How can we manage uncertainties in habitat greenhouse gas emissions?

Estimating emissions and developing mitigation pathways for environmental greenhouse gases presents additional challenges beyond those associated with tracking fossil carbon dioxide (CO2). Firstly, environmental emissions are uncertain and variable in time and space, reflecting the complicated interactions between ecological communities and their physical environment that give rise to emissions. Secondly, environmental greenhouse gas emissions are often dominated by non-CO2 gases, chiefly methane and nitrous oxide, which show in different warming dynamics over time that need to be taken into consideration to determine whether actions achieve a genuine climate across all time-scales.

This project, through The Agile Initiative at the Oxford Martin School, explores these concerns with a focus around biogenic methane emissions. Working with The Wildlife Trusts, we are investigating how recent updates to peatland emission factors would change their estimated greenhouse gas emissions emissions, and attempting to confirm that restoration could help contribute to their ‘net-zero’ ambition, and provide a long-term climate benefit. With the Department of Agriculture, Environment and Rural Affairs (Northern Ireland) we are exploring how projected methane emissions vary with different evaluation methods, to explore some of the policy implications for prioritising different emission reductions.

Linking climate warming and land conversion to species’ range changes across Great Britain

Although increased temperatures are known to reinforce the effects of habitat destruction at local to landscape scales, evidence of their additive or interactive effects is limited, particularly over larger spatial extents and longer timescales. To address these deficiencies, we created a dataset of land-use changes over 75 years, documenting the loss of over half (>3000 km2) the semi-natural grassland of Great Britain. Pairing this dataset with climate change data, we tested for relationships to distribution changes in birds, butterflies, macromoths, and plants (n = 1192 species total). We show that individual or additive effects of climate warming and land conversion unambiguously increased persistence probability for 40% of species, and decreased it for 12%, and these effects were reflected in both range contractions and expansions. Interactive effects were relatively rare, being detected in less than 1 in 5 species, and their overall effect on extinction risk was often weak. Such individualistic responses emphasise the importance of including species-level information in policies targeting biodiversity and climate adaptation.

Spatially targeted nature-based solutions can mitigate climate change and nature loss but require a systems approach

Finite land is under pressure to provide food, timber, human infrastructure, climate change mitigation, and wildlife habitat. Given the inherent trade-offs associated with land-use choices, there is a need to assess how alternative land-use trajectories will impact the delivery of these benefits. Here, we develop nine exploratory, climate change mitigation-driven land-use scenarios for the UK. The scenario that maximized deployment of nature-based solutions reduced greenhouse gas (CO2e) emissions from the land sector by >100% by 2050 but resulted in a 21% decline in food production.

All mitigation scenarios delivered aggregate increases in habitat availability for 109 bird species (including 61 species of conservation concern), although farmland-associated species lost habitat. Our study reiterates the potential of nature-based solutions to address global climate and biodiversity challenges but also highlights risks to farmland wildlife and the importance of food system reform to mitigate potential reductions in primary food production.

Woodland expansion in the presence of deer: 30 years of evidence from the Cairngorms Connect landscape restoration partnership

Restoring native woodlands to areas where they have been lost is a key element for tackling the nature and climate crises. Natural regeneration offers the potential to achieve this cheaply and at scale, but browsing ungulates like deer can inhibit this or alter the pattern of regeneration. This issue is particularly pronounced in the Scottish Highlands, a heavily deforested region with high deer numbers.

We describe the work of the 60,000 ha landscape restoration partnership, Cairngorms Connect, in speeding up natural woodland expansion. We use 30 years of regeneration monitoring to show a consistent, large-scale expansion of native woodland, largely through natural regeneration alongside deer culling, without the use of fences. This was achieved across the partnership, despite differing management histories and land-managing organisations (comprising two statutory agencies, one private landowner and one non-governmental organisation).

During peak periods of woodland expansion, the area of new woodland (i.e. exceeding 100 trees per hectare) increased by 1.2%, 1.7%, 2.7% and 6.0% annually in the four landholdings’ regeneration zones, equating to a total of approximately 164 ha annually of new woodland.
Natural regeneration is however patchy and hard to predict. Higher levels of management intervention may be needed to increase species that are rarer, more palatable or further from seed sources; we recommend long-term field trials to inform this, such as those underway in Cairngorms Connect. Further research should develop techniques for remote sensing of woodland expansion, verified against field data and combined with the development of process-based models to enable us to predict the outcomes of different management scenarios.

