Ladislav Kulla

Climate change increases the drought risk in Central European forests: What are the options for adaptation?

Abstract The paper presents information on the projected drought exposure of Central Europe, describes the anticipated dynamics of the regional forests, and identifies measures facilitating the adaptation of forests to climate change-induced drought risk. On the basis of an ensemble of climate change scenarios we expect substantial drying in southern Slovakia and Hungary, while such trends were found to be less pronounced for the Czech Republic and Austria. In response to these climate trajectories, a change in species composition towards a higher share of drought tolerant species as well as the use of drought resistant provenances are identified as paramount actions in forest adaptation in the region. Adaptation to aggravating climate change may need to use artificial regeneration to enrich local gene pools and increase the drought tolerance of stands. Increasing risks from pests, pathogens and other disturbances are expected as a result of more frequent and severe droughts, underlining the need to put a stronger focus on risk management principles rather than on indicators of productivity in silviculture and forest planning. A consolidation of disturbance monitoring systems and a broader use of pest dynamics and hazard rating models are paramount tools to facilitate this adaptation process in forest management. The effectiveness of all the suggested measures needs to be controlled by efficient forest monitoring systems, the consolidation of which seems to be a timely task. Systematic and long-term implementation of the presented measures should increase forest stability and resilience, and further secure the sustainable provision of ecosystem services under climate change. Abstrakt V článku sú prezentované informácie o očakávanom vývoji sucha v oblasti strednej Európy, je opísaná možná dynamika lesov v podmienkach zmeny klímy, a je vypracovaný systém opatrení umožňujúcich adaptáciu lesov na zmenu klímy. Na základe kolekcie scenárov zmeny klímy bol identifikovaný výrazný nárast intenzity sucha v oblastiach južného Slovenska a Maďarska, zatiaľ čo v oblasti Českej republiky a Rakúska bola zmena relatívne nevýrazná. S ohľadom na tento vývoj predstavuje úprava drevinového zloženia smerom k vyššiemu zastúpeniu sucho tolerujúcich drevín a širšiemu využívaniu proveniencií rezistentných voči suchu jedno zo základných adaptačných opatrení. V prípade výrazných zmien klímy narastá význam umelej obnovy, ktorá predstavuje nástroj na zlepšovanie druhovej a genetickej diverzity porastov a zvyšovanie ich tolerancie voči suchu. Narastajúci vplyv škodcov súvisiaci s rastúcim vplyvom sucha a ďalších abiotických činiteľov naznačuje potrebu orientovať pestovanie a hospodársku úpravu lesa viac na manažment rizík ako na maximalizáciu produkcie. Konsolidácia systémov monitoringu škodlivých činiteľov a širšie využívanie modelov dynamiky škodcov a hodnotenia rizík patria medzi ďalšie dôležité opatrenia podporujúce adaptáciu lesov na zmenu klímy. Všetky uvedené opatrenia musia byť podporené informáciami získanými na základe dlhodobého monitoringu lesa, ktorý však vyžaduje urýchlenú konsolidáciu. Systematická a dlhodobá realizácia prezentovaných opatrení podporí stabilitu a rezilienciu lesov a vytvorí predpoklady pre udržateľné poskytovanie ekosystémových služieb a funkcií v podmienkach zmeny klímy.

Sustainable forest management in a mountain region in the Central Western Carpathians, northeastern Slovakia: the role of climate change

European forestry is facing many challenges, including the need to adapt to climate change and an unprecedented increase in forest damage. We investigated these challenges in a Norway spruce-dominated mountain region in Central Europe. We used the model Sibyla to explore forest biomass production to the year 2100 under climate change and under two alternative management systems: the currently applied management (CM), which strives to actively improve the forest’s adaptive capacity, and no management (NM) as a reference. Because biodiversity is thought to have mostly positive effects on the adaptive capacity of forests and on the quality of ecosystem services, we explored how climate change and management affect indicators of biodiversity. We found a differential response across the elevation-climatic gradient, including a drought-induced decrease in biomass production over large areas. With CM, the support of non-spruce species and the projected improvement of their growth increased tree species diversity. The promotion of species with higher survival rates led to a decrease in forest damage relative to both the present conditions and NM. NM preserved the high density of over-matured spruce trees, which caused forest damage to increase. An abundance of dead wood and large standing trees, which can increase biodiversity, increased with NM. Our results suggest that commercial spruce forests, which are not actively adapted to climate change, tend to preserve their monospecific composition at a cost of increased forest damage. The persisting high rates of damage along with the adverse effects of climate change make the prospects of such forests uncertain.

Test of airborne laser scanning ability to refine and streamline growing stock estimations by yield tables in different stand structures

Abstract Even if stand inventories based on growth tables have been widely discussed over the last years, this method of forest mensuration is still widely applied due to favourable ratio between costs and achievable precision of stand growing stock estimation. The aim of the study was to verify the potential of airborne laser scanning data (ALS) for direct estimation of mean stand height and mean stand density (stocking) as fundamental inputs for forest mensuration based on yield tables. The material from two reference plots with substantially different stand structure was processed by REFLEX software, and confronted with the results of the precise terrestrial inventory. The number of detected tree tops decreased from 100% in the case of super-dominant trees to 30% and 5% in the case of supressed trees at the homogeneous and heterogeneous plot, respectively. The correlation of ALS heights with terrestrially measured heights was R = 0.88 at the homogenous plot, and R = 0.77 at the heterogeneous plot. The tendency to underestimate dominant and to overestimate suppressed trees was revealed at both plots, but was more pronounced at the heterogeneous one. Nevertheless we justified that the mean ALS height calculated from the heights of the detected trees represented the biometric mean stand height linked to the stem with the mean basal area quite well. The stocking estimated by REFLEX software according to delineated crowns´ area was also closer to the real value of stocking than the one obtained by the routine mensuration procedure. The results indicate promising potential of the ALS data processed by REFLEX software to rationalise forest mensuration based on yield tables in even-aged forest structures.

