2026-09-22T03:18:55Zhttps://repository.unam.edu.na/server/oai/requestoai:repository.unam.edu.na:11070/41822025-11-01T22:01:10Zcom_11070_3405com_11070_3311com_11070_3304col_11070_3414
Kwembeya, E. G.
Ondigo, Lilian K.
2025-10-30T14:10:23Z
2025-10-30T14:10:23Z
2021
http://hdl.handle.net/11070/4182
A thesis submitted in fulfilment of the requirements for the Degree of Master of Science (By Thesis)
Aerial parasitic plants, commonly called mistletoes, are a polyphyletic group of
organisms with a common evolutionary ancestor. This study was aimed at determining
composition, spatial abundance within hosts, co-occurrence and host preference of
mistletoes in the central highland savannas. The study site was divided into four
sampling areas based on the presence of the distribution records of the species. Forty
circular plots were demarcated and for every infested host plant species within these
plots, canopy height, two diameter measurements at approximately 90", number of
mistletoes, mistletoe species were recorded. All non-infested plant species within the
plot were also identified and their abundances were recorded. Based on field records
and herbarium records, four mistletoe species were identified and mapped namely;
Oncocalyx welwitschii, Plicosepalus kalachariensis, and Tapinanthus oleifolius,
belonging to the Family Loranthaceae and, Viscum rotundifolium which belongs to
Family Viscaceae. A simple linear regression model established that canopy volume
accounted for 12% of the variation in mistletoe abundance (R2 = 0.12, p < 0.001).
However, canopy diameter was a better predictor of mistletoe abundance than canopy
volume and accounted 20% of the variation in mistletoe abundance within the host
canopy (R2 = 0.20, p = 0.0003). Canopy volume was a poor predictor because it might
have included branches of various sizes even those that do not support mistletoe
establishment. Also gaps within the host canopy as well as the extent and positioning
of branches might have led to an overestimation of the actual volume of the host
canopy that can potentially be infested by parasites. The results further revealed a
statistically significant relationship between mistletoe abundance and vertical canopy
position (x2 = 67.089, df = 6, p < 0.00 l) with most mistletoes occurring in the lower
and middle third of the canopy of the host plant. The presence of V. rotundifolium and
P. kalachariensis on the lower third of the canopy of the host plant could be explained
by habitat preference and deposition behaviour of the Red faced mousebird ( Urocolius
indicus). This means that the selection of this bird species for lower third of canopy
for nesting and roosting, results in defecating of seeds more frequently on this part. On
the contrary, the distribution ofT. oleifolius and 0. welwitschii in the middle third of
the canopy could have been due to perch preference of the Yellow-fronted Tinker
Barbets (Pogoniulus chrysoconus). It is possible they perch in the middle third of the
canopy because there is a low risk of predation. Also, it could be that the branches in
en
University of Namibia
Aerial parasitic plants
Polyphyletic group
Central highland savannas
Namibia
University of Namibia
Composition, spatial abundance, co-occurrence and host preference of mistletoes in the Central highland savanna of Namibia
Thesisopen.access