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Norway spruce (Picea abies (L.) Karst.), planted

Altitude: 310 m a.s.l.

64.1135167º N
19.4735833° E (tower coordinates)
310 m asl (tower)

Site description

The Flakaliden research site is a Norway spruce (Picea abies (L.) Karst.) forest planted in 1963. The climate is boreal, with a mean annual temperature of +2.3 °C. The mean monthly temperature varies from -7.3 °C in January to +14.6 °C in July (mean for the period 1990 - 2004). The length of the growing season (mean daily air temperature > +5 °C) is approximately 140 days. Mean annual precipitation is 600 mm, and soil water content rarely limits biomass production. Experiments performed at the site include long-term nutrient optimisation and climate change manipulation experiments. The experiment covers an area of 8.25 hectares. For further details regarding the site and the treatments see Bergh et al. (1999) and Linder (1995).


Haplic Podsols (FAO 1990) developed on sandy loamy tills with low clay contents (<8%) with a mean depth of 1.2 m and a humus layer depth of 30 - 40 mm.


A standard weather station provides hourly mean values of air temperature, air humidity, wind speed and direction, soil temperature, and incident radiation. Soil moisture and precipitation is only measured during the frost-free period of the year. During winter the depth of snow cover and the depth of the frozen soil are recorded weekly. Additional measurements, with lower intensity, are made of litterfall, foliar nutrients, tree growth, and soil-C- and -N stocks in all experimental plots at the site. In the soil warming plots soil-surface CO2 flux is measured (automatic and portable system) during the snow-free season as well as soil water chemistry and DOC concentration (since 2008).

Exchange of energy, water vapor, and CO2 between the forest and the atmosphere is, since 1997, measured by means of eddy-covariance technique in a mast situated approx. 800 m away from the main experiment (cf. Wallin et al. 2001; Lindroth et al. 2008).

Treatments within the CARBO-Extreme project

The main contribution to CARBO-Extreme from the Flakaliden experiments is a soil-warming treatment. The experiment was installed in the buffer zone of one irrigated and one irrigated-fertilised stand, with two 10 × 10 m plots per treatment. Each heated plot has a paired unheated control plot. The number of trees per plot varies between 21 and 28, but the basal area per plot was initially similar within each treatment. All plots were fenced to exclude animals, and boardwalks were installed to prevent trampling of the ground vegetation.

The soil warming is obtained by means of six, 85-m long, heating cables, per plot buried under the humus layer at a spacing of ca. 20 cm. The heating cables have a capacity of 65 W m-2. The heating system is controlled and monitored by temperature sensors, installed into the first centimetre of the mineral soil, which are monitored continuously and values stored every 15 minutes.

The soil-warming treatment commenced in 1995. The warming starts in early April each year, which is about five weeks before the soil thaws in the unheated plots. The soil temperature is increased 1 °C per week, until a 5 ºC difference between heated and control plots are reached. In late autumn, when the soil temperature in the control plots approaches 0 ºC, the soil temperature of the heated plot is decreased by 1 °C per week. If the control plots do not freeze before 1 November, the temperature reduction is still initiated. For further information on the construction and long-term performance of the soil-warming system, see Bergh & Linder (1999), Strömgren (2001), and Strömgren & Linder (2002).

Related projects

Examples of other relevant ongoing projects:

  • Optimisation of biomass production in young stands of Norway spruce
  • Wood formation under varying environmental conditions
  • Effects of nitrogen deposition and fertilisation on carbon sequestration in managed boreal forests
  • Linking global climate change to local long-term forest productivity
  • Impacts of climate change on boreal forest ecosystems
  • Fingerprints of global climate change and forest management on rhizosphere carbon and nutrient cycles


Aerial photograph (1991)
Aerial photograph of the Flakaliden long-term experimental site taken four years after the treatments started in 1987.,
Soil warming experiment
One of the irrigated-fertilised plots included in the soil-warming experiment in Flakaliden. The soil warming is applied for eight months a year (April – November) and commenced 1995. Photo Sune Linder
Layout of experiments
The main long-term nutrient optimisation experiment at Flakaliden consists of unfertilized control plots (C), irrigated plots (I), plots with annual solid fertilisation (F) and plots with fertilisation combined with irrigation (IL = irrigated + fertilised). The soil-warming plots and there non-heated controls are found in the buffer zones of plots 7A, 8B, and 12B.



