Soil microarthropod community dynamics in extensive green roofs

Green roofs are of increasing interest to ecologists, engineers and architects, as cities grow and aim to become more sustainable. They could be exploited to improve urban biodiversity and ecosystem services, yet almost nothing is known about them from a soil community ecology perspective, despite how critical soil food webs are to ecosystem functioning. This paper provides the first comprehensive study incorporating the annual cycle of green roof soil microarthropods.Microarthropod communities were monitored over 14 months on two extensive green roofs. Abiotic factors, including substrate moisture, were recorded, as were biotic factors such as plant and mycorrhizal colonisation. Microarthropod interactions with these variables were then examined.Microarthropod diversity was low overall, with a few dominant species peaking seasonally. On occasion, total abundance was comparable to other early successional soils. The majority of species present were drought tolerant collembola and xerophillic mites, suggesting that moisture levels on green roofs are a major limiting factor for soil microarthropods.Our results suggest that the microarthropod community present in extensive green roof soils is impoverished, limiting the success of above-ground flora and fauna and ultimately the success of the roof as an urban habitat. We conclude that green roof building guidelines should incorporate soil communities in their design and should aim to be heterogeneous at the roof and landscape level, for the purpose of supporting soil biodiversity and creating sustainable habitats

Quantifying the Soil Community on Green Roofs

With the majority of people living in cities, innovative solutions for greening the urban environment are necessary to provide ecosystem services such as urban cooling and remediating habitat loss. Green roofs are one potential solution within green infrastructure. Few studies have investigated whether green roofs are a good urban habitat, particularly for soil organisms. The soil food web is vital to above-ground ecosystem processes as it regulates nutrients and can alleviate drought stress, so could be an important but overlooked factor in green roof design. This is the first multi-season study to examine green roof soil organisms in detail, whilst tracking abiotic factors and plant cover. The first part of this thesis characterises the microarthropod and microbial community present on two green roofs in Greater london. It was found that the mite population was dominated by a xerophilic family (Scutoverticidae) and that collembola suffered population crashes in summer. Soil bacteria and fungi were low in abundance, but were more prevalent in dry weather. In general the soil community was impoverished and influenced by drought. The second part of this thesis explores the, use of microbial inoculants to improve the soil community. Bacteria, mycorrhiza and Trichoderma were added to a new and mature roof. On the mature roof, plant growth was not affected by treatments, but collembola populations were higher when Trichoderma were added. On the new roof, inoculants negatively affected plant growth and mite populations, but benefitted collembola. Soi l organisms on the new roof colonised independently and from the Sedum plugs. One species of rarely recorded collembola (Sminthurinu5 trinotatus) colonised early after construction. Planting with Sedum was found to improve the soil community compared to leaving the substrate bare. The results presented here highlight that C.ll rrent green roof designs do not support a functional soil community but that microbial inoculants have the potential to improve them.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Green roof soil organisms:Anthropogenic assemblages or natural communities?

Green roofs provide a range of ecosystem services, from stormwater retention to thermal insulation. They can also provide habitat for biodiversity, remediating land lost in development. However, few extensive green roofs are designed with this benefit in mind and, as such, biodiversity often does not reach its full potential. In particular, the soil ecology of green roofs is poorly understood, despite soil microorganisms having a large impact on nutrient cycling and thus plant diversity. In particular, whilst there are studies describing the soil microarthropods and microbial communities present on green roofs, little is known about how these species arrive there. This paper aims to determine how soil microarthropods and microbes colonise green roofs and which species survive post-construction, to inform green roof technosol design and to understand if remediation of impoverished green roof soils is possible. To do this, we conducted a preliminary study by analysing green roof construction materials (substrates and Sedum plugs) for microarthropods, bacteria and fungi before constructing a new green roof. We then monitored survival and independent colonisation over eleven months. Whilst green roof substrates were a poor source of colonisation, Sedum plugs showed potential as a vehicle for colonisation by microbes and, especially, by soil microarthropods. However, the majority of the species present within Sedum plugs were not adapted to the harsh conditions of the green roof, resulting in high mortality. Two ubiquitist species, the Collembola species complex Parisotoma notabilis and a mite of the family Scutoverticidae survived in high abundance after the eleven month sample period, and the functional role of these species on a green roof should be investigated. Some species colonised independently during the study, highlighting that microarthropods and microbes in green roofs consist of a mix of anthropogenic assemblages and natural communities. Mycorrhizal fungi were extremely successful, independently colonising almost all Sedum plants by the end of the study. However, the absence of arbuscules suggests that this colonisation may not have a benefit to plant growth in this instance. Demonstrating that the succession of soil organisms is influenced by the communities present in construction materials has implications for substrate design, demonstrating that soil organisms may be inoculated onto green roofs to provide functioning technosols. In addition, the independent colonisation of mycorrhiza in this study stimulates discussion about the role of commercially applied mycorrhizal fungi in green roof construction

