J A F | 9 r t g q \ l

J. Appl. Ent. 119,643 651 (1995)@ 1995, Blackwell Wissenschafts-Verlag, BerlinrssN 0931-2048

Bark beetle (Gol., Scolytidae) communit ies and host and sitefactors on tree level in Norway spruce primeval natural lorestR. Jaku5Department of Forest Protection and Game Management, Forestry Faculty, Technical University in Zvolen,Slovakia

Abshact: Bark beetle infestations on tree level in spruce primeval natural forest in the'Pol'ana nad Detvou'naturalreserve in Central Slovakia were classified into communities of 11.l,lurgops palliatus lH. glabratus, Dryocoetes hectogaphus,Ips typographus, Xylechinus pilosus, Polygruphus polygraphus and. Xyloterus lineatumllps typographus. Effects of hostand site facto$ in separating the bark beetle communities werc qxantitatively evaluated. Cluster and discriminantanalyses w€re used. The relative influence of each factor for community separation varied among communities. Themost impo ant factors were the state of the matedal, canopy closure and the stage of the p meval natural forest.Dimension, stage of decay, elevation, exposure, soil acidity, potential forest vegetation type and the year of successionhad statistically signif,cant effects.

1 IntroductionBark beetle communities on the Norway spruce (PiceaaDres (L) Karst.) in Central Europe were described byPmrren (1932, 1945, 1955) and Creecrr (1978). Severalauthors (PFEFFER, 1932, 1945: SrouNl, 1959, 1970,1975,1916; CAPECKT, 1978; KATAEV et al., 1984; GRUN-WALD, 1986) have shown interactions between bark beetleinfestations and host and site factors on the Norwayspruce. Sror,rue (1969,1982) and Sn,lnlrr (1986) stud-ied spruce bark beetles in primeval natural forests. Kul-sL,{ and NovArovL (1962) and NovAr (1962) focusedtheir investigations on bark beetle communities in areasaffected by air pollution.

However, the effects and interactions of environ-mental factors on Norway spruce bark beetle com-munities has not been evaluated quantitatively before.

The objective of this study was to classify the barkbeetle infestations on tree level in the spruce primevalnatural forest into bark beetles communities, and toquantitatively evaluate the effects of host and site fac-tors in the separations of these spruce bark beetle com-munities.

2 Material and methods

2.1 The study area

The present study was carried out in the spruce primevalnatural forcst in the'Pol'ana and D€tvou'natuml reserve (Lat49"41'N, Long 19"26'E) in Pol'ana massif in Central Slovakia(Central Europe).

The ancient spruce forest covers about 440 ha at altitudesbetwe€n I 200 and 1457 m above sea level. The bedrock ofthe area consists of andesite. The veg€tation is classifiedas Sorbeto'Piceetum, Acereto-Piceetum, Fageto-Abietum,Abieto-Fagetum and Fageto-Aceretum potential forest veg-etation types (for the potential forest vegetation types seeZLATNiK, 1956).

Thecontent ofpollution in spruce needles is 2.4 times higherthan in areas with no air pollution in Slovakia (MAiKovsKA,1991) .

The reserve was damaged by the gale disaster during thewinter of 1988/1989.

2.2 Sampling program

The study was conducted between 1988 and 1992. During thisperiod, bark beetle infested spruce trees w€re looked for andsampled over the whole study area.

The following data were listed about each infestation: barkbeetle presence, location of infestation on tree, tree diameterat breast height, height or length of the tree, declination ofthe trunk, kind of material (root connection), defoliation,discoloration, elevation, slope, exposure, potential forest veg-etation type, canopy density and the stage of the primevalnatural forest.

Bark beetle presence and location of species on tr€es weredetermin€d by sampling infested bark and by identif,cation ofbark beetle imagoes or galleries. Species detemination andtaxonomy followed PreFFEn (1955). Species other than barkbeetles (Col.. Scolytidael were ignored.

Diameter at breast height (1.3 m) was measured in cm. Incases of infestation only on a snapped part of a tree (top orcrown break), the snapped part was consider€d as a samplingunit and 1.3 m was measured from the break.

Height or length was measured in m. Declination of thetrunk from the horizontal plan and slope was measured indegrees by clinorneter.

The root connection (rc) was classified according to thefollowing scale: snapped tree or part oftree (rc 0%), snappedtree partly connected with roots (rc 10%), partially snappedtree snapped/uprooted trce (rc 20%), snapped/upfooted tree(rc 40%), uprooted tree with poor connection of roots withsoil (rc 45olo), uprooted tree with medium connection ofrootswith soil (rc 65%), uprooted tree with good connection ofroots with soil (rc 9070) and standing tree (rc 100%).

