This chapter addresses the European occupation and the consequent devastation of the Mixed Ombrophyllus Forest (MOF) and Temperate Deciduous Forest (TDF) in the states of Rio Grande do Sul and western Santa Catarina. These two forest typologies are part of the Mata Atlântica, a rich mosaic of tropical and subtropical forests whose previous area stretched from the northeast to the south of Brazil, northeast Argentina and eastern Paraguay. German physician Robert Avé-Lallemant visited the three southern Brazilian states in 1858, where he made the most extensive notes about human population, fauna, and flora. The arrival of immigrants destabilized traditional indigenous communities and caboclo inhabitants, who had lived there until then. Deforestation and the possibility of soil exhaustion linked to it were matters of concern already within a few decades after the settlement of the first immigrants. The industrial census of 1920 shows, among other data, the distribution of timber industries, such as sawmills and factories of boxes, crates, and cooperages.