Population dynamics of Ips typographus in the Bohemian Forest (Czech Republic): Validation of the phenology model PHENIPS and impacts of climate change Lude ˇk Berec a,⇑ , Petr Dolez ˇal b , Martin Hais c a Department of Biosystematics and Ecology, Institute of Entomology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, 37005 C ˇ eské Bude ˇjovice, Czech Republic b Department of Biochemistry and Physiology, Institute of Entomology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, 37005 C ˇ eské Bude ˇjovice, Czech Republic c Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 C ˇ eské Bude ˇjovice, Czech Republic article info Article history: Received 27 September 2012 Received in revised form 10 December 2012 Accepted 17 December 2012 Available online 19 January 2013 Keywords: European spruce bark beetle Insect outbreak Voltinism Forest damage Population dynamics Modeling abstract Phenology models play an important role in insect ecology and pest management. For bark beetle species prone to frequent outbreaks, they help predict swarming periods, discern sister generations hard to rec- ognize in the field yet indispensable in studies of bark beetle population dynamics, predict the extent to which the generations entering diapause develop, as well as help address the omnipresent issue of impacts of climate change. As a prerequisite to developing a simulation model of landscape-level forest disturbances in the Bohemian Forest, including those due to Ips typographus, we validate the phenology model PHENIPS, published in the literature and simulating seasonal development of this species, by data coming from this region. We find a reasonable agreement between the modeled and actually observed bark beetle dynamics, thus strengthening the potential role of PHENIPS in any future attempt to model dynamics of Central European populations of I. typographus. In addition, we use PHENIPS to assess impacts of climate change on temperature-regulated phenology of I. typographus. In contrast to previous studies which used regional climate models to predict future temperature development, we indepen- dently account for changes in the mean air temperature and in the frequency of extreme weather events – for the latter, we assume that the inter-annual air temperature variance will also increase. Since bark beetle development is driven by bark temperatures and both low and high bark temperatures inhibit the development, we find that the effects of increases in the air temperature mean and variance are compen- satory. Hence, if climate is to change so that both these characteristics grow, we expect only a relatively minor change in generation development time. Moreover, initiation of the third filial generation of I. typographus in the Bohemian Forest is predicted to occur only for relatively large shifts in the mean air temperature. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction The European spruce bark beetle, Ips typographus (L.), is one of the most economically important forest pests in Eurasia (Werme- linger, 2004). Changes in landscape character that follow its out- breaks are traceable even decades later. Forest protection and bark beetle biology are therefore popular subjects promoted in the media and of wide public interest. The issue of bark beetle out- breaks in the Czech Republic is commonly related to the issue of management strategies applied in the core zones of the Šumava National Park and its surroundings. Regardless of its enormous economic importance, I. typographus is a natural inhabitant of European forest ecosystems, with numer- ous historical records of its past outbreaks in the Bohemian Forest (of which the Šumava National Park is a part). During its outbreak in the years 1833–1839, the bark beetle infested more than 225,000 m 3 of wood (Jelínek, 1988). Even more dramatic was its 1868–1878 outbreak, when more than 7,000,000 m 3 of wood had to be cut during sanitation loggings, creating clearings on the area of 9000 ha. In the 20th century, the situation was relatively stable except for the period 1991–2001 when spruce stands over an area of 3620 ha were damaged (Skuhravy ´ , 2002). The current outbreak in the Bohemian Forest was initiated by extensive windfalls that were left unmanaged in 2007 after the se- vere windstorm Kyrill. The following years were marked by an enormous increase in bark beetle population density, leading to destruction of more than 1,000,000 spruce trees. Originally profes- sional discussions of foresters and ecologists on optimal bark bee- tle management in the protected areas have gradually become a political problem, threatening the very existence of the Šumava 0378-1127/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.foreco.2012.12.018 ⇑ Corresponding author. Tel.: +420 387 775 293; fax: +420 385 310 354. E-mail addresses: berec@entu.cas.cz (L. Berec), dolezal@entu.cas.cz (P. Dolez ˇal), Martin.Hais@seznam.cz (M. Hais). Forest Ecology and Management 292 (2013) 1–9 Contents lists available at SciVerse ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco