Browsing by Author "Harris, Jim A."

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    The absence or presence of a lytic coliphage affects the response of Escherichia coli to heat, chlorine, or UV exposure
    (Springer, 2018-03-15) Ameh, Ekwu Mark; Tyrrel, Sean; Harris, Jim A.; Ignatiou, Athanasios; Orlova, Elena V.; Nocker, Andreas
    Disinfection aims at maximal inactivation of target organisms and the sustainable suppression of their regrowth. Whereas many disinfection efforts achieve efficient inactivation when the effect is measured directly after treatment, there are questions about the sustainability of this effect. One aspect is that the treated bacteria might recover and regain the ability to grow. In an environmental context, another question is how amenable surviving bacteria are to predation by omnipresent bacteriophages. Provisional data suggested that bacteria when subjected to sublethal heat stress might develop a phage-resistant phenotype. The result made us wonder about the susceptibility to phage-mediated lysis for bacteria exposed to a gradient of chlorine and UV-LED disinfection strengths. Whereas bacteria exposed to low sublethal chlorine doses still underwent phage-mediated lysis, the critical chlorine Ct of 0.5 mg min/L eliminated this susceptibility and induced phage resistance in the cells that survived treatment. In the case of UV, even the smallest tested dose of 2.8 mJ/cm2 abolished phage lysis leading to direct regrowth. Results suggest that bacteria surviving disinfection might have higher environmental survival chances directly after treatment compared to non-treated cells. A reason could possibly lie in their compromised metabolism that is essential for phage replication.
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    Accumulation, transport and potential treatment of surface sediment on car parks with channel drains
    (Cranfield University, 2015-11) Barlow, James Vincent; Harris, Jim A.; Hess, Tim M.
    Urban pollutants have been identified as a significant source of environmental pollution, posing a risk to human health, the environment, and are toxic to flora and fauna. Highways are recognised as one of the key sources of pollution, from both vehicles, and surrounding infrastructure. A number of studies have investigated accumulation of sediment and the associated pollutants on highways, and the runoff generated as a result of rainfall. Car parks share many potential contributory sources of pollutants with highways, but there is a lack of studies regarding car parks, despite them being identified as a significant percentage of urban land use. A series of experiments were undertaken in order to develop an understanding of the characteristics of car park sediment. The physical and chemical characteristics of sediment were analysed at different stages throughout the drainage system. Firstly on the sediment accumulated on car park surfaces, followed by that mobilised and transported into a channel drain during simulated rainfall events. Finally, potential treatment of pollutants within sediment in a channel was quantified. The physical and chemical characteristics of car park sediment was shown to be similar during both the accumulation (build-up) and wash-off stages, suggesting that the accumulated sediment is generally mobilised and transported to the channel drain (wash-off). Furthermore, both the physical and chemical characteristics of the sediment were shown to be similar to those found on highways, thorough the build-up and wash-off phases. Finally, potential treatment of organic pollutants (PAH) by biodegradation was demonstrated, but not comprehensively proved.
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    Adaptation to climate change: legal challenges for protected areas
    (Igitur, Utrecht Publishing and Archiving Services, 2009-07-01T00:00:00Z) Cliquet, A.; Backes, C.; Harris, Jim A.; Howsam, Peter
    Climate change will cause further loss of biodiversity. As negative effects are already taking place, adaptive measures are required to protect biodiversity from the effects of climate change. The EU policy on climate change and biodiversity aims at improving a coherent ecological network in order to have more resilient ecosystems and to provide for connectivity outside core areas. The existing legal framework, the Birds and Habitats Directives, can enable adaptive approaches, by establishing and managing the Natura 2000 network and providing for connectivity measures. However, policy and law so far have mainly been aimed at conserving the status quo of habitats and species within core areas. The question is whether a legal requirement to protect certain species in certain places makes sense when species and even ecosystems are migrating due to climate change. Instead, efforts must be increased to protect ecosystem functions, goods and services from the negative effects of climate change, and to facilitate the ecological restoration of new areas. Even more effort is needed for the implementation of connectivity. If existing legislation proves too weak to face these challenges, a new ‘Ecosystem Framework Directive’ might provide the necessary legal impe
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    Agricultural intensification reduces selection of putative plant growth-promoting rhizobacteria in wheat
    (Oxford University Press (OUP), 2024-01-01) Reid, Tessa E.; Kavamura, Vanessa N.; Torres-Ballesteros, Adriana; Smith, Monique E.; Abadie, Maïder; Pawlett, Mark; Clark, Ian M.; Harris, Jim A.; Mauchline, Tim H.
