Agriculturally Induced 

 Succession 



Agriculturally induced succes- 

 sions incorporate 10 identifiable 

 communities reflecting the very 

 intense invasion by exotic species. 

 These communities are summarized in 

 Table 24. An excellent and concise 

 summary of the composition and 

 structure of these disturbed commu- 

 nities is presented by Hilsenbeck 

 et al. (1979). The following dis- 

 cussion is taken largely from that 

 text. 



Dominant Species 



Muhlenberghia 

 f i lipes 



Typha latifolia 



Citrus, Avocado, 



Mango 



Andropogon qlomeratus 



Bacchar i s hal imif olia 



Bidens pilosa 



Ambrosia artemisiifolia 



Baccnaris hal imifolia 

 Pennisetum purpureum 



Pennisetum purpureum 



Schinus terebinthifol ius 

 Baccharis halimifolia 



Schinus terebinthifolius 



Schinus terebinthifolius 



Psidium guajava 



Salix carpliniana 

 Ludwigia peruviana 



Cladium jaimaicensis 

 TaKQdium distichum 



vegetation community 

 types occurring on 

 abandoned farmlands 

 in the east Everglades 

 (adapted from Hilenbeck 

 et al. 1979). 



Muhly prairies that have been 

 rockplowed, but not farmed, are not 

 common in the east Everglades area. 

 These sites provide an important 

 insight into the response of the 

 prairie community to an episode of 

 general community disruption result- 



ing from the initial stages of agri- 

 cultural preparation of new lands. 



The recovery of the prairie 

 vegetation following the low inten- 

 sity of rockplowing is similar to 

 that following a severe surface 

 fire. In general, the prairie domi- 

 nant, muhly grass ( Muhlenbergia 

 filipes ) appears to suffer a low 

 mortality rate and the co-dominant 

 species, sawgrass ( Cladium jamai- 

 cense ) although persisting, appears 

 to be more strongly diminished by 

 the process. Other species, namely 

 beak rush ( Rhynchospora tracyi ), 

 narrow beardgrass ( Schizachyrium 

 rhizomatum ) , marsh fleabane ( Pluchea 

 rosea ) , smooth cordgrass ( Spartina 

 bakerii ) , and cattail ( Typha lati- 

 folia ) display a variable response 

 to the disturbance. Only cattail 

 and smooth cordgrass appear to 

 increase in abundance, while the 

 other appear to decrease markedly. 

 Bushy beardgrass ( Andropogon qlo - 

 meratus ) is considerably more abun- 

 dant in the community following the 

 rockplowing operation. 



These observations suggest that 

 a single or a limited number of epi- 

 sodes of low intensity rockplowing 

 in muhly prairie communities does 

 not totally destroy the pre-existing 

 community organization nor does it 

 strongly select against the compo- 

 nent species to produce drastic 

 compositional changes. The direct 

 or indirect effects on the prairie 

 communities over time, however, 

 cannot be evaluated with short-term 

 survey techniques. There is a clear 

 indication that some of the rarer 

 species of herbaceous perennials 

 have disappeared, but this conditon 

 could be short-lived and reversible 

 through natural processes. 



The outcome of the rockplowing 

 in conjunction with later farming is 

 markedly different from the outcome 



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