Forster, B., Knížek, M., & Grodzki, W. (Eds.). (1999). Methodology of forest insect and disease survey in central Europe. Proceedings of the second workshop of the IUFRO working party 7.03.10. Second Workshop of the IUFRO Working Party 7.03.10. Sion-Chàt

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International Union of Forestry Research Organizations

Swiss Federal Institute for Forest, Snow and Landscape Research

Methodology of Forest Insect and Disease Survey in Central Europe

Proceedings

of the Second Workshop of the IUFRO Working Party 7.03.10 April20-23, 1999, Sion-Chateauneuf, Switzerland

Editors Beat Forster Milos Knfzek Wojciech Grodzki

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Methodology of Forest Insect and Disease Survey in Central Europe

Proceedings

of the Second Workshop of the IUFRO Working Party 7.03.10 April20-23, 1999, Sion-Chateauneuf, Switzerland

Editors Beat F orster Milos Knizek Wojciech Grodzki

Published by

Swiss Federal Institute for Forest, Snow and Landscape Research Birmensdorf, Switzerland

1999

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Addresses of the Editors:

Beat Forster

Swiss Federal Institute for Forest, Snow and Landscape Research

Ziircherstr. 111

CH-8903 Birmensdorf, Switzerland KniZek

Forestry and Game Management Research Institute - Strnady

CZ-156 04 Praha 5- Zbraslav, Czech Republic Dr. Wojciech Grodzki

Forest Research Institute ul. Fredry 39

PL-30-605 Krakow, Poland

The texts included in these proceedings are the camera-ready versions provided by the authors. They are responsible for

the content and form of their papers.

Available from:

F. Fliick-Wirth, Intemationale Buchhandlung fiir Botanik und Naturwissenschaften,

CH-9053 Teufen, Switzerland sFr. 32. -

©Swiss Federal Institute for Forest, Snow and Landscape Research, 1999

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Recommended form of citation:

r

Forster, B.; Knizek, M.; Grodzki, W. (eds.) 1999:

Methodology of Forest Insect and Disease Survey in Central Europe.

Proceedings ofthe Second Workshop ofthe IUFRO WP 7.03.10, April20-23, 1999, Sion-CMteauneuf, Switzerland. Birmensdorf, Swiss Federal Institute for Forest, Snow and Landscape Research. 300 p.

ISBN 3-905620-78-2

Abstract

Methodology of Forest Insect and Disease Survey in Central Europe The themes of the second international workshop of the IUFRO working party 7.03 .1 0 ,Methodology of Forest Insect and Disease Survey

m

^Central

Europe, were:

- Discussing forest insect and disease survey methods with strategies for integrated pest management. Collection and transfer of national experiences and knowledge. Compilation of tables to compare national survey methods.

- Information about actual pest and disease outbreaks as well as about new harmful organisms in forests.

- Exchanging information on methods of advisory services in forest protection.

- As a special theme, as well as one topic on our field trip, we discussed insects and diseases of pine.

Seventy-six scientists and surveyors from 25 countries joined the meeting presenting 38 papers and 27 posters.

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Preface

The second workshop of the IUFRO unit 7. 03.10 ,Methodology of Forest Insect and Disease Survey in Central Europe, was held in Sion-Chateauneuf, Switzerland, from April 20th to 23rd 1999.

The working group is classified under IUFRO division 7: Forest Health. More information on IUFRO can be found on the Internet at the following address: http://iufro.boku.ac.at/

The workshop was hosted by the Swiss Federal Institute of Forest, Snow and Landscape Research (WSL) and took place at the Wallis Cantonal Agriculture School. Seventy-six scientists and surveyors from 25 countries joined the meeting, presenting 38 papers and 27 posters.

The main objectives of the workshop were:

- Discussing forest insect and disease survey methods with strategies for integrated pest management. Collection and transfer of national experiences and knowledge. Compilation of tables to compare national survey methods.

- Information about actual pest and disease outbreaks as well as about new harmful organisms in forests.

- Exchanging information on methods of advisory services in forest protection.

- As a special theme, as well as one topic on our field trip, we discussed insects and diseases of pine.

Acknowledgements

We gratefully thank Dr. M.F. Broggi, Director and Dr. B. Oester, Department head of the Swiss Federal Institute for Forest, Snow and Landscape Research, who supported our workshop.

We would also like to underline the excellent work of the Forest and Landscape Service of Canton Valais/Wallis. We specially thank the head of the Service, Mr. Ch. Werlen and Mr.

Ch. Pernstich, section leader in forest conservation, as well as the district and community forest officers and staff who helped to organize the field trip.

We also take this opportunity to express our gratitude to Mr. A. Darbellay, Director of the cantonal Agriculture School, for the hospitality at his school and to Mrs. J. Berard, Director of the adjoining household school, for providing the delicious meals with local specialities. Of course we also include the staff of both schools.

Coffee and local wines were generously offered by the Canton Valais/Wallis and the following forest owners: Bourgeoisie de Sion, Burgerschaften Visp and Visperterminen.

Our thanks also goes to the staff of the WSL institute, specially to the members of the Forest Insect and Disease Survey team (including workshop organizer B. Forster) and to the publi- cation service.

