NORTH-WESTERN JOURNAL OF ZOOLOGY 7 (2): 261-269 ©NwjZ, Oradea, Romania, 2011 Article No.: 111132 www.herp-or.uv.ro/nwjz

Are arboreal associated with particular tree canopies?

Stanislav KORENKO1,2*, Emanuel KULA3, Václav ŠIMON3, Veronika MICHALKOVÁ4 and Stano PEKÁR2

1. Department of Agroecology and Biometeorology, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6, Suchdol, Czech Republic. 2. Department of Botany and Zoology, Masaryk University, Faculty of Science, Kotlářská 2, 611 37 Brno, Czech Republic. 3. Department of Forest Protection and Game Management, Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, 613 00 Brno, Czech Republic. 4. Institute of Zoology, Slovak Academy of Sciences, Dúbravská cesta 9, 845 06 Bratislava, Slovakia. * Corresponding author, S. Korenko, E-mail: [email protected]

Received: 21. March 2011 / Accepted: 15. August 2011 / Available online: 25. August 2011

Abstract. communities were investigated in the canopies of three coniferous (Larix decidua, Picea abies, Pinus sylvestris) and three deciduous (Alnus glutinosa, Quercus petraea, Quercus rubra) tree . Our aim was to find out whether these tree species host different spider communities within mixed forest stands. We found that spider abundance and species richness were significantly higher on coniferous trees than on deciduous ones. The community of spiders on coniferous trees was different from the one on deciduous trees. Across three coniferous tree species, there was not a significant difference in either spider abundance or species richness. However, across deciduous tree species there were significant differences both in spider abundance and species richness. Specifically, both abundance and species richness were significantly higher on A. glutinosa than on two Quercus species. The proportion of hunters on coniferous and deciduous trees was similar and did not differ either across coniferous or across deciduous trees. The proportions of three web- weaving guilds differed significantly between deciduous and coniferous trees. The relative frequency of sheet-web weavers was significantly higher on coniferous than on deciduous trees (0.46 vs. 0.15). The relative frequency of orb-web weavers was significantly higher on deciduous than on coniferous trees (0.52 vs. 0.24). Obtained results show that spider community is driven by structural differences among tree crowns.

Key words: arboreal spiders, beta-diversity, habitat association, coniferous, deciduous.

