exotic are small in well-maintained 

 groves, but abandoned grove plant- 

 ings contain many reproductives and 

 seedlings, and it is apparent that 

 Brazilian pepper is rapidly occupy- 

 ing the abandoned sites. 



The plant communities that dev- 

 elop on recently abandoned farmlands 

 ( 1 to 2 years old) are extremely 

 diverse with regard to community 

 dominants and general floristic 

 composition. These species are 



uniformly classified together only 

 because they are on recently aban- 

 doned farmlands. The particular 

 short-term plant community that 

 occupies a given field will differ 

 according to many variables, parti- 

 cularly (1) the crop that was grown 

 prior to abandonment, (2) the time 

 of abandonment, (3) the intensity of 

 past cultivation, (4) the length of 

 time the land has been farmed in the 

 past, (5) the soil type and hydrope- 

 riod, and (6) the actual cultivation 

 practices including the history of 

 pesticide, herbicide, and fertilizer 

 use. In general, there are as many 

 types of annual recovery vegetations 

 as there are fallow fields. 



Napier grass ( Pennisetum pur - 

 pureum ) communities have become 

 increasingly abundant in the study 

 area within the past 10 years. This 

 species is an aggressive colonizer 

 of recently abandoned farmlands, 

 particularly those that have been 

 abandoned for less than 3 years. 

 Once it is established in a field, 

 it tends to persist there, and 

 essentially form a monoculture. 

 Surveys of these lands suggest that 

 napier grass will colonize a fallow 

 field within 2 or 3 years after 

 abandonment. It usually starts as 

 several widely dispersed individual 

 clumps that eventually coalesce and 

 limit the establishment of new colo- 

 nizing species. On fields where it 

 was present prior to the most recent 



clearing and farming operations, 

 napier grass rapidly reestablishes a 

 monoculture from tillers that were 

 present in the soil. 



The napier grass community is 

 characterized by a dense growth of 

 the grass, approximately 1.5 m to 

 3 m (5 to 10 ft) tall, which is 

 present generally as a monoculture. 

 Occasionally, a few associated 

 species are also present. These 

 include saltbush ( Baccharis halimi - 

 folia ) , Brazilian pepper ( Schinus 

 terebinthifolius ) , beggar tick 



( Bidens pilosa ), and primrose willow 

 ( Ludwiqia peruviana ). At present, 

 this community appears to be re- 

 stricted to lands that have been 

 disturbed by agricultural practices 

 and it does not seem to be coloniz- 

 ing natural communities either adja- 

 cent to or distant from napier grass 

 communities. This species is occa- 

 sionally encountered along road 

 berms and similar areas throughout 

 the study area, but it was never 

 found in a natural community. 



Saltbush-Brazilian pepper com- 

 munities represent the typical suc- 

 cessional community that becomes 

 established on farmlands that have 

 been fallow for approximately 5 

 years. After the establishment of 

 these co-dominant species, the rela- 

 tive proportions of each change over 

 time with saltbush ( Baccharis hali- 

 mifolia ) decreasing and Brazilian 

 pepper ( Schinus terebinthifolius ) 

 increasing in relative importance. 

 The rate of change of each species 

 decreases after 15 years or so, and 

 the community becomes, in essence, a 

 Brazilian pepper forest with some 

 saltbush and wax myrtle ( Myrica 

 cerifera ) along edges and in open- 

 ings. 



The average height of the vege- 

 tation is from 1.0 to 5.5 m (3 to 18 

 ft) and the degree of canopy closure 



125 