    The complex evolutionary history of wheat has shaped its associated root microbial community. However, consideration of impacts from agricultural intensification has been limited. This study investigated how endogenous (genome polyploidization) and exogenous (introduction of chemical fertilizers) factors have shaped beneficial rhizobacterial selection. We combined culture-independent and -dependent methods to analyze rhizobacterial community composition and its associated functions at the root–soil interface from a range of ancestral and modern wheat genotypes, grown with and without the addition of chemical fertilizer. In controlled pot experiments, fertilization and soil compartment (rhizosphere, rhizoplane) were the dominant factors shaping rhizobacterial community composition, whereas the expansion of the wheat genome from diploid to allopolyploid caused the next greatest variation. Rhizoplane-derived culturable bacterial collections tested for plant growth-promoting (PGP) traits revealed that fertilization reduced the abundance of putative plant growth-promoting rhizobacteria in allopolyploid wheats but not in wild wheat progenitors. Taxonomic classification of these isolates showed that these differences were largely driven by reduced selection of beneficial root bacteria representative of the Bacteroidota phylum in allopolyploid wheats. Furthermore, the complexity of supported beneficial bacterial populations in hexaploid wheats was greatly reduced in comparison to diploid wild wheats. We therefore propose that the selection of root-associated bacterial genera with PGP functions may be impaired by crop domestication in a fertilizer-dependent manner, a potentially crucial finding to direct future plant breeding programs to improve crop production systems in a changing environment.
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    Assessment of heat mitigation capacity of urban greenspaces with the use of InVEST urban cooling model, verified with day-time land surface temperature data
    (Elsevier, 2021-06-04) Zawadzka, Joanna Ewa; Harris, Jim A.; Corstanje, Ronald
    Accurate quantification of the heat mitigation capacity of urban greenspaces is essential in planning decisions due to increased thermal pressures on existing and new urban environments associated with climate change. However, this often requires data analytical skillsets that may not be available to the planning community. The recently developed InVEST 3.8.7 Urban Cooling model addresses this limitation by using several easily accessible parameters, assigned to a land cover map, to produce a heat mitigation index (HMI) intended to estimate the cooling capacity of vegetation in a spatial context. In this study, we validated the HMI derived for three towns with differing morphologies by comparison to land surface temperature (LST) data using linear regression analysis. We found that the HMI can be used to explain a variable proportion of the variation in LST, with R2 ranging from 0.48 to 0.64 depending on the town, with stronger associations obtained for towns with a higher range of LST values. Higher resemblance to LST data was achieved after resampling of the 2 m resolution model outputs to 30 m resolution, inclusion of water bodies as cooling features, and using cooling distance away from large greenspaces of 100 m. On average, a change in the HMI of 0.1 was associated with 0.76 °C change in LST. We conclude that the model is suitable for assessment of heat mitigation interventions through incorporation of vegetation and water bodies into city plans at scales relevant to masterplans rather than fine-tuning of urban design.
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    Bioremediation of leachate from a green waste composting facility using waste-derived filter media
    (Elsevier, 2008-11) Tyrrel, Sean F.; Seymour, I.; Harris, Jim A.