Defoliation and discolomtion were estimated according toUN-ECE manual (1986) in percentages. Elevations were

u. s. copyriehr crearane ce.rer code sratenent: 0931 2048195119104643 $ I1.00/0

644 R. Jakui

determined from a fofestry map (1 : l0 000) and exposure wasdetermined by hand compass.

The stages ofprimeval natuml forest (growing up ( 1), opti-mum (2), breakdown (3)) were determined according to KoR-pEL' (1989). Canopy closure was estimated on a scale from 0(open space) to I (full canopy).

Potential forest vegetation types were determined from amap of potential forest vegetation tlpes (Dnrnir, 1969).

Data were obtained on 267 infestations. Snapped trees ortheir parts accounted for 177o of sampled mate:f.al.24o wereuprooted trees and 590lo werc standing trees. The mean height(length) of analysed material 'Nas 22 m (SD 9), the meandiameter at breast height was 47 cm (SD 20) and the meanelevation was 1312 m above sea level (SD 65).

2.3 Dala analysis

The degrees of interspecilic associations between bark beetlespecies presented in th€ infestations were evaluated by Orchaiand Jaccard indices (LuDwIG and RrvNor-os, 1988). Thedirections ofassociations were determined according to LUD-wlc and REYNoLDS (1988).

The degree of association between bark beetles, or barkbeetle associations and other quantitative characteristics, wereevaluated by correlation coemcient according to MrsLlvec1 l e5 7) .

The statistical significance ofassociations was tested by chi-square or by Yates's chi-square test according to LUDWIG andR!\.NOLDS (1988).

The classification of samples of bark beetl€ infestation intobark beetle communities was aided by the use of averagelinkage between groups method of cluster analysis (SNEATHand SoKAL, 1973). Bark beetle presence variables and SquaredEuclidean distance were used.

Discriminant analyses (NouRSrs, 1990) were perfomed onthe data to determine if there was a significant differenceamong the groups with regard to host and environmentalfactors and to determine relative importance ofeach factor inthe separation of groups.

Th€ data about exposure were coded on a scale from 0 (SW)to 180 (NO).

The relationship between potential lorest vegetation typesand soil acidity (AMBRos, 1987, quoted in MicHAL, 1992) wasused to calculate the variable 'soil acidity'.

Discriminant functions were calculated to discriminatebetween gach group and the rest of the groups.

Pooled within groups, conelations between discriminatingvariables and canonical disriminant functions were used toassess the contributions ofvariables to discriminant functions.

To test significant differences among groups with respectto facto$ that have shown significant correlation with thediscriminant function. Duncan's multiple range test was used.

The Statistical package SPSS/PC* @ V4.0 was used lorstatistical analysis.

3 Results and discussion3.1 Bark beetle communities

The pal tern ofc luster ing for 267 bark beet le in festa l ionsis shown in the figure. A cutoff distance of 16 (shownas a vertical dashed line in the figure) was used as areference point for identifying groups. At this level ofresemblance there were seven groups. Group 7 was

3.1.1 Group 1.' Hylurgops palliatus/H. glabratus

Group 1 consisted ofinfestations with the frequent pres-ence of Hylurgops palliatus, H. glabratus and Dryocoetesautographus.It is negatively associated with the pres-ence of lps tlpographus and Xyloterus lineatum (tableI ). Among the pres ence of H. pallitttus, H. glabratus andD. autographus arc significant interspecific associations(table 2).

The statistical analyses (tables 3, 4) determine associ-ations of this group with snapped matedal or withmaterial with small root connection lying on grand(small declination) (table 5), lower elevations, a closercanopy, younger stages ofpdmeval natura.l forest (table6), colder exposures and Fageto-Aceretum potentialforest vegetation type (r : 0.16, sig. at 5yo probabilitylevel). There are the negative associations with standingtrees and breakdown stage of primeval natural forest(table 5).

This group is conformity with the zoocenosis of Dr.y-ocoetes and with the part of zoocenosis of Xyloteruslineatum according to PFEFFER (1955) and C*rcrI(1978). The negative association of this group with Xlineatum colld be explained by insufficient moistureand an accelerated fast process of decaying of snappedmaterial.

