Structure of Orthoptera assemblages in step-like habitat islands and neighbouring grasslands

6 Pages·2000·4.1 MB·

by  K. Krausz

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18337 Gresenhorst Structure of Orthoptera assemblages in stepJike habitat islands and
neighbouring grasslands
Literatur
K. Krausz, J. Pdpai, L. Kormoczi, A' Horv5th
BONSEL, A. (2000): Monitoring am DarBer Ort: Untersuchungen des Diinenkomplexes im Hin-
blick auf Bodenentwicklung, Pflanzengesellschaften sowie die Heuschrecken- und
Ameisengemeinschaften. Diplomarbeit. Osnabruck. 49 pp.
DErzEL, P. (1998): Die Heuschrecken Baden-Wurttembergs. Ulmer. Stuttgart. 580 pp. Zusammenfassung
GorrScHALK, E. (1998): Habitatbindung und Populationsdkologie der Westlichen BeiRschrecke lm Stjdosten Ungarns wurden 1996-98 Orthopteren-Assoziationen (13 Ensifera-
(Platycleis albopunctatal. Cuvillier Verlag Gdttingen. 91 pp. ,"0-ig Caeliferi-Arten) vergleichend auf 24 steinzeitlichen GrabhUgeln (Kur-
HoLST, K.T. (1986): The Saltatoria of Northern Europe. Fauna Entomologica Scandinavica Vo- iansl unO 21 nahegelegenen Graslandfltichen untersucht. Es ging dabei um die
lume 16. 127 pp. fruootn""", nach der sich die Assoziationen auf den inselartigen Steppenhggeln
INGR|SCH, S. & KOHLER, G. (1998): Die Heuschrecken Mitteleuropas. Die Neue Brehm-Bucherei Art"n des umgebenden Graslandes rekrutieren. Dazu wurden weiterhin 12
8d.629. Magdeburg. 460 PP. "ta,lnJd schafts- und Habitatparameter herangezogen und die Daten mittels Ordina-
scHMtDT,G Re.o g(1r.9 8M2i)t:t . S3t:r u1k5t3u-r1 u7n0d Bodendecke der Grundmordnengebiete der DDR. Peterm. tEiosn szaeniagltyes es iacuhs,g deawsesrt eht.insichtlich der Orthopteren die Kurgans deutlich vom
Graslaid verschieden waren. lhre Assoziationen waren vor allem signifikant mit
WALTER, H. & BRECKLE, S.-W. (1991): Okologie der Erde. Band 1. UTB. 238 pp. der Vegetationsstruktur gekoppelt. Dagegen spielten der lsolationsgrad der Fld-
wRANtK, w- (1996): Rote Liste der gefdhrdeten Heuschrecken Mecklenburg-Vorpommems. Mi- chen und das Dispersalverm6gen der Arten keine Rolle.
nisterium f. Landwirlschaft und Naturs;hutz. Schwerin. 63 pp.
Abstract
Orthoptera associations were studied on 24, presumably one to three thousand
years old cemetery hills, "kurgans", covered by steppe vegetation and in 21
grassland areas, which were situated nearby and potentially acting as propagula
pools.
Significant differences (p=0.01) were established between the ordination patterns
of the observed and randomly generated associations. The Orthoptera associa-
tionis affected by the structure of vegetation and the orographic differences bet-
ween habitats. Regional scale differences between the studied Orthoptera spe-
cies were revealed, also, however, there was less significant correlation with the
rate of isolation and no correlation was found with migration abili$. The species
composition of kurgan associations were more similar to each other than that of
the nearest grasslands, indicating relative autonomy and these associationsare
more affected by habitat parameters than metacommunity processes, including
the degree of isolation.
lntroduction
T_he tendency that community ecology is becoming popular again is observable
rrr,tne Increasing number of publications on insect communities. In the last dec-
:s!e".c"t "a sloste mof bslatugdeiess. hRaevsee abercehne prsu belimshpehda soinz ed etvheelo pemffeecntt sa nodf setrxutectruiorirn gla cotfo irns-
(sourHwooD
et al. 1979, JERMv 19Bs: GALLE et al. 1991 etc.) on structuring of
anrrcur_ern zooo ls(a
ARTTCULATA 2000 15(2)
insect communities as well as the role of interior regulatory mechanisms, espe- sites and methods
cially the importance of interspecific relations (SrRoNG et al. 1984, BosE & Study
TDhAVeTsDeA lRa t1te9r9 0fa, cGtoArLsL Ea r1e9 t9r4a)d.itionally considered less or not important in herbivo- Frii"etlad sratrmOPil"inr gwere carried out in the Great Hungarian Plain on twenty-four
rous insects (LAWroN & ScHRODER 1978, LAwrolr 1983, Slr,tsor.r & BRowN cemetery hills (so called "kurgans"), usually surrounded by agricultural fields, and
1983). As Jermy stated already in 1976, the permanent food supply does not wenty-one neighbouring grasslands, potentially acting as species pools for kur-
make competition important within herbivorous insect communities. In the last oan assemblages (Fig. 1-). Samples were collected on each sampled site, three
decades, however, the number of observations and experiments on competition imes in each year from 1996 to 1998. We sampled Orthoptera populations w1h
between herbivorous insects has increased. Some researchers assume that sweep nets, using 400-500 sweeps in each plot proportional to the size of habi-
competition is especially important for suitable vegetation patches and oviposi- tat. In the second and third year, in order to prevent an excessive decrease ofthe
tion sites, number of individuals we identified the collected specimens in the field and re-
leased them, only some difficultly determineted species were collected. The lar-
We face a similar dilemma if we want to study Orthoptera assemblages consist- vaes were determined to genus.
ing of mostly herbivorous populations, but the role of predatory species (first of all
grasshoppers) cannot be neglected in these communities either.
Most studies emphasize crucial effects of habitat attributes in structuring Ortho-
ptera assemblages. Vegetation structure, percentage of plant cover, species
composition and spatial pattern rank among the most important habitat attributes
(KEMP et al. 1992).
There are some studies on the interspecific relations among locust populations
(BELovsKy 1991, Belovsxy& Sr,coe 1993, CHASE 1996). ooo
There is, however, fewer information on the effect of external conditions and (
internal mechanisms on Orthoptera assemblages in fragmented and/or isolated
iI
habitats: although these researches give important information for nature conser-
vation, too. The degree of isolation influences the composition of Orthoptera
assemblages differently (GnuE et. al 1991, KTSBENEDEK & BAlor 1996, MABELIS &
Mexeruxnnap 1996). /.t
In Hungary, kurgans are also isolated habitats to a certain extent. They are artifi- \.
cial hill formations usually rising up from monoculture fields in the Great Hungar- .a..
ian Plain,5-15 meters high, con or hemisphere-shaped, 1000-3000 years old. /
They are covered by grasslands, as a rule and the grassland area is
)
800 and 4000 sq. meters. In the past, they served as human residence and .i f-
sites. They are under protection because of their landscape value, archaeologi- ..r:rg.-7-'
cal, faunistical and botanical importance, this latter one especially because of c"''\..r--
the loess vegetation.
In this paper we focus on the role of those external conditions in
0 25 50 75
Orthoptera assemblages. m 100 Kilometers
Interior structuring mechanisms, especially intraspecific competition will be
cussed in a separate paper. Detailed data analyses were concentrated on Fig'1':
questions: Distribution of kurgans in the Great Hungarian prain. (one point in the map
(1) Do the patterns of kurgan Orthoptera assemblages differ from those identifies two kurgans very cloose to each other)
randomly generated assemblages?
