Fróðskaparrit - 01.01.2007, Side 188

186
THE IMPACT OF GRAZING ON MOUNTAIN VEGETATION
AND THE ARBUSCULAR MYCORRHIZAL SYMBIONT
Acknowledgements
This study has been made possible with kindness from
several institutions and grant providers. Faroese Natu-
ral History Museum, Faroese Research Council,
Faroese Agricultural Fund and Nordic Council of
Ministers all have contributed fmancially, technically
and otherwise provided resources. The mycorrhizal
part of this study is part of a PhD-project at thc Uni-
versity of York, supervised by Alastair Fitter.
References
Adler, P.B., Raff, D.A. and Lauenroth, W.K. 2001. The ef-
fect of grazing on the spatial heterogeneity of vegeta-
tion. Oecologia 128: 465-479.
Alonso, I„ Hartley, S.E. and Thurlow, M. 2001. Competi-
tion between heather and grasses on Scottish moor-
lands; interacting effects of nutrient enrichment and
grazing regime. Journal of Vegetation Science 12: 249-
260.
Austrheim, G. and Eriksson, O. 2001. Plant species diver-
sity and grazing in the Scandinavian mountains - pat-
tern and processes at different spatial scales. Ecogra-
phy 24: 683-695.
Bentivenga, S.P. and Hetrick, B.A.D. 1992. The effect of
prairie management practices on mycorrhizal symbio-
sis. Mycologia 84: 522-527.
Bethlenfalvay, G.J. and Dakessian, S. 1984. Grazing ef-
fects on mycorrhizal colonization and floristic compo-
sition of the vegetation on a semiaric range in northem
Nevada. Journal of Range Management 37:312-316.
Bethlenfalvay, G.J., Evans, R.A. and Lesperancc, A.L.
1985. Mycorrhizal colonization of crested wheatgrass
as influenced by grazing. Agronomy Journal 77: 233-
236.
Crawley, M.J. 1990. Rabbit grazing, plant competition and
seedling recruitment in acid grassland. Journal of Ap-
plied Ecology 27: 803-820.
Daft, M.J. and EI-Giahmi, A.A. 1978. Effect of arbuscular
mycorrhiza on plant growth. VIII. Effects of defolia-
tion and Iight on selectcd hosts. New Phytologist 80:
365-372.
Dupre, C. and Diekmann, M. 2001. Difference in species
richness and life-history traits between grazed and
abandoned grasslands in southem Sweden. Ecography
24: 275-286.
Eom, A.-H., Wilson, G.W.T. and Hartnett, D.C. 2001. Ef-
fects of ungulate grazers on arbuscular mycorrhizal
symbiosis and fungal community stmcture in tallgrass
prairie. Mycologia 93: 233-242.
Fosaa, A. M. 2004. Altitudina! distribution of plant com-
munities in the Faroe Islands. Fróðskaparrit 51: 200-
211.
Gehring, C.A. and Whitham, T.G. 1994. Interactions be-
tween aboveground herbivores and the mycorrhizal
mutualists of plants. Trends in Ecology and Evolution
9: 251-255.
Gehring, C.A., Wolf, J.E. and Theimer, T.C. 2002. Terres-
trial vertebrates promote arbuscular mycorrhizal fun-
gal diversity and inoculum potential in a rain forest
soil. Ecology Letters 5: 540-548.
Grace, C. and Stribley, D.P. 1991. A safer procedure for
routine staining of vesicular-arbuscular mycorrhizal
fungi. Mycological Research 95: 1160-1162.
Hartley, S.E. and Amos, L. 1999. Competitive interactions
between Nardus stricta L. and Calluna vulgaris (L)
Hull: the effect of fertilizer and defoliation on above-
and below-ground performance. Journal of Ecology
87: 330-340.
Hartley, S.E. and Mitchell, R.J. 2005. Manipulation of nu-
trient and grazing levels on heather moorlands:
changes in Calluna dominance and consequences for
community composition. Journal ofEcology 93: 990-
1004.
Hokka, V., Mikola, J., Vestberg, M. and Setala, H. 2004. In-
teractive effects of defoliation and an AM fungus on
plants and soil organisms in experimental legume-
grass communities. Oikos 106: 73-84.
Huisman, J., Grover, J.P., van der Wal, R. and van Andel, J.
1999. Competition for light, plant species replace-
ment, and herbivore abundance along productivity
gradients. In: Olff, H„ Brown, V.K. and Drent, R.H.
(eds). Between plants and predators. Blackwell-Sci-
ence, Oxford: 239-269.
Hulme, P.D., Pakeman, R.J., Torvell, L„ Fisher, J.M. and
Gordon, I.J. 1999. The effects of controlled sheep
grazing on the dynamics of upland Agrostis-Festuca
grassland. Journal of Applied Ecology 36: 866-900.
Komer, C. 1999. Alpine Plant Life. Functional plant ecol-
ogy of high mountain ecosystems. Springer-Verlag,
Heidelberg, Germany.
Koske, R.E. and Gemma J.N. 1989. A modified procedure
for staining roots to detect VA mycorrhizas. Mycologi-
cal Researclt 92: 486-505.
Kula, A.A.R., Hartnett, D.C. and Wilson, G.W.T. 2005. Ef-
fects of mycorrhizal symbiosis on tallgrass prairie
plant-herbivore interactions. Ecology Letters 8: 61-69.
Lugo, M.A., Maza, M.E.G. and Cabello, M.N. 2003. Ar-
buscular mycorrhizal fungi in a mountain grassland II:
Seasonal variation of colonization studied, along with
its relation to grazing and metabolic liost type. My-
cologia 95: 407-415.
Magnússon, B. and Magnússon, S.H. 1990. Studies in the
grazing of a drained lowland fen in Iceland. I. The re-
sponses of the vegetation to livestock grazing. Bú-
vísindi 4: 87-108.
McGonigle T.P., Miller, M.H., Evans, D.G., Fairchild, D.G.