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FENNIA

Fennia vol. 183: 1 (2005)

Mapping the spatial distribution of geomorphological processes in the Okstindan area of northern Norway, using Geomorphic Process Units as derived from remote sensing and ground survey

STEPHEN D. GURNEY AND ANNETT BARTSCH

Gurney, Stephen D. & Annett Bartsch (2005). Mapping the spatial distribution of geomorphological processes in the Okstindan area of northern Norway, using Geomorphic Process Units as derived from remote sensing and ground survey. Fennia 183: 1, pp. 1–14. Helsinki. ISSN 0015-0010.

The delineation of Geomorphic Process Units (GPUs) aims to quantify past, current and future geomorphological processes and the sediment flux associated with them. Five GPUs have been identified for the Okstindan area of northern Norway and these were derived from the combination of Landsat satellite imagery (TM and ETM+) with stereo aerial photographs (used to construct a Digital Elevation Model) and ground survey. The Okstindan study area is sub-arctic and mountainous and is dominated by glacial and periglacial processes. The GPUs exclude the glacial system (some 37% of the study area) and hence they are focussed upon periglacial and colluvial processes. The identified GPUs are: 1. solifluction and rill erosion; 2. talus creep, slope wash and rill erosion; 3. accumulation of debris by rock and boulder fall; 4. rockwalls; and 5. stable ground with dissolved transport. The GPUs have been applied to a ‘test site’ within the study area in order to illustrate their potential for mapping the spatial distribution of geomorphological processes. The test site within the study area is a catchment which is representative of the range of geomorphological processes identified.

Stephen D. Gurney, Department of Geography, The University of Reading, PO Box 27, Whiteknights, Reading RG6 6AB, UK. E-mail: s.d.gurney@reading.ac.uk.

Annett Bartsch, Institute of Photogrammetry and Remote Sensing, Vienna University of Technology, Gusshausstrasse 27–29, A-1040 Vienna, Austria. E-mail: ab@ipf.tuwien.ac.at. MS received 26 January 2005.

The impact of elevation, topography and snow load damage of trees on the position of the actual timberline on the fells in central Finnish Lapland

JYRKI AUTIO AND ALFRED COLPAERT

Autio, Jyrki & Alfred Colpaert (2005). The impact of elevation, topography and snow load damage of trees on the position of the actual timberline on the fells in central Finnish Lapland. Fennia 183: 1, pp. 15–36. Helsinki. ISSN 0015-0010.

This study examines the impact of selected environmental variables on the position of the limit of continuous forest (actual timberline) on three fells situated in central Finnish Lapland, namely Aakenustunturi, Yllästunturi and Pyhätunturi. The factors studied are elevation, topography and snow load damage to coniferous trees. The potential for ascending timberlines in the region is discussed. The limit of continuous forest in the study area is hardly ever composed of a single species but rather features alternating occurrences of spruce, pine and mountain birch. The average altitudinal position of the actual timberline is highest on the southern and western slopes (366–428 m a.s.l.), while the lowest altitudes are recorded on the northern and eastern slopes (336–403 m a.s.l.). Prevalence of block fields and slope gradient are the most significant and visible factors controlling the position of the actual timberline. On the studied fells, from 10% to more than 50% of the total length of the actual timberline is controlled by block fields. The lowest occurrence of the limit of continuous forest, at 270 m a.s.l., results from an extremely high proportion of block fields and steep slopes. Snow patches and delayed snow melting also hamper the upward advancement of the forest. Continuous forest reaches its highest altitudes at 440 m a.s.l. on slopes with gentle inclination and land cover other than block fields, and 460 m a.s.l. in sheltered furrows. Average snow load damage to spruce and pine at the actual timberline varies in the ranges 15–58% and 30–76%, respectively. Snow load damages on trees undoubtedly impede the advance of the actual timberline to higher elevation in all exposures. Seedling density (number/ha) on south-facing slopes near the actual timberline is ca. 5 times greater than on the north-facing slopes. Recent regeneration and seedling establishment is almost absent at the treeline near the fell tops. Results suggest that there is potential for actual timberline advance on south-facing slopes with gentle inclination and missing block fields. It is uncertain, however, whether natural regeneration will take place on felltops with few or no trees.