3.L2 Group 2: (Dryocoetes hectographus)

The preseiice of Dr1, ocoetes hectographus, Orthotomicussuturqlis, P o ly grup hus p olygrap hus and Pityophthorustrrigardhi arc significantly associated with group 2, andthe presenbe of D. autographus and lps typographus arenegatively associated with this group (table l). Twoother species, H. palliatus and X. lineatum, are ptesenlwith frequency abo\t 20o . Among D. hectographus, X.lineatum and P. polygraphus are significant interspecificassociations (table 2).

The performed analyses (tables 3, 4) showed positiveassociations of this group with laying material con-nected with roots (preferably uprooted trees) (table 6),taller/longer .trunks, higher elevations, colderexposures, stage of optimum ofpdmeval natural forest(table 5), a closer canopy and earlier years of studyperiod. There are negative associations with standingtrees and stages of growing up and breakdown of pri-meval natural forest (table 5).

This group is approximately in agreement with zoo-cenosis of Xyloterus lineatum and zoocenosis of Drl-ocoetes accordrng to PFEFFER (1955) and CAPECKI(1978). D. qutographus is supplemented by D. hec-tographus. The absolute absence of D. autographuscould be caused by the sampling technique. It is imposs-ible to distinguish galleries of these two species in fieldconditions. Sample ofimagoes contained only one fromthese species. The presence of P. polygraphus, whLchaccording to PFEFFER (1955) and CAPECKT (1978) is aspecies attacking standing trees, could be explained bythe similarity of processes of decay in uprooted treeswith good connection to land and standing trees.

3.1.3 Group 3: Ips typographus

excluded from further analysis, because it involved only Group 3 is characterised by the frequent presence oflpsone case. D,pographus (table 1). The presence of L typogrttphus,

Bark beetle in Norway spruce 645

R e s c a l e d s q u a r e d E u c l i d i a n d i s t a n c e

201 51 0

x 3 /93, I - typoqraphus

6 /34t X- l ineatun - I - tvpoqraphus

7 / L : ( I - t v p o q r a p h u s - P - p o l v q r a p h u s )

5 ,/52: P- polvqraphus

/ 2 4 : H . p a l I i a L u s - H - q l a b r a t u s

. / 1 8 : X - p i l o s u s

. /55: D-hectoqraphus

I

x group ,/ number of cases in group ,/ the most frequentspecies in gt roup -

Fig. Simplifed dendrogramfrom cluster analysis. The auerage linkage between groups methods and squared Euclidiandistance were used. The oertical dashed line represents reference points for determining groups

4

2

Ips amitinus, Pityogenes chalcographus, P. polygraphus,P. grandiclaua and. H. palliatus are significantly associ-ated with this group and the presence of X. Iineqtum rssignificantly negalively associated with this group. Thefrequency of the presence of D. hectographus is 19o/o.Between the presence of I. typographus ar.d I. amitinus,and between I. typographus and P. chalcographus arepositive interspecific associations (table 2).

The analyses (tables 3, 4) proved associations of this

group with materials with low levels of defoliation anddiscoloration, low levels of canopy closure, the break-down stage ofprimeval natural forest (table 6), warmerexposures, higher elevations and less acidic soils. Thereis the statistically significant positive association withsnapped material (table 5), but there are the positiveconelation coemcients with the presence of uprootedand standing tiees.

The species presented in this group could be classified

Table I. Correlation coeffcients andfrequencies for bark beetles presence in groups on spruce material

Species/Group

Ips rypagraphusIps amitinusD r y o c oe tes au tograp husD 4i o c oe tes he c t ogmp husEylwgops palliatusHylurgops glabralllsP i ry ogene s chalc o gmp husP o ly grap hLts po ly grap husPolygraphus subopacusP o ly grup hus grandic laDaX)jlaterus linealum

Pit y op ht ho rus pity ogr ap husPiryophthor s ittga hiOrthotomicus suturalisCrypturgus cinere sCrypturgus pusillusDerulrcctunus micansCryphal s saltuariusH )' las t e s tutlicular ius

Correlations coeffcients and frequencies (%)2 3 4 s

* : signiflcant at 5% probabiiity level.** : significant at l% probability level.