Finally, we specially thank our main sponsors who helped in financing the workshop or travel grants:

- Swiss Agency for Development and Cooperation SDC, Berne

-Federal Office of Environment, Forests and Landscape, Swiss Forest Agency, Berne - IUFRO Secretariat, Vienna

Editors

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Oral presentations

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Forster, B.; Knizek, M.; Grodzki, W. (eds.) 1999: Methodology of Forest Insect and Disease Survey in Central Euro e ofth_e Second Workshop of the IUFRO WP 7.03.10, April20-23, 1999, Sion-Chiiteauneuf, Switzerlanl ·

Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) 13-16. ·

FOREST PROTECTION IN SWITZERLAND

Christoph Zahn, Swiss Agency for the Environment, Forests and Landscape (SAEFL), Swiss Forest Agency (SFA), CH-3003 Berne

Switzerland

Switzerland is a Confederation consisting of 26 cantons that covers 41'285 km²with 6.9 mio inhabitants. The cantons have kept a great deal of independence with a large number of com- petencies regarding legislation and administration. Geographically Switzerland can be divided into 5 regions: Jura, Plateau, Pre-Alps, Alps and Southern slopes of the Alps. This division is justified in many ways: not only does each of these regions have a typical topography and climate, but each differs from the other in regard to political and social structures, such as population density, degree of industrialisation etc.

Forest and Forestry Service

Nearly a third of Switzerland's surface is covered by forest, amounting to 1.234 mio ha. The most important species in Swiss forests are spruce, beech and fir. The largest proportion of spruce is in the Pre-Alps and the Alps, where it represents half the tree. Even in the Plateau, where it seldom occurs naturally, spruce makes up 37% of all the forest trees. The fir trees, between 13 to 18% of the number of the trees, mostly grow in the montane zones of the Jura, the Plateau and the Pre-Alps. Beech is predominant in the Jura and the Plateau, where it represents between a quarter and a third of the total number of trees. All the forests are managed or supervised by the forestry service. In Switzerland the forestry service is divided into two distinct levels of responsibility, the federal and the cantonal level. Forestry policy at the national level is determined by the Confederation, which is responsible for overseeing the proper implementation of forestry legislation. The cantons on the other hand are expected to decide the exact nature of forestry regulations, and to enforce the law within their territory.

Two federal institutes are charged with research in the forestry

-The Federal Institute for Forest, Snow and Landscape Research (FSL) mainly works on applied research directly linked to questions of management and utilisation of forests.

-The Department for Forest and Wood Research at the Federal Institute of Technology has a dual function: on the one hand it conducts fundamental research on all matters related to forestry and the environment, on the other hand it is responsible for the training of forest engi- neers.

The Law on Forests

A century and a half-ago, Swiss forests were in a very bad state. Vast tracts of mountain forests had been cut down to serve the ever-growing need for energy of the industrial age. The negative effects of this were almost immediately evident: floods, avalanches and landslides caused deaths and great material damage. With time people realised the link between the de- struction of forests and the occurrence of such calamities. In 1876 this lead to the passing of the first law to protect the forest. Switzerland was one of the first countries to adopt such a law, although at that time it was limited to mountain forests. This law eventually developed into the Forest Police Act of 1902, which, with partial modifications, remained in force for 90 years. This law was essentially aimed at conserving the existing forest area, with a ban on deforestation and the principle of sustained yield, requiring that "the rate of felling should not exceed the rate of growth". Throughout the 20th century there has been a growing awareness that forest also have a great importance as a natural environment. Eventually, it became nec- essary to adapt the law to new requirements. The new Law on Forests that took effect on

1 January 1993 extends the concept of protection to the whole forest as an ecosystem and en-

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law now gives equal weight to these four functions, which are its guiding principles. In the following these functions will be shortly described.

The Forest's multiple Functions

1) Ecological function: Respect for the environment and the conservation of forests as ecosystems and as part of the landscape are main topics in the Law of Forests. This means management principles that are based on natural conditions and processes with a ban on clear- felling and implementing silvicultural practices imitating nature, while still allowing the pos- sibility of delimiting forest reserves or simply renouncing the management of certain areas used for wood production.

2) Protective function: The role of forests in protecting people and property against natural events such as avalanches, landslides, erosion and rockfall is of great importance throughout the mountainous regions of Switzerland. The Law specifically requires measures to ensure that the forest can at all times fulfil this function. Forest protection measures are mostly applied, where the forest has the protection function.

3) Social function: The population has the right of free access to all Swiss forests, regardless of ownership. This principle illustrates the role of the forest as an area for recreation and tourism.

4) Commercial function: Timber is one of Switzerland's few natural resources. Actually more than 5 mio m3 are harvested. Forestry and the timber industry constitute the fourth largest employers in Switzerland.

Forest Monitoring in Switzerland

The forest will grow without man's intervention. However, we are dependent on the forest, and expect it to perform many functions. Only tended forests can perform those functions in a lasting and reliable way. In order to manage and tend the forest properly we have to get to know it thoroughly. For this the program "Forest Monitoring in Switzerland" was created which records the condition of the forests and studies how they develop. Two Institutions share this work: The Swiss Federal Institute for Forest, Snow and Landscape Research FSL which is concerned with research, investigations and monitoring and the Swiss Agency for the Environment, Forests and Landscape SAEFL which applies the results in policy on forests and environment.

In the following the four sub-programs within "Forest Monitoring in Switzerland" are shortly described. In the sub-program National Forest Inventory (NFI) data are recorded every ten years concerning the structure of forests, above all with a view to sustainable forest management. The Sanasilva Forest Damage Inventory (SSI) was set up in 1985 as a reaction to the threat of forest decline. Crown thinning is monitored every year to estimate the health of the forests. The Long-term Forest Ecosystem Research (LTFER) is a research program in which the reactions of the forest to pollutants and changes in climate are being studied over a period of decades. The Forest Insect and Disease Service (FIDS) has been collecting information about forest damage caused by insects, fungi, bacteria and wildlife since 1985. It provides information concerning measures for prevention and repair.

Forest Protection

The Aim of forest protection is to minimalise the threat by pests and diseases. It will not mean, however, that every harmful insect has to be eradicated. But any gradation has to be stopped, which could weaken the forest in such a manner, that the attack would lead to a loss of important functions, for example the protection against rockfall or avalanches.

