Mapping and assessing the knowledge base of ecological restoration

Peatland restoration pathways to mitigate greenhouse gas emissions and retain peat carbon

Peatlands play a crucial role in the global carbon (C) cycle, making their restoration a key strategy for mitigating greenhouse gas (GHG) emissions and retaining C. This study analyses the most common restoration pathways employed in boreal and temperate peatlands, potentially applicable in tropical peat swamp forests. Our analysis focuses on the GHG emissions and C retention potential of the restoration measures. To assess the C stock change in restored (rewetted) peatlands and afforested peatlands with continuous drainage, we adopt a conceptual approach that considers short-term C capture (GHG exchange between the atmosphere and the peatland ecosystem) and long-term C sequestration in peat. The primary criterion of our conceptual model is the capacity of restoration measures to capture C and reduce GHG emissions. Our findings indicate that carbon dioxide (CO2) is the most influential part of long-term climate impact of restored peatlands, whereas moderate methane (CH4) emissions and low N2O fluxes are relatively unimportant. However, lateral losses of dissolved and particulate C in water can account up to a half of the total C stock change. Among the restored peatland types, Sphagnum paludiculture showed the highest CO2 capture, followed by shallow lakes and reed/grass paludiculture. Shallow lakeshore vegetation in restored peatlands can reduce CO2 emissions and sequester C but still emit CH4, particularly during the first 20 years after restoration. Our conceptual modelling approach reveals that over a 300-year period, under stable climate conditions, drained bog forests can lose up to 50% of initial C content. In managed (regularly harvested) and continuously drained peatland forests, C accumulation in biomass and litter input does not compensate C losses from peat. In contrast, rewetted unmanaged peatland forests are turning into a persistent C sink. The modelling results emphasized the importance of long-term C balance analysis which considers soil C accumulation, moving beyond the short-term C cycling between vegetation and the atmosphere.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10533-023-01103-1.

Hypotheses in urban ecology: building a common knowledge base

Urban ecology is a rapidly growing research field that has to keep pace with the pressing need to tackle the sustainability crisis. As an inherently multi-disciplinary field with close ties to practitioners and administrators, research synthesis and knowledge transfer between those different stakeholders is crucial. Knowledge maps can enhance knowledge transfer and provide orientation to researchers as well as practitioners. A promising option for developing such knowledge maps is to create hypothesis networks, which structure existing hypotheses and aggregate them according to topics and research aims. Combining expert knowledge with information from the literature, we here identify 62 research hypotheses used in urban ecology and link them in such a network. Our network clusters hypotheses into four distinct themes: (i) Urban species traits & evolution, (ii) Urban biotic communities, (iii) Urban habitats and (iv) Urban ecosystems. We discuss the potentials and limitations of this approach. All information is openly provided as part of an extendable Wikidata project, and we invite researchers, practitioners and others interested in urban ecology to contribute additional hypotheses, as well as comment and add to the existing ones. The hypothesis network and Wikidata project form a first step towards a knowledge base for urban ecology, which can be expanded and curated to benefit both practitioners and researchers.

Offsetting environmental impacts beyond climate change: the Circular Ecosystem Compensation approach

Since the Paris Agreement entered into force, climate neutrality and associated compensation schemes are even more on the agenda of politics and companies. Challenges of existing offsetting schemes include the rather theoretical saving scenario and the limited scope of considered impacts. To address some of these limitations, this paper proposes the Circular Ecosystem Compensation (CEC) approach based on monetization of LCA results and Ecosystem Valuation. CEC consists of six steps: i) carrying out a life cycle assessment, ii) reducing the environmental impacts, iii) determining environmental costs applying monetization methods, iv) deriving the environmental value based on restoration costs methods, v) implementing the ecological restoration of ecosystems and vi) monitoring of the renaturation measures. Thus, CEC allows to offset a broad set of environmental impacts beyond climate change (e.g., acidification, eutrophication, land use, water use) in a real ecosystem by renaturation of degraded ecosystems. Environmental burdens and environmental benefits are balanced on a monetary basis, as the renaturation measures are monetized and used to compensate the monetized LCA results, e.g., of a product, organization or individual. In a case study, the implementation of the approach is presented to show the practical implementation of the CEC. The challenges of CEC include the integration of further impact categories, the availability of up-to-date and reliable monetization methods, the asynchrony and time-lag of the compensation from an ecosystem and biodiversity perspective and the proof of cost-efficiency of the renaturation measures. It is further discussed, if CEC can be a step beyond "climate neutrality" towards "environmental neutrality". The proposed approach should be further tested and is intended to foster progress in more comprehensive and robust offsetting of environmental impacts beyond climate change.