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Diversity and Distribution of Canopy Hemi-Parasitic Plant Species in Bwindi Impenetrable Forest, South Western Uganda

Bwindi forest has an exceptionally diverse flora and fauna that supports many species of conservation importance. The forest is, however, currently facing several management challenges, including the deficiency of data on several taxa. The canopy hemi-parasitic plant species (Mistletoes) have for example received little attention. Their identity, diversity, distribution and abundance are not well known. This study surveyed canopy hemi-parasitic plant species of Bwindi forest and determined their diversity and distribution. The specific objectives were to: i) determine the diversity of canopy hemi-parasitic plant species and their host plants in the disturbed and lightly disturbed sites; ii) determine the distribution abundance of canopy hemi-parasitic plants in relation to host characteristics; and iii) relate diversity and distribution of canopy hemi-parasitic plant species to local environmental factors. The forest was stratified into two non-overlapping strata, based on disturbance intensity (disturbed and lightly disturbed forest communities) for data collection. Transects of 1km long were established in disturbed and less disturbed forest communities in each study zone. Data was collected from 20m x 20m plots on alternating sides of each transect. Species composition was compared between disturbed and lightly disturbed sites using analysis of Similarity (ANOSIM). The average dissimilarity (SIMPER) was also considered in all study sites. Spearman rank correlation was used to examine the abundance of hemi-parasitic plants in relation to host characteristics. Canonical Correspondence Analysis (CCA) was used to determine the relationship between the distribution of parasitic species and environmental variables. The results show that a total of 21 canopy hemi-parasitic plant species in six genera and within two families (i.e. Loranthaceae and Viscaceae), occurs in Bwindi. These were hosted by 45 tree species occurring in 28 families. The diversity of hemi-parasitic plants ranged from 1.94-1.92 index and hosts2.43 -2.02and distribution was moderate with evenness (J􏰀) of 0.687. Canopy hemi- parasite plant communities were different in all the study sites, and their abundance, distribution and diversity follows the distribution of preferred hosts. There is a need to conserve host plant diversity in order to maintain the diversity of hemi-parasitic plant species.

2015