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Flakaliden
Flakaliden
Site descriptionThe 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). SoilHaplic 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. MeasurementsA 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 projectThe 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 projectsExamples of other relevant ongoing projects:
Pictures Aerial photograph of the Flakaliden long-term experimental site taken four years after the treatments started in 1987.,  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  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. ContactDan.Berggren@mark.slu.se ReferencesFor a complete list of publications contact Sune.Linder@ess.slu.se 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 |