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Forest Condition Monitoring in Finland – National report

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Photo: Jouni Hyvärinen

Intensive and continuous monitoring of forest ecosystems – Level II in Finland

By Päivi Merilä, Liisa Ukonmaanaho, Pekka Nöjd & Egbert Beuker

Figure 2a.The intensive forest monitoring plot network of forest ecosystems (ICP Forests Level II) in Finland in 2011–.

Current intensive monitoring plot network (2011–)

Since 2011, the number of intensive monitoring plots has been 14. The plots are located in Norway spruce (n = 7) and Scots pine (n = 7) forests in various parts of Finland (Fig. 2a, Table 1, pdf). Most observation plots are located in stands under conventional forest management. Two of the plots (Evo nr. 19, Lieksa nr. 20) also belong to the ICP Integrated Monitoring Programme, representing natural stands in catchment areas. A number of the plots are located close to background, air quality monitoring stations run by the Finnish Meteorological Institute.

Forest ecosystems are diversely monitored on these plots, with the aim of cause-effect analysis. Deposition of air pollutants, the cycles and leaching flux of nutrients, defoliation, abiotic and biotic damage, growth, nutrient status and understorey vegetation are among the attributes monitored (Table 2, pdf). Meteorological measurements are conducted in cooperation with the Finnish Meteorological Institute (Table 3, pdf).

The basic stand characteristics of ICP Level II plots are presented in Table 4, pdf.

Earlier intensive monitoring plot networks (1997–2010)

Finland joined the intensive monitoring of forest ecosystems in 1995. By 1997, 31 intensive monitoring plots had been established in different parts of the country (Fig. 2b, Table 1, pdf): 27 of the plots on mineral soil sites and 4 on peatlands. Seventeen of the plots were located in Scots pine stands and 14 in Norway spruce stands. All the plots, except for the four Integrated Monitoring (ICP-IM) plots, were located in stands under conventional forest management. The IM plots represent natural stands in catchment areas. In 2005, two Norway spruce plots (nrs. 24 and 28) were replaced by two Silver birch plots (nrs. 32 and 33).

Figure 2b. Intensive forest monitoring network 1997–2008. For information on plotwise active periods see Table 1, pdf.

In the period 1995–1997, meteorological stations were installed at 12 Level II plots. The parameters measured were:

  • Air temperature and humidity (within and above the canopy)
  • Precipitation
  • Wind speed and direction
  • Total radiation and PAR radiation
  • Soil temperature and moisture

At the locations Kivalo, Punkaharju, Tammela and Pallasjärvi two or three Level II plots for different tree species were situated close to each other. For these locations, the data from the meteorological stations at one of the plots were used for all plots at that particular location. After the Närpiö plot was closed, the meteorological station was moved to the birch plot in Kivalo. In 2010 and 2011, the meteorological stations were run down and meteorological data for all remaining Level II plots will be obtained from nearby stations of the Finnish Meteorological Institute.

Four of the intensive monitoring plots were established on drained peatland (nrs. 26, 27, 29, 30; active in 1997–2007). The sites were originally wet, sparsely stocked pine mires that represented the most typical drained peatland site types in Finland. The peat in these site types has a low mineral nutrient status, but usually relatively high nitrogen reserves. As this may result in an unbalanced nutrient status in the tree stand, two of the four plots have been fertilized. The four plots were located at two locations in Finland, with a pair of unfertilized and fertilized plots at each location. Three of the plots were established in long-term spruce provenience trials (nrs. 25, 28, 31).

In 2009, in the beginning of EU Life+ funded FutMon project the number of intensive monitoring plots was reduced to 18 plots in order to carry out a similar intensity of monitoring on all the plots (Fig. 2c, Table 1, pdf). Since 2011 the number of intensive monitoring plots has been 14 (Fig. 2a, Table 1, pdf).

Figure 2c. The intensive forest monitoring network of forest ecosystems in Finland in 2009–2010 (ICP Forests/EU Life+ FutMon).

The design of the observation plot and location of the sub-plots

The observation plots proper consist of three sub-plots and a surrounding mantle (sub-plot 4) (Fig. 3, below). The sub-plots are square in shape (30 x 30 m). A 5–10 m wide strip has been left between the sub-plots for possible future use in special studies and for additional sampling. Sampling methods that may have a detrimental, long-term effect on the soil or stand, e.g. soil sampling, deposition and soil water collection, needle and litter sampling etc., are concentrated on one sub-plot. One of the other two sub-plots is reserved for vegetation studies, and the other for tree growth measurements.

The centre point of the observation plot, the corners of the sub-plots and the outer edge of the mantle area have been marked with wooden posts. The mantle is surrounded by a buffer zone. The width of the mantle and buffer zones varies from 10–30 m.

Basic stand measurements and mapping

All the trees on the observation plot have been numbered at a height of 1.3 m on the side of the tree facing the centre point.

The following parameters have been recorded or measured on each tree: tree species, canopy layer, diameter at 1.3 m, tree height, and length of the living crown. The measurements have been performed on the trees on sub-plots 1–3 and those located in the mantle area (sub-plot 4). Twenty additional trees representing different diameter classes have been selected and numbered on the buffer zone (sub-plot 5). In addition to the above measurements, bark thickness has been measured and increment cores taken at 1.3 m height for determining earlier growth and tree age. The forest site type has also been determined.

The location and elevation of all the trees on the observation plots have been mapped using a tachymeter. The exposition and gradient of each sub-plot have also been determined. Care has been taken during the fieldwork to avoid causing unnecessary trampling of the ground vegetation or other forms of damage. Wooden walkways have been laid on the sub-plot used for collecting deposition and soil water.

Figure 3. The Finnish design of the intensive monitoring plots (ICP Forests Level II) and location of the sub-plots.


Cajander, A.K. 1949. Forest types and their significance. Acta Forestalia Fennica 56:1–71.

Venäläinen, A., Tuomenvirta, H., Pirinen, P. & Drebs A. 2005. A basic Finnish climate data set 1961–2000 – description and illustrations. Finnish Meteorological Institute Report no. 2005: 5. 27 pp.

Citation: Merilä, P., Ukonmaanaho, L., Nöjd, P. and Beuker, E. (2013). Intensive and continuous monitoring of forest ecosystems – Level II in Finland. In: Merilä, P. & Jortikka, S. (eds.). Forest Condition Monitoring in Finland – National report. The Finnish Forest Research Institute. [Online report]. Available at [Cited 2013-05-07].

: Updated: 14.10.2014 /SJor |  Photo: Erkki Oksanen, Metla, unless otherwise stated  |  Copyright Metla  |  Feedback