Skógræktarritið - 15.05.2001, Side 176

from this study may reveal mor-
phological responses of the birch
to grazing. The effect of caterpil-
lars is likely subtle and will
require more controlled experi-
ments to detect.
It would be interesting to see if
there is a negative effect of bud
and leaf herbivory on catkin pro-
duction in addition to damage
caused directly to catkins by her-
bivores. In Britain herbivores take
a significant toll of the annual
catkin production (Atkinsson
1992). More work is needed on
the functional ecology of herbi-
vores and their food plants in
Iceland. Future questions should
address the different scales at
which events occur ranging from
the interaction of individual birch
growth and herbivore feeding
patterns, up to the larger scale
questions of how grazing man-
agement and insect outbreaks
affect the birch ecosystem.
Acknowledgements
Thanks to Ása L. Aradóttir, Árni
Bragason, Arnþór Garðarsson,
Erkki Haukioja, Kalle Lertola and
Seppo Neuvonen for their encour-
agement and advice. People at the
icelandic Institute of Natural
History, Akureyri, the Icelandic
Forest Research Station at Mó-
gilsá, and the University of Turku,
Finland, facilitated this study. The
project was enhanced by a NorFA
Fellowship to Soffía and a
Scholarship from Nýsköpunar-
sjóður Námsmanna to Álfheiður.
Borgarprýði
Gróðrarstöð
Smiðjuvöllum 12-20
300 Akranes
Sími 431 5055
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GARÐEYRI EHF.
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Trjáfellingar
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