(2) Which habitat attributes affect the composition of Orthoptera ]lib.,:19y:t" characrerized by rhe foilowing aftribures: (1) size (area) rn sq. m.;
blages? s,rj,:::llPosition (one = kurgans on the -southern creai Hung'arian ptain, two
(3) Does isolation have any importance in structuring these assemblages? ;,;::s^:":-?.i N.orthern Grear Hungarian ptain); (3) retarive neigfit (in the case of
(4) dBieffesirdeensti ael xmteigmraatilo nfa acbtoilritsy, oifs O trhtheorpete aran ys pmecoiedsif?ication influence of ^tnqoresx"n, sb aosnetyd) ;o (v4e)r gsrooeucniense sdsi voerfs pitlya notf sthpee cvieesg ectatutiroinng (Mshaayn n1gogn7-w aiennde 1r 9d9ivge)r; s(i5ty)
eRrrcur_nralG-i6
ARTICULATA 2OOO 1
degree of degradation (according to the degradation scale employed); (6) rram o 45 to 0.62 in random references. Since all values of the random data ex-
age vegetation height (short, medium. tall grasses and tall grasses lain down li)"a rhe field data, it can be stated that ordination pattem of kurgan Ortho-
wind); (7) total vegetation cover; (8) coverage of monocot species; (9) degree tJrl ,"""tOlages differs signiflcantly from randomness (p=0'01)'
isolation (distance from the nearest grassland: minimum 0 m -maximum 1
(1O)permeability of the surrounding areas (e.9. grassland, medic, cereals, Tahrc 1 : List of species collected on kurgans. Frequenry (number of kurgans settled)
sunflower, mixed culture or asphalt road) for Orthoptera species; (1 1) age of -a^n..rl minretion abilitv (accordinq ttoo Naoy 1991 ) aallssoo represented .
lation (before 1782, between 1782 and 1872, after 1872, not isolated yet); (1 Frequency Migration ability
ist of sPecies
presence of an assumed connecting corridor (skip-like habitat between
and the nearest grasslands, presumably promoting Orthoptera migration). Tettigonidae
6EiZiitera nana Fieber, 1853 4 3
Data analysis 6;.iZi*eE arcara (Poda, 1 761) 4 3
alboviftata (Kollar, 1 833) 1
Relations between the Orthoptera assemblages of the single habitats were dinocephatu s discalo{[email protected] 8lq 4 3
lysed with PCoA ordination using Czekanowski's similarity coefficients Ruspotia nitidula (Scopoli' 17AO) 4 3
'1988). Employing this techniques, we computed both the similarity pattern of viidissima (L'' 1758) 2 3
assemblages, and their departure from randomness. For this latter, a null -PTteatttviqctoenisia albopu nctata (FCq9q9'lZ9l) 5 3
was established by randomisation of the values of the original matrix with -Ptetucleis affnis (Fieber, 1853) 't1 3
marginal sums of the rows and the columns, representing species and Tessela na v,flata (Charpentier,'l 825) 21 2
respectively. Deviation from the null model was tested with the distance to Metiootera blcolor (Philippi, 1 830) z
nearest neighbour, analysis of aggregation of points representing each Metiootera roeselii (Zeuner.'1941\ I z
assemblages in the ordination space. The averages of the smallest Gampsocleis g/abra (Herbst, 1786) I e
belonging to each object (kurgans) in the dissimilarity matrix was computed
real field data and 99 random reference data, respectively. The smaller Gryllidae
lated average value: the more aggregated point distribution in ordination space. Oecanthus oellucens (Scoooli. 1 763) 16 2
We studied the external correlates that presumably affect the structure of Acrididae
ptera assemblages with principal coordinate analysis based on Tetix tenuicomis Sahlbero. 1893 1 1
similarity coefficient (Poonrut 1988). The tests were made as follows (GALLE Pezoteftix giomae (Rossi, 1794) 19 1
