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Jiří Trombik, Ivan Barka and Tomáš Hlásny

Abstract

Forest mortality critically affects stand structure and the quality of ecosystem services provided by forests. Spruce bark beetle (Ips typographus) generates rather complex infestation and mortality patterns, and implementation of such patterns in forest models is challenging. We present here the procedure, which allows to simulate the bark beetle-related tree mortality in the forest dynamics model Sibyla. We explored how sensitive various production and stand structure indicators are to tree mortality patterns, which can be generated by bark beetles. We compared the simulation outputs for three unmanaged forest stands with 40, 70 and 100% proportion of spruce as affected by the disturbance-related mortality that occurred in a random pattern and in a patchy pattern. The used tree species and age class-specific mortality rates were derived from the disturbance-related mortality records from Slovakia. The proposed algorithm was developed in the SQLite using the Python language, and the algorithm allowed us to define the degree of spatial clustering of dead trees ranging from a random distribution to a completely clustered distribution; a number of trees that died in either mode is set to remain equal. We found significant differences between the long-term developments of the three investigated forest stands, but we found very little effect of the tested mortality modes on stand increment, tree species composition and diversity, and tree size diversity. Hence, our hypothesis that the different pattern of dead trees emergence should affect the competitive interactions between trees and regeneration, and thus affect selected productivity and stand structure indicators was not confirmed.

Open access

Šárka Grucmanová, Jaroslav Holuša, Jiří Trombik and Karolina Lukášová

Abstract

The paper summarises available data on the occurrence of Ips cembrae in the Czech Republic and analyses the effect of temperature and precipitation on its population growth; compares numbers of beetles of overwintering and offspring generation, and compares the proportion of females and males caught in pheromone traps. The analysed data of the Forestry and Game Management Research Institute about the volume of harvested wood infested by I. cembrae from 1994 to 2013 varied between 150 and 1,415 m3. During the entire study period I. cembrae attacked more than 0.5 m3 per ha of larch forest stands in only four districts. Temperatures over the period from March to October, from April to June and annual average temperatures during the preceding and actual years, and the ratio of the annual rainfall to long-term rainfall average obtained from the Czech Hydrometeorological Institute had no significant effect on the population growth. Adults were also caught with pheromone traps, in which two generations were documented. In 2013, the numbers of caught beetles of the offspring generation exceeded those of the overwintering generation. This was due to warm and dry weather and, probably also due to high reproductive success. Although more females were caught by pheromone trapping, numbers of males and females did not differ significantly. During the studied period several periods of local outbreak of I. cembrae occurred in the Czech Republic, but their causes remained unclear, although the increase of bark beetles populations is generally regarded as a result of hot and dry weather. Larch bark beetle represents only a marginal problem in the Czech Republic.

Open access

Tomáš Hlásny, Csaba Mátyás, Rupert Seidl, Ladislav Kulla, Katarína Merganičová, Jiří Trombik, Laura Dobor, Zoltán Barcza and Bohdan Konôpka

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.