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Title: Thirty years of primary succession on the Storbreen glacier foreland, Jotunheim, Norway : species populations, community dynamics and environmental influences
Author: Nicholls, M. A.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2006
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Changes in arctic-alpine vegetation composition over 30 years in a successional sequence on the Storbreen glacier foreland, Southern Norway, and in the adjacent regional vegetation, are analysed. The study is based on a repeat survey of 410 permanent sites and 24 new sites (located on land exposed since 1970). Classification (TWINSPAN) and ordination (Canonical Correspondence Analysis), diversity indices and transition probabilities, are used to identify changes at the species level, to examine successional dynamics at the community level and to assess the role of the environment in compositional change. Species population changes are extensive, cannot be explained solely in terms of successional change, and appear to be influenced by regional climatic change since 1970. Changing successional patterns are attributed to species-specific effects on performance. In the dense vegetation of the low altitude dwarf-shrub heath, this involves shifts in relative abundance. Some species are increasing in abundance at relatively high-altitude and on relatively young sites, where vegetation is relatively sparse. The study follows the dynamics of the successional sequence over 30 years using a spatio-temporal chronosequence approach to succession. Three spatially-determined successional trajectories are associated with the major landforms in the study area. These trajectories are tending towards: (1) a species-rich, dwarf-shrub heath at low-altitude and at higher altitude, north-facing sites; (2) a species-rich snowbed community at high-altitude, south-facing sites and at lower altitude, north-facing sites; and (3) a species-poor snowbed community at high-altitude, north-facing sites. Mesoscale gradients of altitude and aspects govern qualitative differentiation from an early pioneer stage. Subsequent increases in successional distance indicate divergence.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available