Tollesbury monitoring results

A Centre for Ecology and Hydrology led research and monitoring programme began at Tollesbury in 1994. Its principle aim was to remove some of the uncertainties surrounding the return of agricultural land to intertidal habitat, and specifically to address the following questions:

• Will natural re-colonisation recreate saltmarsh within the setback site and, if so, over what time scale?;
• Is it possible to aid the processes of natural colonisation directly or indirectly?
• Will there be any deleterious effects to the existing saltmarsh?
• Will the hydraulic effects on the estuary/coastline be as predicted by modeling?
• Will the form and sequence of sea wall removal minimises the possibility of any adverse effects on the adjacent estuary?

In response to these questions preliminary conclusions relating to the following topics were found:

• 'Natural' colonisation of the site by plants will take place but is inhibited by several factors, including height of the tidal flats, drainage and the effects of benthic invertebrates;
• Pretreatment including ploughing, leaving bare, leaving cereal stubble or with a surface of ryegrass has an effect but it appears to be short-lived. Increasing surface elevation may be more effective.;
• Post treatment options (including seeding and planting) and creek engineering (not tried);
• There appears to have been little if any impact on adjacent saltmarshes. It is possible that effects of the Tollesbury breach may not detectable at the scale or period over which the monitoring studies took place (Gray 2002).

References

Gray, A.J. 2002. Coastal Realignment - an Overview of Tollesbury. CHaMPs.