The nature and significance of microtopographic effects on vegetation succession on selected glacier forelands, Jotunheimen and Jostedalen, Norway.

This extensive study investigates the relationship between microtopography, prevailing micro-environmental factors and vegetation, with particular reference to succession, on six glacier forelands at successively higher altitudes. The study is successful in answering the three main aims of the thesis: by analysing the specific environmental parameters comprising the microtopographic gradients; by describing the distribution of individual species and plant assemblages across microtopographic gradients of similar type (i.e. moraine slopes) but different ages and altitudes; and by interrelating the vegetational and environmental variation and hence providing an explanation of the vegetation in terms of both successional stage and environmental factors. The principal research contributions are under three headings: findings; presentation techniques; and literature review. The most important findings refer to the major influences on subalpine and alpine vegetation patterns and include the following conclusions: a) Microtopographical effects are more complex than previously acknowledged. b) Exposure, snow-lie and fluvial activity are confounded and the relative importance of these parameters changes with altitude so that exposure is more important on the low-alpine forelands and snow-lie is more important on the mid-alpine forelands. c) Pioneer assemblages are distinct and are more influenced by terrain-age than altitude. d) Most assemblages are not distinct but lichen heath, subalpine mature birch woodland and heath, and snow-bed assemblages show recurrent similarities in constituent species. e) The influence of terrain-age appears to decrease with altitude while microtopographical effects increase. f) Altitudinal effects appear to increase with age. g) Succession is simpler and more predictable with altitude and all types of successional pathway (i.e. divergent, convergent and parallel) are possible. The presentation techniques are considered an improvement on previous display techniques because they allow deeper interpretation of the results at all levels of division. By using these techniques, the complex relationships between assemblages, sites and environmental parameters, at both the assemblage and population levels, are elucidated. The literature review targets the effects of microtopography on vegetation patterns in cold climates (e.g. subalpine, alpine, arctic) and comparison with previous literature suggests that this thesis could be used to explain universal patterns. The present study augments and improves on much of the previous work by using an objective methodology to describe vegetation patterns in a heterogeneous landscape and relate a multitude of environmental parameters to those patterns. This study has provided some interesting and original results and conclusions and the wide-ranging nature of the thesis opens up many avenues for further investigation.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Greenwich

Year dc:date.issued

1998

Author dc:creator

• Foskett, Jacqueline Isabel Jeanne

Advisors dc:contributor.advisor

• Coker, Paddy
• Matthews, John

• QE Geology

Language dc:language

en