Classification of tree species composition using a combination of multispectral imagery and airborne laser scanning data

Abstract Remote Sensing provides a variety of data and resources useful in mapping of forest. Currently, one of the common applications in forestry is the identification of individual trees and tree species composition, using the object-based image analysis, resulting from the classification of aerial or satellite imagery. In the paper, there is presented an approach to the identification of group of tree species (deciduous - coniferous trees) in diverse structures of close-to-nature mixed forests of beech, fir and spruce managed by selective cutting. There is applied the object-oriented classification based on multispectral images with and without the combination with airborne laser scanning data in the eCognition Developer 9 software. In accordance to the comparison of classification results, the using of the airborne laser scanning data allowed identifying ground of terrain and the overall accuracy of classification increased from 84.14% to 87.42%. Classification accuracy of class “coniferous” increased from 82.93% to 85.73% and accuracy of class “deciduous” increased from 84.79% to 90.16%.

Reconstructing past forest status using inventory and tree ring data to support uneven-aged forest management

Abstract The decision to change forest management system from the traditional even-aged to the selection one based on statistical inventory is often limited by a missing previous inventory. To avoid this issue, we used available forest inventory data from ca 2 000 ha of mixed uneven-aged beech-fir-spruce-pine forest and tree ring data from 831 trees to reconstruct forest status from one decade ago. For this purpose, we have created three sets of species-specific models: 1) diameter-stump models to reconstruct the diameter of missing trees, 2) diameter-increment models based on tree ring data to estimate past diameters, and 3) height-diameter models to estimate past tree heights. This approach has allowed us to completely reconstruct the state of the forest as it was ten years ago and use the results as a substitution for a previously missing inventory.

Regionalization of Forests in Slovakia Based on Their Natural Potential

The study presents the results of an analysis of the spatial variability of geologic and climatic factors that predetermine the natural potential of forest sites in Slovakia, as well as the relations between these factors and the natural presence and productivity of tree species. Several national classification systems that combine the existing and newly designed regional and site units were examined and compared in terms of explained variability of both natural presence and productivity of the main tree species in Slovakia: oak, beech, and spruce. Forest management data describing the presence and the productivity of these tree species were extracted from the sample file of the representative forest stands and utilized for the analysis. Maximization of explained variability and minimization of the number of units were predefined as desirable capabilities of a suitable classification system. The results show that including the regional level is a beneficial contribution to the classification system. Generally, combinations of site and regional units explain approximately 50–70 % of the total variability of the tree species’ natural presence, but only about 15–25 % of the total variability of tree species production. A site classification system composed of a maximum of 8 units on the regional level and 80 units on the site level appears to be sufficient for strategic forest management in natural conditions in Slovakia.

Koncept geobiotopu ako možnej vyššej stanovištnej jednotky pre diferencovanie manažmentu lesov

Abstract The paper proposes and justifies an alternative concept of aggregation of forest site types in higher units for purposes of differentiation of forest management. Analysis of variance was performed for both: the natural occurrence of tree species in reserves, as well as the production potential of tree species measured on the representative plots according to Zlatnik´s altitudinal vegetation zones and edaphictrophic series. Based on the results of this analysis, an aggregation of forest site types was suggested along the elevation gradient of climatop, and along the edaphic-trophic and the edaphic-hydric gradients of edaphotop. By intersection of such created 32 categories of geotope with the basic formation groups of forest habitats by Braun-Blanquet geo-botanical school, 53 reconstructive geo-biotopes were formed. The proposed unit was compared using the F-test, Akaike information criterion (AIC), and the index of classification efficiency (EQ) with current typological units in terms of its ability to describe the variability of the analyzed parameters. Finally, the qualitative association of the compared classification models with the European classification systems was assessed. Based on the results obtained, it can be concluded that the site unit geo-biotop is at least comparable with currently used unit MGFT, with the number of categories lower by 72%.

Pokus s uplatnením neceloplošnej umelej obnovy kalamitnej holiny na demonštračnom objekte Husárik / An Experiment with Non-Whole-Area Reforestation of Calamity Clearing on the Demonstration Area Husárik

Abstract The paper deals with non-whole-area artificial reforestation as a new rationalization method of forest regeneration based on a combination of planting of desirable tree species and natural regeneration of other tree species from surrounding adult stands. It presents the first preliminary results of the experiment established on the demonstration area Kysuce - locality Husarik. The first results suggest that non-wholearea artificial regeneration can bring significant cost savings in establishing and subsequent treatment of the forest cultures. On the other hand, the question of ensuring adequate regeneration of desirable tree species in required time remains open at this time, and longer monitoring is necessary. Prispevok sa zaobera neceloplošnou umelou obnovou ako racionalizačnou metodou obnovy lesa založenej na kombinacii zalesňovania žiaducich drevin a prirodzenej obnovy ďalšich drevin z okolitych dospelych porastov. Uvadzaju sa prve, predbežne vysledky pokusu založeneho na vyskumnodemonštračnom objekte Kysuce, lokalita Husarik. Prve vysledky poukazuju na to, že neceloplošna umela obnova može vyznamne ušetriť naklady na založenie ako aj nasledne ošetrovanie lesnych kultur. Na druhej strane, otazka zabezpečenia adekvatnej obnovy žiaducich drevin v požadovanom čase stale ostava otvorena, pričom je potrebny dlhši monitoring vyvoja