Introduction and their abundance in microhabitats (Tews et al. 2004). For example, might be associ- A number of tree species, including both conifer- ated with plant taxa with a particular microhabitat ous and deciduous, grow in temperate forests. The (e.g., branch architecture, structure of tree species composition depends on many habitat leaves/needles, structure of bark, or tree holes) characters in these forests, such as latitude, alti- (Stork et al. 1997). Several studies have investi- tude, slope orientation and local climatic condi- gated the habitat association of arthropods to tree tions. All these characteristics determine the tree canopies (e.g., Lawton 1983, Strong et al. 1984, growth and tree habitus. Each forest has a specific Schowalter 1995, Halaj et al. 1998, 2000, Thunes et history and has been managed in a different way. al. 2003, de Souza & Marins 2005, Southwood et al. Therefore, each forest has a different composition 2005, Larrivée & Buddle 2009), but not one has of tree species. dealt with arboreal spider community associated Forest canopies support remarkably rich ar- with commonly planted tree species in Central thropod assemblages (Moran & Southwood 1982, . Southwood et al. 1982, Stork et al. 1997, Didham & Spiders are among the most abundant arthro- Fagan 2004). Canopies of different tree species pods in tree canopies (Lowman & Wittman 1996) provide a different array of microhabitats and re- and seasonally they comprise about 25 – 97% of sources that can support specific arboreal arthro- arboreal arthropods in forest canopies in temper- pod communities (Strong et al. 1984, Southwood ate climates (Hågvar & Hågvar 1975, Gunnarsson et al. 1982, Schowalter & Zhang 2005). Riechert & 1996). They are important natural enemies of ar- Tracy (1975) suggested that certain plants might thropod pest species (see Nyffeler & Benz 1987, be favoured by certain arthropods because of their Riechert & Bishop 1990), important bioindicators ability to modify the thermal environment. Arbo- (Marc et al. 1999), and useful model organisms in real arthropods are closely associated with ‘key- a wide spectrum of ecological studies (Wise 1993). stone’ structures that determine species richness Spiders play a variety of ecological roles. They are 262 Korenko, S. et al. important predators (Wise 1993) and also provide Healthy trees of similar age and habitus were selected for food for other canopy foragers, such as ants (Halaj sampling. The trees were planted between 1972 and 1990. et al. 1997), birds (Gunnarsson 1996) and bats Sampling was carried out by beating trees at fortnightly intervals from May to October of each year. A square (Krull et al. 1991), thus they trophically connect shaped beating-net of 4 m2 area was put under the tree canopy food webs. Spiders are also affected by and tree branches were beaten with a stick (up to 3 m many habitat characteristics (Wise 1993). Vegeta- above ground). Collected spiders were fixed in ethanol tion structure (e.g., branching or twig density, leaf and identified to species/ in the laboratory using density) and habitat heterogeneity and complexity Heimer and Nentwig (1991), Roberts (1995) and Pekár are important canopy characteristics that influence (1999). spider abundance and species richness (see Hatley & MacMahon 1980, Greenstone 1984, Riechert & Gillespie 1986, Halaj et al. 2000, de Souza & Marins 2005, Corcuera et al. 2008). Higher habitat heterogeneity and complexity of the tree crown provide a greater array of microhabitats, micro- climatic features, alternative food sources, retreat building sites used for hiding, moulting or egg laying, and web attachment sites, all of which en- courage the colonization and establishment of spi- ders (Riechert & Lockley 1984, Agnew & Smith 1989, Gunnarsson 1990, Rypstra et al. 1999). Tree species differ in their habitat characters and con- sequently support different spider assemblages Figure 1. Map of investigated plots (1- 13) in the Sněžník (e.g., Stratton et al. 1979, Jennings & Dimond 1988, Mts. with an insert of the map of the Czech republic. Six Uetz et al. 1999, Southwood et al. 2005, Corcuera investigated tree species were distributed on study plots et al. 2008, Larrivée & Buddle 2009). as follows: Alnus glutinosa – 1, 5, 8, 10; Larix decidua – 2, 7, 11; Picea abies – 6, 12; Pinus sylvestris – 4, 9; Quercus The purpose of this study was to investigate petraea – 3; Quercus rubra – 13. Areas: the white area is arboreal spider community on three coniferous the village of Sneznik; the grey area is forest. Lines: and three deciduous trees commonly planted in white lines stand for paved roads; black lines stand for Central European forests. By means of compara- unpaved roads; dashed lines are forest paths tive analysis of their canopy communities we aimed to find out if there are any specific spider Collected spiders were classified into guilds. Using associations to particular tree species. the classification of Uetz et al. (1999) we defined the fol- lowing guilds: hunters (Anyphaenidae, Clubionidae, Mimetidae, Miturgidae, Philodromidae, Salticidae, Methods Sparassidae, and Zoridae), orb-web weavers (Araneidae, Tetraganthidae and Theridiosomatidae), The investigation was carried out in the area of the sheet-web weavers (), and space-web weav- Snežník Mts. (50°47´ N, 14°05´ E) in the Czech Republic, ers ( and Dictynidae). close to the border with Germany (Fig. 1). In the late sev- Monthly spider abundance data and species richness enties the autochthonous spruce stand was se- were compared among trees by means of Generalised verely damaged by acid rains and frost shock. It was re- Least Squares (GLS) in order to account for serial pseu- placed with a mixed wood stand composed of small doreplication. Both abundance and species richness inte- groups and individually planted trees Acer pseudoplatanus gers were assumed to come from a Poisson distribution L., Alnus glutinosa (L.) Gaertn., Betula pendula Roth, Fagus so the data were a priori log-transformed in order to ho- sylvatica L., Quercus petraea (Matt.) Liebl., Quercus rubra L., mogenise variance and to approach the normal distribu- Larix decidua Miller, Picea abies (L.) Karsten, Picea pungens tion of residuals. AR1 process was added to the model to Engelm, Pinus sylvestris L. and Sorbus aucuparia L. The in- accommodate serial autocorrelation within each season vestigated area is characterised by a cold mountain cli- (Pinheiro & Bates 2000). The comparison of proportions mate and the altitude of the investigated plots varied be- (summed over each season) of different guilds among tween 510 and 690m a.s.l. trees was done using Generalised Linear Models with a In each of 13 study plots (Fig. 1) we investigated ar- binomial error structure. Due to overdispersion, quasi- boreal spider fauna on three coniferous tree species: L. de- binomial family (GLM-qb) was used (Pekár & Brabec cidua, P. abies, P. sylvestris, and three deciduous tree spe- 2009). Proportion test was used to compare relative fre- cies: A. glutinosa, Q. petraea and Q. rubra. The spider as- quencies of guilds among tree types. These analyses were semblages were studied over two years (2005 – 2006). performed within R (R Development Core Team 2009). Spiders associated with tree canopies 263

