Tipping the scales: Varying the spatial scale of the mixture to capture the biodiversity and aesthetic potential of mixed production forests

Coordinated by: Adam Felton at Department of southern Swedish Forest Resource (SLU)
Financier: Formas
Time period: 2016-2019

The ´monoculture´ approach to silviculture is increasingly challenged by growing evidence for the benefits of mixed-species stands. Relative to monocultures, mixtures often have higher aesthetic values and stand-level biodiversity, with associated benefits for other ecosystem services. However, in order to pursue the potential benefits of mixtures, decisions must be made regarding the desired spatial scale to create a mixture. Despite this need, current evidence is insufficient to inform these decisions, due to a lack of knowledge regarding key outcomes of pursuing mixtures at different scales.

There are three alternatives in this regard: intermix different tree species throughout a stand; aggregate patches of single tree species within a stand; or scale-up the mixture concept by placing monocultures of different tree species adjacent to one another. Each alternative is likely to produce different combinations of tradeoffs and synergies among the ecosystem services provided. To test respective outcomes we will use the Norway spruce and birch production forests of southern Sweden. We focus on determining how mixture scale affects forest biodiversity, due to its importance to many ecosystem services, and aesthetics, due to its importance for forest owners, recreation, and societies´ experience of forest landscapes in general. Our results will directly aid decision makers navigating the alternative pathways available for pursuing mixed-species forests.