The role of the National Botanic Garden of Namibia in plant species conservation

Abstract

This study was aimed at determining and comparing plant species diversity, species Composition and species richness in the National Botanic Garden and AloeTrail areas in Windhoek, Namibia. Floristic data were collected following standard random plot sampling procedure, where1m × 1m plots were nested in the 20m x 20m plots to measure herbaceous and woody plant species respectively. A total of 50 and 40 plots were sampled at the Botanic Garden and Aloe Trail areas respectively. The Shannon-Wiener diversity index was used to compute the species diversity of each plot sampled in each area. The Shapiro-Wilk test was used to test the data for normality. The Jaccard index of similarity revealed a 64% percentage similarity in species composition Between the two sites. However, there was no significant difference in the herbaceous Cover (Mann-Whitneystatistic, Z = −1.314,p = 0.189) between the two areas. The Botanic Garden showed a significantly higher species richness than the AloeTrail (ttest, p= 0.000). In addition, the Botanic Garden was found to be significantly more diverse (Mann-Whitneystatistic, U=478, p=0.000) than the AloeTrail because it is a protected area that is fenced and with minimal disturbances. The higher species diversity in the National Botanic Garden is attributable to the role of these living collections in the conservation of plant species.