_0.22** 8 _0.17** I 0.82** 92 _031+* 0 _0.06** 15 0.30** 7t0.00 0 0.00 0 0.23** 8 0.00 0 0.00 0 0.060.24+* s4 o.7o* o 0.46 4 -1.03. 6 0.65 2 -0.690.00 00 0.86,1.,i 95 0.20 19 0.00 0 0.03** 4 0.04*' 6o.sl** 62 0.25 21 0.06** 5 0.00 0 0.04* 4 o.t4 15

_0.63* 8 _0.25 20 0.44** 0 ,0.80** 0 0.23** 62 0.39*+ 100

0.54'r,N 58 0.14 11 0.09 6 0.00 0 0.02+ 2 0.060.00 0 0.12 7 0.03** 16 0.00 0 0.00 0 0.000.00 0 0.07** 7 0.09** 8 0.00 0 0.91** 96 0.000.06 8 0.03 4 0.01 5 0.07 11 0.19* 13 0.000 . 0 0 0 0 . 0 0 0 0 . 1 9 * * 2 - 0 . 0 1 0 0 . 0 0 0 - 0 . 0 0

-0.04 0 0.03 4 -0.00 r 0.64** '72 0.12 10 0.00-022 0 -0.08 4 0.08 8 -0.25 0 0.08 12 0.09-0.00 0 0.12* 0 -0.00 0 0.00 0 -0.00 0 -0.00-0.0? 0 0.21++ 5 -0.04 0 0.08 0 -0.05 0 -0.06

0.00 0 0.05 2 0.07 2 0.09 6 0.10 4 -0.00-0.00 0 0.08 2 -0.00 0 0.16* 6 -0.00 0 -0.00

0.00 0 0.13 5 -0.00 0 0.08 6 0.13 6 0.05

6003

36

00

30.02 0 0.01 0 0.03 1 0.52** 33 -0.01 0 -0.01 0

-0.00 0 -0.00 0 0.09 I 0.00 0 -0.00 0 -0.00 0

646 ) R. Jakus

. i q c q - : e q - . ' l 9 qt l

t t t l

K E a = = 3 8 S a t i; -l -l -i -i.-i.-( -i ; - ; o- l l l

t - l l I

- - q q 9 q 9 . i : - 6 1

t t t r

s r o € N

d c i c i c i d o - d d d c i ol l

q c n 9 " ? q q . 1 - q -t t t t l

- q - - n q q n . l e . lt t t t l

- c 9 . l - - 1 - - c . l - -t t t l

9 9 q . l ! q q - q - -

t i

. l - . 1 . 1 - " 1 q - n - . 1t t l

s:3gsssssiss

E

4 q E

- : a .E

r r r l

e

:

\i

e 6s r

: o

f- .*

3 sx

.::

s n' i €

.x. &.

F^- j+ P.-":

N . Se b€ s

among zoocenosis of Ips typographus, Xyloterus line-atum, Dryocoetes and Polygraphus polygraphus accord-ing to PFEFFER (1955) and C*ncrr (1978).

The presence of zoocenosis with different require-ments 10 temperature and to moisture on one tree couldbe explained by the variability of environmental con-ditions on one tree. The associations of this group,dominated by L typogtaphus, with less acidic soils andhigher elevations, are not in agreement with SToLINA(1959, 1970) .

There is a statistically slgnificant negative correlationbetween elevation and canopy closirre (r : -0.32).There is a stronger correlation between canopy closureand canonical discriminant function than between elev-ation and canonical discriminarit function in this group(table 3). it means that it is the indirect effect ofelevationto discriminant function through canopy closure. Itexplains the effect ofelevation to discriminant functionfor the group.

According to KUDELA and Nov,{rov,{ (1962), dyrngspruces aflected by air pollution are less suitable to LD)pographus attack Trees on more acidic soils are moresusceptible to air pollution. Thus a higher proportion ofdying trees primary affected by air pollution in potentialvegetation types with more acidic soils could explainobserved relationships between soil acidity and dis-criminant function.

3.1.4 Group 4: Xylechinus pilosus

Xylechinus pilosus rs the most fiequent species in group4. The presence of Xylechinus pilosus, Cryphalus" andCrypturgus pussilus are significantly associated with thisgroup, while the presence of X. lineatum and I. typo-graphus are signrficantly negatively associated with thisgroup ( table l ) .

The performed analyses (tables 3, 4) showed positiveassociation of this group with standing trees (table 6),smaller dimensions, higher levels ofdefoliation, a closercanopy closure, the growing up stage of primeval natu-ral forest (table 5) and the later years of study period.

This group is more or less in agreement withzoocenosis of Polygraphus polygraphtts according toPFEFFER (1949, 1955) and CApEcKr (1978). Howeverthe dimensions ofthese trees were insumcient for attackby P. palygraphus.

