Peatland Afforestation: Effects and Restoration
The Flow Country of northern Scotland represents one of the world’s most extensive and ecologically significant blanket bog systems, recently designated as a UNESCO World Heritage Site. This thesis examines the impacts of large-scale non-native conifer afforestation on the biodiversity of this globally important peatland, the ecological outcomes of restoration interventions, and the implications for conservation management and policy. Using a combination of comparative global assessments, long-term species monitoring, and large-scale experimental restoration trials, the research provides new insights into the drivers of biodiversity change and the recovery potential of degraded peatlands. A global comparison of bird assemblages across major blanket bog landscapes demonstrated the exceptional international value of the Flow Country for peatland-dependent bird species. The region supports an unparalleled assemblage, with species richness exceeding that of other high-quality peatland sites worldwide. This finding contributed to the case for its World Heritage inscription and underscored the critical importance of maintaining high-quality wetland biodiversity data for international conservation assessment. Historical afforestation, involving over 67,000 ha of non-native conifer plantations, has profoundly altered avian community composition, replacing specialist open-bog species with woodland-associated taxa generally of lower conservation priority. Synthesis of existing literature and population data showed disproportionate losses among species of high conservation concern, with long-term implications for biodiversity if naturally open habitats are not safeguarded from future afforestation. Long-term monitoring of waterfowl populations revealed divergent trends among species, in some cases contrary to national patterns, emphasising the importance of site-specific ecological processes, including habitat change, predator dynamics, and restoration. Focused study of the Common Scoter demonstrated that local breeding productivity remained stable despite substantial national population declines, suggesting that factors outside the breeding grounds are driving wider trends. Two large-scale, replicated forest-to-bog restoration experiments, implemented using a Before–After–Control–Impact design, provided rare, robust evidence on restoration efficacy. Enhanced hydrological and vegetation restoration methods accelerated the return of bog-like conditions compared to standard approaches, with clear benefits for habitat quality. Complementary surveys revealed rapid recolonisation by mobile bird species, but slower recovery of invertebrate prey communities, indicating that full ecosystem functionality may lag behind vegetation change. Analyses of recolonisation patterns by peatland specialist birds showed that hydrological ground surface reprofiling to raise the water table enabled faster colonisation of sensitive waders such as Dunlin and Golden Plover, although densities remain lower than in intact bogs. Occupancy modelling demonstrated persistent edge effects from adjacent forestry, hindering wader recovery decades after planting. Strategic removal or buffering of plantations emerged as a key management priority to mitigate these effects and support the restoration of target bird communities. Collectively, this body of work advances understanding of both the ecological impacts of historical peatland afforestation and the mechanisms underpinning effective restoration. The findings highlight the enduring influence of forestry legacies, the value of targeted hydrological interventions, and the necessity of long-term, multi-taxa monitoring to track recovery trajectories. By integrating global biodiversity assessment with local experimental and observational evidence, this thesis provides a robust scientific foundation for improving peatland management policies aimed at reversing biodiversity loss, enhancing ecosystem resilience, and securing the conservation value of the world’s most extensive blanket bog landscapes.
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