PhD defence: Jonas Morsing Thomasen

Jonas Morsing Thomasen defends his thesis:

Lessons from an open-ended ecological restoration project
Short-term effects of removing commercial spruce stands along the small stream Øle Å, and reflections on evaluation

Supervisors:
Professor Karsten Raulund-Rasmusssen, IGN
Professor Kaj Sand-Jensen, Department of Biology, KU
Associate professor Lars Båstrup-Spohr, Department of Biology, KU

Assesment Committee:
Professor Nikolai Friberg, AU
Researcher Eliza Maher Hasselquist, SLU, Sweden
Professor Henrik Vejre (chair), IGN

Summary:
Effects of human land-use modification on ecosystems has gained increasing attention globally, and restorative efforts are applied widely. An open-ended approach to trajectory development is suggested in some situations, but open-endedness challenges classic approaches to evaluation, and a novel management approach may complicate stakeholder support.
This PhD thesis uses an ecological restoration case, in which spruce plantations were felled in the riparian corridor of the upper stream Øle Å, Bornholm, Denmark. The thesis investigates the structural changes caused by the intervention, the initial development throughout five subsequent years, as well as values and concerns of stakeholders during the process. Finally, the thesis elaborates on evaluation of cases with an open-ended approach.
Before the intervention, baseline monitoring settled how spruce stands formed monocultures that limited the light availability and had little ground cover of only a few plant species. In the stream, the oxygen level was coupled to the discharge rate, with values close to 0 % during summer and close to 100 % during winter. Stakeholders were engaged in a partnership. They provided local knowledge during meetings and expressed concerns about the suddenness of the planned intervention.
In 2014, approximately 6.5 ha of Norway spruce (Picea abies) stands along the stream was felled, and the area was left for spontaneous development. The intervention caused an immediate increase in light influx and increased the diversity of land-use types locally. Impacted areas had a negative effect on forest bird abundance, but attracted certain open-land species for a few years. Terrestrial plants increased in cover and species richness, in a successive patterns where initial colonists were replaced by more competitive species and an initial establishment of young trees. The cover and richness of aquatic plants increased moderately. The spruce litter layer that remained on the ground filtered for species with different traits as opposed to where the mineral soil was exposed, and it hampered vegetation establishment under the present level of wildlife grazing. N-cycling was disrupted by the felling, and elevated concentrations of nitrate was found in the seepage water during the three subsequent winters, but not in the stream water. Concentrations decreased to preintervention levels, and this decline was linked to the establishment of ground vegetation.
During the involvement process, stakeholders gained a more positive view on ecological restoration, in general. Also, a majority agreed to the specific approach of avoiding future management of the development along Øle Å, even though some expressed certain conditions. Value adjustments were identified both among stakeholders and project managers.
The situation within five years after the intervention was characterized by dynamics and an initiated development. In such situations, an evaluation within few years of the intervention is suggested to focus on the planning and implementation phases, i.e. if the intervention was successfully targeted at the degrading constituent, whether it was sufficient, whether it caused unnecessary harm to the system, and if stakeholders’ potential concerns were investigated and incorporated. In the case of the Øle Å restoration, the dominance of commercial spruce stands was successfully reduced in the riparian corridor, and the intervention appears to have been sufficient to initiate a natural 4 development. Despite prior concerns, the intervention was not found to cause elevated temperature or nitrate concentrations in the stream.

A digital version of the PhD thesis can be obtained from the PhD secretary at phd@ign.ku.dk before the defence. After the defence the thesis will become available from the Royal Danish Libary at kb@kb.dk.