Two decades of dune slack restoration in North Wales: Diversity, Community and Habitat Specialists - Dataset and analysis code

For the restoration scrub and trees were removed along with 10cm of nutrient rich topsoil to explose bare sand. Ten 2m x 2m quadrates were established and surveyed in subsequent years (surveyed between May and July in: 2006, 2007, 2008, 2009, 2010, 2011, 2013, 2014, 2018, 2020, 2021 and 2022) to monitor botanical succession. These quadrats are referred to as "scraped" in the dataset which a comparable non-restored area was survery in 2022 as a point of comparision and referred to in the dataset as "unscraped".Species data was collated from all previous survey years as follows: individual quadrat and abundance data (the DOMIN scale, a 1 to 10 scale for abundance (Rodwell, 2006) was used in previous surveys) for 2006, 2007, 2008, 2018, 2020 and 2021 (termed ‘full survey years’); total species list only for 2009, 2010, 2011, 2013 and 2014. Due to the nature of the vegetation – short with numerous very small plants – distinguishing between some closely related species can be difficult. This is likely to have resulted in differences in professional opinion between different surveyors over the years. Data was cleaned to account for these potential differences and enable anaylsis (see paper appendix for the full specifics of what was done). To be able to analyse comparable data, the DOMIN scores from previous full survey year were converted to percentage values using the mid-point percentage value of each DOMIN grouping. Soil data was not collected as part of the previous surveys, therefore EIVs were used as a proxy measure to assess any changes in abiotic factors over time. Mean EIVs for light (L), moisture (F), reaction (R), nitrogen (N), and salt (S) (Hill et al., 1999) were calculated for all species on the total species list for all survey years to assess any changes in functional type over time. The EIV’s were not weighted as the species lists contained no abundance data.Processed data and R code for Indicator Species Analysis, NMDS and EIVs are also included.