Synthesis and applications. We show that collaborative deer management across multiple adjoining landholdings can achieve rapid landscape-scale native woodland expansion with minimal need for planting or fencing. Our results show the power of monitoring regeneration directly, to inform deer management for an area. We demonstrate that by uniting over a shared vision, organisations with differing management approaches and histories can build understanding alongside landscape-scale ecological restoration.

Field-Scale Floating Treatment Wetlands: Quantifying Ecosystem Service Provision from Monoculture vs. Polyculture Macrophyte Communities

Global water security is critical for human health, well-being, and economic stability. However, freshwater environments are under increasing anthropogenic pressure and now, more than ever, there is an urgent need for integrated approaches that couple issues of water security and the remediation of degraded aquatic environments. One such strategy is the use of floating treatment wetlands (FTW), which are artificial floating mats that sustain and support the growth of macrophytes capable of removing nutrients from over-enriched waterbodies. In this study, we quantify a range of indicators associated with FTWs, planted with different vegetation community types (i.e., monocultures and polycultures) over the course of a three-year field-scale study. The composition of the two different types of FTWs changed significantly with a convergence in diversity and community composition between the two types of FTWs. Phytoremediation potential of the two FTW communities, in terms of nutrient standing stocks, were also similar but did compare favourably to comparable wild-growing plant communities. There were few substantial differences in invertebrate habitat provision under the FTWs, although the high incidence of predators demonstrated that FTWs can support diverse macroinvertebrate communities. This field-scale study provides important practical insights for environmental managers and demonstrates the potential for enhanced ecosystem service provision from employing nature-based solutions, such as FTWs, in freshwater restoration projects.

Saving Scotland’s Rainforest: managing the impact of deer

This report to Scottish Environment LINK Deer Group was commissioned by Woodland Trust Scotland.

The report lays out the challenge at hand: to reduce deer’s negative impact on the rainforest while also retaining their key role as a natural part of its ecosystem.

Regional scale integrated land use planning to meet multiple objectives: Good in theory but challenging in practice

Pressure is increasing globally to deliver integrated land use at large spatial scales (10–100 s km2) to address the climate and biodiversity emergencies through delivery of nature-based solutions. There is also pressure to decentralise land use decision-making to sub-national levels of government and multi-stakeholder partnerships, with the aim of improving policy targeting, coordination and participation. Whilst there has been significant research on these issues at smaller spatial and administrative scales, it is limited at larger scales. This paper addresses this gap, investigating whether the introduction of additional regional institutions can help address these challenges. It draws insights from Scotland’s decade old Land Use Strategy (LUS) and evolving Regional Land Use Partnerships (RLUPs) that aim to mitigate climate change through encouraging improved and integrated land use and land management. We find that despite considerable stakeholder support, such approaches may not deliver on their ambitions. An overarching finding relates to the importance of political commitment to implementation at these larger scales, which is crucial for establishing clear objectives, giving regions authority to respond to regional priorities, and ensuring adequate resourcing. This affects buy-in from stakeholders and the resolution of policy coordination challenges that the partnerships are meant to address. It has wider implications for the delivery of national climate policies, given the importance of land management in most climate change strategies. The insights, and the analytical framework used, are relevant for any country grappling with the challenge of implementing nature-based solutions at ever larger scales whilst bridging local and national land use priorities.

Mainstreaming Nature-Based Solutions in City Planning: Examining Scale, Focus, and Visibility as Drivers of Intervention Success in Liverpool, UK

Nature-based solutions (NBS) have been central to the European Union’s drive to address climate change, ecological degradation, and promote urban prosperity. Via an examination of the Horizon 2020-funded URBAN GreenUP project in Liverpool, this paper explores mainstreaming NBS in city planning. It uses evidence from pre- and post-intervention surveys with Liverpool residents and interviews with local business, environmental, government, and community sector experts to illustrate how a complex interplay of scale, location, focus, and visibility of NBS influences perceptions of the added value of NBS. This paper highlights the requirement that NBS interventions be bespoke and responsive to the overarching needs of residents and other stakeholders. Moreover, we underscore the importance of expert input into the design, location, and maintenance of NBS and call for these key drivers of successful delivery to be better integrated into work programs. This paper also notes that the type and size of NBS interventions impact perceptions of their value, with smaller projects being viewed as less socially and ecologically valuable compared to larger investments. We conclude that while small-scale NBS can support climatic, health, or ecological improvements in specific instances, strategic, larger-scale, and more visible investments are required to accrue substantive benefits and gain acceptance of NBS as a legitimate and effective planning tool.

