0198566123.pdf

particular species being evident over the period
since 1979 (Bush et al. 1992; Whittaker et al. 1998).
The business of forest succession is ongoing.

A dispersal-structured model of island recolonization

The community-level changes have been under-
pinned by trends within the colonization data

134 COMMUNITY ASSEMBLY AND DYNAMICS

(Whittakeret al. 1989, 1992a). Figure 5.6 simplifies

these trends into three time-slices, restricting the

treatment to the island of Rakata, for which the best

data (least confounded by volcanic disturbance) are

available. The figures are for all species recorded

from the island, whether still present or not

(Whittaker and Jones 1994a). Phase 1 represents the

pioneering stage during which wind-dispersed pio-

neers, first ferns, and then grasses and composites

Sea Animal

Wind

Colonization rate increases as

attraction to frugivores increases

Pioneers lose ground

Colonization

continues at a

reduced pace

0.18

Ferns

1.18 1.32

0.86

Other

Sea Animal

Wind

Habitat

restrictions only

Species with large, heavy,

winged seeds, such as

many mature forest

canopy trees

Restricted groups:

colonization improbable

Large seeded bat-spread

or terrestrial mammal-spread

species

Animal

Wind

Delayed

colonization

of interior

Phase 1

Rapid colonization

of strand-line

Simple succession

1.64

0.14

1.0

Ferns

1.0

Other

Wind

0.83

Ferns

0.83

Other

0.29 1.26

Phase 3

Colonization rate declines

Diplochorous species

spread to interior by

birds and bats

More forest trees arrive

Local populations of bats

and birds critical to

mozaic development

Sea Sea Animal

Phase 2

(ferns, grasses, composites) as habitat availability increases

Rapid colonization of interior by pioneers Forest epiphytes increase

Figure 5.6Plant recolonization of Rakata Island (Krakatau group) since sterilization in 1883. The three phases correspond with survey periods
and represent convenient subdivisions of the successional process. Phase 1, 1883–1897; phase 2, 1898–1919; phase 3, 1920–1989. Arrow
widths are proportional to the increase in cumulative species number in species/year (these values are also given by each arrow). The flora is
subdivided into the primary dispersal categories, i.e. the means by which each species is considered most likely to have colonized: animal-
dispersed (zoochorous), wind-dispersed (anemochorous), and sea-dispersed (thalassochorous). The model distinguishes between strand-line (outer
circle) and interior habitats and, in the fourth figure, identifies constraints on further colonization. (From Whittaker and Jones 1994 a.)