The objectives of this review were to:

• Review the ecosystem effects of common cord-grass
• Map the distribution and extent of common cord-grass in Ireland
• Review the options for the control and management of common cord-grass
• Develop a common cord grass control action plan that can be applied to coastal sites in Ireland

Literature review suggested that the perceived impacts of common cord-grass are often speculative. There was evidence of an impact on macrobenthos diversity, which may explain reported impacts on wading birds that feed on these organisms. There is also evidence that it can impact eelgrass Zostera beds. However, few other reported impacts had strong support and there were suggestions that common cord-grass might facilitate other species. There are also uncertainties about the relationship of sediment regimes and common cord-grass, and the potential impact of management and dieback.

Data analysis was undertaken in PostGIS. The extent of common cord-grass was determined based on the two Saltmarsh Monitoring Projects and the SAMFHIRES project. These provided excellent and up to date coverage, suggesting that the extent of common cord-grass was in the range 688 to 1,223 ha. These data combined with presence based records of the species showed that common cord-grass was widely distributed in Ireland, with records intersecting 167 out of 214 coastal sites.

The threat posed by common cord-grass to Annex I habitats was assessed. It was found to pose a substantial threat to three Annex I habitats, with particular concern for the rarest habitat considered (H1420).

Based on the literature review, a mixture of cutting, smothering, excavation and herbicide application could be used to control common cord-grass. However, this came with caveats, as some techniques, such as cutting, are unlikely to be effective on their own, and all techniques risk impacting other species and habitats in the vicinity. We therefore developed a management decision tool to help guide managers though the analysis required to determine the amount of survey and management action required for a site. This was provisionally implemented on the 167 coastal sites with records of common cord-grass to estimate the extent and costs of actions required.

Note that common cord-grass is currently subject to a degree of nomenclatural uncertainty. Formerly known as Spartina anglica, it is now considered to be a member of the genus Sporobolus, as Sporobolus anglicus. However, this change has not been universally accepted.

Further information from Claire Lush.

Exegesis, working in partnership with NatureBureau, were contracted to undertake an EU LIFE+ supported review of S. anglica as part of Natural England's Improvement Programme for England’s Natura 2000 Sites.

S. anglica has been implicated in a number of impacts on saltmarsh habitats, including increased accretion rates, changed to erosion patterns, reductions in eelgrass Zostera beds and glasswort Salicornia communities, and reduction of areas suitable for bird feeding. We conducted a review of these impacts, which led us to conclude that the overall impact of S. anglica could not clearly be regarded as either positive or negative, as it is hard to separate the impacts caused by S. anglica from those resulting from other processes. For example, causal links between S. anglica and reduction in bird feeding areas were not identified. There is also evidence of S. anglica co-dominating with Salicornia in mixed communities where only S. anglica was known previously, possibly due to a decrease in accretion rates.

We collated recent survey data and species records to assess the extent and distribution of S. anglica. Unfortunately, due the limited coverage of recent survey data very few areas of S. anglica dominated communities could be identified, so the estimate of extent was considered to be a gross underestimate. Recommendations were made to gain a more complete knowledge of the extent of S. anglica using remote sensing and field survey. In contrast, data showing the distribution of S. anglica were more readily available than previously, allowing detailed distribution maps to be created. These showed that the distribution of S. anglica appears to have been relatively stable, having changed little since 1970.

We developed a S. anglica monitoring protocol that aimed to collect information that could be used to determine the extent of S. anglica and to help decide whether management was required. Draft survey forms were tested on sites in the Severn Estuary, Essex coast and North Northumberland Coast, following which improvements were made.

A review of S. anglica control techniques was undertaken, covering physical removal, cutting, grazing, smothering, rotoburying, treatment with herbicides and biological control. This allowed the most effective methods of controlling S. anglica to be identified, but it was noted that any control should be undertaken cautiously and based upon sound evidence, as its removal was likely to result in sediment discharge and potential impacts on designated features. A management decision flow chart was created that aims to help managers of Natura 2000 sites decide where management is most appropriate.

Read the report.

We subsequently undertook a similar review of common cord-grass in Ireland.

Further information from Claire Lush.