    The evaluation of two waste-derived materials used to treat compost leachate by biofiltration is described in this paper. Nine biofilters were constructed using 240 l, high density polyethylene containers. Three containers were filled without compaction with 200 l of each of three types of filter media. Waste-derived filter media (compost and oversize) were compared to a mineral control (granite chips). The filters were fed with compost leachate from a typical green waste composting facility at hydraulic loading rates ranging from 0.05 m3/m3/day to 0.5 m3/m3/day over a period of twelve months. The oversize medium emerged as the most effective demonstrating characteristics of consistency of effluent quality and resilience to stress. The oversize medium produced an effluent of <10 mg/l ammoniacal nitrogen on >95% of sampling occasions. The organic component of compost leachate was dominated by compounds that proved to be recalcitrant to biodegradation. The solids content of the treated effluent remained too high to be acceptable for direct discharge to a watercourse without further treatment and if discharge to a watercourse is to be considered, a polishing stage (e.g., reed bed) able to remove solids and dampen occasional peaks of ammoniacal nitrogen should be employed.
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    A bird's eye view: using circuit theory to study urban landscape connectivity for birds
    (Springer, 2017-06-28) Grafius, Darren Ronald; Corstanje, Ronald; Siriwardena, Gavin M.; Plummer, Kate E.; Harris, Jim A.
    Context Connectivity is fundamental to understanding how landscape form influences ecological function. However, uncertainties persist due to the difficulty and expense of gathering empirical data to drive or to validate connectivity models, especially in urban areas, where relationships are multifaceted and the habitat matrix cannot be considered to be binary. Objectives This research used circuit theory to model urban bird flows (i.e. ‘current’), and compared results to observed abundance. The aims were to explore the ability of this approach to predict wildlife flows and to test relationships between modelled connectivity and variation in abundance. Methods Circuitscape was used to model functional connectivity in Bedford, Luton/Dunstable, and Milton Keynes, UK, for great tits (Parus major) and blue tits (Cyanistes caeruleus), drawing parameters from published studies of woodland bird flows in urban environments. Model performance was then tested against observed abundance data. Results Modelled current showed a weak yet positive agreement with combined abundance for P. major and C. caeruleus. Weaker correlations were found for other woodland species, suggesting the approach may be expandable if re-parameterised. Conclusions Trees provide suitable habitat for urban woodland bird species, but their location in large, contiguous patches and corridors along barriers also facilitates connectivity networks throughout the urban matrix. Urban connectivity studies are well-served by the advantages of circuit theory approaches, and benefit from the empirical study of wildlife flows in these landscapes to parameterise this type of modelling more explicitly. Such results can prove informative and beneficial in designing urban green space and new developments.
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    Bundling ecosystem services at a high resolution in the UK: trade-offs and synergies in urban landscapes
    (Springer, 2021-04-29) Karimi, James D.; Corstanje, Ron; Harris, Jim A.
    Context Ecosystem service bundles can be defined as the spatial co-occurrence of ecosystem services in a landscape. The understanding of the delivery of multiple ecosystem services as bundles in urban areas is limited. This study modelled ecosystem services in an urban area comprising the towns of Milton Keynes, Bedford and Luton. Objectives The objectives of this study were to assess (1) how ecosystem service bundles scale at a 2 m spatial resolution and (2) identify and analyse the composition of ecosystem service bundles. Methods Six ecosystem services were modelled with the InVEST framework at a 2 m resolution. The correlations between ecosystem services were calculated using the Spearman rank correlation coefficient method. Principal Component Analysis and K-means cluster analysis were used to analyse the distributions, spatial trade-offs and synergies of multiple ecosystem services. Results The results showed that regulating services had the tendency to form trade-offs and synergies. There was a significant tendency for trade-offs between supporting service Habitat quality and Pollinator abundance. Four bundle types were identified which showed specialised areas with prevalent soil erosion with high levels in water supply, areas with high values in nutrient retention, areas with high levels in carbon storage and urban areas with pollinator abundance. Conclusions This study demonstrates the existence of synergies and trade-offs between ecosystem services and the formation of ecosystem service bundles in urban areas. This study provides a better understanding of the interactions between services and improve the management choices in ecosystem service provision in urban and landscape planning.
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    Characterisation and control of the biosolids storage environment: Implications for E. coli dynamics
    (Elsevier, 2020-08-15) Fane, Sarah Elizabeth; Nocker, Andreas; Vale, Peter C. J.; Rivas Casado, Monica; Cartmell, Elise; Harris, Jim A.; Bajón Fernández, Yadira; Tyrrel, Sean F.
