Saltmarsh Conservation, Management and Restoration

Coastal Systems and Continental Margins

verfasst von: J. Patrick Doody

Verlag: Springer Netherlands

Buchreihe : Coastal Systems and Continental Margins

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

Coastal habitats provide the link between the land and the sea. They are dynamic, combine to form ecosystems of great complexity and provide significant areas for wildlife. Their landscapes are treasured by visitors, painters and musicians. They also provide locations for significant economic activity and are intimately bound up with fisheries, providing food and shelter for some species of commercially exploited fish stocks. The habitats themselves provide a buffer to tides and wave action, which may be particularly important in areas where relative sea level is rising and during storm periods. Managing these assets in the face of continuing pressure from human populations on a sustainable basis is a major task.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Lying at the margin of muddy/sandy foreshores and the land, saltmarsh has characteristics of both the marine and terrestrial environment. Many ecological textbooks describe the ‘natural’ saltmarsh succession. Some of the early classic ecological studies were of the saltmarsh vegetation on the North Norfolk coast (see, e.g. Chapman 1938, 1939, 1941) or the Dovey Estuary in west Wales (Yapp et al. 1917). These early studies helped provide the basis, not only for describing saltmarsh development, but also as part of a wider understanding of vegetation succession. The relationship between tidal inundation and the parallel spatial zonation, often observed within the habitat, was established. The importance of soil properties, plant species strategies, community structure and function as well as trophic relationships and energy flows were also identified and further elaborated (e.g. Ranwell 1972; Long & Mason 1983). Other work relates the vegetation to its geomorphological origins (see in particular Adam 1990).

Chapter 2. Human Influences

Despite the apparent and perceived ‘naturalness’ of the studied systems, few saltmarshes are entirely free from human influence. For centuries, grazing by domestic animals and haymaking took place in Europe and North America. The erection of embankments helped extend the period when grazing could take place and facilitate haymaking. In the early days, these were no more than low earth banks. With improvement in engineering techniques, permanent exclusion of the tide became possible. Some of the subsequent uses have modified the original marsh helping to create new areas with different, but valuable ‘semi-natural’ assets. Other activities are more destructive. Overall, permanent enclosure removes the natural ability of the saltmarsh to respond to the forces of wind, waves and tidal actions, especially during storms. The description that follows provides a summary of the progressively more destructive changes brought about by human activities and the implications for their nature conservation values.

Chapter 3. Nature Conservation

Chapter 2 describes ways in which the increasing human population has altered the natural coastal environment. The loss of species and habitat due to human exploitation led to the development of the nature conservation movement, not just for coastal areas but more generally. Initially the conservation of species and habitats was the concern of scientists, naturalists and others interested in nature. Conservation often meant ‘preservation’ of the environment and natural resources. The cornerstone of the nature conservation effort was the selection of ‘protected’ sites, using criteria designed to identify the most valuable natural or semi-natural assets, normally in terms of habitats and species. Once established and boundaries drawn, the sites became ‘sacrosanct’. Their future conservation rested on the prevention of loss and damage from harmful human developments. Where change occurred, which resulted in the original nature conservation values deteriorating, management formed a key part of the conservation strategy.

Chapter 4. States and Values

Chapter 1 describes the processes associated with saltmarsh development. Chapter 2 provides a summary of the main human influences affecting change within the saltmarsh habitat. Chapter 3 sets out some of the changes in perception of the importance of ‘natural’ and semi-natural habitats to wider socio-economic values.

Chapter 5. The Physical States

It is clear that saltmarshes have a range of values that change with the physical or biological conditions that influence them. The two general approaches to managing and restoring saltmarsh depend on whether the aim is to create or restore saltmarsh habitat, or manage existing saltmarsh vegetation. This Chapter deals with the first of these, which involves the trends and trade-offs associated with the creation, maintenance or restoration of the habitat. The principal concerns here relate to economic and social values, including those associated with flood protection (Section 4.3) as well as nature conservation. These include ‘quantitative’ parameters such as location, area, width and height of the saltmarsh. The ‘qualitative’ issues associated with nature conservation, such as the presence of specialist or rare plant and animal communities or vegetation complexity, are covered in Chapter 7.

Chapter 6. Physical States, Restoration Methods

This chapter provides a summary of the main methods of restoration, i.e. the established ways of moving from the ‘existing state’ where saltmarsh is lost, to the ‘desired state’ where saltmarsh is restored.

Chapter 7. Vegetation States

The physical conditions determine whether saltmarsh develops or not. Its lateral extent and vertical accretion rates depend on the establishment and growth of vegetation. Under natural conditions the tides, sediment dynamics drainage and exposure to waves influence the way the vegetation responds. Climatic variation also plays a part in determining the type of plant communities developing in different geographical locations (Section 4.5.1).

Chapter 8. Grazing Management

Grazing by both native herbivores and domestic stock is an important element in the development of saltmarshes in temperate regions. By removing the vegetation, the animals significantly alter the value of the habitat. Changes in grazing pressure can have both dramatic and subtle affects on the nature of the vegetation and its associated animals. As such, setting or changing grazing levels on a particular saltmarsh requires careful planning.

Chapter 9. Spartina

Spartina species form a group of salt-tolerant grasses which occur in several different parts of the world. Geographically centred along the east coast of North and South America, outliers occur on the west coast of North America, Europe and Tristan da Cunha (Table 19).

Chapter 10. Conclusions

This book has described saltmarshes, their development and position in the wider coastal ecosystems (Chapter 1). It has considered the extent of human influence from grazing management, through to enclosure for agriculture (arable and rice cultivation) and the development of infrastructure such as ports, harbours, industry, housing and roads (Chapter 2). Recognition that losses have been extensive, putting at risk both nature conservation and socio-economic interests, led to a change in the view of the role of saltmarshes (Chapter 3). Consideration of the values attached to different physical and biological (vegetated) ‘states’ (Chapter 4) led to the development of ‘models’ for habitat restoration and vegetation management. Included in this were discussions of the trends and trade-offs associated with moving between the different physical states (Chapter 5) and ways of achieving these (Chapter 6). Similar considerations apply in relation to grazing management dealt with in Chapters 7 and 8. An additional chapter considers the special case of Spartina spp. (Chapter 9).

Backmatter

Titel: Saltmarsh Conservation, Management and Restoration
verfasst von: J. Patrick Doody
Verlag: Springer Netherlands
Electronic ISBN: 978-1-4020-5748-9
Print ISBN: 978-1-4020-4603-2
DOI: https://doi.org/10.1007/978-1-4020-5748-9