A Study of the invasion of riparian systems in the Obafemi Awolowo University by Lagerstroemia Indica Linn.

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Date
2016
Journal Title
Journal ISSN
Volume Title
Publisher
Botany,Obafemi Awolowo University
Abstract
The study investigated and determined the extent and pattern of invasion of riparian systems of Obafemi Awolowo University by Lagerstroemia indica and elucidated the factors that make this invasion possible by determining the species composition and densities, relationship in terms of girth size distribution between the plant and native species of the plant communities. The reproduction mechanism in L. indica and its impacts on some soil properties and ecological thresholds along the riparian systems gradient were also determined with the view to providing information on the best way to control the invasive plant. Ten sampling plots, 50 m x 50 m were established in the riparian forests at different locations within Obafemi Awolowo University. In each sample plot, all the tree species ≥ 2 m in height were identified to species level and enumerated. The girths at breast height (gbh) of woody plants were measured. The data collected were used to establish the floristic composition, density, basal area, species diversity and evenness in the plots. Histograms of the girth size distribution of invasive L. indica and the native woody species in each plot were prepared, and compared for the rate of invasion of L. indica. Aspects of reproduction mechanism were observed, that is its growth from the root stocks. Five soil samples were collected along five transects perpendicular to the stream in each plot at the depth of 0 - 15 cm. The soil samples were analyzed for pH, bulk density, organic matter, organic carbon, total nitrogen and available phosphorus. The data obtained were analysed using descriptive and inferential statistics. Ecological threshold in the distribution of plant species along the riparian forest gradient on the soil properties data set were determined using Threshold Indicator Taxa Analysis (TITAN). ran in programming R language. The results showed that a total of forty (40) woody plant species belonging to twenty-one families were recorded in the study plots. Girth size class distribution of eight (1, 2, 3, 4, 5, 7, 8, and 10) plots showed that densities of L. indica were higher than that of native species. Which indicated high invasion and two (6 and 9) plots, had low densities of L. indica, which implied moderate invasion. Shannon-Wiener index showed that woody species diversity was highest in plot 6 (H’ = 2.6108) and lowest in plot 5 (H’ = 0.8620), while Sorensen index of similarity showed that plots 6 and 10, and plots 9 and 10 were the most similar (60%) in species composition. There were no significant differences (p > 0.05) in the soil properties in the study plots. Ecological threshold estimation showed that there was variability in the soil properties that determined the distribution of some plant species in the riparian system. The study concluded that invasion of L. indica drastically affected the biological and ecological attributes of the riparian systems by reducing the species composition of native plant species in Obafemi Awolowo University.
Description
xv,143p
Keywords
Plant species, Biological, Ecological, Riparian systems, Invasion of riparian systems, Lagerstroemia indica Linn
Citation
Arowolo,A.H (2016). A Study of the invasion of riparian systems in the Obafemi Awolowo University by Lagerstroemia Indica Linn. Obafemi Awolowo University
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