Norton, D. A.; Ladley, J. J.; Owen, H. J. 1997. Distribution and population structure of the loranthaceous mistletoes Alepis flavida, Peraxilla colensoi, and Peraxilla tetrapetala within two New Zealand Nothofagus forests. New Zealand Journal of Botany 35: 323-336.
Abstract
Our results confirm the findings of an earlier study
that suggested niche partitioning in the way Alepis flavida
and Peraxilla tetrapetala utilise the available resources within
the Nothofagus solandri canopy; Alepis flavida is
almost exclusively an outer branch parasite while Peraxilla tetrapetala
occurs most often on inner branches and the host trunk. Peraxilla
colensoi has a similar distribution within host trees to Peraxilla
tetrapetala, except that it parasitises Nothofagus menziesii.
All three mistletoes showed non-random distribution patterns in terms
of the host trees they parasitise, being found more often on larger
trees. Larger host trees also carry a greater volume of mistletoe than
do smaller host trees. For Alepis flavida and Peraxilla
tetrapetala we found no evidence of host exclusion, whereby the
presence of one mistletoe excludes the other mistletoe species establishing,
observing the converse where host trees were more likely to have both
mistletoe species present than expected. Peraxilla colensoi
was found to be more common in Nothofagus-podocarp forest than
in Nothofagus or Nothofagus-Weinmannia-Metrosideros
forest. Alepis flavida and Peraxilla tetrapetala population
structures suggest that recruitment of young mistletoe plants has been
relatively continuous over the past few years in the Nothofagus
solandri forest we studied while the Peraxilla colensoi
population structure showed an apparent absence of small plants suggesting
a lack of recruitment in the Nothofagus menziesii forest we
studied.