Understanding and Applying Ecological Principles in Cities

Renaturing cities requires a thorough understanding of how plants and animals interact with the urban environment and humans. But cities are a challenging environment for ecologists to work in, with high levels of heterogeneity and rapid rates of change. In addition, the hostile conditions often found in cities mean that each city, and region of a city, can have their own unique geographical context. In this chapter, we contrast urban ecological research in the UK and Brazil, to demonstrate the challenges and approaches needed to renature cities. In so doing, we provide a platform for global transferability of these locally contextualised approaches. The UK has a long history of urbanisation and, as a result of increasing extinction debts over 200 years, well-established urban ecological research. Research is generally focused on encouraging species back into the city. In contrast, Brazil is a biodiversity hotspot with relatively rich urban flora and fauna. This rich ecosystem is imperilled by current rapid urbanisation and lack of support for urban nature by city-dwellers. By working together and transferring expertise, UK and Brazilian researchers stand a better chance of understanding urban ecological processes and unlocking renaturing processes in each location. We present one such method for applying ecological knowledge to cities, so-called Ecological Engineering, in particular by discussing ecomimicry—the adaptive approach needed to apply global ecological principles to local urban challenges. By reading the ecological landscape in which urban developments sit and applying tailored green infrastructure solutions to new developments and greenspaces, cities may be able to reduce the rate at which extinction debt is accumulated

“I like to get my hands stuck in the soil”: A pilot study in the acceptance of soil-less methods of cultivation in community gardens

The aim of this paper is to investigate the role that soil-less methods of food production can play in urban agriculture, particularly in projects that are run by community groups. Over the last years, a drive by people to engage in sustainable lifestyles has resulted in a surge in urban agriculture.Typically, on-soil horticulture is greatly appreciated by urban farmers for its invaluable contribution to urban ecology. Yet, some community projects across Europe are experimenting with indoor soilless methods, which offer an opportunity to reduce the waste of resources such as water and space, including valuable green space. Against this backdrop, the paper investigates the drivers and barriers that may facilitate or hinder soil-less methods for urban farmers. We triangulate information from the literature with a small-scale pilot study, based on interviews in a community garden in Portsmouth, UK, in which a small hydroponic unit was utilised by a group of experienced farmers.We subsequently compare results with a previous pilot study, similar in design but with interviewees who have limited experience in growing food. Qualitative results show a general appreciation of the environmental advantages that the hydroponic unit can yield and at the same time diffidence towards a hydroponic produce which is perceived as non-natural in both groups. Quantitative analysis showed that 90% of experienced farmers had prior knowledge of soil-less methods against 42% of the wider sample group. We conclude that, for the participants to the pilots, higher knowledge of soil-less systems does not necessarily lead to higher acceptance. Yet, feedback gathered suggests that there is interest in soil-less methods, which appears to be linked to the propensity of community gardens to test new arrangements and techniques within their projects

Can microbial inoculants boost soil food webs and vegetation development on newly constructed extensive green roofs?

