tree monocultures

Abstract

Over the last centuries, natural forests have been replaced by extensive and homogeneous tree monocultures that cause strong impacts on ecological interactions and ecosystem processes. We expect, however, that ecologically-sustainable management practices can help to mitigate these effects. This study investigates how the replacement of Araucaria Forest by ecologically-managed tree monocultures affects leaf damage patterns produced by external chewers, internal chewers, leaf miners, galling insects, and pathogens, as well as the incidence of epiphylls. The study was performed in the São Francisco de Paula National Forest (southern Brazil) on 12 1-ha plots of Araucaria Forest and ecologically managed plantations of Araucaria, Pinus and Eucalyptus. Overall, 9955 leaves of the understory community (up to 1 m tall) were sampled and analyzed. The mean and the frequency distribution pattern of leaf damage were very similar between Araucaria Forest and all three tree monocultures. Also, there was no difference between habitats in the percentage of leaves attacked by different feeding guilds of insect herbivores and by pathogens. Araucaria Forest had a higher percentage of leaves with epiphylls than Eucalyptus plantation, probably due to its shadier and moister microclimate. Ecologically managed tree monocultures sustain a wide variety of herbivorous insects, pathogens and epiphylls which helps the maintenance of key ecological interactions and the functioning of the ecosystem.