3.1.5 Group 5: Polygraphus polygraphus

Group 5 is characterised by a high frequency of P.polygraphus. The presence of P. polygraphus, X. line-atum, Polygraphus subopacus, D. hectographus, H. pal-

.liatus and H. glabratus are significantly positivelyassociated with this group and the presence of I. typo-graphus rs negatively associated with this group (table

There are significant positive interspecific associ-ations between P.polygraphus and X. lineatum,belweerP. polygraphus and P. subopaan, atd between P. poly-graphus and Pityophthorus pityographus (table 2). Anegative association exists between P. polygraphus andD. hectographus and between P. polygraphus and H.palliatus.

)

Bark beetle in Norway spruce 647

- . : q q . . t . , t . .1 - q q n c t .1

t t t t t l

. t q q q ! q q - c n ! . 1 0 9 9

I

- - - < t n q . l n \ q ! t . 1 - q

l l I oI

q - . 1 - . q q n . : o 9 q n q c l

t t t t l

E A

. 9 4

t s 6v -

. 9 0

E : o5 ; -

c z i3 r X

: - q

" " -x

, 2 ; ' -

9 ; E

i i o ' -

- i F

.9 .9,<

E !'l €

. 2 X . t )

: ; b

w 3 €P i ! ?K 9 Yv ! ! ' ^

a z ",.!

q q - e n . 1 9 n . . l . t 6 l q . l

l l l o

* d

t l t l

l l t t l l

t t t l

, . o d

d - q q 9 - : n . l a l 9 9 9 -

. ' t - : - - . l n q 9 n \ - q q

l l I o

n - - q . t . . t . . i . t n . t q . 1 q

t t l t l

SsFi .9g; s;; ̂,,, gu(,

(-)(J

(.)

(.)

l l

s

'b

i!

R

*

ExposureMean S.D.

DeclinationMean S .L .

6 5 4 1 G . 1 2 3 6 5 4

G . 3 2 1 5 6 4

G . 2 377 3',7 28 8 3 8 39 6 4 3 69 8 3 9 5

109 53 4116 44 1 *

26] 29.1 I33.2 34.',7 249.t 4t.3 3 *55.6 3',7.480.5 23.5 5 *86.1 16.5 4 *

Canopy closure DefoliationG . 3 6 2 5 1 4

0.18 0 .16 30.22 0.14 60 .35 0 . i8 2 *0.36 0.270.39 0.20 I *

6 5 3 3 38 0 3 3 2 *8 1 3 2 1 *8 6 2 4 5 *

Discoloration

l l 60.54 0.30 4 * 94 13 4 *

Tree diameter al breasl heighlG . 4 2 3 1 6 s 2 4 1 5 6

19.'/ 14.5 438.2 15.3 2 x

50.3 20.35t.'7 20.0 I *

52.1 16.2 6 *

54.5 18.2

Tree height/t€ngth

62798 l828891

Year

G . 33 8 33 7 23 5 428 I7 5 52 0 6

G . 4 2 1 3 6 5 G . 2 18.8 7.9 4 1.9 I.3 2

19.8 8.4 2 * 3.2 r.722.6 10.7 I * 3.6 1.8 4 *

22.7 8.4 3 * 3.7 1.3 3 *

23.3 7.4 3.8 1.0 6 *

25.3 8.9 5 * 4.0 1.8 5 *

+Denotes pairs olgroups signilicantly diferent at the 0.050 level.S.D. : Standard Deviations.G. : Groups.

4 3 6 5

R. JakuS

Table 4, Summary of the results Duncan's multiple range tests of influence of the host and enuironmentgl factors onpresence of the groups on spruce materiaL The quantitatiae uqriable with st{rtisticttlly significant result from Dis-criminant Anab)sis were used. (There are no significant differences in altitudes between groups)

Table 5.C o r r e lation c o efrt c ient sfor groupspresence mstages ofpr imeu al natur al Jbr e s t

Table 6.C orr e lation c o eff cient sfor clusterspfesence onkinds o;f trees

Stage/Groups

g.owing upoptimumbreakdown

l 2Corlelations coemcients

0.01 -0.23**0.03 -0.07

_0.12* _0.28**

0.060.18**0.2'7**

0.24** -0.07 -0.08-0.12 0.29+* 0.04

0.10 -0 .04 .0 .19**+ : significant at 57o probability level

** : significant at l7o probability level

Tr€es/Groups

snappeduprootedstanding

t 2Correlations coemcients

3 4

0.4s** 0.l9**-0.03 0.42**_0 .18+* _0 .28**

0.26**0.030.10

-0 . t2 ,0 . t5* 0 .08-0 .12 0 .13 * 0 .124

0.34** 0.4,7** 0.14** = significant at 57o probability level.