Paired Wilcoxon signed-rank test (W) was used to com- erous trees was in each month significantly higher pare abundances between coniferous and deciduous trees than on deciduous trees (GLS, F1,84: 31.5, P < for selected spider species (genera or family). To identify 0.0001, Fig. 2A). Across three coniferous tree spe- the dis/similarity of spider community among particular cies there were no significant differences in spider tree species, hierarchical cluster analysis (HCA) with the Jaccard similarity index was performed. Absolute values abundances (GLS, F2,37: 0.3, P: 0.8, Fig. 3A). Across of HCA were standardised by sample size for a particular deciduous trees, there was a significant difference tree. The analysis was done in PC-ORD for Windows, in spider abundance (GLS, F2,35: 16.2, P < 0.0001). version 4.17 (McCune & Mefford 1999). The Jaccard simi- The abundance was higher on A. glutinosa than on larity index, one of the most widely used ecological two Quercus species (Fig. 3B). measures of compositional dis/similarity (Chao et al. 2005), was estimated for pairs of tree species. The coeffi- Species richness cient has values between 1 for identical samples and 0 for The richness of spiders did not change during the samples with no similarity (Jaccard 1908). season (GLS, F2,84: 1.7, P: 0.19). The richness of spi-

ders on coniferous trees every month was signifi- Results cantly higher than on deciduous trees (GLS, F1,84: 21, P < 0.0001, Figs. 2B). There was no significant During the study 3,841 spider specimens were col- difference in spider richness among three conifer- lected. These belonged to 56 species and 14 fami- ous tree species (GLS, F2,37: 1.9, P: 0.16, Fig. 3A), lies (Table 1). but there was a significant difference among three Spider abundance deciduous tree species (GLS, F2,39: 59.3, P < 0.0001, The abundance of all spiders increased signifi- Fig. 3B). Specifically, species richness was signifi- cantly during the season in both years (GLS, F2,84: cantly higher on A. glutinosa than on Quercus spe- 8.7, P: 0.0004). The abundance of spiders on conif- cies.

Table 1. Total abundance of spiders collected on the trees during two years of investigation. Nr – relative abundance.

Family/foraging guild Nr Species [%] Larix.d Picea .a Picea Pinus .s Pinus Alnus.g Q.rubra Q.petrae Mimetidae / hunters furcata (Villers) 1 0.03 Theridiidae / space-web weavers Achaeridion conigerum Simon 1 0.03 Enoplognatha ovata (Clerck) 13 15 7 57 2 1 2.47 tristis (Hahn) 3 0.08 Neottiura bimaculata (Linneaus) 2 1 0.08 Paidiscura pallens (Blackwall) 3 2 0.13 Parasteatoda lunata (Clerck) 2 1 3 1 1 0.21 impressa L. Koch 1 1 2 0.10 Phylloneta sisyphia (Clerck) 103 65 138 69 3 3 9.92 Platnickina tincta (Walckenaer) 9 3 3 1 0.42 Seycellocesa vittatus (C. L. Koch) 1 0.03 pinastri L. Koch 1 1 0.05 Theridion varians Hahn 23 6 9 16 6 1 6.04 unidentified 29 100 81 11 3 8 1.59 Theridiosomatidae/orb-web weavers gemmosum (L. Koch) 1 0.03 Linyphiidae / sheet-web weavers socialis (Sundevall) 5 4 1 1 0.29 Entelecara congenera (O. P.-Cambridge) 3 9 18 1 0.81 Erigone atra Blackwall 1 1 1 2 0.13 Erigone dentipalpis (Wider) 1 0.03 Floronia bucculenta (Clerck) 1 3 0.10 Linyphia hortensis Sundevall 1 0.03 Linyphia triangularis (Clerck) 341 175 343 38 6 13 23.9 Meioneta rurestris (C. L. Koch) 2 0.05

