New Zealand Journal of Botany abstracts
B99062Received 13 December 1999; accepted 13 April 2000
Regional patterns of plant species richness in southern New Zealand
GEOFFREY ROGERS
Science & Research Unit
Science, Technology and Information Services
Department of Conservation
P.O. Box 5244
Dunedin, New Zealand
JAKE OVERTON
Landcare Research
Private Bag 3127
Hamilton, New Zealand
Abstract We examine the proposition that spatial
heterogeneity, as modelled by land area, productivity-influencing climatic
variables, and elevation, is a useful predictor of regional patterns of species
richness in 56 regions of southern New Zealand stretching from mid Canterbury
to Campbell Island. We also examine whether regional patterns of taxonomic
richness support the concept of a Late Cenozoic radiation of upland floras and
that this was sourced from just a few genera in a few widespread to
cosmopolitan families.
We found several contrasting geographical patterns in taxonomic richness.
Several mainly mountain regions just east of the main divide in western
Canterbury, Otago, and Southland are unusually species-rich, but not genus- or
family-rich. Conversely, several coastal regions of eastern South Island are
unusually genus- and family-rich, but not species-rich. Four geographically
distinct groups of regions share relatively species-, genus-, and
family-depauperate floras: maritime-influenced regions of Fiordland, the
Chatham and subantarctic islands, inland and lowland basins of Otago and
Southland, and eastern Otago's block mountains. Various combinations of
elevation range, climatic variability, and land area explain 54% to 61% of the
variability in richness of species, genera, families, and life-form groups.
Mean daily temperature of the coldest month appears the strongest climatic
variable at depressing floristic richness, although moderate degrees of
continentality of climate increase it.
We conclude that both propositions are supported by the present study.
Databases of regional-scale patterns of plant species richness should be useful
for selecting mainland islands for ecosystem restoration, estimating ecosystem
or guild diversity, and testing the ecological distinctiveness of ecological
regions and districts.
Keywords biodiversity; species richness; taxonomic richness;
gamma-diversity; environmental diversity
New Zealand Journal of Botany, 2000, Vol. 38: 629-633
0028-825X/00/3804-0629 $7.00 (c) The Royal Society of New Zealand 2000
PDF file of entire paper: medium quality (1282K); (scanned from paper original: notes about this process)
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