    E. coli survival in biosolids storage may present a risk of non-compliance with guidelines designed to ensure a quality product safe for agricultural use. The storage environment may affect E. coli survival but presently, storage characteristics are not well profiled. Typically biosolids storage environments are not actively controlled or monitored to support increased product quality or improved microbial compliance. This two-phased study aimed to identify the environmental factors that control bacterial concentrations through a long term, controlled monitoring study (phase 1) and a field-scale demonstration trial modifying precursors to bacterial growth (phase 2). Digested and dewatered biosolids were stored in operational-scale stockpiles to elucidate factors controlling E. coli dynamics. E. coli concentrations, stockpile dry solids, temperature, redox and ambient weather data were monitored. Results from ANCOVA analysis showed statistically significant (p < 0.05) E. coli reductions across storage periods with greater die-off in summer months. Stockpile temperature had a statistically significant effect on E. coli survival. A 4.5 Log reduction was measured in summer (maximum temperature 31 °C). In the phase 2 modification trials, covered stockpiles were able to maintain a temperature >25 °C for a 28 day period and achieved a 3.7 Log E. coli reduction. In winter months E. coli suppression was limited with concentrations >6 Log10 CFU g−1 DS maintained. The ANCOVA analysis has identified the significant role that physical environmental factors, such as stockpile temperature, has on E. coli dynamics and the opportunities for control
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    Characterising the biophysical, economic and social impacts of soil carbon sequestration as a greenhouse gas removal technology
    (Wiley, 2019-09-18) Sykes, Alasdair J.; Macleod, Michael; Eory, Vera; Rees, Robert M.; Payen, Florian; Myrgiotis, Vasilis; Williams, Mathew; Sohi, Saran; Hillier, Jon; Moran, Dominic; Manning, David A. C.; Goglio, Pietro; Seghetta, Michele; Williams, Adrian; Harris, Jim A.; Dondini, Marta; Walton, Jack; House, Joanna; Smith, Pete
    To limit warming to well below 2°C, most scenario projections rely on greenhouse gas removal technologies (GGRTs); one such GGRT uses soil carbon sequestration (SCS) in agricultural land. In addition to their role in mitigating climate change, SCS practices play a role in delivering agroecosystem resilience, climate change adaptability, and food security. Environmental heterogeneity and differences in agricultural practices challenge the practical implementation of SCS, and our analysis addresses the associated knowledge gap. Previous assessments have focused on global potentials, but there is a need among policy makers to operationalise SCS. Here, we assess a range of practices already proposed to deliver SCS, and distil these into a subset of specific measures. We provide a multi‐disciplinary summary of the barriers and potential incentives toward practical implementation of these measures. First, we identify specific practices with potential for both a positive impact on SCS at farm level, and an uptake rate compatible with global impact. These focus on: a. optimising crop primary productivity (e.g. nutrient optimisation, pH management, irrigation) b. reducing soil disturbance and managing soil physical properties (e.g. improved rotations, minimum till) c. minimising deliberate removal of C or lateral transport via erosion processes (e.g. support measures, bare fallow reduction) d. addition of C produced outside the system (e.g. organic manure amendments, biochar addition) e. provision of additional C inputs within the cropping system (e.g. agroforestry, cover cropping) We then consider economic and non‐cost barriers and incentives for land managers implementing these measures, along with the potential externalised impacts of implementation. This offers a framework and reference point for holistic assessment of the impacts of SCS. Finally, we summarise and discuss the ability of extant scientific approaches to quantify the technical potential and externalities of SCS measures, and the barriers and incentives to their implementation in global agricultural systems.
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    Competitive exclusion as a means to reduce Escherichia coli regrowth in digested sludge
    (Cranfield University, 2014-09) Williams, Tyson; Harris, Jim A.; Tyrrel, Sean; Ritz, K.
