Current Problems and Tasks of Forest Protection in Poland
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Folia Forestalia Polonica, Series A – Forestry, 2018, Vol. 60 (3), 161–172 ORIGINAL ARTICLE DOI: 10.2478/ffp-2018-0016 Current problems and tasks of forest protection in Poland Iwona Skrzecz1 , Aldona Perlińska2 1 Forest Research Institute, Department of Forest Protection, Sękocin Stary, Braci Leśnej 3, 05-090 Raszyn, Poland, phone: +48 22 7150541, e-mail: [email protected] 2 General Directorate of the State Forests, Department of Forest Protection, Grójecka 127, 02-124 Warszawa, Poland AbstrAct Current problems of forest protection concern the declining health of forest stands due to climate change and the re- sulting extreme weather events such as heat waves, droughts, hurricane winds, heavy rainfalls and floods. Repeated impacts of these factors increase susceptibility of forest stands to pest insects and fungal pathogens. Norway spruce (Picea abies [L.] H. Karst) is sensitive to high air temperatures and water shortage. Long lasting droughts during the last two decades, have been one of the reasons behind Norway spruce dieback due to severe outbreak of European spruce bark beetle Ips typographus (L.) in the mountainous regions of southern Poland. In the Scots pine (Pinus sylvestris L.) stands, water balance disorders have enhanced the colonization of weekend trees by steelblue jewel beetle Phaenops cyanea (F.) and engraver beetle Ips acuminatus (Gyll.), as well as contributed to the spread of fungal diseases caused by Gremmeniella abietina (Lagerb.) Cenangium ferruginosum Fr. and Sphaeropsis sapinea Fr. fungi. Water related stress leads to weakening of oak stands, which are attacked by Agrilus spp. beetles and pathogens from the genus Phytophthora. It is possible that long lasting droughts initiated the spread of infectious ash disease caused by Hymenoscyphus fraxineus (= Chalara fraxinea), which resulted in the epidemic of ash dieback throughout Europe. Until recently, the use of plant protection products was the most common method of forest protection against pest insects and pathogens. Poland’s accession to the European Union has affected the marketing and use of plant protec- tion products in the country. The implementation of the EU legislation (Directive 91/414/EEC, Directive 2009/128/ EC and Regulation No 1107/2009) has resulted in decreased assortment of pesticides registered for the protection of forests. High costs and long registration process considerably limited the interest of producers in placing the plant protection products on the market. Systematic decrease in the number of plant protection products possible to register for use in forestry, as well as the principles of integrated plant protection established in the EU in 2014 call for seek- ing plant protection methods based on the natural enemies of pests, such as pathogenic microorganisms, parasites and predators. Therefore, contemporary forest protection requires the advancement of integrated methods for pest insect and disease control through developing methods of forecasting forest dangers, the use of natural enemies and agro-technical methods for regulation of pests, as well as the development of decision support systems as a tool fa- cilitating introduction of integrated forest protection principles. Such support systems help to establish optimal terms for the implementation of protection measures, so as to increase their efficiency while limiting the use of chemical pesticides to an absolute minimum. © 2018 by the Committee on Forestry Sciences and Wood Technology of the Polish Academy of Sciences and the Forest Research Institute in S´kocin Stary Received 23 January 2018 / Accepted 15 March 2018 162 Iwona Skrzecz, Aldona Perlińska Key words Drought, water stress, stand weakening, insects, pathogens, plant protection products, invasive species, integrated pest management, forest protection IntroductIon sects as well. Tree root pathogens and saprophytes that break down wood grow better at higher soil tempera- Forest management comprises the protection of forests tures (Sierota and Małecka 2016). Root systems dam- that involves monitoring present and identifying future aged by drought, sudden freezing or as a result of hur- factors with negative impacts on forest ecosystems, ricane become the portal of entry for fungal pathogens along with applying a range of methods to reduce risks that initiate the multistage process of tree stand disease, caused by these factors (Szabla and Szujecki 2016). often ending with tree death, in which harmful insects One of the most important issues in contemporary for- participate actively (Mykhayliv and Sierota 2010). est protection is the declining health of Poland’s stands due to climate change impacts associated with earlier rarely observed