** : significant at 1% probability level.

Bark beetle in Norway spruce

The analyses (tables 3, 4) showed positive associ-ations ofthis group with standing trees (table 6), biggerdimensions, a higher level of defoliation and discolor-ation, a closer canopy, more acidic soils and the stageof optimum of primeval natural forest (table 5) andnegative association with laying trees and Abieto fag-etum potential forest vegetation type (r: -0.15, sig.at 5% probability level).

The majority of infestations presented in this groupare dominated by species of zoocenosis Polygraphuspolygraphus according to PFEFFER (1955) and Clrncrr(1978). Part of the species belongs to zocenosis of Xyl-oterus lineqtum and DD,ocoetes.

3.1.6 Group 6: Xyloterus lineatum/Ips typographus

Xyloterus lineatum and Ips typographus are the mostfrequent species in this group. The presence of X. line-atum, I. tlpogrqphus and D. hectographus are srg-nificantly associated with this group (table 1).

There are significant positive interspecific associ-ations between X. Iineatum arrd I. typographus andbetween .Y. Iineatum and D . hectogrqphus (table 2) .

This group is associated with a high level of defoli-ation and discoloration (tables 3, 4) uprooted and stand-ing trees (table 6), a low level of canopy closure, abreakdown stage of primeval natural forest (table 5),Abieto Fagetum (r:0.12, sig. at 5% probability level)and later years of study period.

The species pxesented in this group belong to twomajor zoocenosis. They are zoocenosis of Xyloterus line-etum and zoocenosis of lps typographus according toPTEFFER (1955) and CArECKI (1978). There is presentzoocenosts of Dryocoetes.

The species composition in group 6 is in agreementwith species compositin on standing trees in the secondyear infestation ofzoocenosis ofL tlpographus accord-ing to PTEFFER (1949,1955).

The association of this group with relatively warmermicroclimatic conditions represents the requirementsof Ips typographus zoocenosis (SroLINA, 1969, 19'10:CAnEcKI, 1978) and it is similar to group 3.

3.2 The influence ofhost and site factors

Presented results with regard to preference of bark bee-tle species or communities to specific host and environ-mental conditions are in agreement with previousreports (PIEFIER, 1955; SToLINA, 1969, 1970, 19'76;C,r.rEcrr, 1978; GniiNwALD, 1986; Sne.n,AP.r., 1986). Theperformed analyses (tables 3,4, 5,6) show the significantdifferences among the groups with relation to host andsite factors.

The relative importance of each factor in the groupseparation varies among groups (table 3).

The most important host factors are root connectionand tree declination. These two factors represent thestate of spruce material and its resistance to bark beetleattack. At least one of these factors is signiflcantly cor-related with canonical discriminant function in all fivegroups (table 3). The correlation analysis (table 4)showed the significant associations of all bark beetlecommunities (groups) with the different status ofspruce

material. The influence offactors connect€d to the statusof material (root connection and tree declination) tobark beetle communities' discrimination is in agreementwith CAPECKT (1978) and KATmv et al. (1984).

Defoli 1on and discoloration are factors linked withthe advancement of death of the host tissue and withthe success of bark beetle infestation. These factors aresignificantly correlated with the canonical discriminantfunctions in four groups (table 3). The influence ofthesefactors in the discrimination of suitability of sprucematedal for different bark beetle communities is inagreement with PFerren (1955) and CApEcKr (1978).

Dimensions of material (d.b.h.,length/height) are sig-nificantly correlated with discriminant functions inthree groups (table 3). This effect is in conformity withSroLrNA (1969, 1976).

The abiotic environmental factors (elevation, slope,exposure) are weakly correlated with the discriminantfunction (able 3). Elevation and exposure are sig-nificantly correlated with the discriminant functions inthree groups- The influence ofexposure and partial elev-ation is in agreement with PFEFFER (1932) and C,{rrcrl(1978). There is an indirect effect of elevation to dis-criminant function in group 3.

Soil acidity is significantly correlated with the dis-criminant function in twq groups. This factor is con-nected with resistance ofthe ecosystem to air pollution.

The statistical analysis did not show signiflcantassociation of bark beetle communities with the hostand site factors quoted as typical in areas affected by airpollution (MlnrrNE., 1961; KUDELA and Novnov.r,1962). However, several standing spruces at the topmostpart ofthe reserve were infected by D. /?ectographus andX. lineatum in a way similar to air pollution damagedareas, and the association of group 3 with less acidicsoils could be explained by the effect of air pollution.

. The role of geobiocenotic properties of the environ-ment, expressed by potential forest vegetation types andpartially by the soil's acidity, as a factor influencing thepresence of bark beetles is in agreement with SToLINA(1959,197s).

