Monitoring Bark Beetle Forest Damage in Central Europe. A Remote Sensing Approach Validated with Field Data

Over the last decades, climate change has triggered an increase in the frequency of spruce bark beetle (Ips typographus L.) in Central Europe. More than 50% of forests in the Czech Republic are seriously threatened by this pest, leading to high ecological and economic losses. The exponential increase of bark beetle infestation hinders the implementation of costly field campaigns to prevent and mitigate its effects. Remote sensing may help to overcome such limitations as it provides frequent and spatially continuous data on vegetation condition. Using Sentinel-2 images as main input, two models have been developed to test the ability of this data source to map bark beetle damage and severity. All models were based on a change detection approach, and required the generation of previous forest mask and dominant species maps. The first damage mapping model was developed for 2019 and 2020, and it was based on bi-temporal regressions in spruce areas to estimate forest vitality and bark beetle damage. A second model was developed for 2020 considering all forest area, but excluding clear-cuts and completely dead areas, in order to map only changes in stands dominated by alive trees. The three products were validated with in situ data. All the maps showed high accuracies (acc > 0.80). Accuracy was higher than 0.95 and F1-score was higher than 0.88 for areas with high severity, with omission errors under 0.09 in all cases. This confirmed the ability of all the models to detect bark beetle attack at the last phases. Areas with no damage or low severity showed more complex results. The no damage category yielded greater commission errors and relative bias (CEs = 0.30–0.42, relB = 0.42–0.51). The similar results obtained for 2020 leaving out clear-cuts and dead trees proved that the proposed methods could be used to help forest managers fight bark beetle pests. These biotic damage products based on Sentinel-2 can be set up for any location to derive regular forest vitality maps and inform of early damage.

Forest vitality (ICP level I and sample plot level II - Crni vrh and Mokra Gora) with a special emphasis on abiotic agents in the Republic of Serbia in 2019

The vitality of forests depends on environmental conditions and a great number of abiotic factors, such as climatic characteristics, atmospheric deposition, forest fires, direct atmospheric impacts. Nevertheless, abiotic agents are group of the most important factor threatening the trees sampled and monitored for more than a decade and a half in continuity. Therefore, further analysis can provide different trends of their direct effects and degrees of their out-turn. International program for further and more detailed monitoring of the forest condition in the Republic of Serbia (ICP Forests), which is carried out on both Level I and Level II(Mokra Gora and Crni Vrh) sample plots, will enable scientists to determine the vitality of forests both at the local and at the regional level. Results are vitality and health state of the forest ecosistems with emphasis on abiotic factors.

Air pollution load and stand nutrition in the Forest District Jablunkov, part Nýdek

Concentrations of air pollutants measured by passive samplers, atmospheric deposition to forest ecosystems, soil water chemistry, nutrient content in the soil and foliage were all measured within a study of the causes of forest decline in Nýdek Forest Range, Jablunkov Forest District (Silesian Beskids). Declining Norway spruce stands are situated in a region of historically high air pollution load, mainly from the Třinec and Ostrava agglomeration. Air pollution significantly decreased in the second half of the 1990s. Forest soils showing the insufficiency of main nutrients remain today as the main factor affecting the forest vitality. The situation in the soil is subsequently reflected in the nutrition level of the assimilation tissues. Simultaneous effects of other stressors (e.g. biotic, meteorological ones) can support a sudden worsening of the stand health and cause serious damage.