CHAPTER 3 



ZONATION ON THE MARSHES 



Striking patterns of plant 

 zonation on the New England marshes 

 attracted the attention of coastal 

 ecologists and, beginning with the 

 classic studies of Johnson and York 

 (1915), there has been a continuing 

 effort to understand the rr,echanisnis 

 responsible for the distribution and 

 groupings of higher plants, as well as 

 algae and animals, on these marshes 

 (e.g., Nichols 1920; Johnson 1925; 

 Taylor 1938; Chapman 1940; Miller and 

 Egler 1950; Webber 1967; Daiber 1977). 

 Most of the early efforts were des- 

 criptive, and we now have a reasonably 

 complete picture of the various marsh 

 species (for example, a taxonomic 

 guide for the Northeastern United 

 States was prepared by Moul 1973). 

 Progress has also been made in under- 

 standing the significance (or lack of 

 it) of various plant groupings and in 

 appreciating the other factors in 

 addition to tides that influence marsh 

 vegetation (Niering and V/arren 1980). 



HIGHER PLANTS 



( Pan i cum virgatum ), although where 

 fresh water enters the marsh, cattails 

 ( Typha spp. ) or reeds ( Phragmite s) 

 often dominate (Figure 15), But the 

 situation is complicated. As Redfield 

 (1972) observed, "The distinction 

 between high marsh and the upper 

 levels of the intertidal marsh cannot 

 be clearly drawn." Many writers seem 

 to consider at least a portion of the 

 stunted S^. alterniflora , which grows 

 away from the creekbanks, as belonging 

 to the high marsh, and the 

 characterization of any portion of the 

 marsh as "intertidal" may be 

 ambiguous. While it has often been 

 reported that S^. alterniflora grows up 

 to the level of mean high water, and 

 that this should define the 

 "intertidal" marsh, a careful analysis 

 of this proposition by Lagna (1975) 

 has shown that it has little merit 

 except as a rough approximation. 

 Because the level of MHW is an 

 arbitrary datum based on a 19-year 

 record, it would be a remarkable 

 coincidence if MHW was a finely tuned 

 botanical indicator. 



The working defi niton of a New 

 England high marsh is often a 

 taxonomic one, encompassing the area 

 dominated by salt marsh hay or fox 

 grass ( Spartina patens) and spike 

 grass "( Distichlis spicata ), in 

 contrast to the regularly flooded 

 marsh on which cordgrass ( Spartina 

 alterniflora ) is virtually a 

 monospecific dominant. Along the 

 upland border, the high marsh often 

 develops large areas of black grass 

 ( Juncus gerardi ) and switch grass 



21 



Our model of salt marsh 

 vegetation must include a certain 

 amount of overlap in boundaries. 

 Factors other than tidal range may 

 also influence the vegetation 

 patterns. The more prominent factors 

 have recently been summarized by 

 Niering and Warren (1980), including 

 salinity (Taylor 1938; Adams 1963; 

 Parrondo et al. 1978), nutrients 

 (Adams 1963; Mendelssohn 1979), and 

 soil oxygen (Linthurst 1979). All 

 factors contribute in varying degrees 



