Experimental statistics

Forest ecosystem condition indicators

At the second stage of the Project, a key set of statistical forest variables was prepared according to groups and classes of ecosystem condition variables. A set of 16 forest condition variables divided into 3 groups (abiotic ecosystems, biotic ecosystems and landscape characteristics) was compiled and described. The variables were calculated and presented by spatial unit (wards, municipalities and 1 km grids) and at national level at the beginning (around 2000) and at the end of the period (2021).

Table 1. The basic set of statistical forest variables by group and class of ecosystem condition characteristics

Group	Class	Variables	Unit of measurement
Abiotic ecosystem characteristics	Physical state characteristics	Proportion of organic soils	per cent
	Physical state characteristics	Proportion of drained organic soils	per cent
	Chemical state characteristics	Mass of organic carbon in forest liter and upper soil (0–30 cm) layer	t C eq./ha
Biotic ecosystem characteristics	Compositional state characteristics	Proportion of mixed stands	per cent
		Proportion of natural stands	per cent
		Proportion of artificially regenerated stands	per cent
	Structural state characteristics	Average stocking level of stands	-
		Proportion of low density stands	per cent
		Proportion of modal density (stocking level) stands	per cent
		Annual volume of naturally dying trees	cubic m/ha
		Proportion of old stands	per cent
	Functional state characteristics	Growing stock volume	cubic m/ha
	Functional state characteristics	Mass of organic carbon in living forest biomass	t C eq./ha
Landscape characteristics	Landscape characteristics	Rate of forest area increase during 10 years	per cent
		Forest edge density	m
		Proximity to the nearest forest	m

Reference levels have been defined for each variable in the set, i.e. what value of the variable should be in the ideal case and in the worst case.

The values of the variables in the set were converted into indicator values on a scale from 0 to 1 through a linear transformation by using the defined reference levels.

An indicator is a transformed statistical variable. During the transformation, a uniform measurement scale is set for the variables according to the established reference levels, with the ideal value of the reference level being equated one, and the worst value – to zero.

Table 2. Forest condition indicators and the directions of reference level values

Class	Indicator	Ecosystem type – forest
		Directions of reference level values
		Low level	Upper level (ideal)
Physical state characteristics	Proportion of organic soils	min	max
Physical state characteristics	Proportion of drained organic soils	max	min
Chemical state characteristics	Mass of organic carbon in forest liter and upper soil (0–30 cm) layer	min	max
Compositional state characteristics	Proportion of mixed stands	min	max
	Proportion of natural stands	min	max
	Proportion of artificially regenerated stands	max	min
Structural state characteristics	Average stocking level of stands	max	min
	Proportion of low density stands	min	max
	Proportion of modal density (stocking level) stands	min	max
	Annual volume of naturally dying trees	min	max
	Proportion of old stands	min	max
Functional state characteristics	Growing stock volume	min	max
Functional state characteristics	Mass of organic carbon in living forest biomass	min	max
Landscape characteristics	Rate of forest area increase during 10 years	min	max
	Forest edge density	min	max
	Proximity to the nearest forest	max	min

In order to assess the condition of the forest ecosystem, the weights of the forest ecosystem condition indicators were first determined, considering the condition that in the ideal case (reference condition) the aggregated value of the forest condition indicators should be equal to 1.

The highest weights were given to the indicators in the landscape class: proximity to the nearest forest – 0.17, rate of forest area increase during 10 years – 0.13, forest edge density (per 1 ha) – 0.10. The following indicators have been given considerable weight in assessing the condition of the forest ecosystem: proportion of mixed stands (class of compositional state characteristics) – 0.11, proportion of old stands (structural state characteristics) – 0.10. The lowest weights were given to the following indicators: proportion of organic soils (physical state characteristics) and average stocking level of stands (structural state characteristics) – 0.01 each. It is important to note that some of the forest ecosystem condition indicators compensate each other, and at the same time gain considerable weight, such as the following indicators under the functional state characteristics class: growing stock volume and mass of organic carbon in living forest biomass – 0.06 each.

Considering the estimated weights of the indicators, the key indicators of the set of the statistical indicators were converted into composite indicators, i.e. indices and sub-indices, according to the groups and classes of indicators. The Forest Ecosystem Condition Index at the beginning and at the end of the period was calculated at the national level and aggregated to the municipal and ward levels.

The Forest Ecosystem Condition Index indicates the state of the ecosystem compared to reference (ideal) condition. The better the condition of the forest, the closer the index value is to 1.

The main result of this Project is the development of the Forest Ecosystem Condition Index at national, municipal and ward levels.

Forest ecosystem condition index

Indicators of forests condition (arcgis.com)

Indicators of forests condition (open data)

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This project was funded by the European Union.

The content of this project represents the views of the author only and is his/her sole responsibility. The European Commission does not accept any responsibility for use that may be made of the information it contains.

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Experimental statistics

Forest ecosystem condition indicators

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