Canopy closure is the most important environmentalfactor. It is signiflcantly correlated with the canonicaldiscriminant functions in all groups (table 3) and withelevation. The etrect of canopy closure to bark beetlecommunities is in agreement with GRuNwr.r-o (1986).

The stage of primeval natural forest is significantlycorrelated with the canonical discriminant functions infive groups (table 3). Each group is significantly associ-ated with at least one stage of primeval natural forest(table 6). It is significantly correlated with canopy clos-ure (r: -0.46), dimensions (r:0.30 and 0.19) anddeclinations of trees (r : -0.23). The relationshipsbetween stages ofprimeval natural forest and bark bee-tle communities are in agreement with STOLTNA (1969,1982).

The year of observation is significantly correlatedwith the discriminant functions in 3 groups (table 3).This factor corresponds with bark beetle succession onspruce material that was available in reserve. Group 2is associated with earlier years of obseryations, whenthere were large amounts ofuprooted and snapped treesafter the sale disaster. GrouD 6 is associated with later

650 R. Jakus

years of observations, when there was a lack ofsnappedand uprooted trees and lps typogrqphus started to attackstanding trees. Described processes are in agreementwith C-r.pscrr (1978) and KATAEV et al. (1984).

4 Conclusions

The relative influence of each factor for the com-munities' separation varies among groups. The mostimportant factors are the status of the host material(root connection and declination of trunk), the canopyclosure and the stage of primeval natural forest. Thedimension and stage of decay, elevation, exposure, soilacidity, potential forest vegetation type and year ofsuccession have significant effects.

Laying material in the stages of growing up and withoptimum ofprimeval natural forest at close canopy andcolder environment is, according to root connection,infested by beetles from zoocenosis (zoocenosis accord-ing to PFEFFER, 1955; CAPECKT, 1978) Dryocoetes orfrom zoocenosis Xyloterus lineqtum. This material, atthe stage of breakdown of primeval natural forest ina more open canopy and a warner environment, is,according to root connection, infected by a combinationof zoocenosis of Ips typographus, and zoocenosis ofDryocoetes, Xyloterus lineutum and Polygraphus poly-graphus.

Standing trees of small dimensions at the stage ofgrowing up of primeval natural forest at close canopyare preferably attacked by Xylechinus p//osrr. Standingtrees at the stage of optimum ofprimeval natural forestin a closed canopy are preferable attacked by Pol1,-graphus polygraphas. Standing trees at the stage of thedestruction of primeval natural forest in a more opencanopy in warmer environmental conditions are firstattacked by beetles from zoocenosis lps typogrsphus,and the following year by beetles from zoocenosis ofX ylo t erus I i ncar um and Dryocoetct.

These results suggest that a reliable hazard ratingsystem could be developed for bark beetles in Norwayspruce primeval natural forests. This system could beused in the management of protected areas, especiallyin conditions offorest decline. Development and testingof such a rating systems will be the subject of futurestudy.

Acknowledgements

The author wishes to thank Dr GocoLA (Technical Universityin Zvolen) for helpful discussions. Dr ScHLvTER (Lund Uni-versity) for comments on the manuscdpt, Dr SLAVTK (head-quarters of The Reserve of Biosphere Polana) for support ofresearch, the Swedish Institute for scholarship in Sweden, staffmembers of the Mountain Hotel Polana and the Institute ofForest Ecology SAV for generous use oftheir accommodationfacilities and ROBERT BnlnsoN for revision of the language.

References

CAPEcKI, 2., 1978: Untersuchungen iiber kambio- und xylo-phage Ins€kten in durch Wind und WZichte beschadigtenFichtenbest,inden im Gebirge. In: Prace Institutu Bad-

awczego LeSnictva. Warszawa 563,3'7 Il'1 (in Polish,Germ. summary).

DEKRiT, J., 1968: Proposal for forest natural resene inPol'ana. (MScthesis). Zvolen. For. Fac. Univ. ofForestryand Wood Techn., Zvolen 72, (in Slovak).

GRiiNWALD, M., 1986: Ecological segregation ofbark beetles(Coleoptera, Scolytidae) ofspruce. J. Appl. Ent. 101, 17G178.

KArAxv, O. A.; GoLUrvrNA, L. C.; KALTNTN, A. N., 1984:Gale-disaster area, like environment, causing mass out-break ofbark beetles. M.S.N.T. Ekologia i zashchita lesa(Lesny_e ekosystemy i ich zashchita.) 4 8 (in Russian).

