Fróðskaparrit - 01.01.2007, Side 179

The impact of grazing on mountain
vegetation and the arbuscular
mycorrhizal symbiont
177
Hvussu seyðabit ávirkar jjallavøkstur og arbuskul
sopprót
Anna Maria Fosaa' and Erla O/sen2
Faroese Museum of Nalural History, Debesartrøð, FO-IOO Torshavn, Faróe Islands.
Email: 1 anmarfos@ngs.fo and 2erla@ngs.fo
Abstract
ln 2000 an cnclosurc expcriment was established at
one lowland ( 70 m a.s.l) and one alpine (600 m a.s.l.)
site in the Faroe Islands. After five years of enclosure,
significant increascs were seen in vegetation biomass
at both altitudes as both the cover and vegetation
height increased. Five species changed their abun-
dance significanlly. Only minor changes of species
loss and gain were seen. Palatable grasses increased
their abundance in enclosed plots, both at the lowland
and the alpine site.
Roots from Agrostis capillaris were examined for
arbuscular mycorrhizal (AM) colonisation, and the
colonisation found to be greater at grazed plots. The
plant species that had a significantly negative response
to grazing were typically classified as normally myc-
orrhizal, whilc spccies that prolifcrated in grazed plots
were either classified as rarely mycorrhizal or as less
palatable.
Úrtak
í 2000 varð farið undir at kanna gróður við at seta
girðingar upp til at halda seyði burtur. Ein girðing var
gjørd í láglendi (70 m oman sjóvar) og ein í hálendi
(600 m oman sjóvar). Tá ið fimm ár vóru liðin, var
greitt, at plantunøgdin var størri innan fyri girðingar-
nar; tað sást bæði á hæddini á plantunum og gróðrar-
lagnutn. Títtleikin hjá fímm plantusløgum broyttist
munandi, men eingin týðiligur munur kom á plantu-
samansetingina orsakað av girðingini. Meira av grøs-
um, sum seyði dámar at bíta, vóru inni í girðingunum.
Hetta hcndi bæði í láglendi og hálendi.
Røtur á vanligum finagrasi (Agrostis capillaris)
vórðu kannaðar fyri arbuskul-sopprót, og nøgdin av
sopprót var størri uttan fyri girðingarnar, har sum bit
er. Tey plantusløgini, sum minkaðu munandi í títtleika,
tá ið tey vórðu bitin, vórðu slík, sum vanliga hava
sopprót, og tey sløg, sum tóku seg fram uttan fyri girð-
ingarnar, hava annaðhvørt ikki vanliga nakað serligt
av sopprót, ella eru ikki serliga átulig hjá seyði.
Introduction
Many studies have shown that herbivory
has a profound effect on plant communi-
ties through processes of grazing, tram-
pling, and urination. Grazing affects speci-
es richness by changing the competition
relationship between species and thus the
spatial heterogeneity of the vegetation due
Fróðskaparrit 55. bók 2007: 177-187