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The Measures of forest protection in Switzerland are more or less similar as in other countries. Great importance is given to the prevention of damage rather than repair, since the pos- sibilities for action when damage has occurred are often limited. Because the management principles are based on natural conditions and processes the use of environmentally harmful substances is very restricted, including any kind of plant treatment substance such as pesticides. This explains how important it is to prevent any bigger infection by biotic agents. A list of authorised products is kept, and anybody wanting to use such substances needs special training and a permit. We use pesticides only on logged stems. Preventive measures within the forest include installations such as bark beetle traps and the clearance of felling areas to prevent the propagation of parasites and diseases. Damage is repaired by felling and debark- ing the affected trees and destroying the bark and lopped branches. To co-ordinate and regu- late plant protection in international trade, the Federal Plant Protection Service was called into life, composed of federal forestry and agriculture services. The measures imposed, such as the phytosanitary certificates, mostly correspond to EU regulations.

The Forest Insect and Disease Service (FIDS) plays a very important role in pest-control. It is responsible for the information and counselling of the cantons - every canton has a responsible for forest protection - and collaborates intensively with the Swiss Forest Agency (SF A).

The Service gathers data and provides current information on any organism causing damage to forests. The FIDS and the SF A edit a list, where figure the names of the organisms that can cause important damage in the Swiss forest stands:

Pests

lps typographus, lps amitinus Pityogenes chalcographus Pityokteines sp.

Tomicus sp.

lps acuminatus Ips sexdentatus Ips cembrae

Dreyfusia nordmannianae

Fungi

Ceratocystis ulmi

Cryphonectria parasitica Ascocalyx sp.

Bacteria

Erwinia amylovora

The costs of preventive and repair measures for the above mentioned organisms are indemni- fied by the Confederation and the cantons that are concerned.

The most important pest in Switzerland is lps typographus. The chart below shows the evo- lution of unregulated felling (in 1 '000 m3) because of beetle damage during the last 14 years.

600 :§.

Cl 500

c c:; 400

IL E g 300

200 c 100

::I 0

..._

82 84 86

Unregulated Felling

----

⁸⁸ ⁹⁰

^/

Year

I I "' ""' ""-

92 94 96 98

In 1990 occurred a very big storm "Vivian". In the following years a massive development of

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The costs for the measures of forest protection follow this trend at the same rate.

Problems and Questions

After a spectacular rise in the sums allocated by the Confederation in 1991 the subsidies have been gradually sinking for the past couple of years. This is due not only to climate conditions but also to budget cuts and the downward trend is likely to continue over the next few years.

Nevertheless the forest pests and diseases will persist and one has to maintain and improve their control. Therefore ...

1) ... we have to refine our 'traditional' measures of forest protection and develop new ones:

-Do we know methods for example in bio-controlling the bark beetle (antagonists, ... )?

2) ... we need efficient and effective alternatives:

-Should we focus on supporting measures (special silviculture methods, ... )?

3) ... we should know the criteria that distinguish a pest-resistant forest stand from another one:

- How can we get the difference?

4) ... we should be able to recognise potential danger of important pests and diseases in time:

- Do we know the accurate prognosis methods?

5) ... we should know more about the biology of our important pests and diseases:

- What facts or circumstances does mostly influence their development?

6) ... we should know what does happen when climate changes:

- What new pests and diseases have we to expect?

This is not the end of the list. But it shows that there still exist enough problems to be solved by the entomologists, the phytopathologists and many other researchers.

Literature:

-Criteria and Indicators for Sustainable Forest Management in Switzerland by Evelyn Coleman Brantschen, SAEFL, Swiss Forest Agency, Berne 1997 -Forest Monitoring in Switzerland 1996-1999, SAEFL & FSL, Edition 1997

-Forests and wood in Switzerland/Wood and forests in Switzerland, SAEFL, Edition 1999

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Forster, B.; Knizek, M.; Grodzki, W. (eds.) 1999: Methodology of Forest Insect and Disease Survey in Central Europe.

Proceedings ofthe Second Workshop ofthe IUFRO WP 7.03.10, April20-23, 1999, Sion-Chateauneuf, Switzerland.

Birmensdorf, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) 17-23.

RECENT PEST OUTBREAKS AND SURVEY METHODOLOGY PRACTICED IN CROATIAN FORESTRY

INTRODUCTION

Boris Hra.Sovec

Forest Protection Department Faculty of Forestry, University of Zagreb Svetosimunska 25, HR-10000 Zagreb, Croatia

e-mail: boris.hrasovec@zg. tel.hr Miroslav Harapin

Forestry Institute Jastrebarsko Pokomog10, HR-10000 Zagreb, Croatia

Close to one half of Republic of Croatia is covered by forests and their various degradation stages (2,49 million hectares- 44% of total state area). State forests comprise 81,4% of these while only 18,6% are privately owned. Among state forests, the majority (80,1%) are

managed by public enterprise "Hrvatske sume" (i.e. "Croatian Forests"), and the rest (1,3%) reside under various protection categories like national parks, natural parks, forest reserves etc. About 1 million hectares managed by state enterprise are very valuable high forests and about '14 million hectares are various continental and Mediterranean coppices. Growing stock amounts to 324 million m3, with an annual volume increment of 9,6 million m³and annual felling of approximately 5,3 million m3. Most numerous tree species are: beech (37% by growing stock), pedunculate, sessile and other species of oak growing in lowland riparian forests and hilly belt (24%) while conifers represent only 14% by growing stock and most important one is common frr growing in mountainous natural mixed beech-fir forests.