    In recent years, it has been reported that numbers of Escherichia coli increase significantly following centrifugation of sludge during the treatment process. E. coli is used as an indicator of the microbiological quality of sludge-derived products destined for agricultural recycling and of the efficacy of the sludge treatment processes. The re-growth phenomenon is of concern because of the potential for additional treatment requirement / higher disposal costs and loss of consumer confidence associated with a compliance failure. It is hypothesised that a competitive exclusion treatment could be the solution wherein the digestate be exposed to a ‘probiotic’ or defined mixture of micro-organisms, to effectively out compete or eliminate any resident E. coli remaining following treatment. The competitive exclusion principle as a treatment method has already seen application in various industrial sectors, the most well-known being the poultry industry. In experiments it was determined that an antimicrobial producing organism would be most likely to succeed. From the candidates screened, Lactobacillus reuteri proved the most promising. L. reuteri is a known producer of reuterin in the presence of glycerol and organic acids as a part of its normal metabolic activity. In sludge derived nutrient broth in the presence of glycerol and low pH, L. reuteri addition resulted in a reduction of E. coli to undetectable levels. In sludge cake under the same conditions, L. reuteri was less successful. However the addition of glycerol and L. reuteri to sludge cake restricted E. coli growth to a 2 log increase from the initial concentration of E. coli recorded following pasteurisation (an average of around 1x102 cfu/gDs), in comparison in the positive control a 4 log increase was recorded. From this result the sludge cake could be defined as conventionally treated. It can be concluded that competitive exclusion and L. reuteri show promise as a treatment for reducing E. coli re-growth in sludge cake
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    Data - Immobilisation of anaerobic digestate supplied nitrogen into soil microbial biomass is dependent on lability of high organic carbon mat
    (Cranfield University, 2024-03-11 09:09) van Midden, Christina; Harris, Jim A.; Shaw, Liz; Sizmur, Tom; Morgan, Hayden; Pawlett, Mark
    Research data for a 150 day incubation study to determine the effects of mixing high organic carbon materials into anaerobic digestate on soil microbial immobilisation of digestate supplied nitrogen and on soil microbial communities. This dateset contains raw data on microbial biomass carbon and nitrogen, soil available nitrogen (ammonium-N and total oxides of nitrate-nitrite), total soil nitrogen, and PLFA biomarkers.
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    Data underpinning the paper "Ecological Connectivity Networks in Rapidly Expanding Cities"
    (Cranfield University, 2018-03-12 11:53) najihah Muhamad nor, Amal; Corstanje, Ronald; Harris, Jim A.; Grafius, Darren
    Data used in the accompanying paper. Data is presented in MS Word summaries for easy previews. Additionally, the zip folder contains original data in the folders:- Birds*;- Cumulative cost**;- Eco network**;- Jakarta (Birds*, Boundary*, Clipbound*, Conefor*, Focal node*);- Kuala Lumpur (Boundary*, Focalnode*, Image2014*, Resistance*, Shortregion*);- Metro Manila (Boundary*, Focalnode*, image2014*, Resistance**, Linkage mapper* including xlsx link table);- Resistance**;* ArcGIS shapefiles (dbf, prj, sbn, sbx, shp, shx, xml)** jpg files
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    Data underpinning the paper "Impact of rapid urban expansion on green space structure"
    (Cranfield University, 2017-05-26 09:08) najihah Muhamad nor, Amal; Corstanje, Ronald; Harris, Jim A.; Brewer, Tim
    These data could be opened in Microsoft Excel and ArcGIS software.
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    Defining and quantifying the resilience of responses to disturbance: a conceptual and modelling approach from soil science
    (Nature Publishing Group, 2016-06-22) Todman, Lindsay; Fraser, Fiona; Corstanje, Ronald; Deeks, Lynda K.; Harris, Jim A.; Pawlett, Mark; Ritz, Karl; Whitmore, Andrew P.
    There are several conceptual definitions of resilience pertaining to environmental systems and, even if resilience is clearly defined in a particular context, it is challenging to quantify. We identify four characteristics of the response of a system function to disturbance that relate to “resilience”: (1) degree of return of the function to a reference level; (2) time taken to reach a new quasi-stable state; (3) rate (i.e. gradient) at which the function reaches the new state; (4) cumulative magnitude of the function (i.e. area under the curve) before a new state is reached. We develop metrics to quantify these characteristics based on an analogy with a mechanical spring and damper system. Using the example of the response of a soil function (respiration) to disturbance, we demonstrate that these metrics effectively discriminate key features of the dynamic response. Although any one of these characteristics could define resilience, each may lead to different insights and conclusions. The salient properties of a resilient response must thus be identified for different contexts. Because the temporal resolution of data affects the accurate determination of these metrics, we recommend that at least twelve measurements are made over the temporal range for which the response is expected.
