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Nature-based solutions are seen to benefit both society and biodiversity. However, research into their future resilience is required. Soft capping is a nature-based conservation strategy that mimics the natural colonisation of plants on top of ruined walls and reduces rates of material deterioration. To remain effective, soft capping species must be tolerant of future climatic conditions. We use the Maxent species distribution model to assess the resilience of soft capping species to low and high emission scenarios across Britain and Ireland. We assess the mid- and end-century presence probability of four native and archaeophyte species used in soft capping (Sedum album, S. acre, S. anglicum and Saxifraga granulata). Future presence probabilities were calculated using the climate models HadGEM3-GC31-LL, IPSL-CM6A-LR and MIROC6. Results suggest that current sedum-based soft caps will remain viable until mid-century with additional maintenance (e.g. watering) during droughts, although soft caps predominantly formed of Sedum album may be prone to failure in south-eastern England. In the future, species more resilient to arid conditions may need to be preferentially selected for soft capping to ensure resilience under a warming climate. Species distribution modelling provides a useful way of predicting the future resilience of nature-based solutions. [ABSTRACT FROM AUTHOR]

Two sets of twelve Portland limestone tablets were attached to carousels outside and under the open, lightweight shelter at Bishop's Palace (Witney, England) for 18 months to assess the influence of shelters on soiling and microbiological growth on stone. At the start, and at 6-month intervals, tablets were analysed using microscopy (optical and SEM), colour measurement (spectrophotometry), weight change measurement and salt content determination (ion chromatography). Concentrations of NO2 and SO2 were also monitored for a month using diffusion tubes. In addition, results were compared with those obtained by the UK National Materials Exposure Programme (NMEP) on chemical weathering rates. Differences in soiling and biological growth on sheltered and unsheltered samples, and their influence on limestone decay were established. The shelter is likely to reduce biological growth by modifying the micro-environmental conditions. However, it may also exacerbate dust deposition, which might increase decay rates in the long-term. [ABSTRACT FROM AUTHOR]

Abstract: Decadal limestone erosion rates from a 30-year study of St Pauls Cathedral, London are compared with recession rates derived from applying Lipfert''s and Tidblad''s dose-response functions to the available rainfall and sulphur dioxide data from central London. Comparison of the measured erosion rates and the dose-response function derived recession rates shows consistently higher loss for the measured erosion rates, between 49 and 35 microns per year for measured rates as opposed to 15–12 microns per year for derived rates. Measured erosion rates were 3.33 times as high as derived recession rates towards the start of the 30 year measurement period, falling to almost 2.75 times by the 2000s. Analysis of the disparity suggests that, despite the magnitude of the differences between the two methods, they both record the same patterns of decline in erosion rates as sulphur dioxide levels decline. The disparity may result from using a common index of erosion, loss of height, to express the outcomes of two different measurement systems quantifying surface loss in different ways. [Copyright &y& Elsevier]

Ivy is often blamed for damaging masonry walls and seen as something that should be removed wherever possible. However, under some circumstances the positive benefits of ivy can outweigh any deteriorative effects. This paper reports on findings from a three-year research project, commissioned by English Heritage, and their implications for managing ivy on historic masonry walls. From field monitoring at a range of sites in England, it was found that ivy provides a thermal blanket for walls, protecting them from extremes of heat and cold and fluctuations in relative humidity. Similarly, studies in and around Oxford show that ivy can minimize particulate pollution reaching walls. Field experiments in Oxford also reveal that ivy rootlets adhering to stone generally only create minor (if any) damage to the stone surface. However, it was also found that ivy can penetrate existing voids and cause damage. A balanced appraisal should inform decisions to remove, leave or even plant ivy. If ivy is allowed to grow on walls, regular and careful maintenance and monitoring are essential. [ABSTRACT FROM AUTHOR]

As part of the Environmental Monitoring of Integrated Transport Strategies (EMITS) project, which examined the impact of the Oxford Transport Strategy (OTS) on the soiling and decay of buildings and structures in central Oxford, England, a simple photographic survey of a sample of roadside walls was carried out in 1997, with re-surveys in 1999 and 2003. Thirty photographs were taken each time, covering an area of stonework approximately 30 × 30 cm in dimensions at 1–1.3 m above pavement level. The resulting images have been used to investigate, both qualitatively as well as quantitatively, the progression of soiling and decay. Comparison of images by eye reveals a number of minor changes in soiling and decay patterns, but generally indicates stability except at one site where dramatic, superficial damage occurred over 2 years. Quantitative analysis of decay features (concavities resulting from surface blistering, flaking, and scaling), using simple techniques in Adobe Photoshop, shows variable pixel-based size proportions of concavities across 6 years of survey. Colour images (in Lab Color) generally have a reduced proportion of pixels, representing decay features in comparison to black and white (Grayscale) images. The study conveys that colour images provide more information both for general observations of soiling and decay patterns and for segmentation of decay-produced concavities. The study indicates that simple repeat photography can reveal useful information about changing patterns of both soiling and decay, although unavoidable variation in external lighting conditions between re-surveys is a factor limiting the accuracy of change detection. [ABSTRACT FROM AUTHOR]

Travertine dams along the Slade Brook, Gloucestershire, occur over a 700-m length of stream, making this the largest active site of its kind so far recorded in the British Isles. The dams have considerable conservation value owing to their unusual geomorphology and influence on water flow (ponding and cascades) and their specialized flora and fauna. [ABSTRACT FROM AUTHOR]