How to Bloom the Green Desert: Eucalyptus Plantations and Native Forests in Uruguay beyond Black and White Perspectives

The ongoing debate on the boon or bane of monocultural timber plantations demonstrates the need to develop alternative approaches that achieve forest productivity while conserving biodiversity. We assessed the diversity of tree species in native forests and in Eucalyptus plantations, and evaluated the potential use of native species to enhance plantation management. For this purpose, we established one-hectare permanent plots in nine native forests (riverine and park forests) and nine Eucalyptus plantations in the northwestern part of Uruguay. Forest inventories were carried out on 200 m2 plots and regeneration was assessed along transects in 9 m2 subplots. Riverine forests have the highest Shannon diversity index (2.5) followed by park forests (2.1) and Eucalyptus plantations (1.3). Tree density was high in riverine forests (1913/ha) and plantations (1315/ha), whereas park forests have lower tree density (796/ha). Regeneration density was high in riverine forests (39136/ha) and park forests (7500/ha): however, native species can regenerate in the understory of plantations (727/ha), and this underlines the possibility of developing a mixed species approach to reduce the negative impact of monocultures. Differences in the composition of plant communities were denoted between native forests and plantations, although native forests were similar in composition, even in the presence of exotic species. Native forests harbor specialist species that are absent from plantations, and therefore perform a decisive role in maintaining local biodiversity. Strategies to enhance species diversity and structural diversity within plantations or to establish mixed buffer strips containing native species at the edge of plantations are potential measures to enhance biodiversity and foster the integration of plantations into the local landscape.