Root Fungus Colonization along an Altitudinal Gradient in North Norway

Mycorrhizal symbiosis is generally advantageous for plants in nutrient-poor soils, but this advantage may be low in arcto-alpine conditions. While the relative coverage of nonmycorrhizal plant species has been found to increase along an altitudinal gradient, the within-species patterns of mycorrhizal colonization in arctic and alpine plants are not well known, and different results have been obtained in relation to altitude. We investigated arbuscular mycorrhizal (AM) and dark-septate endophytic (DSE) root colonization in six subarctic herbaceous plants Ranunculus glacialis L., Saxifraga aizoides L., Sibbaldia procumbens L., Solidago virgaurea L., Trientalis europaea L., and Viola biflora L. along an altitudinal gradient (0–1400 m a.s.l.) at Mt. Paras, North Norway. We did not find any consistent decline in the different types of fungus colonization along the entire gradient. There was no statistically significant shift in coarse AM or DSE colonization with altitude. However, fine endophyte type AM colonization showed a statistically significant, positive relationship with altitude. These results suggest that root colonization of any particular mycorrhizal species may yield different gradient patterns with altitude than the relative coverages of mycorrhizal and nonmycorrhizal plant taxa. Because of its positive association with altitude, fine endophyte colonization may have a specific role in the nutrition of arctic and alpine plants.