Forest edge development
Abstract: This thesis investigates design guidelines and management systems for the development of stationary forest edges with a graded profile in infrastructure and urban environments. The spatial restriction for the edge to move forward caused by human land use counteracts the natural dynamics and development patterns of graded forest edges. However graded forest edges with successively increasing height from the periphery to the interior of the forest edge are often seen as ideal as they supports important multiple functions while at the same time keeping hazardous trees away from tracks, roads, power lines and houses. This calls for suitable management systems and design guidelines. This thesis focuses on the woody species assemblies and vegetation structures. Two starting points of forest edge development was investigated in Southern Sweden; 1) Planted designed forest edges in the Landscape Laboratory of Alnarp, and 2) Natural regenerated forest edges, after clearing along a 610 km railway line between Malmö and Stockholm. Based on the studies it is proposed that the planning of active forest edge development should depart from basic abiotic gradients and it is important to incorporate vegetation structure at site and landscape level into the long-term planning. The management and design actions taken in relation to this should acknowledge the importance of controlling tree dominance. Traits and species strategies relating to tolerance of shade, drought, waterlogging, browsing as well as dispersal mode and growth form can be used as interpretive framework for forest edges assembly and to guide management actions. When assembling species in relation to these traits, placement along the cross section of the forest edge should be a central aspect of the planting design. Based on the findings two management systems were conceptualized; Zoned Selective Coppice that departs from threshold heights and spatial zonation, respectively Functional Species Control that focus on control of dominating tree species. Further a guideline for planting principle was conceptualized. Three long term experimental trials have been developed and established to enable controlled evaluation of these management systems and design guidelines.
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