264 Korenko, S. et al.

Table 1. (Continued)

Family/foraging guild Nr Species [%] Larix.d Picea .a Picea Pinus .s Pinus Alnus.g Q.rubra Q.petrae Neriene emphana (Walckenaer) 26 9 3 4 1 1 1.15 Neriene peltata (Wider) 8 2 6 2 1 0.49 Neriene spp. 17 3 0.52 Oedothorax retusus (Westring) 1 0.03 Pityohyphantes phrygianus (C.L.Koch) 1 1 0.05 Trematocephalus cristatus (Wider) 5 3 6 7 0.55 Tetragnathidae / orb-web weavers Metellina mengei (Blackwall) 1 1 2 1 0.13 Metellina segmentata (Clerck) 4 22 3 9 1 1.02 Metellina spp. 6 23 1 13 1.12 Tetragnatha obtusa C. L. Koch 12 7 5 3 2 1 0.78 Tetragnatha pinicola L. Koch 58 41 51 30 6 2 4.89 Araneidae / orb-web weavers (Walckenaer) 1 3 3 1 0.21 diadematus Clerck 3 1 2 2 1 1 0.26 Araneus marmoreus Clerck 2 1 8 4 2 0.44 Araneus spp. 96 24 35 69 15 6 6.38 Araneus sturmi (Hahn) 1 3 0.10 Araneus triguttatus (Fabricius) 2 1 0.08 cucurbitina (Clerck) 39 11 22 99 7 25 5.29 Cyclosa conica (Pallas) 3 1 0.10 Mangora acalypha (Walckenaer) 3 3 3 2 0.29 Dictynidae / space-web weavers Dictyna sp. 1 0.03 Miturgidae / hunters erraticum (Walck.) 2 1 0.08 Clubionidae / hunters lutescens Westring 2 0.05 Clubiona reclusa O. P.-Cambridge 1 0.03 Clubiona spp. 4 12 3 20 6 1.17 Clubiona terrestris Westring 1 1 0.03 Zoridae / hunters Zora spinimana (Sundevall) 2 1 0.08 Sparassidae / hunters virescens (Clerck) 2 4 3 6 4 1 0.52 Philodromidae / hunters Philodromus spp. 263 22 183 115 44 38 17.3 Thomisidae / hunters dorsata (Fabricius) 64 1 14 43 10 13 3.78 Misumena vatia (Clerck) 2 1 1 4 1 0.23 Xysticus audax (Schrank) 17 5 6 3 0.81 Xysticus cristatus (Clerck) 1 1 0.05 Xysticus spp. 50 15 28 13 2 2.81 Salticidae / hunters Dendryphantes rudis (Sundevall) 4 0.10 arcuata (Clerck) 1 0.03 (Clerck) 28 34 7 21 4 2 2.50 Heliophanus sp. 1 0.03 cingulatus (Panzer) 1 0.03

Number of species 36 33 36 35 21 16 56

Number of specimens 633 633 680 136 124 1257 1011 3841

Spiders associated with tree canopies 265

A 120 90 Deciduous A Abundance Coniferous 80 Richness 100 70 80 60

60 50 N Abundance 40 40 30

20 20

0 10 May Jun Jul Aug Sep Oct

0 18 Larix.d (N=17) Picea.a (N=12) Pinus.s (N=17) B Deciduous 16 50 Coniferous B 14 45 Abundance Richness 12 40

10 35

8

Richness 30 6

N 25 4 20 2 15 0 May Jun Jul Aug Sep Oct 10

Figure 2. Comparison of the spider abundance (A) and 5 species richness (number of species) (B) on coniferous 0 and deciduous tree species during two years. Points Alnus.g (N=17) Q.petrae (N=15) Q.rubra (N=12) are means, whiskers are standard errors of the mean.