a|.1991). The sampling sites (kurgans and other grasslands) were ordinated Calliptamus barbarus (Costa. 1836) 2
PCoA on the basis of the composition of their Orthoptera assemblages. Then Cailiptamus lfallcus (L., 1758) 12 a
relative position of the points in the factor space was expressed by Oedipoda caerulescens (L.. 175g) 3
sional Euclidean distances. Spearman's rank correlation was computed Aiolopus thalassrnus (Fabricius, 17gl ) 4 3
tdlnhis etthsaeen csdetiussdt atyon wcneeesa troeaosntk d g thrdaeifs fedslriafefnendrce,e nsist omilnai gtviroeangt ieointnad itacioebnsil itsaytn roudfc reteualriceehf, dprieoffaeplru eslanpctaieotisna. linto OvuDmmomcoooicocceseetsasst lutuuus srs u pshru eabffeirrpeamevesoiu crs(ohZ lo/e(iBsitdt re(aisErlsoivstuee t(rd.Cs tm,1h ga1a5r9n6p2n)e1,n )1ti egr4,g )1 g25) 1430 z322
eration. Following NAGY's (1992) classification, we divided the Orthoptera Stenobolhrus craGiGhamentier. 1 82S) 3 1
csciiheeossr twi nwittohin gtmheroded ees rpcaeatecte iegssho or(irewt siwt hain cngcoso ;r wd(3iinn)g gvs et oroy rt h moenoirlb ymi lewi,gi trlhoa ntwigo innw gain bsgitleuitdym spapsne)d;c iw(e2sin). gm loebnigleth: (1 wqw9t,,tasotf!mt@nttppPppguuqss a bbqrigu/,unsfn tuecluuhssa ((rTLph.e,u n1nt7bie5egrr,)o .1 81 ,g 15 )5) 182 33J
:#y:1rrgglg,9!!qus (Eversmann, 1 859) e
Results :Yl+]w1t 'tq.r.up pg p.us s opoarrasallerul uss ( Z(Zeetttetersrsteteddt,t , 1 18 g2211 ) ) 12 51
WSteru fcotuunred aclotomgpeathreerd 3t2o Orartnhdoopmtera species on the studied kurgan habitats (Tr :-":'':rrqyrrn!!lp:p us3 lbdte2cln/lsyguisn a(tBursis o(uDte, G.l ege4rg, 1 773j 2114 3z
1). The species number varied from 6 to 18 in the individual kurgans and did
increase significantly with habitat size (Fig. 2.). Orthoptera assemblages of
gans show an aggregation paftern in PCoA factor space (Fig. 3.). The average
nearest neighbou/s distances was 0.32 in the real field data, whereas it
aRrrcuuqrazui-;tt
170 ARTICULATA 2OOO
Correlation: r = 0.10982
P=0.609
Erternal correlates
irre composition of Orthoptera assemblages of kurgans showed close correlation
*i1, tn" degradation degree of vegetation, percentage of total plant coverage
1B and the average height of the vegetation. lt also correlated definitely with the
diversity of vegetation, but no correlation was observed with the isolation
,iai 1'-A "aoitericbiuetse s (distance of nearest grassland,"permeability" of the fields around the
'o kurqans, existence of a presumable corridor, the age of isolation), and with the
o*)M naOitat size. The composition of assemblages correlated slightly with distances
o among kurgans, showed significant correlation only with the second axis which
do) tz oossibly referred to regional differences among ranges of studied species. The
Et composition of Orthoptera assemblages of kurgans also correlated with the rela-
tive height of the kurgans'
o ,v
3
En
c
05
+
4 2.9 1 o
2.5 2.7 3 3.3 03 +
Oq
log size of habitat islands o
+
++ o
Fig.2.: Regression analysis between logarithm of habitat island size (m2) and +
number of Orthoptera assemblages. 01 +q I oBo
qo o
0.35 Oeo
o25 qc o -0.1 +
+ o
3oo ++ o o
0.15 o
o o
-0.3 *.1
o ?+
0.05
o
KUrgan
+ grassland
.0.05 -05
og -04
-o.2 0.0 o1 o2 03 04
-0.15
o
o Fig' 4.:
o Comparing kurgans, as habitat islands and the nearest grasslands on the
-U,IJ oo basis of Orthoptera assemblages, in PCoA ordination space, using Czeka-
o
nowski's similarity coefficient" o-kurgans, +-grassland
"0.35
-04 .0.3 "0.1 0.0 0.1 ^ut*,"t""tblages segregated distincfly from those of nearby grasslands (Fig.