extreme weather events, such as heat dIebAcK of conIferous stAnds waves, droughts, heavy rains followed by floods, se- vere hailstorms, hurricanes and whirlwinds (Allen et Norway spruce Picea abies (L.) H. Karst – a dominant al. 2010; Vanguelova 2010). Polish winters are getting tree species in mountain forests growing in Southern warmer, come later in the year and are not as long as Poland – is particularly sensitive to hydrothermal stress. they used to be, so the growing season is extended. Long drought periods, prevailing in the last two dec- Systematic impact of extreme weather negatively af- ades, have exaggerated the Norway spruce forest de- fects forest health, and as a result, tree stands are mas- cline in the Polish mountains (Szabla 2009; Grodzki sively attacked by harmful insects or severely infected et al. 2010, 2014). This process was intensified in the by fungal pathogens. summer 2006, when weeks of droughts and extreme- Air temperature is the most important factor with ly high air temperatures in the Beskidy Mts. (western direct effects on entomofauna. The average temperature Carpathians) initiated a large-scale process of Norway increase by 1–2oC can lead to changes in insect physi- spruce dieback (Grodzki et al. 2014). Extreme weather ological processes, shorter developmental stages, which favoured expansion of root fungi of the genus Armillar- can be followed by increased numbers of insect gen- ia. Consecutively, fungal pathogen infections lowered erations in the season, as well as modification of insect the threshold of natural resistance of Norway spruce dispersal and movement (Netherer and Schopf 2010; stands, which as a result were massively colonized by Jaworski and Hilszczański 2013). Insects that are sec- secondary insects, namely bark beetles Ips typographus ondary pests of forest trees can serve as an example, as (L.) and other co-occurring insect species. In 2016, the climate warming contributes to increasing the number decline of Norway spruce stands was observed on the of their generations emerging in the year (Öhrn 2012). total area of over 40.2 thousand ha, and nearly 560,000 On the other hand, high air temperatures (over 30oC) m3 of timber was jeopardized (Milewski 2016). In the can negatively affect population dynamics by limiting last decade, the problem has been recorded just in the insect fertility and feeding activity (Christiansen and south of the country (the Forest Districts situated in the Bakke 1968; Wermelinger and Seifert 1998). Extreme Beskid Śląski and Żywiecki Mts.); however, since 2015, air temperatures can have indirect effects on insect it has been also observed in the south-western regions, population numbers, such as decreased biological activ- therefore, sustainability of forest stands in the region ity of natural enemies, in particular pathogenic bacte- of Silesia (in particular – Lower Silesia) has also been ria, viruses, fungi and nematodes (Lacey et al. 2015). threatened. Furthermore, long-term drought and water deficiency in Prolonged dry periods and high air temperatures, the soil have adverse effects on host plants, thus – on in- more than ever in July and August 2015, have resulted Folia Forestalia Polonica, Series A – Forestry, 2018, Vol. 60 (3), 161–172 Current problems and tasks of forest protection in Poland 163 in a rapid decrease of groundwater levels. Even Scots fore planting hindered appropriate development of larch pine Pinus silvestris L. with its taproot system was not seedling roots, which resulted in inadequate formation able to handle stress due to water deficiency – especial- of mycorrhizas. Larch weakening was observed in Po- ly, when it grows on fertile sites. In 2015, Scots pine land’s southern regions, in forests harshly affected by decline was observed in the total area of over 40 thou- large larch bark beetle – Ips cembrae (Heer) (Grodzki sand ha, including the area of nearly 1.5 thousand ha, 2010). Larch deterioration was also recorded on post- where the Scots pine trees severely colonized by sec- fire areas reforested withLarix trees as forecrop – plant- ondary insects or infected by fungal diseases had to be ed densely in the soil degraded by fire. In this case, the clear-cut (Forest Research Institute 2016). The decline most likely reasons behind larch deterioration are in- of Scots pine has been increasingly observed in Central sufficient amounts of available nutrients in the soil and and Southern Poland. needle-infecting fungus Meria laricis Vuill.), which Scots pine forests have been continuously damaged spreads out via adjoining shoots of too densely planted by fungal diseases and secondary insects. Steelblue trees (Jalkanen 2016). jewel beetle Phaenops cyanea (F.) is placed at the top of the list of pest insects, which colonizes sun-heated forest edges formed due to windbreaks,