Population stage structure,survival and recruitment in the endangered East African forest herb <Emphasis Type="Italic">Saintpaulia</Emphasis> |
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Authors: | Johanna Kolehmainen Pia Mutikainen |
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Institution: | (1) Department of Applied Biology, University of Helsinki, P.O. Box 27, 00014 Helsinki, Finland;(2) Department of Biology, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland |
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Abstract: | Climatic seasonality, local habitat quality, and edge effects created by forest fragmentation due to human activity may affect
the performance of endangered rain forest understory herbs. Viability and seasonal dynamics of the populations of the endangered
Saintpaulia
confusa, S. difficilis, and S. grotei were studied in a protected seasonal submontane forest in NE Tanzania by examining plant life-history traits, population
stage structure, and the effects of habitat quality on plant performance. The population stage structures were of the dynamic
type. There was a lower frequency of seedlings (57.9%) and higher frequency of juvenile (13.3%) and adult plants (28.8%) in
S. confusa than in S. difficilis (74%, 10.7% and 15.3%, respectively). Seedling recruitment occurred from May to August with an average of 54, 103 and 38
emerged seedlings per 1 m2 study plot (S. confusa, S. difficilis, and S. grotei, respectively). Presence of the seed bank was also an indication of the regeneration potential of the populations. Mortality
was high during the dry and hot season from December to March. Survival was lowest in juvenile plants, higher in sterile adult
plants and the highest in fertile adult plants. Because survival was the lowest on dry substrates under open canopy, our data
suggest that forest fragmentation, by reducing shade and humidity, will increase mortality in Saintpaulia. Furthermore, since the mortality was highest in seedlings and juveniles, forest fragmentation is likely to impede the regeneration
of the Saintpaulia populations. |
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Keywords: | African violet Eastern Arc Mountains Gesneriaceae Habitat quality Life history Seasonality |
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