It is clear that such natural wealth, managed mainly by state company, calls for an adequate pest survey organization and related forest protection measures. This is why in 1980 the Croatian Ministry of Agriculture and Forestry established a Diagnose and Prognose Service located in Forest Research Institute Jastrebarsko.

SURVEY METHODOLOGY

Since ownership structure of Croatian forest land is largely dominated by state forests, activity of the Diagnose and Prognose Service (DPS) is closely connected with closely related department in state enterprise "Hrvatske sume". Field data is collected by trained personnel working in 16 Regional Forestry Administrations which cover the majority of the Croatian forested land through network of 171 Forest Stations. These specialists collect data, prepare them for periodical yearly report, coordinate peld activities regarding detection, survey, evaluation and suppressive measures, should they be needed. Collected data prepared in predefined forms are sent to DPS where further analysis takes place. Here, all the regional data are summarized, biological samples are reared and tested on parasitism and health condition and finally, decisions are being made where and when to undertake suppressive measures. According to need, professionals from DPS often check the situation in the field and help regional foresters through permanent education and expertise with less often occurring pests and diseases.

Various methods are applied in order to asses the population densities of most important

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survey techniques. Fundamental principles governing the use of certain method are as

follows: it (method) should be simple enough for the field personnel to be able to conduct it, it should be accurate enough, i.e. give the satisfying density estimations and fmally, it should be finished well ahead possible damages occur so there is sufficient time left for planning the suppression measures. We can classify these survey methods in several groups. Some of the oldest ones and still very much used are those involving counting of various insect development stages on sample plots or transect paths (Harapin et al. 1996).

Egg masses of Lymantria dispar are counted regularly on a yearly basis and this is done both on continental (transect method) and coastal area (sample plots). Intensity of attack is ex- pressed by percentage of trees with egg masses for current year and these are classified into five classes, lowest having less than 1% "attacked" trees and highest having more than 50%

"attacked" trees. Regarding the qualitative analysis and determining the health state of defoli- ating insects, egg masses are often checked against parasitism for the following pests: Lyman- tria dispar, Euproctis chrysorrhoea, Malacosoma neustria, Thaumetopoea processionea, T.

pityocampa and Neodiprion sertifer.

Larvae of some insect pests are counted in some special circumstances and this applies more to forest nurseries where grubs and larvae of Scarabaeidae, Noctuidae and Elateridae are counted and if critical numbers are achieved suppressive measures have to be undertaken. On a qualitative basis, larvae are often laboratory reared and checked against parasitism or other biological agents expected to contribute the crack-down of heavy infestation period. Besides formerly mentioned defoliators larvae of Tortrix viridana, Apethymus abdominalis, various Geometridae and some more important Scolytidae are also being laboratory checked. In the continental region caterpillar nests of overwintering E. chrysorrhoea are counted on a transects in lowland riparian forests. The same is done throughout coastal and island pine forests with T. pityocampa.

Pupae or cocoons are sometimes being counted and used for assessment of population buildup for several pests among which more often T. pityocampa, N sertifer, Stereonychus fraxini and Dendrolimus pini. Laboratory analysis of qualitative population elements is

periodically carried out on pupae of the above mentioned pests.

Adults are also targeted for population density assessment and this is done in several ways.

Most often, adults are collected by some means of trapping technique. Well established method for assessment of population densities and critical population levels is used for two of the most important loopers: Erannis defoliaria and Operophthera brumata. Their wingless females are caught and counted on sticky trap-belts during the emergence period October- January. Another method for trapping the soil emerging pests is by using the wire-mesh covered cages (some Geometridae, A. abdominalis and acorn pests such as Curculio spp. and Cydia spp. ).

Modem methods for adult trapping in monitoring purposes involving sexual pheromones are used only fragmentary and more as an experimental addition to permanent evolvement of survey techniques (Paranthrene tabaniformis, Gypsonoma aceriana, Ostrinia nubilalis, Zeu- zera pyrina). Aggregation pheromones of lps typographus, Pityogenes chalcographus and Trypodendron lineatum are being consistently used as a monitoring tool in continental region.

Though spruce forest in Croatia are not nearly endangered as those in Central Europe, this method has caught foothold especially in those limited areas where spruce has been introduced during mid century and where it grows out of its natural habitat.

There is however one special method of branch sampling developed for specific needs of population density and defoliation risk assessment in our broadlived oak forests. Its

originator, Dr. Miroslav Harapin introduced it by the late eighties with intention to better

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assess unclear situation regarding flowering and acorn production and causes for early crop loss (Harapin 1993). Another important issue were problems with population density

assessment of some early defoliators which overwinter on oak twigs in egg stage. Today, this has become a widely accepted method providing fairly accurate predictions of what is going to happen in sampled forests in the following spring.

Table 1. Sample results of a four-year branch analysis regarding flowering capacity, defoliation prediction and insect pests involved (regional forestry administration samples given in the table represent larger part of Quercus robur forests in Croatia, "?"

symbol means no data available)

Number

Number Dead Flowers Defolia-

Year of Sprouted tion Pest

samples of twigs shoot tips Male Female _(%)

BJELOV AR REGIONAL FORESTRY ADMINISTRATION

1989/90 12 88 57 30 15 8 25 leafroll., loopers, casebearer, sawfly 1990/91 36 252 130 74 585 119 35 leafroll., loopers, casebearer, sawfly 1991192 62 400 233 166 1810 425 20 leafroll., loopers, casebearer, sawfly 1992/93 53 283 228 168 732 239 75 leafroll., loopers, casebearer, sawfly

