Abstract/Summary

This project focuses on post-construction vegetation recovery of saltmarsh and sand dunes following the installation of offshore cables and pipelines. With an increased reliance on renewable energy, sensitive coastal habitats are likely to be subject to future impacts. Past projects can provide a useful record of change to help determine vegetation recovery in terms of time frames and naturalness. The overall aim of the project is to provide evidence to aid the decision-making process. Central to this research is determining which attributes of restored vegetation might best reflect recovery, how long does recovery take, and what are the likely recovery outcomes. Detailed botanical surveys were completed on and off the pipeline and across different vegetation zones. Species data were initially analysed using a Generalised Linear Model, with subsequent ordination using Canonical Correspondence Analysis. Tentative recovery times are provided. These time frames are indicative as each site and construction project is dependent on the vegetation zones and community types present, construction methods, severity of impact and restoration techniques used. With recovery taking anything from 10 years where impacts are less severe (i.e. in the driftline, low-mid marsh, and pioneer marsh) to much longer recovery times >25 years in sensitive vegetation types (i.e. midupper marsh, dune slacks) or where there have been greater impacts. The study found that sand dunes were generally more resilient to construction than saltmarsh, with the exception of dune slacks which typically became drier resulting in a loss of wet-tolerant herbs. In sand dunes there are opportunities to have a positive impact e.g. creating scrapes, or open areas with bare sand supporting early successional species. In saltmarsh, impacts associated with construction tended to be more severe (e.g. compaction, changes in topography and modification of creeks), often resulting in atypical development of early successional marsh.