Changes in the frequency of common plant species across linear features in Wales from 1990 to 2016: implications for potential delivery of ecosystem services

In 2016, twenty-one 1 km squares recorded in Wales as part of the Countryside Survey of Great Britain were revisited. One hundred and thirty-seven quadrats alongside linear features that had all been recorded in the same place in 1990, 1998 and 2007 were re-found and the plant species compositions recorded. Changes in individual species frequency were analysed and the results summarised by a number of ecosystem services and one disservice whose delivery are linked to functionally important species being present. Results indicated a continuation of a trend towards increased shading and woody cover seen between the first Countryside Survey in 1978 and the last in 2007. Most species showed no significant change in frequency suggesting that the significant directional trend seems only to have impacted a subset of the species present. A greater sample size would be required to capture impacts on a larger number of species including a wider range of Common Standards Monitoring positive indicator species that may find refuge on the linear network in lowland Wales. Having grouped species by the ecosystem services they help deliver, we found that injurious weeds (an ecosystem disservice to food production) either declined or remained stable, a greater number of butterfly larval food plants decreased than increased and there was a net decline in potential nectar yield. Consistent with the successional trend, increasing species in these service-providing groups tended to be tall or shade-tolerant herbs and tree species. Decreasing species tended to be short, shade-intolerant forbs.