Green roofs are a key to providing nature-based solutions in cities. However, most green roofs installed in the Northern hemisphere are shallow, stonecrop planted systems (“extensive” green roofs), which have been shown to support limited biodiversity and could be more effective at providing ecosystem services. One issue with this type of extensive green roof is that rootzones are almost sterile on construction, relying on natural colonisation to provide a soil food web. This is a slow process, meaning plant growth can also be slow. Our aim was to determine if a soil food web could be introduced when the green roof is built. We applied microbial inoculants (mycorrhizal fungi and bacteria (Bacillus spp.)) to a new green roof and monitored plant growth and the soil food web (bacteria, mycorrhizal fungi and microarthropods). Different inoculants altered the composition of microarthropod communities, potentially impacting later succession. In particular, bacterial inoculants increased microarthropod populations. This is one of the first studies to demonstrate that the addition of microbial inoculants impacts not only plant growth, but also faunal components of the soil food web, which could have implications for long-term resilience. Bacteria were effective at aiding mycorrhizal colonisation of plants roots, but this colonisation had no impact on the growth of our selected stonecrops, Sedum album, Petrosedum reflexum and Phedimus spurius. We suggest that if a beneficial mycorrhiza could be found to promote the growth of these specific species on green roofs, bacteria could be effective “helper” species to aid colonisation. This study enables green roof researchers and the industry to justify further exploration of the impact of microbial inoculants on green roofs

Valuing Wrexham's Urban Forest

Urban forests are a valuable source of ecosystem services in towns and cities. They help us alleviate problems associated with densely packed populations by improving local air quality, capturing carbon and reducing flooding. They also provide food and habitat for animals, such as birds and bees, and improve social cohesion in communities.However, the value of urban trees, both quantifiable and otherwise, is often overlooked within planning developments. By valuing the quantifiable services provided by trees in Wrexham County Borough, Wrexham County Borough Council and Natural Resources Wales can increase the profile of the County‟s urban forests, ensuring their value is maintained and improved upon. In addition, valuing these ecosystem services helps town planners, landscape architects and tree officers to plan where trees will be planted for the maximum benefit.A survey of Wrexham County Boroughs trees‟ to value a number of ecosystem services was undertaken in summer 2013 with the aid of i-Tree Eco, used for the first time in Wales. i-Tree Eco is a model developed by the US Forest Service that allows scientists to measure a range of ecosystem services provided by urban trees, from carbon sequestration to pollutant removal. The study was funded by Natural Resources Wales and Wrexham County Borough Council and was carried out by Forest Research. The quality of life for residents of Wrexham is significantly improved by its urban forest, helping alleviate flash flooding and sewer blockages, providing cleaner air and supporting wildlife such as pollinators. In addition, Wrexham‟s urban forest contributes significantly to the local economy, saving around £1.44 million in services per year. This would be enough money to plant nearly 800 medium sized oak trees in Wrexham and iscomparable to the amount needed to refurbish Wrexham cemetery (Wrexham.com, 2014). Wrexham has a high density of trees but low canopy cover compared to similar sized towns. A further 28% of Wrexham‟s urban space could be planted with trees, bringingWrexham in line with other urban areas. Wrexham‟s urban forest could also be improved by planting a higher diversity of tree species, improving its resilience to pests and diseases. The number of large trees in Wrexham is above average for the UK and, in particular,there are many impressive old oaks. However, there are fewer large trees than recommended for a future-proofed urban forest, suggesting some room for improvement. Increasing planting of large stature trees may future proof Wrexham‟s impressive stock of large growing trees. A summary of key results is presented on page 5

