Diversification of coniferous monocultures in the last 30 years and implications for forest restoration: a case study from temperate lower montane forests in Central Europe

Abstract Planted monocultures of even-aged coniferous tree species are abundant worldwide but increasingly damaged by biotic and abiotic stressors disturbances. In Central Europe, a fundamental goal ecologically oriented forest management is thus the conversion pure often stands into structurally more diverse mixed broad-leaved forests. This achieved single-tree selection resulting in small canopy openings that promote artificial or natural regeneration. Consequently, aims at altering stand structure communities. order to describe status quo derive implications for management, we investigated changes composition Bavarian Spessart mountains southwest Germany. We conducted resurvey 108 semi-permanent plots four different types Norway spruce, Scots pine, Douglas fir, European larch about 30 years after initial survey. found significant differences stratification cover respective layers between two sampling periods indicated an increase structural heterogeneity. While richness overstorey remained constant, diversity shrub lower layer increased significantly. Regenerating “winner” included late-successional (e.g., beech, sessile oak), pioneer silver birch, rowan) shade-tolerant fir) species. Although spruce was significantly reduced overstorey, it regenerated parts extensively understorey. conclude overall successful terms diversifying Its effects are, though, still emerging transitional phase. Besides preferred regeneration target species, may consider active measures guide facilitated community previously towards maturity.