Figure 3. Comparison of abundance and species rich- ness on three coniferous (A) and three deciduous (B) Similarity of spider assemblages among trees tree species. Bars are means (pooled over two years), HCA split the tree species into two distinct whiskers are standard errors of the mean. groups, coniferous and deciduous (Fig. 4). The

Jaccard similarity index was higher among conif- weavers was significantly higher on coniferous erous trees (varying from 0.5 to 0.72) than among than on deciduous trees (0.46 vs. 0.15, Proportion deciduous trees (varying from 0.42 to 0.51). Values test, X21: 190, P < 0.0001). The relative frequency of of indices between coniferous and deciduous trees orb-web weavers was significantly higher on de- varied from 0.24 to 0.60 (Table 2). ciduous than on coniferous trees (0.52 vs. 0.24, Guild composition Proportion test, X21: 177, P < 0.0001). The proportion of hunters on coniferous and Across coniferous trees as well as across de- deciduous trees was similar (GLM-qb, F1,16: 1.3, P: ciduous trees the relative frequencies of sheet- 0.26) and did not differ either across coniferous or web, space-web and orb-web guilds were similar across deciduous trees (Fig. 5A). The proportions (GLM-qb, F4,18 < 0.9, P > 0.46). of three web-weaving guilds differed significantly With respect to hunters, some species were signifi- between deciduous and coniferous trees (GLM-qb, cantly more abundant on coniferous than decidu-

F1,50: 36.9, P < 0.0001, Fig. 5B). The relative fre- ous trees: Xysticus (Thomisidae) (Wilcoxon test, W: quency of space-web spiders was similar for de- 120, P: 0.0001), Philodromus (Philodromidae) (Wil- ciduous and coniferous trees (0.31, Proportion test, coxon test, W: 133, P: 0.0001), and Salticidae (Wil-

X21: 2, P: 0.16). The relative frequency of sheet-web coxon test, W: 74, P: 0.0015). A similar affinity was

266 Korenko, S. et al.

Figure 4. Hierarchical cluster analyses of studied tree species. Aster means coniferous tree; orb means deciduous tree.

Table 2. Jaccard index of similarity among coniferous trees (white boxes); among de- ciduous trees (black boxes) and between coniferous and deciduous (grey boxes).

Larix Picea .a Pinus .s Alnus.g Q.petrae Q.rubra 0.43 0.24 0.42 0.42 0.51 Q.petrae 0.54 0.43 0.44 0.47 Alnus.g 0.60 0.52 0.59 Pinus .s 0.52 0.72 Picea .a 0.50

A 100% found in two sheet-web weavers Linyphia triangu- Weavers laris (Wilcoxon test, W: 120, P: 0.0001) and Entele- Hunters 80% cara congenera (Wilcoxon test, W: 41, P: 0.01), and one space-web weaver of genus Phylloneta (Wil- coxon test, W: 153, P: 0.0001). 60%

Proportion 40% Discussion

20% Here we compared arboreal spider communities on commonly planted coniferous and deciduous 0% trees species in Central Europe. These tree species Alnus.g Quercus Quercus Larix.d Picea.a Pinus.s p. r. are also an important part of forest biomass in both commercial plantations and in autochtho- B 100% nous stands. Studies directly dealing with differ- ences in spider community between coniferous

80% and deciduous trees are few. Halaj et al. (1998) compared spider community on the deciduous red alder (Alnus rubra Bong) and four coniferous trees 60% in , but the majority studies were done exclusively on coniferous (e.g., Stratton et al.

