The Ecology of Tidal Freshwater Marshes of the - USGS National ...

many of the tidal freshwater marshes ofthis region, often competing with otherplants to their exclusion. When not inpure stands, this grass associates with avariety of ot'ier emergent macrophytos includingsawgrass, cattails, wild rice, alli yator weed, water parsnip, and arrowarum(Figure 9).6) Mixed Aquatic Community Type - Themixed aquatic community consists of anextrenely variable conglomeration offreshwater marsh vegetation (Figure 10).Generally occurring in the upper intertidalzone of the marsh, it is comuosed ofa number of codominarlt species which forman intricate mosaic over the narsh surface.Important species include arrowarum,rose-ma1 1 ow, smart\.reecls, water-hemp,burrnarigolds, sweetflag, cattails, ricecutqrass, 1 oosestri fey arrowhead, and jewelweed.Certain comoonents of the mixedaquatic type dominate on a seasonal basis.7) Big Cordgrass Comrnunity Type - Bigcordyrass is often seen growing in nearlypure stands in narrow bands along tidalcreeks and sloughs, or on levee portionsof 01 igohal ine garshes (Figure 11).Arrow-arum and pickerelweed are associatedwith big cordgrass in these locales, butvdhon stands extend further up onto themarsh, this species will inter:nix withca ttai 1 s, cornr?ion reed, rice cutgrass, andwild rice.3) Bald Cypress/Black GUT Commuqity Ty~eThe bald cypress/black gum type (Figure12) generally represents an ecotonal communityforming the boundary between themarsh itself and wooded swam or up1 andforest. Situated in the most landwardportions of tile tidal freshwater marsh atapproximately the level of mean highwater, this comvunity consists of a mixtureof herbs, shrubs, and trees. Otheroverstory species include tupelo gum, redmaple, and ash, as well as shrubs such aswax-myrtl e and buttonbush. Understoryspecies include typical tnarsh plants, a7-tilough their diversity and density isreduced because of shading.Zonation-Figure 3. Cattail community type.The presence of reoccurring groups ofspecies which fom recognizable patternsin many wet1 and habitats has encouraged