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Detecting changes in the state of reindeer pastures in northernmost Finland, 1995–2005.
- Alfred Colpaert, Jouko Kumpula
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- Journal:
- Polar Record / Volume 48 / Issue 1 / January 2012
- Published online by Cambridge University Press:
- 29 November 2011, pp. 74-82
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The state of pastures in the Finnish reindeer management area has been monitored since 1995 using remote sensing and field inventory. The first inventory was made in 1995–1996, updated in the beginning of 2000s and repeated in 2005–2008. By comparing results from 1995–1996 and 2005–2008 we can observe clear changes in forest cover, structure and ground lichen abundance. To evaluate pasture/vegetation changes on the basis of separate classifications we have used a grid approach. By implementing a 500 by 500 m grid network and summarizing pasture classes for every grid cell we can visualize and quantify intensity of change. By comparing 1995–1996 and 2005–2008 we can see a clear decrease in the number of cells classified old growth dominated forest, and also an increase of fragmentation can be detected. With a 7.5 ha threshold the amount of old growth forest was reduced by 5%, for 20 ha the decrease was 21%. This indicates a significant change in forest landscape structure, fragmentation and reduction of reindeer winter pasture value in large areas. Pixel wise comparison showed no substantial changes in pasture areas. There is a degree of uncertainty in change detection; changes in remote sensing instrument, changes in processing software and methodology, changes in field methods and ancillary data, and obviously also bias introduced by differences between analysts. When comparing reindeer lichen biomass between 1995–1996 and 2005–2008 on the basis of field site data, the measured lichen biomass has declined in 19 out of the 20 reindeer management districts. Only one district showed slight improvement, in three districts there was a notable drop in lichen biomass, from over 1500 kg/ha to about 500 kg/ha. Also amount of arboreal lichens declined due to felling of old growth forest, confirming the findings on the grid cell level. Consequently grass, shrub and sapling stands increased as felled areas start to grow graminoids and herbs.
Remote sensing, a tool for reindeer range land management
- Alfred Colpaert, Jouko Kumpula, Mauri Nieminen
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- Journal:
- Polar Record / Volume 31 / Issue 177 / April 1995
- Published online by Cambridge University Press:
- 27 October 2009, pp. 235-244
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The Finnish reindeer-herding area lies in the northern boreal forest zone. The herding area is divided into 57 reindeer management districts with a total area of 114,355 km2 (excluding water areas). The official number of reindeer in the year 1992 was 263,789, or 2.3 reindeer per square kilometre. In 1946 the density was only about one reindeer per square kilometre. The increased pressure on the mid-winter lichen pastures has reduced the volume of lichen. Also the decreased area of old coniferous forests with arboreal lichens has diminished the supply of food during the late-winter months. The lack of suitable winter pastures has led to the need for supplementary feeding with hay.
The intention of this study was to develop and test methods for cost-effective reindeer range land inventory and to assess the present state of pastures in seven districts. Use was made of Landsat 5 TM satellite imagery that was processed with remote sensing and GIS software. The analysis of well-known field sites proved the image classification to be between 80 and 90% accurate. By comparing field data and classification results, estimates can be made on the available fodder reserves in the different pasture types. The results show that mid-winter pastures are both scarce and degraded in six of the seven areas investigated. Only one area (Muotkatunturi) has mid-winter pastures in reasonably good condition. Late-winter pastures with arboreal lichens are more widespread than mid-winter pastures and determine the amount of additional winter feeding required. Summer pastures are abundant in all seven reindeer-herding districts and are therefore not a limiting factor. The method used is objective, inexpensive, and fast when compared to conventional methods. Information can be produced on the quantity and quality of reindeer pastures. This knowledge can be used to make better estimates of the natural grazing capacity of reindeer districts in Finland.