Vegetation patterns in salt marshes of Otago, New Zealand

Abstract Thirteen salt marshes of coastal Otago, New Zealand, were sampled and described using classification and ordination techniques, in an attempt to understand more about vegetation patterns both within marshes and amongst different marshes. Ordination indicates that the same set of primary factors is responsible for the salt marsh vegetation patterns of most marshes. These factors are all related to tides and are difficult to separate. Secondary factors common to most marshes are related to soil moisture, water ponding, and fresh water flow. This consistency results in characteristic and typical salt marsh communities zoned according to these factors. Each marsh, however, has anomalies which may be an important feature of that marsh. These create numerous peculiar and often unique plant communities which characterise the individual marshes. Often they can be correlated with edaphic differences or various cultural effects. With many marshes having been sampled, the simple community relationships seen within individual marshes become complex and difficult to interpret. As more marshes are examined the trends that can be seen by examining only a few marshes are seen to be misleading. Although superficially similar to salt marshes, lagoons are distinguished by a general absence of the typical plant communities. The flora is very similar to that of salt marshes, but the species associate in quite different ways.