Spatial and temporal changes in salt marsh distribution in the Dee estuary, NW England, determined from aerial photographs

Abstract

Vegetation changes in salt marsh communities of the Dee estuary, northwest England, were analysed with a combination of remote sensing techniques using data dating back to the 1950s. The distribution of communities in 1997 was classified using Airborne Thematic Mapper data and used to develop a methodology for the analysis of black and white photographs of the marsh. These methods were then applied retrogressively to a time sequence of monochrome photographs running from 1955 to 1975. At the apex of the salt marshes on the English shore of the Dee estuary, the marsh expanded dramatically to 1975, and consisted predominantly of pioneer and low marsh vegetation types. Between 1975 and 1997, however, there was only a slight increase in salt marsh area, but with an increase in mid and high marsh vegetation, replacing pioneer marsh. In a second area of the salt marsh on the English shore, a different pattern of salt marsh expansion was observed. The area occupied by marsh continued to increase right up to 1997, with extensive pioneer vegetation suggesting a process of continuing expansion. However, the pattern of marsh colonisation appeared to be different in 1997 compared to 1975. The significance of the changes in salt marsh distribution within the Dee estuary are discussed in relation to the historical pattern of salt marsh colonisation, the importance of Spartina anglica in the process and the implications for strategic management of the estuarine resources.

Coastal marsh soils in Poland: characteristics and problems of classification

“…Due to specificity of the Baltic Sea, the coastal marsh soils are not subject to regular sea tides, and have different properties than typical salt marsh soils from regions such as the North Sea (Giani 1992, Irish Sea (Huckle et al 2004) or Pacific Coast (Shlyakhov and Kostenkov 1999).…”

Changes to the coastal flora of Wirral, Merseyside (v.c.58)

“…The vegetation of the salt-marshes today is very different to that described by Marker (1967), Taylor & Burrows (1968) and even Huckle et al (2000Huckle et al ( , 2004. It is also much more complex.…”

“…It reached Heswall by 1964 and today it is near Caldy with a secondary marsh at Red Rocks, West Kirby and Hoylake. A later description and the development of the lower and mid-marsh zones is provided by Huckle et al (2000Huckle et al ( , 2004.…”

Establishment, spread, and impact of an invasive planthopper on its invasive host plant: Prokelisia marginata (Homoptera: Delphacidae) exploiting Spartina anglica (Poales: Poaceae) in Britain

“…Daehler and Strong (1995) found that the top–down effects of insect herbivores on S. alterniflora in San Francisco Bay were minimal and suggested that this may be because few other stressors have a major impact on the plant, which occurs in large, monospecific stands and is subject to little or no interspecific competition (Strong & Ayres, 2013). Dense, monospecific stands are less frequent in Britain, however, where S. anglica is usually present in more mixed communities with other halophytes (Boorman, 2003; Dargie, 2000; Gray et al ., 1991; Huckle et al ., 2004). S. anglica in Britain may consequently be subject to greater competition‐induced stress, already noted as a potential contributing factor to the die‐back recorded in recent decades (Lacambra et al ., 2004), and may thus be inherently more vulnerable to the deleterious impacts of a novel and abundant insect herbivore.…”