4 - Coping with the environment

Summary

Introduction

The saltmarsh environment is far removed from the optimum for growth of most plant species. Environmental characteristics of saltmarshes which would be inimical to plants include:

High (but variable) salinity in the soil solution;

Essential nutrient ions present as a low proportion of the total ionic

composition of the soil solution;

Anaerobic soil conditions.

Tidal immersion may have a number of effects including:

Temperature shock;

Changes in photoperiod;

Mechanical effects of tidal currents;

Deposition of sediment on leaf surfaces.

Interest in the physiological ecology of saltmarsh plants has a long history but most research has been on the effects of salinity and other aspects of the environment have received little attention.

It is the salinity of saltmarshes which distinguishes them from freshwater marshes and fens but the concentration of interest on salinity has possibly led to a narrow view of the important factors operating to differentiate between saltmarsh communities. While it may be appropriate to see the selection of the saltmarsh flora from the broader terrestrial flora as being on the basis of salt tolerance, selection for particular microhabitats within the saltmarsh may have favoured other traits. Within the framework of a salt-tolerant flora selection for occurrence in different communities may have been in terms of tolerance to varying degrees of soil anaerobiosis, ability to thrive under particular soil nitrogen levels, or ability to withstand currents of particular velocity.