Invertebrate biodiversity continues to decline in cropland

Modern agriculture has drastically changed global landscapes and introduced pressures on wildlife populations. Policy and management of agricultural systems has changed over the last 30 years, a period characterized not only by intensive agricultural practices but also by an increasing push towards sustainability. It is crucial that we understand the long-term consequences of agriculture on beneficial invertebrates and assess if policy and management approaches recently introduced are supporting their recovery. In this study, we use large citizen science datasets to derive trends in invertebrate occupancy in Great Britain between 1990 and 2019. We compare these trends between regions of no- (0%), low- (greater than 0–50%) and high-cropland (greater than 50%) cover, which includes arable and horticultural crops. Although we detect general declines, invertebrate groups are declining most strongly in high-cropland cover regions. This suggests that even in the light of improved policy and management over the last 30 years, the way we are managing cropland is failing to conserve and restore invertebrate communities. New policy-based drivers and incentives are required to support the resilience and sustainability of agricultural ecosystems. Post-Brexit changes in UK agricultural policy and reforms under the Environment Act offer opportunities to improve agricultural landscapes for the benefit of biodiversity and society.

The sound of restored soil: using ecoacoustics to measure soil biodiversity in a temperate forest restoration context

Forest restoration requires monitoring to assess above- and belowground communities, which is challenging due to practical and resource limitations. Ecological acoustic survey methods––also known as “ecoacoustics”––are increasingly available and provide a rapid, effective, and non-intrusive means of monitoring biodiversity. Aboveground ecoacoustics is widespread, but soil ecoacoustics has yet to be utilized in restoration despite its demonstrable effectiveness at detecting soniferous soil meso- and macrofauna. This study applied ecoacoustic tools and indices (Acoustic Complexity Index, Normalized Difference Soundscape Index, and Bioacoustic Index) to measure belowground (and aboveground as secondary) biodiversity in a forest restoration site spanning two age classes. We collected n = 198 belowground acoustic samples and n = 180 aboveground samples from three recently deforested (felled <3 years ago) and three deciduous forest plots undergoing restoration (for the last 30–51 years) across three monthly visits in South Yorkshire, U.K. We used a belowground sampling device and sound-attenuation chamber to record soil communities and passive acoustic monitoring to record aboveground sounds. We found that restored plot acoustic complexity and diversity were significantly higher than deforested plots in the sound-attenuation chamber, but there were no inter-plot differences in in-situ soil or aboveground samples. We also found that restored plots had a significantly greater high-frequency to low-frequency ratio (suggesting higher biophony to anthrophony ratios) for in-situ and sound chamber soil but no association for aboveground samples. Our results suggest that ecoacoustics has immense potential to monitor belowground biodiversity, adding to the restoration ecologist’s toolkit and supporting global ecosystem recovery.

Natural Capital Markets: What farmers and policymakers need to know

Farmers are facing a volatile and uncertain future. From changes to the Common
Agriculture Policy, post Brexit, to the impacts of climate change and a nature crisis,
let alone the turbulent geopolitics affecting global food markets – all of these are
having a substantial impact on the farming operating context.

The introduction of ELMs in England and [their own sustainable land management
schemes] in Wales and Scotland and Northern Ireland is having far reaching
effects on many farmers’ balance sheets. The shift towards payments for
the provision and management of ‘public goods’ – those ecosystem services
that are not normally paid for in the marketplace – have the potential to make
a positive impact on the climate and nature crisis. But these environmental
land management schemes do not fill the gap left by CAP; and it is no surprise
therefore that farmers are now starting to look closely at the emerging
‘natural capital’ markets.

Biodiversity and ecosystem function responses to woodland creation

Using data collection across natural gradients and designed experiments, this project explores aboveground processes of forest establishment and interactions with belowground communities and soil properties, providing evidence on outcomes of forest expansion by natural regeneration vs planting.

Working within Trees for Life’s Wild Trees Survey in the Scottish Highlands, we are exploring the dynamics of tree regeneration in remnant native woodland and links to soil communities, soil physical properties and soil chemical properties. This is complemented by forest experiments comparing natural regeneration to tree planting and consequences for carbon sequestration and biodiversity colonisation, co-designed with Highlands Rewilding in Scotland.

