New Zealand Journal of Botany abstract
B96064
Received 30 October 1996; accepted 3 April 1997
Distribution and population structure of the loranthaceous mistletoes Alepis
flavida, Peraxilla colensoi, and Peraxilla tetrapetala within
two New Zealand Nothofagus forests
DAVID A. NORTON
JENNY J. LADLEY
HAMISH J. OWEN*
Conservation Research Group
School of Forestry
University of Canterbury
Private Bag 4800
Christchurch, New Zealand
*Present address: Carter Holt Harvey, Private Bag 242, Whangamata, New
Zealand
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.
Keywords Alepis flavida; Peraxilla colensoi;
Peraxilla tetrapetala; Loranthaceae; mistletoes; population structure;
parasitism; ecology; conservation; Nothofagus menziesii; Nothofagus
solandri
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