Population Structure of Catha Edulis (Vahl) Forssk. Ex Endl. And Its Impact on Woody Species Composition in Vumba, Zimbabwe

Evelyn Ngarakana, Clemence Zimudzi, Shakkie Kativu, Brita Stedje


Different variants of C. edulis have been introduced to Southern Africa by Somali and Ethiopian immigrants over the last few decades. Sites occupied by C. edulis in the Eastern Highlands of Zimbabwe tend to be species poor, with C. edulis dominating the flora. An investigation was carried out to establish the population structure of C. edulis within Vumba forest of Zimbabwe and its impact on native species. Results showed that, sites occupied by C. edulis were less diverse in terms of species composition with a total of 6 co-occurring species, while adjacent sites without C. edulis had a total of 15 species. Independent T test results showed that in both Shannon diversity index and Equitability test, the t Stat values of 60.56 and 63.82, respectively, were greater than the t Critical value of 2.78. Hence there is a significant difference in species diversity and evenness between C. edulis occupied sites and adjacent unoccupied sites. Diameter class distribution of C. edulis showed an inverse J-distribution across sites occupied by the species under different regimes of disturbance. Co-occurring species showed an irregular bell-shaped distribution with complete absence of individuals in classes 0-8 cm, 21-24 cm and 29-35 cm, suggesting that the species are in poor regeneration capacity. It was concluded that C. edulis has a high regeneration potential while populations of competing native species are in apparent unstable condition.  The predominance of C. edulis in sections furthest away from disturbance suggests an encroachment of the species beyond disturbed sites.


species; distribution; dominance; encroachment; composition; plant

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DOI: http://dx.doi.org/10.52155/ijpsat.v30.1.3877


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