Working with The Carbon Community experiment in Wales, we are assessing biodiversity responses to treatments designed to optimise woodland carbon sequestration: forest type (Sitka spruce monoculture vs mixed native broadleaf), soil microbiome inoculation and enhanced weathering.

Short-range multispectral imaging is an inexpensive, fast, and accurate approach to estimate biodiversity in a temperate calcareous grassland

Image sensing technologies are rapidly increasing the cost-effectiveness of biodiversity monitoring efforts. Species differences in the reflectance of electromagnetic radiation can be used as a surrogate estimate plant biodiversity using multispectral image data. However, these efforts are often hampered by logistical difficulties in broad-scale implementation. Here, we investigate the utility of multispectral imaging technology from commercially available unmanned aerial vehicles (UAVs, or drones) in estimating biodiversity metrics at a fine spatial resolution (0.1–0.5 cm pixel resolution) in a temperate calcareous grassland in Oxfordshire, UK. We calculate a suite of moments (coefficient of variation, standard deviation, skewness, and kurtosis) for the distribution of radiance from multispectral images at five wavelength bands (Blue 450 ± 16 nm; Green 560 ± 16 nm; Red 650 ± 16 nm; Red Edge 730 ± 16 nm; Near Infrared 840 ± 16 nm) and test their effectiveness at estimating ground-truthed biodiversity metrics from in situ botanical surveys for 37–1 × 1 m quadrats. We find positive associations between the average coefficient of variation in spectral radiance and both the Shannon–Weiner and Simpson’s biodiversity indices. Furthermore, the average coefficient of variation in spectral radiance is consistent and highly repeatable across sampling days and recording heights. Positive associations with biodiversity indices hold irrespective of the image recording height (2–8 m), but we report reductions in estimates of spectral diversity with increases to UAV recording height. UAV imaging reduced sampling time by a factor of 16 relative to in situ botanical surveys. We demonstrate the utility of multispectral radiance moments as an indicator of biodiversity in this temperate calcareous grassland at a fine spatial resolution using a widely available UAV monitoring system with a coarse spectral resolution. The use of UAV technology with multispectral sensors has far-reaching potential to provide cost-effective and high-resolution monitoring of biodiversity.

Barriers and tools for implementing Nature-based solutions for rail climate change adaptation

Globally, the need for railways to adapt to the impacts of climate change is increasing rapidly. Nature-based Solutions (NbS) have been identified as potential climate change adaptation (CCA) options for rail infrastructure; however, the limited number of examples of their application on railways highlights that many factors still need to be considered to enable their wider implementation. This study identifies barriers to NbS uptake by the rail industry through a systematic literature review, categorising them into seven key themes, whilst also considering potential tools to facilitate their uptake. The ongoing development of NbS standards and guidance is confirmed as a means to resolve the barriers likely to be faced. A framework to support the uptake of NbS in the rail industry is presented and discussed in the context of the existing literature, with climate change risk assessments being recognised as the entry point for CCA in rail infrastructure management.

Slow development of woodland vegetation and bird communities during 33 years of passive rewilding in open farmland

Passive rewilding is a potential tool for expanding woodland cover and restoring biodiversity by abandoning land management and allowing natural vegetation succession to occur. Land can be abandoned to passive rewilding deliberately or due to socio-economic change. Despite abandonment being a major driver of land use change, few have studied the long-term outcomes for vegetation and biodiversity in Western Europe. Studies are also biased towards sites that are close to seed sources and favourable to woodland colonisation. In this case-study, we reconstruct a time series of passive rewilding over 33 years on 25 ha of former farmland that had been subject to soil tipping, far from woodland seed sources. Natural colonisation by shrubs and trees was surveyed at three points during the time series, using field mapping and lidar. Breeding birds were surveyed at three time points, and compared with surveys from nearby farmland. Results showed that natural colonisation of woody vegetation was slow, with open grassland dominating the old fields for two decades, and small wetlands developing spontaneously. After 33 years, thorny shrub thickets covered 53% of the site and former hedgerows became subsumed or degraded, but trees remained scarce. However, the resulting habitat mosaic of shrubland, grassland and wetland supported a locally distinctive bird community. Farmland bird species declined as passive rewilding progressed, but this was countered by relatively more wetland birds and an increase in woodland birds, particularly songbirds, compared to nearby farmland. Alongside biodiversity benefits, shrubland establishment by passive rewilding could potentially provide ecosystem services via abundant blossom resources for pollinators, and recreation and berry-gathering opportunities for people. Although closed-canopy woodland remained a distant prospect even after 33 years, the habitat mosaic arising from passive rewilding could be considered a valuable outcome, which could contribute to nature recovery and provision of ecosystem services.

