ORDINATION OF NIGERIAN GUINEA SAVANNA PLANT COMMUNITIES
ORDINATION OF NIGERIAN GUINEA SAVANNA PLANT COMMUNITIES
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Date
1980-05
Authors
OSAN0T0, G. 0.
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Abstract
This thesis is an attempt to provide an objective quantitative
ecological interpretation to the trends and aggregations of the flora
within representative portions of the so-called Nigerian Northern Guinea
Savanna Zone, using ordination and classification. The aim of the
investigation was to test the homogeneity of the plant distribution on
which the delineation of the ecological zone had been established.
My field surveys were preceded by preliminary stratifications of the
environment into relatively homogeneous domains, partly based on
geomorphological differences in the environment, using aerial photographic
interpretations, and partly based on visible distinct forms of land use.
419 species were encountered in 714 quadrats.
I used a standard agglomerative Cluster Analytic technique available
in the Oxford University Computing Laboratory to sort plant communities
from the floristic data matrices which I had already arranged into sets
of synoptic matrices. The Cluster Analytic results were cross-checked
with Rao's Canonical Factor Analysis which I introduced into synecological
investigations as an ordination method from the Statistical Packages for
the Social Sciences of Nie, et al (1975).
Fifty relatively distinct communities of different sizes and four
sub-communities were detected by the two multivariate analytic methods.
The communities represent relatively distinct floral assemblages. Nine
primary factors controlling floral distribution, apart from the climate,
were identified, largely by quantitative methods.
I conclude that the 'Northern Guinea Savanna' has no ecological
homogeneity apart from climate, and its use alone as a reason for
delimiting the zone from the rest of the Country's vegetation is
inconsistent with the very bases of ecology. I suggest 'cerrado' as a
comprehensive substitute for "the catachrestic word, savanna, which is
applied to nearly every type of tropical vegetation from swamps to
Description
A thesis submitted for the
degree of
Doctor of Philosophy
in the University of Oxford
Wolfson College, May 1980.
Oxford,
Keywords
ORDINATION,, NIGERIAN,, GUINEA,, SAVANNA,, PLANT,, COMMUNITIES,