Pre-Columbian Mounds Harbor Distinctive Forest Communities in the Southern Campos of American Pampas

Located in the southern Campos of the Pampa biome, Uruguay is one of the least forested countries in Latin America and the Caribbean. In the eastern lowlands, associated with wetlands environments to the Laguna Merín basin, hundreds of forest islands develop on pre-Columbian earthen mounds, locally known as cerritos de indios. Our study characterizes the composition and diversity of cerritos forests, comparing them with other native forests in the country and assessing their impact on the current landscape heterogeneity. We analyzed 25 cerritos from five mound complexes, and identified trees and shrubs, recording their DBH, height, growth pattern, and importance value index. Our results show that cerritos forests do not have direct analogs in the native forest categories of Uruguay. Their dominance pattern is singular, giving the strong co-dominance of Celtis tala and Scutia buxifolia together with species rare in other woody communities. The cerritos forests showed a coverage physiognomically equivalent, independently of the environmental unit considered, reaffirming that they are edaphic communities developed on elevated archaeological anthrosols. In the context of Uruguay and particularly of the eastern wetlands, where the forest cover is very scarce, the contribution of cerritos forests must be underlined as a legacy from the indigenous past and for their current contribution to landscape functional and structural diversity.