B-2 



that the Chesapeake Bay region should actually be considered an 

 Eastern Oak-Hickory Forest region due to the dominance of oaks 

 Quercus spp . and hickories Carya spp . in the climax communities. 



The following is a breakdown of the major plant 

 community types occurring in the Chesapeake Bay region with an 

 indication of some of the critical environmental factors 

 (limiting factors) controlling the community. After each 

 description of a plant community type, some of the typical ani- 

 mal species associated with it are listed. 



Aquatic Ecosystems 



The northern portion of the Atlantic Coastal Plain is 

 characterized by drowned river valleys, the best example of which 

 is the Chesapeake Bay. The Chesapeake Bay is a unique estuary 

 comprised of the drowned Susquehanna River Valley and several of 

 its tributaries. The bay is unique because of its size and 

 isolation from the Atlantic Ocean. 



Salt Marsh 



The salt marsh community is here divided into two 

 different phases, the regularly flooded phase, and the irregularly 

 flooded phase. Salt marsh develops in the low areas where 

 inundation by salt water is frequent enough to prevent the sur- 

 vival of non-salt-tolerant species. The vegetation is dominated 

 by various grasses and sedges. Woody species occur only on the 

 higher ridges in this community. 



The regularly flooded salt marshes occur along the open 

 ocean and in the shallow sounds behind barrier islands. They are 

 inundated twice daily to a depth of six inches or more by the 

 highly saline waters of normal high tides. The flushing action 

 of the tides is essential to this salt marsh community. It 

 brings in certain nutrients from the surrounding estuary and 

 flushes out toxic waste materials. Tidal creeks meander through 

 the salt marsh and are rich in silt and organic debris from inland 

 runoff. This provides additional nutrient supply to the surround- 

 ing marshes. 



The regularly flooded salt marshes are generally dominated 

 by saltmarsh cordgrass Spartina altemiflora . Saltmeadow cordgrass 

 Spartina patens , salt grass Distichlis spicata , black needlerush 

 Juncus roemerianus and glasswort Salicornia spp . are usually abun- 

 dant. Along the more elevated ridges of the marsh, groundsel 

 Baccharis halimifolia , marsh elder Iva frutescens , sea oxeye 

 Borrichia frutescens , and sea lavender Limonium spp . occur. 