:E(%) 163 1023 648 (63) 438 (42) 3142 791 (20) 39

KARLOVAC REGIONAL FORESTRY ADMINISTRATION

1989/90 2 68 63

-

⁶²⁸ ⁷ ¹⁵ leafrollers, loopers

1990/91 11 88 56 41 1217 132 60 oak sawfly

1991192 3 17 6 16 67 47

- -

1992/93 17 73 55 67 295 198 30 leafrollers, loopers

L (⁰^/o) ³³ ²⁴⁶ 180 (73) 124 (50) 2207 384 (15) 35

ZAGREB REGIONAL FORESTRY ADMINISTRATION

1989/90 10 67 36

-

⁴⁷¹ ⁸ ³⁰ leafrollers, loopers, casebearer

1990/91 27 187 125 32 633 209 45 oak sawfly, loopers

1991192 12 88 35 47 164 8 15 oak sawtly, loopers

1992/93 65 367 256 157 936 274 65 oak sawfly, loopers, casebearer :E(%) 114 709 452 (64) 236 (33) 2204 499 (18) 36

VINKOVCI REGIONAL FORESTRY ADMINISTRATION

1989/90 40 219 170 29 1357 95 50 leafroll., loopers, casebearer, sawfly 1990/91 41 229 210 41 868 170 20 oak sawtly, 1oopers, casebearer

1991192 ? ? ? ? ? ? ? ?

1992/93 25 164 86 73 104 42 25 leafroll., loopers, casebearer, sawfly :E(%) 106 612 466 (76) 143 (23) 2329 307 (12) 32

:E<%>1 422 2590 1746 (67) 941 (36) 9882 1981 (17) 36

During late fall and winter, samples are taken from randomly chosen oak trees from upper strata. Usually, trees are felled down (which is mainly during the normal felling period in these forests), then 4-7 branches, 7(}-80 ems in length, are taken from upper parts of crown, preferably from all four aspects. Branches are transported to a centralized laboratory managed by DPS service where they are given water supply, room temperature and daily supply of sunlight. Underneath, white sheets of paper are secured on which early signs of defoliation can be recorded (excrements). Also, the defoliating fauna, their composition and densities can be easily assessed and related to available food supply, i.e. buds and sprouting leaves.

Another important outcome of this method is prediction of flowering capacity for sampled trees (ratio between female and male buds) which is becoming more and more important from the silvicultural standpoint since eighties and nineties were the years of growing problems

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Furthermore, another assessment can be made on the basis of ratio between nonsprouting branches. This data (assuming the samples were correctly picked and promptly transported to laboratory) will predict the intensity of oak dieback ("Waldsterben") so often addressed during seventies and onwards.

Table 2. More important insect pests recorded during the 1979-1998 period, area attacked and most recent short-term trends

Area attacked during the

Insect Order Host period 1979-1998 (ha) Trend

average maximum

Lymantria dispar Lepidoptera Broadlives 77943 136000 --+

Geometridae Lepidoptera Broadlives 19096 64013 --+

Tortrix viridana Lepidoptera Oaks 13983 64013 t

Euproctis chrysorrhoea Lepidoptera Quercus robur, Q. 2712 11091 ttt

tpetraea

I,Apethymus abdomina/is Hymenoptera Quercus robur 1005 3640 t

Malacosoma neustria Lepidoptera Quercus robur 737 8022 ttt

Stereonychus fraxini Coleoptera Fraxinus angustifolia 6996 31529 t

Thaumetopoea pityocampa Lepidoptera Pinus spp. 4702 18193 -!.

!Argyresthia fundella Lepidoptera Abies alba 2766 39582 --+

Coleophora laricel/a Lepidoptera Larix europaea 14 287 t

iRhyacionia buo/iana Lepidoptera Pinus spp. 42 189 t

Dioryctria sp/endidella Lepidoptera Pinaceae 12 135 -!.

Pristiphora abietina Hymenoptera Picea abies 17 209 --+

Neodiprion sertifer Hymenoptera Pinus spp. 16 92 -!.

Sacchiphantes viridis, S. abietis Homoptera Picea abies 160 1203 --+

Dreyfusia nuesslini Homoptera Abies alba 49 820 -!.

Scolytidae Coleoptera Pinaceae 1594 4410 --+t

Melasoma populi Coleoptera Poplar cultivars 683 2927 -!.

Phyllodecta vitellinae Coleoptera Poplar cultivars 537 2967 -!.

Saperda populnea Coleoptera Poplar cultivars 141 1020 -!.

Cryptorrhynchus lapathi Coleoptera Poplar and willow 124 954 --+

cultivars

Paranthrene tabaniformis Lepidoptera Poplar cultivars 95 986 -!.

Thaumetopoea processionea Lepidoptera IQuercus spp. 298 2000 tt

PEST OUTBREAKS AND RECENT TRENDS

As in many neighboring countries, situation in Croatia, regarding more important insect pests is in many ways similar. There are, off course, some differences due to a specific forest phy- tocoenoses and climatic predisposing factors. We will discuss only the main pest species and some important groups regarding their relative importance to Croatian forestry.

There is more than twenty species of defoliators, sap suckers and xylophages screened regularly or on a periodical basis with various survey methods used in Croatian forests and forest nurseries. Table 2 lists those which caused some serious damage in the past twenty years and some that show rising short-term trends during the last two years.

The most serious pests in the lowland riparian forests and partly in the hilly belt of continental Croatia are L. dispar, T. viridana and several geometrid species among which E. defoliaria

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and 0. brumata lead in severity of attack.

During the past two decades three major peaks in L. dispar population density occurred (Fig.