Proportion 40% 1979, Jennings et al. 1988, 1990, Gunnarsson 1990, Space-web Mason 1992) or on deciduous trees (e.g., Agnew Sheet-web Orb-web 20% et al. 1989, Raizer & Amaral 2001, de Souza & Martins 2004). Both spider abundance and species richness 0% Alnus.g Q.petrae Q.rubra Larix.d Picea.a Pinus.s were higher on coniferous than on deciduous trees. The “resource diversity” hypothesis Figures 5. Comparison of the relative frequency of web- (Lawton 1983) predicts that there is a positive cor- weaving spider guilds: orb-web, sheet-web and space- web weavers on coniferous (A) and deciduous (B) relation between the diversity of arthropods and trees. habitat variability; thus we assume that coniferous trees provide a more diverse spectrum of micro- Spiders associated with tree canopies 267 habitats than deciduous trees. Differences in spi- branchlet density and spider abundance, but he der assemblage between coniferous and decidu- also found a negative correlation with the foliage ous trees have been observed by Halaj et al. (1998), area. Our results agree with the observations of but that study compared only one deciduous tree both Brierton et al. (2003) and Corcuera et al. with several coniferous trees. In our study the (2008). Monitored A. glutinosa canopies supported similarity among coniferous trees was higher than higher spider abundance and species richness than among deciduous trees. The similarity in spider Quercus canopies. Alnus glutinosa trees have a fauna between Pinus resinosa Ait. and Picea glauca more structured tree crown (higher branch, (Moench) was also reported by Stratton et al. branchlet and leaf density). In contrast, A. gluti- (1979). Halaj et al. (1998) found that in the cano- nosa leaves have a smaller foliage area than Quer- pies of coniferous trees, hunters of genus Philo- cus trees (Aas & Riedmiller 1994). Tree crown ar- dromus spp. (expect for P. abies) and sheet-web chitecture and leaf density arrangement seem to weaver L. triangularis were observed to be eu- be essential to provide a higher abundance of dominant. Gunnarsson (1988, 1990) observed prey, more protection from predators and more Philodromus spiders on P. abies trees in high abun- favourable microhabitats (Almquist 1970, Stork et dance in Northern Europe. Jennings & Dimond al. 1997). (1988) and Jennings et al. (1990) found differences Spiders are generally considered as important in spider community among coniferous tree spe- indicators of environment (Marc et al. 1999). Both cies. They suggested that the curved needles of the hunters and web weavers are very sensitive to red spruce Picea rubens Sarg. provide a more di- habitat structure (Uetz 1991). Hunters perceive verse habitat for spiders than the flat needles of their environment mostly by means of vibratory the balsam fir Abies balsamea (L.) Mill. do. Gun- cues which are mediated through the substrate on narsson (1988, 1990) observed a positive correla- which they live. The survival of hunters depends tion between needle density of the Norway spruce on their ability to move around and hide in a P. abies and spider abundance in Northern Europe. complex environment and thus avoid predation. A higher needle density on tree branches provides Web weavers must anchor their capture web to spider habitat quality, possibly by providing in- the appropriate substratum, and more complex creased protection against foliage-foraging birds and more diverse habitats provide more appropri- (Askenmo et al. 1977). Thus, the structure of nee- ate sites for a greater range of web weavers (Uetz dles seems to be a very important factor influenc- 1991). Our results are in agreement with the ob- ing spider fauna (e.g., Halaj et al. 2000). servations of Stratton et al. (1979) and Halaj et al. Within deciduous trees, we found significant (1998). The abundance of hunters was not signifi- differences in both spider abundance and species cantly different within conifers or deciduous trees. richness between A. glutinosa and Quercus trees. We observed a similar proportion of hunters on all Unexpectedly, deciduous A. glutinosa exhibited a three coniferous trees; Stratton et al. (1979) ob- higher similarity to coniferous trees than to Quer- served a similar proportion (about 0.3) of hunters cus trees. The observed high similarity in the spi- on coniferous trees in North America. Halaj et al. der fauna between Q. petraea and Q. rubra is in (1998) also observed a similar proportion of hunt- agreement with observations on fauna ers among several coniferous trees. There could be by Southwood et al. (2005). The higher spider even genus/species specific affiliation to micro- abundance and species richness on A. glutinosa in habitat in canopies. Specifically, Stratton et al. comparison with Quercus species could be attrib- (1979) assumed that ambushers from the Thomisi- uted to differences in the crown structure (e.g., the dae family use the clustering of needles on coni- density of branches/branchlets/leaves, foliage fers as a suitable hiding place. Mason (1992) ob- area). A positive correlation between spider abun- served also that ambushers from Thomisidae and dance and leaf density was observed by Brierton Philodromidae are among the most abundant spi- et al. (2003), who compared spider abundance on ders on coniferous trees. Our results confirmed the sugar maple Acer saccharus Marsh and white this assumption: ambushers from the genera Xys- ash Fraxinus americana L. Because Acer saccharus ticus (Thomisidae) and Philodromus (Philodromi- had a higher average number of leaves per meter dae) were significantly more abundant on conifer- of branch than Fraxinus americana, it consequently ous trees. Mason (1992) observed the dominant hosted more spiders. Corcuera et al. (2008) also position of stalkers from the Salticidae family in found a positive correlation between leaf/ the spider community on two coniferous trees