are more similar to each other than to neighbouring grasslands. When
Fig. 3.: PCoA ordination of kurgans on the basis of their Orthoptera assemblages ^ulo:_rr^e"l,_"Ya.t ing distances computed in ordination space with reai topographic dis-
rqnces'
(Czekanowski's similarity coefficient was used). isolation indices, structural differences of vegetation and'differences of
ont,"r.oilldidlqa
172 ARTICULATA 2OOO 1 173
relief, we observe a cl6se Correlation between the presence or absence of a pre- semblages of each kurgans are more similar to each other than expected from
sum;ble corridor and the similarity between kurgans and its nearest grassland random data. From these results we can also conclude the existence of assem-
neighbour (p=0.05). However, we could not demonstrate, the effect of structural bly rules of kurgan OrthoPterans.
diff6rences'of vegetation and the effect of differences deriving from the hill char-
acter of kurgans either. ln studying annual species composition of Orthoptera Are kurgans islands?
assemblage; on each kurgans, we €n detect hardly any of its changes during From our results the question arises whether kurgans can be regarded as habitat
this period. islands for orthoptera assemblages. we found that the traditional principles of
On the basis of these results, a conclusion can be drawn that kurgans have their island biogeography can not be proved for kurgan assemblages though they can
own Orthoptera assemblages which are less influenced by nearby grasslands, be verified also in the case of some terrestrial habitat islands. Our result agrees
but the quality of kurgans as habitats seems to be important. with studies by Gnlm et al. (1992) canied out in 56 isolated habitats (out of
Almost natf otthe kurgan species (13 species) had little (5 species) and moder- which 9 were kurgans), in the southern Great Hungarian plain. They also found
ate (8 species) migration ability according to NAGY (1992). When ordinating the that neither species number nor shannon diversity of cicadinea and orthoptera
kurgans'on the basis of the migration groups of grasshoppers, and computing the communities increase with size of isolated habitats and they demonstrated even
relitionship of PCoA scores with the studied attributes, we found a significant a slight negative correlation between species number or diversity and habitat size
correlation between each group and vegetation structure and kurgan height. in the case of cicadinea group. According to their interpretation the reason of
these observations may be the lower resistance of small habitat islands against
Table 2.: Spearmann's rank correlation between ('l) the Euclidean distances between species invasion from neighbouring areas, which may result in increasing- spe.
kurgans and grasslands lying nearest to them, computed on the basis of the cies number in spite of the small habitat size. on the other hand, special circum-
ccasozitotrerniipkbaauoln tseEiotsuiw oconslifk d ikeo's1ua rnOsg iarmdtnhiissloat paraitntenycrd ea c tohcaeeosfmisfrie cpnimueetnbaintlr,agb g yae fnrsgod,r m a(is 2nsb) l PianthCnaedro y Ad p idfaofaeirrtdra.e i,enn euacuketilksobl nqinb u:se apttnhwatrc:ee eeet,hn r udehsimeain bedginti-a-t ssnptaaemncceieelsys tnohuf emp hbdyeistrot,r piabhsua twgiooenul ls.a Tninhdse ea csrtcmsh a(itslelr cRstiouzNreaG l( 8ce0ot0 ma-4pl.0l e01x0gi 8tym4 )2 o;a fol shf oot hsmet upksulta rnbgeats n csmo nmasyaid yee frafeelsdco,t
mensional Euclidean distance computing from quantitative data, isolation: be the cause why species number does not increase with island area. The re-
distance to nearest grassland habitat, permeabel: how far the orthoptera spe- sults of KTSBENEDEK & BALot (1996), BALDI& KTSBENEDEK (1999) also support the
cies can cross fieldJaround the habitat islands, corridor: presence or absence latter. In these studies, size effect was demonstrated in the case of orthoptera
of assumed connecting corridor, age: age of isolation, height relativ height of assemblages living in isolated but larger grassland patches. DAVTES & MnRouus
kurgans, diffdegrad: differences of degradation of the vegetation between kur- (1998) examined carabid assemblages and did not prove that the species num-
garis and their iearby grasslands , diffvegheight: height of vegetation, diffveg- ber increased with the size of forest patches though ihere were larger size differ-
cover: total coverage of vegetation ences among the studied habitat islands.
