bracken fern ( Pteridium aquili- 

 nium ) , brake fern ( Pteris lonifo - 

 lia) , leather fern ( Achrostichum 

 danaeaefolium ) , bushy beardgrass 

 ( Andropogon qlomeratus ), and night- 

 shade (Solanumspp) . The canopy and 

 understory of this community is 

 devoid of native hammock or bayhead 

 species, and it appears that the 

 exotic trees will ultimately domi- 

 nate recovery vegetation that devel- 

 ops on this site. 



Cajeput forests, at present, 

 are confined primarily to the east- 

 ern margin of Shark Slough west of 

 L-31E. Cajeput develops most rapid- 

 ly on sawgrass peat soils, but is 

 also found on marls and marly peat 

 soils east of the Shark Slough. 

 These communities are structurally 

 very similar to cypress dome forests 

 in a central location with progres- 

 sively shorter and smaller indivi- 

 duals arrayed towards the periphery 

 of the community. This forest type 

 consists of the exotic tree species 

 cajeput ( Melaleuca quinquenervia ) 

 and little else. 



This type of forest appears to 

 be becoming more common along the 

 eastern margins of the Shark Slough 

 at the expense of natural communi- 

 ties, particularly sawgrass marsh 

 and muhly prairies. This trend is 

 very significant in regard to the 

 future management of natural marsh 

 ecosystems that are identical to 

 these and are contained within the 

 nearby Everglades National Park. 

 These sawgrass marshes would appear 

 to have an increasing susceptibility 

 to cajeput colonization as the re- 

 producing population of this species 

 extends westward into previously 

 undisturbed natural marshlands. 



Australian pine forests are 

 considerably more abundant within 



the study area than are cajeput 

 forests. Australian pine forests 



seem to be the typical exotic tree 

 community on Perrine marl soils, and 

 are quite common and widespread 

 throughout the rocky gladelands in 

 the vicinity of Chekika hammock and 

 along the eastern boundary of Ever- 

 glades National Park. As a rule, 

 Australian pine forests occupy 

 slightly elevated sites that have 

 roughly the same hydroperiod as bay- 

 head forest communities. It appears 

 that this exotic forest community 

 frequently develops on sites that 

 once supported bayhead or tropical 

 hammock vegetation that was removed 

 by one or a series of severe fires. 



This community is characterized 

 by a monoculture of Australian pine 

 ( Casuarina equisetifolia ) , forming a 

 closed canopy layer approximately 12 

 to 15 m (40 to 50 ft) high. Seed- 

 ling and saplings are currently rare 

 under the canopy and are generally 

 uncommon along the margins of the 

 forest. Understory vegetation is 

 largely absent and the forest floor 

 is composed of a dense layer of 

 Australian pine litter and a few 

 species of ubiquitous annuals. 

 There are generally a few outliers 

 within several hundred meters of the 

 forest and these individuals are 

 frequently reproductive trees. 



At present, Australian pine 

 forest vegetation appears to be 

 stable with respect to major succes- 

 sional changes, and as such does not 

 seem to be either dramatically in- 

 creasing nor decreasing in area or 

 overall density within the study 

 area. Individual reproductives, 



however, appear to be slightly in- 

 creasing in abundance throughout the 

 rocky gladelands, but this non-con- 

 tinuous population is frequently 

 killed by fires or lighting. 



122 



