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Graphical abstract Highlights • Healthy wetlands had higher C uptake, N&P uptake efficiency & flood attenuation. • Their value coupled with marginal agriculture advocates more strategic use of wetlands. • High downstream demand for ES suggests potential for payments for ES scheme. • The rapid tool didn't adequately assess degraded wetland ecosystem services (ES). • Healthy wetlands were accurately scored for ecosystem service provision by the tool. Abstract Wetlands globally are highly threatened by agriculture, and damage associated with it, such as invasion by alien species and the impacts of fertilizers and pesticides. South African palmiet wetlands make an interesting case study to investigate this, as they are valuable valley-bottom, peat-forming systems, highly threatened by agricultural development. Currently most agriculture in these palmiet wetlands is marginal (low agricultural productivity) due to the challenges of farming a system that experiences severe floods and erodes rapidly, forming gullies, when wetland vegetation is disturbed. The current situation seems to be a lose-lose situation for nature and society. We aimed to assess this conflict between water-related services and agriculture objectively by comparing provision of fifteen ecosystem services by degraded and pristine sections of three palmiet wetlands using a rapid ecosystem service assessment tool (WET-Ecoservices). To validate this technique, we compared results to those obtained from examining three key ecosystem service complexes in slightly more detail. We found that pristine palmiet wetlands provide valuable ecosystem services to society, which are currently being compromised for private, marginal agricultural gain. These pristine wetlands sequester between 21 and 41 g.m−2 of carbon per year, have nitrogen and phosphorus uptake efficiencies of 62–85% and 16–89% respectively, and provide about 16 times more flood attenuation relative to degraded ones. The full impact of degradation on wetland ecosystem services was not entirely captured by the rapid ecosystem service assessment tool: WET-Ecoservices. We suggest some adaptations to this tool for the valley-bottom wetland hydro-geomorphic unit. Overall, these wetlands have high potential for incorporation into a Payments for Ecosystem Services scheme, due to the ecosystem services provided and their position above important municipal dams. We recommend collaboration between private landowners struggling with marginal agriculture, and decision makers in cities dealing with water shortages and debt to ensure the most efficient and judicious use of these palmiet wetland ecosystem services. [ABSTRACT FROM AUTHOR]

Quantification of ecosystem services ( ES) is an important step in operationalizing the concept for management and decision-making. With the exponential increase in ES research, ES have become a 'catch-all phrase', which some suggest has led to a poorly defined, impractical and ambiguous concept. An overview of the methods used in ES quantification is needed to examine their scientific rigour and provide guidelines for selecting appropriate measures., We present a systematic review of 405 peer-reviewed ES research papers to address the question: 'Is the biophysical and socio-economic reality of ES adequately quantified? First, we considered whether ES measures are scientifically rigorous enough by considering four predefined criteria (the type of data used, quantification of uncertainty, validation done and data reported). Secondly, using a novel approach, we determined which part of the ES cascade was measured: the ecosystem property, function, service, benefit or value., Our results showed that each of the 21 ES analysed had on average 24 different measures, which may indicate the complex reality of ES and/or suggest a potential lack of consensus on what constitutes an ES. We found that uncertainty is often not included and validation mostly missing., When analysing which part(s) of the ES cascade each measure corresponded to, we found that for regulating ES, ecosystem properties and functions (ecological aspects) are more commonly quantified (67% of measures). Conversely for provisioning ES, benefits and values (socio-economic aspects) are more commonly quantified (68%). Cultural ES are predominantly quantified using scores (35%)., In conclusion, ES appear to be poorly quantified in many cases, as often only one side of the cascade is considered (either the ecological or socio-economic side) and oversimplified and variable indicators are often used., Policy implications. This review provides a detailed overview of ecosystem services ( ES) quantification (ranging from simple scores to advanced methods) with the aim to support future ES quantification and ultimately the successful application of the ES concept. [ABSTRACT FROM AUTHOR]

Valley-bottom wetlands are valuable assets as they provide many ecosystem services to mankind. Despite their value, valley-bottom wetlands are often exploited and land-use/land-cover ( LULC) change results in trade-offs in ecosystem services. We coupled physically based hydrological modeling and spatial analysis to examine the effects of LULC change on water-related ecosystem services in the Kromme catchment: an important water-providing catchment for the city of Port Elizabeth. LULC scenarios were constructed to match 5 different decades in the last 50 years to explore the potential effects of restoring the catchment to different historic benchmarks. In the Kromme catchment, valley-bottom wetlands have declined by 84%, driven by key LULC changes: an increase in irrigated land (307 ha) and invasion by alien trees (336 ha). If the wetlands were restored to the relatively pristine extent and condition of the 1950s, riverflow could increase by approximately 1.13 million m3/a, about 6% of the current supply to Port Elizabeth. Wetland restoration would also significantly improve the catchment's ability to absorb extreme rainfall events, decreasing flood damage. We conclude that in the face of the water scarcity in this region, all ecosystem services, particularly those related to water flow regulation, should be taken into account by decision makers in charge of land zonation. Zonation decisions should not continue to be made on the basis of provisioning ecosystem services alone (i.e. food provision or dam yield). We recommend prioritization of the preservation and restoration of valley-bottom wetlands providing water-related ecosystem services to settlements downstream. [ABSTRACT FROM AUTHOR]

[Display omitted] • Alien tree clearing is predicted to increase mean streamflow by 15.1–29.5%. • Clearing trees in riparian areas had a 1.7x greater impact than terrestrial areas. • Greatest impacts were in the mid to low flows, and in dry relative to wet years. • Caused by decreasing transpiration and increasing overland flow and interflow. • Clearing exotic trees from treeless ecosystems may improve water security. Ecological restoration efforts at scale have been shown to play an important role in reducing human impact on the environment, improving climate change adaptation and halting extinctions globally. Upscaling restoration efforts requires funding, and therefore evidence of the benefits of restoration is needed. This study aims to contribute towards addressing these gaps by: (1) bolstering the evidence base of the water-related impacts of investment into ecological restoration by improving the methods of predicting the streamflow impacts of alien tree clearing; and (2) exploring the potential size of the variability in catchment responses at a fine-scale (60x60 m) in one particular region by comparing four different neighbouring catchments. We model the impacts on streamflow in four strategic water providing catchments using the fully-distributed MIKE-SHE modelling tool. We find that the benefits of clearing mature infestations of alien trees, such as pines, from naturally tree-less ecosystems can increase available surface water resources by 15.1 to 29.5%. Clearing riparian invasions is predicted to have a 1.7 times greater impact compared to terrestrial (non-riparian) invasions. The largest modelled impact of restoration on streamflow is on the mid to low flows, and this impact is greater in dry years relative to wet years. The findings are novel in that they shed light on the types of spatial uncertainties that can be expected in modelled gains, with implications for generalisation. These findings are important for leveraging investment to upscale restoration efforts in water scarce regions, as they suggest improved water security during the dry season and droughts. Upscaling efforts is essential if the degradation of ecosystems globally is to be prevented, halted and reversed, as proposed by the United Nations Decade on Ecosystem Restoration. [ABSTRACT FROM AUTHOR]