1 ). The highest one was by the beginning of eighties with more than 130000 hectares attacked. Second peak followed by the late eighties and the third one peaked in 1994 (Androic &

Harapin 1996). Each of the following was smaller by attacked area. It is worth mentioning that L. dispar became more serious pest in coastal area in last decade and less important in inland Croatia. Its last gradation starting on the Istria peninsula swiftly plagued the whole coast reaching the southern parts near Metkovic in merely three years. The problems concerning suppression in coastal region arise from fact that no economic damage can be calculated in these brush type degraded forests composed mainly from pubescent oak where no measures are taken and gradation is left to end by itself. In valued lowland Q. robur forests, potential

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Fig. 1. Population density trends of the most important pests

Lymantria dispar Tortrix viridana

economic loss is calculated by the fact that about 30% of the increment is lost if total defoliation occurs (Klepac & Spaic 1965). Parasitism levels and occurrence of other biotic re- gulators are checked during the gradation period and they play important role in creating prognostic charts and yearly suppression plans.

Geometrids are the second most important group of forest defoliators whose importance grew especially in lowland forest ecosystems during eighties and nineties. It seems that similar trends have been experienced in some regionally close countries (Cs6ka 1998, Mihalache et al. 1998). Two of the aforementioned species are by far most widely dispersed causing major damages but some other species contribute regionally by incrementing the defoliating effect (Colotois pennaria, Agriopis aurantiaria).

Tortrix viridana and its close relatives (Archips xylosteanus, A. crataeganus, A. podanus) also play an important role both in continental

Q.

robur and

Q.

petraea forests as in coastal

Q.

ilex forests and maquis. Infested areas very often coincide with those attacked by geometrids therefore prognostic charts are compiled taking this additive effect into account. Both geometrid and tortricid group of defoliators are being monitored predominantly by winter branch

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Among other defoliating insects some deserve special attention due to their periodical and regional defoliating impact. Euproctis chrysorrhoea and Malacosoma neustria are good examples. Both are constantly present throughout the whole lowland region but not causing damages in larger areas. E. chrysorrhoea occurs in coastal region but there its caterpillars prefer feeding on Arbutus unedo, sparing the oak trees. However, in areas where they occur periodically, and this is just the case in two last years in central riparian area of Sava river (SE of Zagreb ), damages are very serious and intensive measures are being undertaken. In such gradation years egg masses (M neustria) and caterpillar nests (E. chrysorrhoea) are being collected for the survey purposes.

Ape thymus abdomina/is and A. braccatus are the two tenthredinids which were recorded in lowland oak forests by late fifties and have periodically entered gradation stages since then.

Latest gradation was in mid-eighties.

Stereonychus fraxini is causing severe damages on Fraxinus angustifolia and there are several factors that hamper our efforts to efficiently survey and suppress this serious defoliator. For the population density assessment overwintering adults are collected by scrubbing the moss from tree trunks covering the 1m high imaginary cylinder area. This is where at least one half of the population overwinters. It is still not quite certain whether this holds true in various stand situations. Next crucial problem occurs when suppression measures are definitively needed. Since first damages occur practically during sprouting there is always a problem with inadequate area for any kind of pesticide deposition. And thirdly, narrow-leafed ash grows predominantly in mixed oak-ash forests where dispersed ash trees cause additional treatment difficulties.

Among other defoliating insects we would like to point out some rising populations of ten- thredinid species among which Caliroa annulipes seems to have the leading role in the last three years. It started damaging young plants in some forest nurseries but in 1998 it heavily attacked some young oak stands.

Conifer species are most numerous in coastal and mountainous region. Pine processionary moth is widespread and sometimes very important pest in whole coastal region. It is regularly monitored since it is always present in some parts in relatively large numbers. Egg masses, cocoons and caterpillar nests are collected and quantitatively and qualitatively analyzed. If suppression measures are needed they are conducted either by mechanical collecting and bur- ning of winter nests or by chemical treatments with BT or IGR based compounds.

Abies alba, as our most important conifer species, has specific guild of defoliators. However, one lepidopterous species emerged as far most important and destructive. During mid-fifties Argyresthia fundella started its devastating gradation in the hearth of mountainous region. It remained important pest with this first eruption being the strongest. In the past twenty years its average attack area amounts 2766 hectares with 1980 being the year of largest occurrence (almost 40000 ha). Population density assessment is done by counting the cocoons on sample branches and calculating this number per thousand fir needles. Regarding this ratio, attacked area is charted into five infestation classes. During the last two decades there have not been any major gradation occurrences.

Problems regarding xylophages can be categorized in three main groups: technical damages occurring on logged and dying trees both in lowland oak forests as in fir and spruce forests of mountainous region (Trypodendron spp., Xyleborus spp. and Platypus cylindrus), physiological damages with resulting tree dyout (Agrilus spp., Pityokteines spinidens, 1 typogra- phus, Pytiogenes chalcographus) and combined technical and physiological damages in pop-

lar and willow cultures caused by various Coleoptera and Lepidoptera (Table 2). We should underline that scolityd damages on spruce are by far smaller in scale compared to other

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central European countries since common spruce grows mainly in mixed beech-fir forests of central Croatia and is not endangered like in other countries. Off course, same trends like in other countries are evident but in much smaller scale (Cs6ka 1998, Grodzki 1998, Knffek et al. 1998, Zolubas & Ziogas 1998).

CONCLUSION

Diagnostic and survey procedures practiced in Croatian forestry play important role in implementing the sustainable forestry principles. All the serious and most damaging insect pests are regularly monitored and their damage impact properly and aptly prognosed. Suppressive measures, coordinated from DPS service, are shifting toward ecologically more appropriate biote- chnical and biological compounds. Less and less synthetic pesticides are used and when nece- ssary, only those with lesser toxicity and shorter persistency are used.