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    Developing a multifunctional indicator framework for soil health
    (Elsevier, 2025-06) Hannam, Jacqueline A.; Harris, Maddie; Deeks, Lynda K.; Hoskins, Hannah; Hutchison, James; Withers, Amy J; Harris, Jim A.; Way, Lawrence; Rickson, R. Jane
    We developed a proof-of-concept indicator framework to monitor soil health based on the delivery of ecosystem services. Instead of distilling soil health to one metric, the framework enables simultaneous comparison of the delivery and trade-offs between different ecosystem services that are delivered by soils, accounting for inherent capability determined by soil type and land use. The framework has potential to explore a whole systems approach, ascertaining soil system response in real time that can detect emergent properties of the system. Initial development of the framework ranked salient soil properties known to be linked and pertinent to the delivery of ecosystem services. These key soil properties, together with other environmental variables were used to create simple conceptual models representing a causal network for soils’ contributions to the ecosystem services of climate regulation, food production, water regulation and below-ground biodiversity. The conceptual models were developed into Bayesian Belief Networks populated with relevant national data and expert judgement. The resulting outputs gave an indication of how well (i.e. healthy) a soil can deliver each ecosystem service at a land parcel scale presented in a dashboard app. The output at a specific location can be contextualised or benchmarked against to the range of values for areas with similar soil and land use types. The idea was to build the model with readily available data and knowledge but with flexibility for iterative development to refine the framework and models and improve outputs over time. This enables indicator updates using inputs of local knowledge of land management, or when additional soil data becomes available, or when soil policy drivers change, or our understanding of the conceptual and statistical models are improved. The indicator framework can be applied and adapted for use in multiple contexts from reporting national policy targets on soil health to determining soil health for a farmer at the field level.
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    Disruption of cells in biosolids affects E. coli dynamics in storage
    (IWA Publishing, 2019-05-22) Fane, Sarah Elizabeth; Madureira, D.; Nocker, Andreas; Vale, Peter C. J.; Rivas Casado, Monica; Wilson, A.; Bajón Fernández, Yadira; Harris, Jim A.; Cartmell, Elise; Tyrrel, Sean
    Achieving microbial compliance during biosolids storage can be complicated by the unpredictable increase of Escherichia coli. Thermal treatment during anaerobic digestion (AD) and the effects of dewatering may be a significant factor contributing to indicator survival. Shear forces present during dewatering may promote cell damage, releasing nutrient for E. coli growth. The effect of cell damage on E. coli survival was assessed in laboratory-scale thermal and physical disruption experiments. E. coli growth curves for disrupted treatments were compared with control conditions and quantified using flow cytometry and membrane filtration techniques. A significant difference (p < 0.05) in the level of damaged cells between control and disrupted conditions was observed. For thermal and physical disruption treatments, the peak of E. coli concentration increased significantly by 1.8 Log and 2.4 Log (CFU (colony forming units) g−1 DS), respectively, compared with control treatments. Research findings contribute to the understanding of bacterial growth and death dynamics in biosolids
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    Distinct respiratory responses of soils to complex organic substrate are governed predominantly by soil architecture and its microbial community
    (Elsevier, 2016-12-01) Fraser, Fiona; Todman, Lindsay C.; Corstanje, Ronald; Deeks, Lynda K.; Harris, Jim A.; Pawlett, Mark; Whitmore, Andrew P.; Ritz, Karl
    Factors governing the turnover of organic matter (OM) added to soils, including substrate quality, climate, environment and biology, are well known, but their relative importance has been difficult to ascertain due to the interconnected nature of the soil system. This has made their inclusion in mechanistic models of OM turnover or nutrient cycling difficult despite the potential power of these models to unravel complex interactions. Using high temporal-resolution respirometery (6 min measurement intervals), we monitored the respiratory response of 67 soils sampled from across England and Wales over a 5 day period following the addition of a complex organic substrate (green barley powder). Four respiratory response archetypes were observed, characterised by different rates of respiration as well as different time-dependent patterns. We also found that it was possible to predict, with 95% accuracy, which type of respiratory behaviour a soil would exhibit based on certain physical and chemical soil properties combined with the size and phenotypic structure of the microbial community. Bulk density, microbial biomass carbon, water holding capacity and microbial community phenotype were identified as the four most important factors in predicting the soils’ respiratory responses using a Bayesian belief network. These results show that the size and constitution of the microbial community are as important as physico-chemical properties of a soil in governing the respiratory response to OM addition. Such a combination suggests that the 'architecture' of the soil, i.e. the integration of the spatial organisation of the environment and the interactions between the communities living and functioning within the pore networks, is fundamentally important in regulating such processes.
