Spatial and temporal vegetation analysis of Amberley Wild Brooks over two decades

Abstract

Plant species presence data from 170 ditches at Amberley Wild Brooks in 2017 were compared to those of 1998. Overall functional changes are apparent, and spatial interpolation by Inverse Distance Weighting suggests that areas of the site are exhibiting varying character in space and time. Vegetation traits suggest a response to drier, more saline and more open conditions since 1998. Stress-tolerating species now dominate ruderals and competitors, and the site supports a similar number of hydrophytes and a greater number of species overall. Site-wide nutrient input was not observed in either Ellenberg N or LEAFPACS2 metrics although there are local patterns which warrant investigation. Using these data there appears to have been no decrease in overall presence of the rare and scarce species of the 1998 survey except Sium latifolium L. In terms of plant climatic optima the site has shifted southwards, to warmer and drier conditions, which correlates to the change in 25-year averages of climate to 1998 and to 2017 at the closest Met Office weather station. These patterns are applicable to site management and flood risk management proposals, giving potential for spatial modelling to predict outcomes under different management scenarios.