Improvements should be made in future through the following: intensifying the sampling procedures for some insects occurring on irregular basis and especially in areas with high degree of tree dyout, implementing the pheromone monitoring programs for more species with special regard to some lepidopteran pests in poplar cultures and lowland oak forests, intensifying the branch sampling method and widening its use on other types of forests.

Clearly, all of this can be obtained only with substantial support from the relevant state institutions and major forestry company but if benefits from DPS activities are confronted to its cost, only positive conclusion can be achieved.

REFERENCES

ANDROIC, M. & M. HARAPIN, 1996: Stetna entomofana. In D. Klepac (ed.), Hrast lufujak u Hrvatskoj, Vinkovci, 241-245.

CSOKA, G., 1998: Recent trend of damage caused by pests and pathogensin the Hungarian forests. In: Grodzki, Knizek & Forster (eds.), Proceedings, First Workshop of the IUFRO WP 7.03.10, Warszawa, 115-120.

GRODZKI, W., 1998: Threats to mountain forests in Poland by bark beetles. In: Grodzki, Knizek & Forster (eds.), Proceedings, First Workshop of the IUFRO WP 7.03.10, Warszawa, 167-172.

HARAPIN, M., 1993: Survey of some factors regarding acorn crop of common oak (Que reus robur L.). Radovi, Vol. 28 (1-2): 185-191.

HARAPIN, M., M. HALAMBEK, B. LIOVIC, S. NOV AK-AGBABA & DINKA MATO- SEVIC, 1996: Diagnosis and prognosis in forest pathology. In: S. Sever (ed.), Za8tita suma i pridobivanje drva, Sumarski fakultet Sveucilista u Zagrebu i Sumarski institut Jastrebarsko, Zagreb, 69-74.

KLEPAC, D. & I. SPAIC, 1965: Utjecaj nekih defolijatora na debljinski prirast hrasta lufuja- ka. Sumarski list (89) 3-4: 93-101.

KNiZEK, M., P. ZAHRADNiK & J. LISKA, 1998: Outbreaks of bark beetles in mountain conditions. In: Grodzki, Knizek & Forster (eds.), Proceedings, First Workshop of the IUFRO WP 7.03.10, Warszawa, 173-176.

MIHALACHE, G., V. MIHALCIUS, A. SIMIONESCU & M. IANCULESCU, 1998: Aspects regarding the phytosanitary state ofRomanian forests in the period 1997-1998. In:

Grodzki, Knizek & Forster (eds.), Proceedings, First Workshop of the IUFRO WP 7.03.10, Warszawa, 141-151.

ZOLUBAS, P. & A. ZIOGAS, 1998: Recent outbreaks of lps typographus in Lithuania. In:

Grodzki, Knizek & Forster (eds.), Proceedings, First Workshop of the IUFRO WP 7.03.10, Warszawa, 197-198.

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Forster, B.; Knizek, M.; Grodzki, W. (eds.) 1999: Methodology ofForest Insect and Disease Survey in Central Europe.

Proceedings ofthe Second Workshop ofthe IUFRO WP 7.03.10, April20-23, 1999, Sion-Chiiteauneuf, Switzerland.

Birmensdorf, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) 24-29.

NATIONWIDE FOREST DAMAGE SURVEYS IN FINLAND Seppo Nevalainen

Finnish Forest Research Institute, Joensuu Research Station P.O. Box 68, FIN- 80160 Joensuu, Finland

Different levels of surveys

The area of forest land in Finland is 20,085 million hectares. The Finnish National Forest In- ventory (NFI) has produced information on forest resources over this area for more than 70 years. The first inventory dates back to 1921-1924. Different forms of damage in statistically rep- resentative samples have been registered since the Seventh inventory (1977- 1984). In the Sev- enth inventory, however, the only identified causes of damage were wind, snow, moose (Alces alces L.) and pine- twisting rust (Melampsora pinitorqua (Braun) Rostr.). The Eighth NFI (1986- 1994) was the first to include more detailed information on health of forests, including diseases and pests. The Ninth NFI started in 1996, and concentrates, in addition to forest health, especially to aspects of multiple use of forests and biodiversity. About 150 stand or tree variables are assessed or measured in the NFI, on more than 70 000 field plots. Satellite images and digital maps have been routinely exploited since the Eight NFI, to produce up-to-date information of forests, and for smaller areas than before. The new inventory method is thus called multi-source inventory (Tomppo 1996).

Detach L- or square- shaped tracts, instead of continuous inventory lines, have been used since the Fifth NFI (1964). Fixed size sample plots were also replaced with relascope (Bitterlich) plots at that time. Survey designs have been somewhat variable in different inventories and in different parts of the country. The distance between tracts increases from south to north, and is 7 x 7 km in southern and mid- Finland in the Ninth NFI. The tracts are comprised of 14-18 relascope plots, with a 250- or 300- m distance between plots (fig.1).

A network of 3009 permanent sample plots was established during the years 1985-86, covering the whole country systematically. These plots were established in order to provide data for a large number of investigations, e.g. the effect of air pollutants on forest ecosystems and the state of health of the forests, and to produce information about the changes in forests, which cannot be obtained in traditional inventories using temporary plots. The sampling units were four-plot clusters in a 16 x 16 km grid with a 400-m distance between fixed- sized circle plots (0,1-0,3 ha each) in southern Finland, and three plot clusters in a 32 x 24 km grid in northern Finland (plots 600 m apart). These plots have been measured three times, 1985/86, 1990 and 1995. A new network of permanent plots is established during the Ninth NFI: every fourth cluster is marked as permanent, however, the plots on one side of the quadrangle- shaped tract are not measured (fig.

1).

