Satellites • Other remote sensing techniques • Saltmarsh morphology • Vegetation • Species specific studies

Vegetation

Systematic surveys of landscapes, habitats and species are a first stage in understanding the biology/ecology of a saltmarsh. Scale is a key consideration when undertaking such surveys. Wide-scale saltmarsh survey, based on an assessment of existing survey data supplemented with field work to cover unsurveyed areas, was used to describe the resource in Great Britain in the mid to late 1980’s (Burd, 1989). This information was also used to aid the selection of sites for statutory protection. Attempts have also been made to bring information together at a wider European scale (Dijkema, 1984). Though this study was hampered by the variety of definitions and survey methodologies adopted across Europe, it did provide a broad indication of the nature, scale and importance of the resource.

These studies provide a broad understanding of the distribution, scale and quality of the saltmarsh resource, as well as an indication of some of the issues affecting it. However, they do not tell us anything about change or the causes of change. For this, a series of comparable data are required. In some locations there has been a repeat using the same techniques as the Saltmarsh Survey of Great Britain and some work to quantify change (such as in the Wash) for English Nature.

Saltmarsh zonation and transitions are key elements in assessing and monitoring marsh vegetation. Identifying these elements often requires detailed site surveys timed to occur at particular times of the year. Classifications of key saltmarsh species and communities can be used to broadly define the different intensities of survey applicable (as they define the variability in the vegetation assemblages) and indicate variability on a widespread geographical basis. The level of classification used must be that most appropriate to the issue for which the information is required. The field survey methodology developed for the National Vegetation Classification (NVC) is typically the most appropriate for the majority of surveys that aim to provide a detailed vegetation map and identify broad changes over time. Details of this can be found in Rodwell (2000).