Comparing tree functional traits and species diversity along an increasing rainfall gradient in northern Namibia
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Date
2025
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University of Namibia
Abstract
Changes in precipitation patterns have the ability to affect the composition and the
variety of species within a plant community by altering their functional traits.
However, there has been a tendency to underestimate the importance of functional
diversity. This is particularly common in Namibia, despite a clear, gradient in
precipitation and where forecasts have predicted changes in precipitation regimes in
the future. This study examined how tree species diversity and functional traits
changed along an increasing rainfall gradient in northern Namibia. It employed a
quantitative approach with systematic sampling at 13 points along an approximately
1200 km transect. Tree species diversity fluctuated along the gradient and average
annual rainfall did not appear to have a significant effect, yet species diversity was
highest at sites with high rainfall. There was no statistical difference in the species
diversity among sites, but the estimated beta diversity was high. Plant functional
diversity indices and plant functional traits varied along the gradient. All three
functional diversity indices revealed weak relationships with species diversity. Among
the three functional diversity indices, only functional richness was significantly
affected by annual average rainfall. While the current study presents some contrasting
results, it remains relevant by providing an understanding of the dynamics between
plant species diversity and functional diversity. The results of the current study support
the conclusion that plant species diversity and plant functional diversity are both vital
components of ecosystem functioning, and that future research should incorporate a
wider array of functional traits and use more comprehensive data collection methods
that can build on the findings to further elucidate these complex interactions
Description
A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Wildlife Management and Ecotourism
Keywords
Climate change, Plant ecology, Precipitation, Species composition, Functional indices, Species evenness, Species richness, Functional traits, Namibia, University of Namibia