Mageto Evans, Abel Kamweya, John Ochora, Samson Maobe
Abstract: It has been observed that anthropogenic activities namely, farming, tree harvesting, seasonal fire regimes, introduction of exotic tree species like Eucalyptus and Greviella, and collection of herbs for medicinal use are going on and form a major threat for the orchid Polystachya fusiformis (Thou.) Lindl. This study determined the relative abundance and distribution of the species Polystachya fusiformis (Thou.) Lindl. in the Manga range ecosystem of Kisii, Western Kenya during two flowering seasons. Other results of the present study were analyzed with SPSS version 17 for paired sample correlations, OriginPro7 t-Test and ANOVA, Minitab 16 chi-square test. From the analysis there is a significant correlation between altitude and number of orchid population clusters with a p-value of 0.008 in the distribution of Polystachya fusiformis (Thou.) Lindl. which led to rejection of the null hypothesis. The Levenes test for equal variance shows that at 0.05 there is a significant difference between altitude and number of clusters as indicated by the P value of 0.00004. Of the 88 sites sampled, only 41sites had orchid clusters. Principal component analysis using Unscrambler 9.7 indicated that many of the orchid population clusters fell within the range of one or two orchid population clusters. The score plots from the two Hotelings outputs show how well data is distributed including sample patterns, groupings, similarities and differences during the study. The two analyses illustrated how fire affects the orchid population on fire prone sites of the range. Orchid population clusters progressively increased with increase with altitude range (from 1800m to 1850m) above sea level, but number of orchid population clusters decreased towards 1950m. Sites with minimal anthropogenic disturbances (1796m, 1830m, 1854m, 1886m, and 1890m) had a higher number of orchid population clusters.
Keywords: Orchidaceae, Polystachya fusiformis, mycorrhiza, pollinia, herbivory