The effects of a decade of agri-environment intervention in a lowland farm landscape on population trends of birds and butterflies
  1. Declines in farmland biodiversity remain evident despite over three decades of research and implementation of agri-environment schemes (AES). Although positive effects of AES are often demonstrated locally or in the short term, studies exploring longer term trends in biodiversity often show contradictory results. Evidence for the potential of AES to drive beneficial changes in populations remains sparse, especially for mobile taxa such as birds and butterflies.
  2. We analysed the abundance of 12 widespread bird and 9 butterfly species from a 10-year study of AES intervention in a farmland landscape in southern England. We compared estimates of annual population growth rates from our study landscape with rates derived from large-scale national monitoring schemes in equivalent landscapes without substantial AES.
  3. Species trends in our study landscape were frequently stable or increasing, in contrast to concurrent declining trends in equivalent landscapes without AES. These differences were significant for total abundance of granivorous species and for chaffinch Fringilla coelebs, blue tit Cyanistes caeruleus and great tit Parus major individually. For butterflies, differences in trends were significantly more positive for gatekeeper Pyronia tithonus and green-veined white Pieris napi, while small white P. rapae showed a trend that was significantly more negative in our study landscape.
  4. Synthesis and applications. Our results demonstrate that, for some bird and butterfly species, the higher abundances associated with areas of AES uptake within a typical commercial farmland landscape can co-occur with positive or stable population trends over long time scales and that these trends can show significant differences from those in equivalent landscapes without substantial AES interventions. Our results suggest that previously observed inconsistencies in AES benefits may in part reflect a lack of long-term studies with accurate data on AES uptake and quality (i.e. successful implementation and management). Our results, thus, affirm the importance of delivering and monitoring high-quality AES options if the design and implementation of the next generation of AES is to achieve significant benefits for biodiversity.
Making green pledges support biodiversity: Nature-based solution design can be informed by landscape ecology principles

To address climate change and meet global commitments, nature-based climate (NbCS) solutions i.e. actions that aim to address climate change in sustainable way, are becoming increasingly popular. This is often expressed in so called “green pledges” that promote large scale programs of tree planting, often in plantations. Establishment of such plantations could deliver benefits to biodiversity, but this is not guaranteed, and recommendations on how to manage nature-based solutions (NbS) for biodiversity are limited and not embedded in scientific knowledge. Evidence from landscape ecology can inform general principles of NbCS design. Here, we synthesise evidence and make recommendations that can help “green pledges” to benefit biodiversity conservation. We call for an integrated approach, where NbCS tree planting projects move beyond carbon storage to create functional and diverse habitats providing multiple long-term services while safeguarding biodiversity.

The potential contribution of terrestrial nature-based solutions to a national ‘net zero’ climate target
  1. Many national governments have incorporated nature-based solutions (NbS) in their plans to reduce net greenhouse gas emissions. However, uncertainties persist regarding both feasibility and consequences of major NbS deployment. Using the United Kingdom as a national-level case study, we examined the potential contribution of three terrestrial NbS: peatland restoration, saltmarsh creation and woodland creation.
  2. While there is substantial political and societal interest in these three NbS, they also have strong potential for competition with other land uses, which will be a critical barrier to substantial deployment. We conducted a national mapping exercise to assess the potential area available for woodland creation. We then assessed the combined climate change mitigation potential to 2100 for the three NbS options under a range of ambition levels.
  3. In line with the most ambitious targets examined, 2 Mha of land is potentially available for new woodland. However, climate change mitigation benefits of woodland are strongly dependent on management choices. By 2100, scenarios with a greater proportion of broadleaved woodlands outsequester non-native conifer plantations, which are limited by regular timber harvesting.
  4. Peatland restoration offers the greatest mitigation per unit area, whilst the contribution from saltmarsh creation is limited by the small areas involved. Overall, the contribution of these NbS to the United Kingdom’s net zero emissions target is relatively modest. Even with the most ambitious targets considered here, by 2100, the total cumulative mitigation from the three NbS is equivalent to only 3 years’ worth of UK emissions at current levels.
  5. Policy implications. Major deployment of nature-based solutions (NbS) is possible in the United Kingdom but reaching ‘net zero’ primarily requires substantial and sustained reductions in fossil fuel use. However, facilitating these NbS at the national scale could offer many additional benefits for people and biodiversity. This demands that policy-makers commit to a UK-wide strategic approach that prioritises the ‘nature’ aspect of NbS. In the push to reach ‘net zero’, climate change mitigation should not be used to justify land management practices that threaten biodiversity ambitions.
Stewardship Innovation: The Forgotten Component in Maximising the Value of Urban Nature-Based Solutions

