In spatially heterogeneous habitats, plant community change may reflec
t spatially localized population-level processes that are sensitive to
the size of an average habitat patch. However, local species turnover
can also be determined by initial conditions and large-scale processe
s, in which case patch size effects may be overridden. To examine the
role of patch size in directing secondary succession, we subdivided a
newly abandoned agricultural field into an array of experimental patch
es (32, 288, and 5000 m(2), grouped to sample equivalent portions of t
he field), and have thereafter censused the resident plant and animal
communities at regular intervals. Here we report results from the firs
t 6 yr of studies on the changing vascular plant community in an exper
imentally fragmented landscape. The general course of change in all pa
tches followed a trajectory typical of old-field succession, toward in
creasing dominance by longer lived and larger plant species. The same
group of species that dominated at the start of the study continued to
dominate after 6 yr, although in very different proportional abundanc
es. Larger patches were more species rich than their smaller counterpa
rts, and had a higher proportion of nonshared species, but the additio
nal species were transient and low in abundance. Spatial heterogeneity
in vegetation, measured as local community dissimilarity, increased i
n all patches but to a lesser extent in the largest patches, where cen
suses of nearby permanent quadrats indicated less divergence over time
. At a population level, the strongest effect of patch size was that l
ocal populations of clonal species were more prone to disappear from t
he smallest patches. Nevertheless, summary measures of temporal commun
ity change did not reflect significant differences in localized specie
s turnover. We conclude that patch size does not markedly affect the r
ate or pattern of early secondary succession, at the scales imposed in
our experiment.