Jyrki Autio, Department of Geography, University of Oulu, PO Box 3000, FI-90014 Oulu, Finland. E-mail: jyrki.autio@oulu.fi.

Alfred Colpaert, Department of Geography, University of Joensuu, PO Box 111, FI-0101 Joensuu, Finland. E-mail: alfred.colpaert@joensuu.fi. MS submitted 08 December 2004.

Regional distribution and biodiversity perspectives of Finnish grasslands

SONJA KIVINEN

Kivinen, Sonja (2005). Regional distribution and biodiversity perspectives of Finnish grasslands. Fennia 183: 1, pp. 37–56. Helsinki. ISSN 0015-0010.

The preservation of viable agricultural landscapes is essential in Finland and throughout Europe, because a considerable proportion of threatened species are associated with rural habitats, particularly various grasslands. In this study, the regional distribution of Finnish grasslands was studied using an existing nationwide digital land-use database. Further, the occurrence of traditional rural biotopes and selected butterfly and bird species living in different grassland habitats was investigated in relation to agricultural landscape mosaic. The results showed that grasslands were typically abundant in versatile agricultural regions, land uplift shores as well as in agriculturally marginal landscapes experiencing decrease of agricultural activities. Grasslands were generally scarce in intensively cultivated agricultural landscapes. The occurrence and siting of traditional rural biotopes in grassland networks vary greatly regionally, abundant and well-connected traditional rural biotopes being found e.g. in river valleys and few isolated biotopes in intensively cultivated or agriculturally marginal, forested regions. Furthermore, the nationwide occurrence of selected butterfly and bird species was positively related to the abundance of grasslands. Overall, grasslands enrich the Finnish agricultural landscape both at the habitat and species level. In addition to species-rich semi-natural grasslands, other low-productive grasslands also hold significant potential in the maintenance of diverse agricultural environments.

Sonja Kivinen, Finnish Environment Institute, Research Programme for Biodiversity, PO Box 140, FI-00251 Helsinki, Finland. E-mail: sonja.kivinen@ymparisto.fi. MS submitted 05 November 2004.

Changes of emergent aquatic macrophyte cover in seven large boreal lakes in Finland with special reference to water level regulation

SARI PARTANEN AND SEPPO HELLSTEN

Partanen, Sari & Seppo Hellsten (2005). Changes of emergent aquatic macrophyte cover in seven large boreal lakes in Finland with special reference to water level regulation. Fennia 183: 1, pp. 57–79. Helsinki. ISSN 0015-0010.

The latest studies on the development of aquatic vegetation in Finland have mainly focused on relatively small lakes. Research on emergent macrophytes in large lakes poses challenges as the habitats as well as the conditions of the lakes vary. Black and white aerial photographs from 1947–1963 and colour, mainly infrared aerial photographs from 1996–2000 were used to study quantitative vegetation changes in seven large (80–1116 km 2) lakes in Finland: Kemijärvi, Unnukka, Kallavesi, Päijänne, Näsijärvi, Pyhäjärvi and Vanajavesi. Vegetation changes were evaluated by comparing the situation before large-scale water level regulation and eutrophication to the current situation. Quantitative changes in emergent vegetation were frequently noticeable. Vegetation had decreased by 31–93% in three study lakes due to the mean water level rise and increased by 49–73% in three study lakes due to the spring flood reduction and suitable surrounding soils. The cover changes were in general relatively uniform between different study sites in each of the study lakes. The regulated and unregulated situations differed statistically from each other. The results point out the crucial impact of changing water levels and the significance of the surrounding soils to the cover of emergent aquatic vegetation.

Sari Partanen & Seppo Hellsten, Finnish Environment Institute, Research Department, Research Programme for Integrated River Basin Management, PO Box 413, FI-90014 University of Oulu, Finland. E-mails: sari.partanen@ymparisto.fi, seppo.hellsten@ymparisto.fi. MS submitted 08 October 2004.


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