KoRpEL', S., 1989: Die Urwiilder der Slowakei. Bratislava,Veda 331 (in Slovak, Germ. summary).

KUDELA, M.: Novirov^, E., 1962: Insekten- und Wild-schiiden in den rauchgeschedigten Waldbestzinden. Les-nictvi 35, 6, 493-501 (in Czech, Germ. summary).

LuDwrc, J. A.; REyNoLDs, J. F., 1988: Statistical ecology.New York, Wiley-Interscience publication.

MAI:rovsKi, B., 1991: The influence ofair pollution to foresttrees. In Viskum vplyvu imisii na z6kladn6 ekologick6zloiky lesa. (Partial final report from rcsearch project).Ed. by TuzINsKi, L., et al. Zvolen, Forest Res. Inst. 121(in Slovak).

MARTINEK, V., 1961:On the problem ofnatality andgmdationof bark beetle lps tlpogruphus L. in C€ntral Europe.Rozpravy CSAV, 71, 3, l-71 (in Czech, Germ. summary).

MicHAL, I., 1992: Ekological stability. Brno, Veronika. 243(in Czech).

MysLI\Ec, V., 1957: Statistical methods of agricultural andfbrestry research. Praha, SZN. 555 (in Czech).

NouRSrs, M. J., 1990: SPSS/PC+ Advanced Statistics ltrademarkl 4.0 for the IBM PC/XT/AT and PS/2. SPSS Inc.,Chicago.

NovAK, V-, 1962: Die Erforschung der Sukzession der unterder Rinde lebenden Insekten aufden im Ezgebirge durchExhalationen krzinkelnden Biiumen. Lesnictyi 35, 5, 329341 (in Czech, Germ. summary).

PFEFFER, A., 1932: Les bostryches dans les forest de la HauteTatra. Lesnicka pric e l\ 246-268 (In Czech, French sum-mary).

PFEFFER, A., 1945: The decay of spruce in mountainousprotection forests. Lesnickil prltce 28, 4 5, I45 159(in Czech).

PlEF,.ER. A.. lq55: Bark beetles Scol)ridae. Praha. CSAV.324 (in Czech, Germ. summary).

SHARAPA, T. 8., 1986: The ecological individualiti€s of barkbeetles in spruce forests in Kandalakscckoy naturalreserve. Ekologia i zashchita lesa, Ekologia lesnych zhi-votnych, Leningrad,55 57 (in Russian).

SNEATH, P. H. A.; SOKAL, R. R., 1973: Numerical taxonomy.San Francisco, Freeman.

SToLINA, M., 1959: Relationship between ins€cts and plantcommunilies in foresl t)pological unirs. fas. as. spolea.entomol. 56, 3, 213-220 (in Slovak).

SToLINA, M., 1969: The iofluence of bark beetles to devel-opment of structure of natural mountainous forcsts inWestem Karpaty. Lesnicky aasopis. 15, l, 45-63 (inSlovak).

SToLINA, M., 1970: On the problem of indifference of Ipstypographu.. Zbornik ved. prdc. Les. l 'aculry VSLDZvoIen 12,3,61 16 (ln Slovak, Engl. summary).

SroLrNA, M., 1975: Geobiocenologic units in studying phy-tophagous forest insects. Lesnicky aasopis 21, 4, 31'7-322(in Slovak, Engl. summary).

SroLrNA, M., 1976: Resistance potential of stands, an indi-cator of the degree of their exposure to danger inducedby hamful insects. Lesnictvi 22, 2, l5'7-I'70 (in Slovak,Engl. summary).

Bark beetle in Norway spruce 651

SToLTNA, M., 1982: Hardiness poteltial of natural sprucestands and its variations. Lesnictvi 28, 11, 961-975 (inSlovak, Engl. summary).

UN-ECE, 1986: Dmft manual on methodologies and criteriafor harmonized sampling, assessment, monitoring andanalysis of the effects of air pollution on forest adoptedby the Programme Task Force at its 2nd Meeling.2l-22May, Freiburg.

ZLATNiK, A., 1956: Th€ outline of forest typology on bio-

geocenologic basis and differentiation of Czechoslovakforests according to groups of forests types. In: PEstdnilesi III, Ed. by PoUNSK?, B. et al. Praha, SZN. 317+01(in Czech).

Author's address: R. JAKUS, Department ofForest Protectionand Game Management, Forestry Faculty, Technical Uni-versity in Zvolen, T. G. Masaryka 20,960 53 Zvolen, Slovakia