Fig. 7

(a) PCA scores and (b) loadings for soil data (abbreviations define sites where samples were collected, Scotland: SRC, SOM, SLM, SAP; North West England: ESA, ESB; North East England: EDB). The North East England soil sample, EDB, has a high C:N ratio, and a lower pH than the other samples. EDB soil was found to be naturally different from the others on the PCA scores plot, with a greater separation in the Y-plane (PC2). ESB has a higher C:N than the other sites. SOM and SAP have high phosphorus, water loss, and LOI (organic carbon) compared with SRC, SLM, ESA, ESB, and EDB. SLM was a mixed sample, sharing similar soil traits with ESA and SRC. Note: An extreme sample was removed. SAP3 was a non-homologous urban environment and one of the three soil samples was an outlier. The bar graphs in Fig. 6a and b show high standard deviation for loss on ignition and percentage water loss for SAP, due to this sample