FIG. 3-1 Early stages in the pond sere: open water, floating 

 stage, emergent vegetation, swamp shrubs. Everglades National 

 Park, Florida. 



widely or spread more readily into new areas than 

 do other kinds. The composition of the community 

 that develops and the rapidity with which it becomes 

 established depends, in large part, on the rates at 

 which different species invade. 



When the volcanic island of Krakatoa in the East 

 Indies blew up in 1883, all plant and animal life on 

 it and on two adjacent islands was destroyed. The 

 following year, the only living animal reported was a 

 single small spider. In 1886, it was apparent that the 

 pioneer plant stage consisted of a crust of blue-green 

 algae covering the lava. A few mosses were also 

 present, as were many ferns, and a scattering of some 

 15 species of flowering plants including 4 species of 

 grass. The vegetation stage following the algae con- 

 sisted predominantly of ferns, but the grasses 

 had become dominant over most of the island. By 

 1906, woodland had appeared, which has since de- 

 veloped into an increasingly luxuriant mixed forest. 

 Dispersal of seeds, spores, and other propagules was 

 effected by wind, sea, animals, and man, in that de- 



scending order of importance. The order in which 

 the propagules reached the islands greatly influenced 

 the succession that occurred ; as vegetation developed 

 it reacted on the soil and habitat, bringing about con- 

 ditions amenable to the return of the tropical rain 

 forest (Richards 1952). 



Very little study of animal life was made until 

 1908, and then only for three or four days. At that 

 time, 202 species were found on Krakatoa and 29 on 

 a nearby island. There were no earthworms, snakes, 

 or mammals present, but there were many spiders 

 and centipedes, a number of insects, 2 species each 

 of land snails and lizards, and 16 species of birds. A 

 more thorough survey in 1921 revealed 770 species 

 of animals including rats, apparently introduced in 

 1918, and bats, first noticed in 1920. In 1933, 1100 

 species were found, including 3 species of earth- 

 worms, but true forest mammals had not y§t appeared 

 and many families of forest birds were unrepre- 

 sented. As with plants, the invasion by animals de- 

 pended on wind, sea, and man and other animals, in 

 that descending order of importance. Survival and 

 establishment of the animal species was correlated 

 with the stage of vegetation that was reached. It is 

 of interest, however, that scavenger species appeared 

 first, then omnivores, herbivores, and finally preda- 

 tors and parasites. Succession of animals depended 

 in large part on the speed with which they reached 

 the island and on their finding proper food and shelter 

 (Dammerman 1948). 



Bioseres may be broadly grouped as priseres and 

 sttbseres, depending on whether they develop on pri- 

 mary or secondary bare areas. A primary bare area 

 is a sterile habitat, such as rock, sand, clay, or water. 

 A secondary bare area is a denudation resulting from 

 temporary flooding, fire, logging, cultivation, over- 

 grazing, or other phenomenon that does not produce 

 an extreme disturbance of the soil or substratum. 

 Since in the latter the habitat has already sup- 

 ported community life, and since the soil or sub- 

 stratum is already in an advanced stage of develop- 

 ment, the resulting subsere progresses rapidly and the 

 early pioneer stages of the prisere do not usually oc- 

 cur. A subsere will develop following the destruction 

 of any stage in a prisere, and the species composition 

 of the stages in the subsere will be influenced by the 

 particular priseral community that was destroyed. 



The early stages or communities that make up the 

 prisere depend largely on the type of bare area on 

 which the prisere originates. As succession proceeds, 

 however, later stages in the various seres in any area 

 having a relatively uniform and humid climate come 

 to be more and more alike. The successional devel- 

 opment from widely diversified communities in ini- 

 tially different habitats to closely similar or identical 

 climax communities in habitats that have also become 

 much alike is called convergence. 



22 Background 



