Climate change speaks to almost every field of human activity, so it is foolish to think that forestry will be avoided. In addition to the impact on timber production, many non-productive – no less important – functions of the forest ecosystem may be affected. For example, carbon accumulation, climate regulation and area hydrology, or the promotion of biodiversity are at risk. Approaches on how to reduce the negative impact of drought on the condition of forests in our country and in neighbouring countries were provided by a study from the workshop of 5 research institutes in the Central European region, including the CULS Faculty of Forestry and Wood Sciences.
The authors focused on the map evaluation of areas that are at risk of the greatest increase in drought intensity by the end of the century. The maps created by interpolation of data describing the future climate showed that the most significant changes can be expected in Hungary and the southern regions of Slovakia, while less dramatic developments are expected in the Czech Republic and Austria (Fig. 1). Based on map-presented projections of climate change, a list of recommendations for forestry activities of key Central European tree species was compiled.
The importance of oaks, which will benefit the drier climate, is expected to increase. An interesting fact is that at the expense of our species of oaks, their Mediterranean relatives may increase (or may be actively used in forestry activities) in the area of ??their current occurrence. Suitable conditions for growing beech will recede to higher positions, because in lower positions the beech will be exposed to increasing drought and damage by bark and defoliating insects, which we have rarely encountered in our country so far. The forests up to an altitude of about 500 m will be particularly endangered. Probably the most dynamic changes await spruce stands, which are grown far beyond the boundaries of natural areas in the conditions of Central Europe. In addition to the changing climate (manifested mainly by an increase in drought and a higher frequency of storms), our most abundant tree species – spruce (53 %) – will be threatened by a higher number of generations of the spruce bark beetle. It is also possible to expect an increase in the importance of other species, such as the double-spined bark beetle.
The authors consider the reduction of the representation of vulnerable coniferous stands in low and middle altitudes and in drought-endangered habitats also reduction of beech to be important adaptation measures. They recommend replacing these woody plants with less vulnerable and drought-tolerant species, especially with some oak species. Enriching the stands with oak seems to be convenient up to altitudes of about 800 m. This is considered one of the successful ways to improve the stability of current stands and reduce the overall vulnerability of the forest exposed to climate change.
From the above, it is clear that suitable conditions for spruce remain especially in the areas of its natural occurrence or as an enriching, not dominant species. However, given the current economic importance, spruce needs to be considered in perspective, but not in its current representation and expansion.
The authors also recommend that adaptation measures not neglect species that will strengthen biodiversity and thus support the natural adaptation mechanisms of the forest: ash, field maple, wild service tree or small-leaved lime. Conifers include drought-tolerant Scots pine, larch, or even non-native Douglas fir.
During restoration, it is recommended to effectively use a combination of the advantages of artificial and natural regeneration in order to obtain the species composition outlined in the previous paragraph. The use of natural regeneration has proven to be very suitable in many studies not only for reasons of species but also genetic diversity, which is an important factor influencing the natural adaptive capacity of the forest.
Concepts of nature-friendly management and management maintaining the canopy of vegetation have an important place in the adaptation of the forest to climate change. Not surprisingly, the authors of the study warn against large clearings, in the vicinity of which there would be adverse effects on the water regime, as well as an increase in the susceptibility of stands to other biotic and abiotic threats. An important measure is to shorten the rotation period of vulnerable trees (especially spruce), which would contribute not only to shortening the period when the forest is exposed to harmful factors, but also to speeding up the transition to a more suitable species composition.
Adaptation measures implemented at the level of forest stands must be followed by measures at the level of forest units, river basins and the wider landscape. An important concept is to support the connectivity of forest units and reduce the degree of their fragmentation, which can improve the natural adaptation mechanisms of the forest by creating conditions for the natural movement of species and the flow of genetic information.
As the published recommendations concern approximately 100,000 km2 of forests in the mentioned region (a third more than the area of ??the Czech Republic), it is the best time to start work. At a time of accelerating climate change, which today's largely altered forests cannot withstand through their internal mechanisms, human intervention is needed. With the help of a complex of measures in the field of plant establishment, thinning and logging, appropriate use of the genetic potential of woody plants, etc., the forester can contribute to the stability of forest stands, i.e. future forest responses to various disturbances brought by climate change.
Figure 1. Expected change in precipitation totals during the growing season by the end of the century in Central Europe. The colored background shows the difference in precipitation totals between the periods (2071–2100) - (1961–1990) in millimeters, the isolines indicate the percentage change.
Hlásny, T., Mátyás, C., Seidl, R., Kulla, L., Merganičová, K., Trombik, J., Dobor, L., Barcza, Z., Konôpka, B. (2014) Climate change increase the drought risk in Central European forests: What are the options for adaptation? Lesnícky časopis d– Forestry Journal 60, 5–18.
doc. RNDr. Tomáš Hlásny, PhD.
He obtained a doctorate at the Technical University in Zvolen in the field of landscape ecology in 2004 and obtained a habilitation at the Technical University in Ostrava in the field of geoinformatics four years later. Since 2008 he has been working at the Faculty of Forestry and Wood Sciences at the CULS at the Department of Forest Protection and Entomology.
Prepared by: Jiří Lehejček