268 Korenko, S. et al.

(Pseudotsugata and Abies trees). Similarly, Halaj et References al. (2000) observed that salticids avoided bare Aas, G., Riedmiller, A. (1994): Trees of Britain and Europe. Harper branches and preferred branches with a higher Collins Publishers, London. complexity, such as on coniferous trees. A higher Agnew, C.W, Smith, J.W.Jr. (1989): Ecology of spiders (Araneae) in a peanut agroecosystem. Environmental Entomology 18: 30–42. abundance of salticids on coniferous trees was also Almquist, S. (1970): Thermal tolerances and preference of some observed in this study. dune-living spiders. Oikos 21: 229–234. The proportions of three web-weaver guilds Askenmo, C., von Bromssen, A., Ekman, J., Jansson, C. (1977): Impact of some wintering birds on spider abundance in spruce. differed significantly between deciduous and co- Oikos 28: 90–94. niferous trees, but it did not differ within each Brierton, B.M., Allen, D.C., Jennings, D.T. (2003): Spider fauna of group. Sheet-web weavers were significantly more sugar maple and white ash in northern and central New York state. Journal of Arachnology 31: 350–362. associated with coniferous trees. Generally, it is Chao, A., Chazdon, R.L., Colwell, R.K., Shen, T.-J. (2005): A new assumed that sheet-web weavers are associated statistical approach for assessing similarity of composition with with more structured microhabitats as needles are incidence and abundance data. Ecology Letters 8: 148–159. Corcuera, P., Jiménez, M.L., Valverde, P.L. (2008): Does the crucial to support their webs. Halaj et al. (2000) microarchitecture of Mexican dry forest foliage influence spider observed a positive correlation between needle distribution? Journal of Arachnology 36: 552–556. densities on the branches of Pseudotsuga menziesii de Souza, A.L.T., Martins, R.P. (2004): Distribution of plant dwelling spiders: inflorescences versus vegetative branches. and the abundance of sheet-web spiders. In con- Austral Ecology 29: 342–349. trast, orb-web weavers were observed with a sig- de Souza, A.L.T., Martins, R.P. (2005): Foliage density of branches nificantly higher relative abundance on deciduous and distribution of plant-dwelling spiders. Biotropica 37: 416– 420. trees. The association of orb-web weavers with de- Didham, R.K., Fagan, L.L. (2004): Forest canopies. pp 68–80. In: ciduous Alnus rubra trees was also observed by Burley, J., Evans, J., Youngquist, J. (eds.) Encyclopaedia of Forest Halaj et al. (1998). Space-web weavers appear to Sciences. Academic Press, Elsevier Science, London. Greenstone, M.H. (1984): Determinants of web spider species be habitat generalists, occurring numerously on diversity: Vegetation structural diversity vs. prey availability. both deciduous trees and coniferous trees. The Oecologia 62: 299–304. relative spider abundance of space-web weavers Gunnarsson, B. (1988): Spruce-living spiders and forest decline: the importance of needle-loss. Biological Conservation 43: 39–319. did not differ significantly between coniferous and Gunnarsson, B. (1990): Vegetation structure and the abundance and deciduous trees expect for space-web weavers of size distribution of spruce-living spiders. Journal of genus Phylloneta. Both genera were more abun- Ecology 59: 743–752. Gunnarsson, B. (1996): Bird predation and vegetation structure dant on coniferous trees. affecting spruce-living arthropods in a temperate forest. Journal Our study revealed differences in spider as- of Animal Ecology 65: 389–397. semblage on different tree species within the Hågvar, E.B., Hågvar, S. (1975): Studies on the invertebrate fauna on branches of spruce (Picea abies) (L.) during winter. mixed forest of Central Europe. Marked differ- Norwegian Journal of Entomology 22: 23–30. ences were found between coniferous and decidu- Halaj, J., Ross, D.W., Moldenke, A.R. (1997): Negative effects of ant ous trees and also among deciduous tree species. foraging on spiders in Douglas-fir canopies. Oecologia 109: 313– 322. Spider abundance and richness were higher on Halaj, J., Ross, D.W., Moldenke, A.R. (1998): Habitat structure and Alnus than on Quercus trees. Differences were neg- prey availability as predictors of the abundance and community ligible among coniferous trees, but not among de- organization of spiders in western Oregon forest canopies. Journal of Arachnology 26: 203–220. ciduous trees. We assume that the differences be- Halaj, J., Ross, D.W., Moldenke, A.R. (2000): Importance of habitat tween coniferous and deciduous trees are due to structure to the arthropod food-web in Douglas-fir canopies. different microclimatic conditions in their crowns. Oikos 90: 139–152. Hatley, C.L., MacMahon, J.A. (1980): Spider community