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    Downscaling Landsat-8 land surface temperature maps in diverse urban landscapes using multivariate adaptive regression splines and very high resolution auxiliary data
    (Taylor and Francis, 2019-03-25) Zawadzka, Joanna Ewa; Corstanje, Ronald; Harris, Jim A.; Truckell, Ian
    We propose a method for spatial downscaling of Landsat 8-derived LST maps from 100(30 m) resolution down to 2–4 m with the use of the Multiple Adaptive Regression Splines (MARS) models coupled with very high resolution auxiliary data derived from hyperspectral aerial imagery and large-scale topographic maps. We applied the method to four Landsat 8 scenes, two collected in summer and two in winter, for three British towns collectively representing a variety of urban form. We used several spectral indices as well as fractional coverage of water and paved surfaces as LST predictors, and applied a novel method for the correction of temporal mismatch between spectral indices derived from aerial and satellite imagery captured at different dates, allowing for the application of the downscaling method for multiple dates without the need for repeating the aerial survey. Our results suggest that the method performed well for the summer dates, achieving RMSE of 1.40–1.83 K prior to and 0.76–1.21 K after correction for residuals. We conclude that the MARS models, by addressing the non-linear relationship of LST at coarse and fine spatial resolutions, can be successfully applied to produce high resolution LST maps suitable for studies of urban thermal environment at local scales.
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    Ecological connectivity networks in rapidly expanding cities
    (Elsevier, 2017-06-23) Nor, Amal Najihah Muhamad; Corstanje, Ronald; Harris, Jim A.; Grafius, Darren R.; Siriwardena, Gavin M.
    Urban expansion increases fragmentation of the landscape. In effect, fragmentation decreases connectivity, causes green space loss and impacts upon the ecology and function of green space. Restoration of the functionality of green space often requires restoring the ecological connectivity of this green space within the city matrix. However, identifying ecological corridors that integrate different structural and functional connectivity of green space remains vague. Assessing connectivity for developing an ecological network by using efficient models is essential to improve these networks under rapid urban expansion. This paper presents a novel methodological approach to assess and model connectivity for the Eurasian tree sparrow (Passer montanus) and Yellow-vented bulbul (Pycnonotus goiavier) in three cities (Kuala Lumpur, Malaysia; Jakarta, Indonesia and Metro Manila, Philippines). The approach identifies potential priority corridors for ecological connectivity networks. The study combined circuit models, connectivity analysis and least-cost models to identify potential corridors by integrating structure and function of green space patches to provide reliable ecological connectivity network models in the cities. Relevant parameters such as landscape resistance and green space structure (vegetation density, patch size and patch distance) were derived from an expert and literature-based approach based on the preference of bird behaviour. The integrated models allowed the assessment of connectivity for both species using different measures of green space structure revealing the potential corridors and least-cost pathways for both bird species at the patch sites. The implementation of improvements to the identified corridors could increase the connectivity of green space. This study provides examples of how combining models can contribute to the improvement of ecological networks in rapidly expanding cities and demonstrates the usefulness of such models for biodiversity conservation and urban planning.