In Lithuanian forests, spruce canopy defoliation (loss of needle mass due to adverse environmental factors) shows no trend. This is an indication of the good viability of spruce trees that remain green.

26 June 2024. The Government of the Republic of Lithuania approved the State Environmental Monitoring Programme for 2024-2029, which systematically collects information on the state of the country's natural environment and the changes occurring in it, both spontaneously and as a result of anthropogenic influence. Gintaras Kulbokas, Head of the National Forest Inventory Division of the State Forest Service, was actively involved in the preparation of the programme.

Measures 2.1 and 3.1 of the Programme's Wildlife Area are the responsibility of the State Forest Service. It carries out Level I and organises intensive Level II monitoring of forest conditions. These monitors are carried out within the framework of the international ICP Forests programme and the Service is the national Focal Centre for the ICP Forests programme. The ICP Forests International Focal Point regularly publishes annual publications, which also publicizes the data collected in Lithuania.

ICP-Forests statistics show that in Lithuania, as in Europe, the Scots pine (Pinus sylvestris) is one of the main and most common tree species. The results of national and European ICP-Forest Level I forest monitoring show similar trends in the status of pine. Statistics show that the condition of pine trees in Europe and Lithuania is consistently deteriorating, i.e. average crown defoliation has increased by 4.2 and 5.8% points in Europe and Lithuania respectively over the last 20 years of monitoring.

In contrast, Norway spruce (Picea abies) is the second most common conifer species. It is the second most common species in the EU, with a distribution ranging from Scandinavia to northern Italy and from north-eastern Spain to Romania. Norway spruce is only found in southern Europe at higher altitudes – in the mountains, as it prefers a cooler and wetter climate.

The forests in the best condition, with the lowest average defoliation, are found in Scandinavia and the Balkan region. The worst condition of Norway spruce trees is recorded in Central Europe. Observations in European forests over the last 20 years show an increase in the average defoliation of Norway spruce of almost 5% points. In Lithuanian forests, meanwhile, spruce canopy defoliation does not show a trend, although it varies between 19.1 and 23.3%. This indicates good regeneration and the viability of spruce trees that remain green. It is also worth noting that the average annual volume increment of spruce forests in Lithuania (9.73 m3/ha, NMI 2023) is significantly higher than the average increment of all stands (9.09 m3/ha), and only lags behind fast-growing aspen forests in relatively middle-aged stands (41-50 years) (11.8 m3/ha in spruce forests and 15.9 m3/ha in aspen forests).

Remember that defoliation is one of the most commonly used forest monitoring indicators, characterising the loss of established foliage or needle mass due to adverse environmental factors.