The correlation between the distances of habitats presumed to be isolated and
f:ir=gisriz-iel- i|-lsrizi-e- |dTrst an-e rlp-bn tdiv- i9T999-9l-4-liY 99-h-.9!l!i egcry9r LI,S Igmncqjlq s1lai9rmg9ei5lra) drciitasietnas nb cbeee std.weemeonn sstoramteed pbhuytt oopnhlay,g-ovuesry isnlsigehcftl ya isns ethmisb lsaig-uedsy b(KeRcAaUusSeZ oeft thael.
Gi1n"..":".1 1.n".-"sf., ,n"-.."Is -. =iIp* {im,,1-9- l_np=.i o*r-c l1[pp-="-oo"or zc-s LlPp==oroomz-g]!_ n!. - i rwKReoeacnlusauyr taip,vn erpNo rNhve ees1iudggm hgi6tna )ob .lsfy ek uvthrergroaaunlg ssh te uaffde iccehtssa nt(hegeuin rsugtr r.mur ci&ctur orwec lniomlfc aoetrertu,h aotehpcteen ri mat 'pagosgrsotea,mn KcbeEla Mgopef sw1 ghingicd2hi,-
I n.s*, ln.ffi The composition and structure of vegetation seem to be important environmental
raclors, their effects on orthoptera assemblages were demonstrated in most
ltudied habitats atso (ANDERSoN 1964, JoERN a tnwr_on t s8t;.
Discussion lne^distance to the nearest grassland, which was expected to have the strongest
Non random structure LTI?,_on."-p"cies' composition of isolated assemblages due to its possible ipe-
Revealing the difference from random is the first step in every pattern study' For ;es' Pool function, did not influence the composition of orthoptera assemblages
the statislical evaluation of the results, traditional tests could not be employed in l\TS^ 9n the studied kurgans, even when each was studied separately each
the multivariate cases, therefore we applied null models in this study by randomi- IIlt9Pt".t" group of different migration abitity. These resutts contrasted with sev-
sation of real field abundance values. The paftern of kurgan Orthoptera assem- ;:::"-,y9'": in which negative correlation was found between an increasing de-
blages differs significantly from random structures, namely it shows more aggre- ::::,-"f isolation and existence of some species (or the decrease of a species di-
gat6O OistriOution in ordination space than the random ones. lt means that as- v=rsrty was pointed out when studying more isolated habitats Bnz & Gnncrn-
nnrrcuil.
ARTTCULATA 2000 15(2) rA2000 15(2)
BoyERo 1995). We could not demonstrate any correlation of the species compo- JERMy, T. ('1985): ls there competition between phythophagous insects? - z. zool. syst. Evol. -
sition of Orthoptera assemblages with either the permeability of the surrounding forschung 23 275-285.
cultivated lands, or the age of the isolation. From among isolated attributes, only JoARN, A. & LAWLoR L R (1981): Guild structure in grasshopper assemblages based on food
the existence of presumable habitat corridors seemed to be the affecting factor in and microhabitat resources. - Oikos 37: 93-104
structuring kurgan assemblages, however, we did not study the actual role of KEMP, W.P. {1992): Rangeland grasshopper (Orthoptera: Acrididae) community structure: a
these coriidorJin distributing Orthoptera species, so the importance of their con- working hypotesis. - Environ. Entomol. 21(3\: 461470
necting role is not known (GnuE et al. 1995). K|SBENEpEK, T & BALDI, A. (1996): lsland biogeography of orthopterans in steppe patches - 7th
Our mlin conclusion is that kurgans have their own Orthoptera assemblages and EURECO , Budapest: 16'l-162.
the structure of which is influenced more by habitat parameters than by the de- KoHLMANN, T. (1 996): Zur Heuschreckenfauna auf Ackerbrachen - veranderungen nach 4 Jah-
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KRnUsz, K., PApAr, J. & GALLE L. (1995): composition of orthoptera assemblages in grassland
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