Valuing the urban trees in Bridgend county borough

Urban forests provide a range of services, often termed ecosystem services, that help alleviate problems associated with urbanisation. Trees improve local air quality, capture carbon, reduce flooding and cool urban environments. They provide habitat for animals,and can improve social cohesion in communities. Ecosystem service provision is directly influenced by management actions that affect the overall structure of an urban forest.The first step to improve the management of an urban forest is to better understand its current structure, composition and distribution in order to obtain a baseline from which to set goals and to monitor progress. By measuring the structure of the urban forest (the tree species present, their size and condition), the benefits of the urban forest can be determined and the value of these benefits calculated and expressed in monetary terms.Valuing services provided by the urban trees in Bridgend County Borough (Bridgend CB) could allow Bridgend County Borough Council (Bridgend CBC) and Natural Resources Wales (NRW) to increase the profile of the urban forest thereby helping to ensure its value is maintained and improved upon. The Bridgend CB, as described in this study, is spread across 5 separate urban districts with a total area of 4,400 ha. In order to gain a better understanding of the urban trees in Bridgend CB and to value the services they provide, an i-Tree Eco survey was undertaken in the summer of 2014. i-Tree Eco is a model developed by the US Forest Service to measure a range of ecosystem services provided by urban trees. This study was funded by NRW and Bridgend CBC and the survey was carried out by Barton Trees. This report presents a baseline quantitative assessment of the air pollution removal, carbon storage and sequestration, rainfall interception and visual amenity of the urban forest of Bridgend CB, and is accompanied with detailed information on the forest’s structure and composition. Residents in Bridgend CB benefit significantly from the urban trees present, including the provision of ecosystem services worth £950,000 per year. This value, however, excludes many of the ecosystem services of trees that are mnot currently assessed by i-Tree Eco, including cooling local air temperatures and reducing noise pollution. Therefore, this value is a conservative estimate of the ecosystem services provided. This study captures a snapshot-in-time ‘picture’ of the urban forest. It does not consider how the urban forest has changed over time or the reasons for this. Decisions on how the structure and composition of Bridgend CB’s urban forest should change in the future or how to ensure that it is resilient to the effects of a changing climate are beyond the scope of this report, though this study goes a long way to providing the necessary baseline data required to inform such decision making

Robotics and Automated Systems for Environmental Sustainability: Monitoring Terrestrial Biodiversity

It is critical to protect Earth’s biodiversity, not just for its own intrinsic value, but also for the ecosystem services it underpins. Yet biodiversity is in crisis, with up to 1 million animal and plant species at risk of extinction, many within decades. This dire projection has captured world attention and triggered major mitigation efforts, but we are faced with problems in assessing global trends in biodiversity – which species, taxa, habitats and ecosystems are suffering the greatest declines? Are current mitigation measures having any positive impact? To answer key questions such as these, ecologists are seeking the help of robotics and automated systems (RAS) experts in the monumental task of attempting to monitor the state of biodiversity.In this White Paper, we have surveyed recent literature and consulted more than 120 international expert ecologists and engineers working in the fields of biodiversity and robotics. We have done this to evaluate the potential for developing robotic and autonomous systems that could massively extend the scope of terrestrial biodiversity monitoring across habitats globally. The complexities of biodiversity itself, and the many barriers and challenges that must be overcome in monitoring it, are formidable. We assess each of these barriers in turn, highlighting currently available RAS solutions, as well as nascent technologies that may be relevant to future RAS for biodiversity (RAS-BD) monitoring. Using this information, we have drawn up a roadmap of actions needed to address the barriers that should be easiest to overcome. Encouragingly, we find that a variety of existing RAS capabilities may be transferable to a biodiversity monitoring context. Beyond these are the harder barriers, where promising novel ideas being researched at UK universities and research institutes may, in time, become integral parts of future RAS-BD monitoring technology. We believe that RAS-BD technology has great potential to complement and considerably extend the field survey work undertaken by expert human observers. In the UK, we are fortunate in having particular strengths in both biodiversity and robotics research; as a nation we are in an ideal position to integrate them and become a leading force in the development and application of RAS-BD monitoring. To this end, we propose these recommendations that we hope will guide future government strategy in an area that is vital to the future of humanity:● The creation and funding of an integrated multidisciplinary task force, including academics and industry specialists with expertise in RAS and biodiversity, to support technological research and development.● Future UK funding and focus should be prioritised to utilise existing RAS capabilities to develop first generation RAS-BD technology for monitoring biodiversity.● Relevant nascent technologies being researched by numerous UK academic teams need increased and accelerated research and development funding to turn pioneering concepts into enhanced RAS-BD technology suited to overcoming the hardest monitoring barriers that ecologists encounter.● Education strategies should be developed to foster links between aspiring engineers, biologists andcomputer technologists, both in the curriculum of schools, and at later stages in universities and research facilities