Tropical Forest Community Ecology

368 Chris J. Peterson and Walter P. Carson

INTRODUCTION

Is post-agricultural succession in the tropics
fundamentally different than in the temperate
zone? A number of broad models of succession
have been developed for and tested in temper-
ate systems since Clements (1916) presented the
first general theory nearly a century ago. Can we
apply these models to tropical systems? Because
tropical systems typically have greater species
diversity, putatively more benign environmen-
tal conditions, and more complex and intimate
plant–animal interactions, processes underlying
succession in the tropics could be qualitatively
different than processes within temperate com-
munities. Here, we briefly describe nine prominent
conceptualandlife-historybasedmodelsthatwere
developed for temperate systems but appear to be
applicable to tropical succession. We ask whether
these models have provided a conceptual basis for
or motivated studies of post-agricultural succes-
sion in the tropics. We then identify the empirical
basis for the major constraints on woody species
recruitment in abandoned tropical pastures. We
suggest that the facilitation mechanism encapsu-
lated within the nucleation model (Yarranton and
Morrison 1974) provides a potential robust foun-
dation for new conceptual models of succession
in post-agricultural communities in the tropics.
Finally, we conclude with a description of five
areas where additional research will help provide
a foundation for both the testin gand buildin gof
general models of post-agricultural succession in
the tropics.

SCOPE OF THE CHAPTER

The scope of this chapter includes studies of
early succession in tropical habitats that were
previously in agriculture. We focus on the first
40–50 years of succession. We do not consider
succession followin glo g gin gwithout a griculture
(e.g., Swaine and Hall 1983), succession after
removal of exotic tree plantations (Duncan and
Chapman 2003), or succession in different-sized
gaps in intact forests (e.g., Schnitzer and Carson
2001, Pearsonet al. 2003). Although we have
examined 61 publications, this chapter is not

a comprehensive review of patterns of struc-

tural and compositional change (for this see

Finegan 1996, Guariguata and Ostertag 2001,

Meli 2003).

OVERVIEW OF PROMINENT

MODELS OR CONCEPTUAL

FRAMEWORKS OF SUCCESSION

Here we briefly introduce nine prominent gen-

eral models of secondary succession, all of which

may apply to post-agricultural succession in the

tropics. Typically, these models are not mutually

exclusive, often have different foci, vary in their

mechanistic detail, or attempt to describe different

components of succession.

Relay floristics

Under relay floristics, succession proceeds as

early colonists and their respective communities

modify the environment in such a way that they

facilitate and thereby hasten their own replace-

ment by later colonists and communities that are

not present at the beginning of succession. The

result is that whole communities arise and decline

in near unison, rather than individualistic species

dynamics; thus the synchronicity of turnover of

species is very high. This captures the essence of

Clements’ (1916) views of succession. The relay

floristics model is not spatial and does not consider

the influence of animals (e.g., dispersers, herbi-

vores, seed predators;Table 22.1). Nor is variation

in propagule availability considered as a major

influence on successional trajectories. Amon gthe

life-history traits that are considered important,

tolerance of environmental extremes is proba-

bly foremost (Table 22.1). Early colonizers are

thought to moderate these harsh conditions and

thereby facilitate the arrival and survival of a suite

of later successional species.

Initial floristic composition

In 1954, Egler proposed the initial floristic

composition (IFC) model of succession and con-

trasted it with relay floristics. Under the original