Nature-based solutions (NBS) enable the ecosystem service benefits associated with natural landscapes to be embedded into the built environment, simultaneously providing environmental, social, and economic benefits. This represents a mechanism for renaturing cities that can address many of the interrelated challenges associated with urbanisation and climate change. If NBS can be delivered effectively on citywide scales, it presents an opportunity for the development of sustainable, resilient, and liveable cities. Examples of innovation in relation to planning and delivering NBS are emerging globally. However, the stewardship plan, an essential element of NBS that typically underpins the long-term success of these high-profile initiatives, is often overlooked or under-planned. Careful consideration of the technical, financing, and governance aspects of NBS stewardship can be critical to determining whether an NBS is able to deliver the multifunctional benefits for which it was designed, adapt to changing needs and environmental conditions, and avoid becoming a liability to those communities it was designed to benefit. Here we present a series of case studies demonstrating how innovation in NBS stewardship can secure and maximise the long-term success of NBS and avoid the legacy of neglected or poorly managed green wash.

Does restoring native forest restore ecosystem functioning? Evidence from a large-scale reforestation project in the Scottish Highlands

Given the worldwide plans for extensive tree planting we urgently need to understand how and where implementation will contribute to goals such as those for carbon sequestration. We used a long-term, large-scale native reforestation project in the Scottish Highlands to assess the response of carbon storage and other ecosystem functions to reforestation and grazing exclusion. We measured above-ground carbon, topsoil carbon, topsoil nitrogen, decomposition rates, soil invertebrate feeding activity, tree regeneration, and ground-layer and moss height at 14 sites that are in the early stages of reforestation and fenced to exclude grazing. Reforestation areas were compared to unforested and mature forest areas that are both grazed and ungrazed, using 10 × 10 m plots. Above-ground carbon in the reforestation plots (1.4 kg/m² [95% CI: 0.6, 2.6], average age 20 years since reforestation) was c. 8% of the mature forest plots (17.1 kg/m² [13.1, 21.8]). Topsoil carbon was lower in the reforestation plots (18.78 kg/m² [11.79, 25.78]) than in the unforested (29.82 kg/m² [24.34, 35.29]) or mature forest (31.39 kg/m² [22.91, 39.88]) plots. Responses of other functions to the reforestation and grazing interventions varied. Our results suggest that reforestation may trigger carbon loss from areas with high initial soil carbon even with low disturbance establishment, at least in the short term. Our work emphasises where we lack knowledge: on the potential for long-term re-accumulation of soil carbon under semi-natural native reforestation, soil carbon sequestration in the deeper soil layers and the response of soil carbon to natural regeneration.

Evaluating wider benefits of natural flood management strategies: An ecosystem-based adaptation perspective

Climate change is projected to alter river flows and the magnitude/frequency characteristics of floods and droughts. Ecosystem-based adaptation highlights the interdependence of human and natural systems, and the potential to buffer the impacts of climate change by maintaining functioning ecosystems that continue to provide multiple societal benefits. Natural flood management (NFM), emphasising the restoration of innate hydrological pathways, provides important regulating services in relation to both runoff rates and water quality and is heralded as a potentially important climate change adaptation strategy. This paper draws together 25 NFM schemes, providing a meta-analysis of hydrological performance along with a wider consideration of their net (dis) benefits. Increasing woodland coverage, whilst positively linked to peak flow reduction (more pronounced for low magnitude events), biodiversity and carbon storage, can adversely impact other provisioning service-especially food production. Similarly, reversing historical land drainage operations appears to have mixed impacts on flood alleviation, carbon sequestration and water quality depending on landscape setting and local catchment characteristics. Wetlands and floodplain restoration strategies typically have fewer disbenefits and provide improvements for regulating and supporting services. It is concluded that future NFM proposals should be framed as ecosystem-based assessments, with trade-offs considered on a case-by-case basis.

