Dense willow monocultures are 

 not very common within the bounda- 

 ries of the study area, being found 

 most frequently on the older aban- 

 doned farmlands south of Fla S.R. 

 27, east of Everglades National Park 

 in the northern portion of the Aero- 

 jet property. Willow monocultures 

 appear to develop on rockplowed 

 Perrine marls that have a hydrope- 

 riod in excess of 3 months, which 

 effectively prevents the establish- 

 ment of Brazilian pepper and other 

 hardwoods. 



This vegetation is typically a 

 rather open monoculture of willow 

 ( Salix caroliniana ) approximately 4 

 to 6 m (13 to 20 ft) tall. Several 

 marsh species characteristic of dis- 

 turbed lands and general secondary 

 successions are present. These 



include primrose willow ( Ludwiqia 

 peruviana ) , loosestrife ( Lythrum 

 lineare ) , bushy beardgrass ( Andropo - 

 gon qlomeratus ), saltbush ( Baccharis 

 halimifolia ) , and milkweed vine 

 ( Sarcostemma clausa ). A thin, mat- 

 ted ground cover is provided by 

 matter figwort ( Bacopa monnieri ) and 

 fleabane ( Eriqeron vermis ). 



Sawgrass-cypress-bayhead ana- 

 log communities occupy farmlands 

 that were abandoned prior to the 

 widespread use of rockplowing 

 (pre-1950s). Since abandonment, 



the recovery vegetation has devel- 

 oped and stabilized so that it 

 closely resembles a natural com- 

 munity quite similar to an open 

 canopy cypress forest and sawgrass 

 marsh. Exotic tree species are 



almost entirely absent, except for 

 an occasional Australian pine that 

 has colonized an elevated crop 

 mound. 



The community is largely domi- 

 nated by a dense growth of sawgrass 

 ( Cladium jamaicensis ) that is quite 

 uniform in height, ranging between 



0.8 and 1.2 m (3 to 4 ft). Locally 

 abundant are several other sawgrass 

 marsh species including aromatic 

 figwort ( Bacopa caroliniana ), beak 

 rush ( Rhynchospora tracyi ), nodding 

 beak rush ( Rhynchospora microarpa ), 

 musky mint ( Hyptis alata ) , and marsh 

 pink ( Sabatia brevifolia ). Some 



arboreal vegetation is usually 

 present composed of: bald cypress 

 ( Taxodium distichum ), dahoon holly 

 ( Ilex cassine ), red bay ( Persea 

 borbonia ) , myrsine ( Myrsine flori- 

 dana ) , saltbush ( Baccharis halimifo - 

 lia ) , sweet bay ( Magnolia virqin - 

 ica ) , willow ( Salix caroliniana ), 

 and coco plum ( Cyrysobalanus icaco ). 

 This vegetation is widely scattered 

 in nature and tends to occur on the 

 slightly elevated crop mounds. 



Before the extensive use of the 

 rockplow as an agricultural tool and 

 the wholesale naturalization of 

 exotic tree species, abandoned marl 

 farmlands rapidly reverted to commu- 

 nities that were quasi-natural in 

 floristics and structure. Under the 

 present conditions of agricultural 

 cultivation and land use patterns, 

 this type of successional recovery 

 does not occur, and former marshes 

 and prairies become dominated by 

 arboreal vegetation usually contain- 

 ing some proportion of exotic trees 

 and shrubs. 



6.2 HABITAT PARTITIONING 

 FOR FISH AND WILDLIFE 

 PRODUCTION 



6.21 ENERGY FLOW 



Figure 47 presents a summary 

 diagram of energy flow through the 

 freshwater portion of the lower 

 Everglades. This diagram is best 

 viewed as a very generalized organi- 

 zational scheme rather than an at- 

 tempt to accurately document the 

 food habits of the over 350 vertebr- 

 ate species reported from the area. 



127 



