Tree Monoculture Plantations Decrease Plant Diversity in the Italian Prealps

Vanessa Manuzi ¹, Simone Balestra ¹, Pietro Gatti ¹, Gianalberto Losapio ²

Department of Biosciences, University of Milan ¹, Department of Biosciences, University of Milan and Institute of Earth Surface Dynamics, Faculty of Geoscience and Environment, University of Lausanne. ²

On one hand, afforestation and reforestation can contribute to mitigate climate change impacts via carbon sequestration. On the other hand, these actions can also have counteractive effects on ecological systems by negatively affecting biodiversity. However, the long term consequences of afforestation and reforestation for biodiversity are poorly understood. We address the long-term, centennial impact of afforestation and reforestation policies dated 1920s in Italian Prealps. Afforestation and reforestation actions were implemented with tree monoculture of spruce (Picea abies). We conducted a comparative study examining plant community composition and functional diversity along with environmental factors (i.e., luminosity and ground surface temperature) among spruce monoculture plantations, native deciduous mixed forests, and pastures. Our results reveal the long-lasting impact of afforestation and reforestation on biodiversity. Spruce monoculture plantation decreases plant species richness by 39 % and 56 % as compared to native mixed forest and pasture, respectively. Likewise, the diversity of plant functional forms decreases in spruce plantation as compared to mixed forests and pastures. Although luminosity and ground surface temperature do not vary from mixed forests to spruce plantations while they substantially change in pastures, we found a positive relationship between plant diversity and these two environmental factors. Our research provides novel evidence that tree monoculture plantations negatively impact biodiversity still one hundred years after reforestation. As biodiversity loss and climate change are two interwoven processes, they must not be treated separately. Solution: For what concerns future afforestation and reforestation programs, we recommend that they include biodiversity-driven actions and address win--win solutions, for their effectiveness in climate change mitigation would otherwise be compromised.

Main author career stage: Master student

Contribution type: Poster

First choice session: 3. Biodiversity and global change

Second choice session: 2. Ecology