Sowing the Seeds of Seagrass Recovery Using Hessian Bags

Seagrass meadows are an important wetland habitat that have been degraded globally but have an important carbon storage role. In order to expand the restoration of these productive and biodiverse habitats methods are required that can be used for large scale habitat creation across a range of environmental conditions. The spreading of seagrass seeds has been proven to be a successful method for restoring seagrass around the world, however in places where tidal range is large such methods become limited by resultant water movements. Here we describe and test a method for deploying seagrass seeds of the species Zostera marina over large scales using a new, simple method “Bags of Seagrass Seeds Line (BoSSLine).” This method involved planting seeds and sediment using natural fiber hessian bags deployed along strings anchored onto the seabed. When deployed in a suitable environment 94% of bags developed mature seagrass shoots, unfortunately one site subjected to a large storm event resulted in sediment burial of the bags and no seed germination. Bags were filled with 100 seeds with each leading to the development of 2.37 ± 2.41 mature shoots (206 ± 87 mm in length) 10 months after planting. The method was proven successful however the experiments illustrated the need to ensure habitat suitability prior to their use. Low seed success rate was comparable to other restoration studies, however further trials are recommended to ensure ways to improve this rate. In conclusion, this study provides evidence for an effective, simple method “Bags of Seagrass Seeds Line (BoSSLine)” for deploying seeds of the seagrass Zostera marina over large scales.

Evaluating natural infrastructure for flood management within the watersheds of selected global cities

Cities are dependent on their upstream watersheds for storage and gradual release of water into river systems. These watersheds act as important flood mitigation infrastructure, providing an essential ecosystem service. In this paper we use metrics from the WaterWorld model to examine the flood management-relevant natural infrastructure of the upstream watersheds of selected global cities. These metrics enable the characterisation of different types, magnitudes and geographical distributions of potential natural flood storage. The storages are categorised as either green (forest canopy, wetland and soil) or blue (water body and floodplain) storages and the proportion of green to blue indicates how different city upstream basin contexts provide different types and levels of storage which may buffer flood risk. We apply the WaterWorld method for examining flood risk as the ratio of accumulated modelled annual runoff volume to accumulated available green and blue water storage capacity. The aim of these metrics is to highlight areas where there is more runoff than storage capacity and thus where the maintenance or restoration of further natural infrastructure (such as canopy cover, wetlands and soil) could aid in storing more water and thus better alleviate flood risks. Such information is needed by urban planners, city authorities and governments to help prepare cities for climate change impacts.

A restatement of the natural science evidence concerning catchment-based ‘natural’ flood management in the UK

Flooding is a very costly natural hazard in the UK and is expected to increase further under future climate change scenarios. Flood defences are commonly deployed to protect communities and property from flooding, but in recent years flood management policy has looked towards solutions that seek to mitigate flood risk at flood-prone sites through targeted interventions throughout the catchment, sometimes using techniques which involve working with natural processes. This paper describes a project to provide a succinct summary of the natural science evidence base concerning the effectiveness of catchment-based ‘natural’ flood management in the UK. The evidence summary is designed to be read by an informed but not technically specialist audience. Each evidence statement is placed into one of four categories describing the nature of the underlying information. The evidence summary forms the appendix to this paper and an annotated bibliography is provided in the electronic supplementary material.

Estimating the Costs and Benefits of Adapting Agriculture to Climate Change

A changing climate will inevitably impact on the natural environment, including agriculture. Anticipatory adaptation is necessary to minimise the negative impacts of climate change, to take advantage of opportunities, and to ensure that food and fibre production is maintained. More detailed information is required as to which adaptation measures will yield relatively greater social rates of return. Such information would help define an efficient adaptation agenda in the agricultural sector. This article identifies key adaptation strategies across England’s agricultural sector, and applies cost–benefit analysis to these to determine their net present values, highlighting where the greatest returns can be made, and the role for policy. The results span a wide range, with some soil management activities indicating a negative NPV of £122 million over the course of this century, to a positive NPV of £3,279 million in the case of some livestock adaptations to heat stress. Animal disease surveillance and peatland restoration also generated high NPVs of £1,850 million and £1,840 million, respectively. Adaptations addressing crop disease, water storage measures and managed coastal realignment generated more modest values ranging from £1 million to £61 million. Direct comparison of the numbers is misleading however as some refer to the national level while others are site‐specific. The analysis provides a basis for a discussion on priorities and planning for adaptation in the agricultural sector.