A systematic subsample was taken from the permanent plots of the Eight NFI, e.g. the first plot of the tract in mineral soils was chosen, rejecting every tenth tract. These 450 plots are used in national forest health monitoring (1986 onwards) for annual assessment of forest vitality (defoliation, discolouration) and also biotic and abiotic injuries. All the dominant or eo-dominant coniferous or birch trees are used as sample trees.

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Principles of damage recording

Forest damage has been assessed in every plot situated on forest land. By definition, the mean annual increment of wood should be at least 1 rn³ha-¹on forest land. Forest damage is assessed using three different codes: the symptom, the cause and the apparent severity of the damage (damage degree). Recently, also the time and duration of the event is recorded (table 1). The possible occurrence of damage is assessed at the sample tree and at the stand levels (e.g. the stand in which the centre point of the plot is situated, is assessed for damage). Normally only one, the primary damage is recorded for each sample tree or stand. Damage is recorded only if it is caused by an external agent, i.e. genetic malformations or male flowering are not recorded as damage. In principle a similar coding system (table 1) is used in all inventories, although the codes for symptoms and causal agents vary slightly in different levels of inventory, and change a little even between years. In addition, the coding of symptoms, especially that of discolouring, is much more detailed in national forest health monitoring.

Table 1. Ninth National Forest Inventory of Finland 1996-. Description ofthe variables and codes used for assessing forest damage.

Variable

Damage symptom

Causal agent of damage

Degree of damage (stand level= importance of the damage)

Codes

0) no damage 1) dead standing tree(s) 2) fallen tree or standing stem(s) broken below the crown 3) decayed standing trees 4) stern or root damage within 1 m from the stem 5) resin flow (above 1,5 m in stem) 6) broken or dry top (in the upper half of the crown) 7) other crown malformations 8) technical defects on stem 9) dead or broken large branches A) unnaturally pruned branches (from below) B) defoliation C) discolouration D) multiple symptoms (in a stand) due to ageing

0) unknown

A. Abiotic/ anthropogenic A1) wind A2) snow A3) frost A4) other climatic factors A5) fire A6) soil factors A 7) harvesting A8) air pollution (identified source) A9) other human activity

B. Animals B 1) voles B2) elk, deer or reindeer B3) other vertebrates B4) Tomicus sp. B5) Hylobius abietis B6) Diprionidae B7) other de- foliators B8) /ps sp. B9) other identified insect BO) non-identified in- sect

C. Fungi Cl) Heterobasidion annosum C2) other decay fungi

C3) Gremmeniella abietina C4) Melampsora pinitorqua C5) Perider- mium pini C6) other rust fungi C7) needle cast fungi C8) other identified fungi CO) non-identified fungi

D. other factors D1) competition between plants

0) slight damage, symptoms observed, but the damage does not reduce the silvicultural quality of the stand 1) moderate, the stand quality is reduced by one class 2) severe, the stand quality is reduced by more than one class 3) complete, artificial regeneration is required

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Table 1 (continued) Degree of damage (sample tree level=

apparent severity of the damage)

Time and duration of the damage event

0) slight damage which does not affect the development of a tree 1) damage that affects growth temporarily; does not lower the value or amount of timber 2) damage that decreases the value or the amount of timber produced 3) lethal, or the tree is already dead

0) started less than two years ago 1) started 2-5 years ago, still continuing or spreading out 2) started 2-5 years ago, already ceased 3) started more than 5 years ago, still continuing or spreading out 4) started more than 5 years ago, already ceased

Experiences and examples

The forest damage data has been utilized in various ways. However, the data has been applied in very few scientific reports. The statistics of forest damage (of stand damage that reduces stand quality) are published in official forest statistics. Regional reports on forest resources, as well as annual reports of forest vitality usually contain a section on abiotic/ biotic damage. Natiowide damage results (the Eight NFI, permanent and temporary plots) have been presented in several occasions and reports, e.g. Jukola- Sulonen et al. 1987, Nevalainen and Yli-Kojola 1990. Ac- cording to the latest published official statistics, fungi are the most important of the identified causal agents, but in northern Finland abiotic factors are most important (table 2).

Table 2. The occurrence of different causes of damage that reduced the silvicultural quality of the stands (degree of damage greater than 0) in the National Forest Inventory 1986-1997. Source:

Finnish Statistical Yearbook ofForestry 1998.

% of forest land area

Not iden- Abiotic Fungi Insects Mam- Others Total

tified mals

South Finland 3,6 2,4 5,1 0,3 1,4 1,9 14,7

North Finland 9,4 9,2 8,9 0,4 1,2 2,2 31,2

Whole country 6,2 5,4 6,9 0,3 1,3 2,1 22,1

The massive NFI dataset allows for the simultaneous comparison of several environmental and silvicultural factors affecting the occurrence of diseases and pests. It also provides raw data for risk modelling. Furthermore, it is possible to combine other spatial data and/or models with the NFI field measurements. Tarnminen (1985) used the data of the seventh NFI to estimate the abundance of butt-rot in spruce in southern Finland. Latitude, elevation, temperature sum, paludi- fication and fertility of the site and stand age were the variables which best the rot fre- quency. Butt-rot could be detected quite reliably jn NFI by taking increment cores at stump

Forster, B., Knížek, M., & Grodzki, W. (Eds.). (1999). Methodology of forest insect and disease survey in central Europe. Proceedings of the second workshop of the IUFRO working party 7.03.10. Second Workshop of the IUFRO Working Party 7.03.10. Sion-Chàt

Methodology of Forest Insect and Disease Survey in Central Europe

Methodology of Forest Insect and Disease Survey in Central Europe

Proceedings

of the Second Workshop of the IUFRO Working Party 7.03.10 April20-23, 1999, Sion-Chateauneuf, Switzerland

Abstract

m

Contents

Preface

Acknowledgements

Oral presentations

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