For a complete list of publications contact

Bergh J. 1997. Climatic and nutritional constraints to productivity in Norway spruce. Acta Universitatis Agriculturae Sueciae, Silvestria 37, 34 pp. Doctoral thesis. ISBN 91-576-5321-6
Bergh, J. & Linder, S. 1999. Effects of soil warming during spring on photosynthetic recovery in boreal Norway spruce stands. Global Change Biology 5: 245-253. Bergh, J., Linder, S., Lundmark, T. & Elfving, B. 1999. The effect of water and nutrient availability on the productivity of Norway spruce in northern and southern Sweden. Forest Ecology and Management 119: 51-62.
Bergh, J., Linder, S. & Bergström, J. 2005. Potential production for Norway spruce in Sweden. Forest Ecology and Management 204: 1-10.
Eliasson, P. 2007. Impacts of climate change on carbon and nitrogen cycles in boreal forest ecosystems. Doctoral Thesis. Department of Ecology, SLU, Uppsala. Acta Universitatis Agriculturae Sueciae 2007: 89, 41 pp. ISSN 1652-6880, ISBN 978-91-576-7388-6
Eliasson, P.E., McMurtrie, R.E., Pepper, D.A., Strömgren, M., Linder, S. & Ågren, G.I. 2005. The response of heterotrophic CO2-flux to soil warming. Global Change Biology 11: 167-181.
Jarvis, P.G. & Linder, S. 2000. Constraints to growth of boreal forests. Nature 405: 904-905.
Kirschbaum, M.U.F. 2004. Soil respiration under prolonged warming: Are rate reductions caused by acclimation or substrate loss? Global Change Biology 10: 1870-1877. Linder, S. 1995. Foliar analysis for detecting and correcting nutrient imbalances in Norway spruce. Ecological Bulletins (Copenhagen) 44: 178-190.
Lindberg, N. 2003. Soil fauna and global change. Responses to experimental drought, irrigation, fertilisation and soil warming. Acta Universitatis Agriculturae Sueciae, Silvestria 270, 37 pp. Doctoral thesis. ISBN 91-576-6504-4
Lindroth, A., Klemedtsson, L., Grelle, A., Weslien, P. & Langvall, O. 2008. Measurement of net ecosystem exchange, productivity and respiration in three spruce forests in Sweden shows unexpectedly large soil carbon losses. Biogeochemistry 89: 43-60.
Majdi, H. & Öhrvik, J. 2004. Interactive effects of soil warming and fertilization on root production, mortality, and longevity in a Norway spruce stand in northern Sweden. Global Change Biology 10: 182-188.
Medhurst, J., Parsby, J., Linder, S., Wallin, G., Ceschia E. & Slaney, M. 2006. A whole-tree chamber system for examining tree-level physiological responses of field-grown trees to environmental variation and climate change. Plant, Cell and Environment 29: 1853-1869.
Olsson, P., Linder, S., Giesler, R. & Högberg, P. 2005. Fertilization of boreal forest reduces both autotrophic and heterotrophic soil respiration. Global Change Biology 11: 1745-1753.
Remén, C., Persson, T., Finlay, R. & Ahlström, K. 2008. Responses of oribatid mites to tree girdling and nutrient addition in boreal coniferous forests. Soil Biology & Biochemistry 40: 2881-2890.
Slaney, M., Wallin, G., Medhurst, J. & Linder, S. 2007. Impact of elevated [CO2] and temperature on bud burst and shoot growth of boreal Norway spruce. Tree Physiology 27: 301-312.
Strömgren, M. 2001. Soil-surface CO2 flux and growth in a boreal Norway spruce stand. Effects of soil warming and nutrition. Acta Universitatis Agriculturae Sueciae, Silvestria 220, 44 pp. Doctoral thesis. ISBN 91-576-6304-1
Strömgren, M. & Linder, S. 2002. Effects of nutrition and soil warming on stemwood production in a boreal Norway spruce stand. Global Change Biology 8: 1194-1204.
Wallin, G., Linder, S., Lindroth, A., Räntfors, M., Flemberg, S. & Grelle, A. 2001. Carbon dioxide exchange of boreal Norway spruce at the shoot, tree and ecosystem level. Tree Physiology 21: 969-976.

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