organization: seasonal variation and the role of vegetation architecture. Environmental Entomology 9: 632–639. Heimer, S., Nentwig, W. (1991): Spinnen Mitteleuropas. Paul Parey, Acknowledgement. This work was carried out under Berlin and Hamburg. projects funded by the grant project MSM 6215648902, Jaccard, P. (1908): Nouvelles recherches sur la distribution florale. and on the financial support of regional join stock Bulletin de la Société Vaudoise des Sciences Naturelles 44: 223– 270. companies and concerns: Netex Ltd. and Alcan Děčín Jennings, D.T., Dimond, J.B. (1988): Arboreal spiders (Araneae) on Extrusions Ltd. in Děčín, District Authorities in Děčín, balsam fir and spruces in eastcentral Maine. Journal of ČEZ Co. Prague, Lafarge cement Co. in Čížkovice, Arachnology 16: 223–235. Severočeské doly Co. Chomutov, Dieter Bussmann Ltd. in Jennings, D.T., Dimond, J.B., Watt, B.A. (1990): Population densities Ústí n. L. SK was supported by the project of Ministry for of spiders (Araneae) and spruce budworms (Lepidoptera, Education and Youth of the Czech Republic MSM Tortricidae) on foliage of balsam fir and red spruce in east- central Maine. Journal of Arachnology 18: 181–193. 6046070901. SP was supported by project MSM Krull, D., Schumm, A., Metzner, W., Neuweiler, G. (1991): Foraging 0021622416. areas and foraging behavior in the notch-eared bat, Myotis

Spiders associated with tree canopies 269

emarginatus (Vespertilionidae). Behavioral Ecology and Roberts, M.J. (1995): Spiders of Britain and Northern Europe. Sociobiology 28: 247–253. Harper Collins Publishers, Bath. Larrivée, M., Buddle, C.M. (2009): Diversity of canopy and Rypstra, A.L., Carter, P.E., Balfour, R.A., Marshall, S.D. (1999): uderstorey spiders in north-temperate hardwood forests. Architectural features of agricultural habitats and their impact Agricultural and Forest Entomology 11: 225–237. on the spider inhabitants. Journal of Arachnology 27: 371–377. Lawton, J.H. (1983): Plant architecture and the diversity of Southwood, T.R.E., Moran, V.C., Kennedy, C.E.J. (1982): The phytophagous insects. Annual Review of Entomology 28: 23–39. richness, abundance and biomass of the arthropod communities Lowman, M.D., Wittman, P.K. (1996): Forest canopies: methods, on trees. Journal of Animal Ecology 51: 635–649. hypotheses, and future direction. Annual Review of Ecology Southwood T.R.E., Wint, G.R.W., Kennedy, C.E.J., Greenwood, S.R. and Systematics 27: 55–81. (2005): The composition of the arthropod fauna of the canopies McCune, B., Mefford, M.J. (1999): Multivariate Analysis of of some species of (Quercus). European Journal of Ecological Data Version 4.17. MjM Software, Gleneden Beach, Entomology 102: 65–72. Oregon, U.S.A. Schowalter, T.D. (1995): Canopy arthropod communities in relation Marc, P., Canard, A., Ysnel, F. (1999): Spiders (Araneae) useful for to forest age and alternative harvest practices in western pest limitation and bioindication. Agriculture, Ecosystems and Oregon. Forest Ecology and Management 78: 115–125. Environment 74: 229–273. Schowalter, T.D., Zhang, Y.L. (2005): Canopy arthropod Mason, R.R. (1992): Populations of arboreal spiders (Araneae) on assemblages in four overstory and three understorey plant douglas-firs and true firs in the interior pacific northwest. species in a mixed-conifer old-growth forest in California. Forest Environmental Entomology 21(1): 75–80. Science 51: 233–242. Moran, V.C., Southwood, T.R.E. (1982): The guild composition of Stork, N.E., Didham, R.K., Adis, J. (1997): Canopy arthropod arthropod communities in trees. Journal of Animal Ecology 51: studies for the future. pp 551–561. In: Stork, N.E., Adis, J., 289–306. Didham, R.K. (eds.) Canopy arthropods. Chapman & Hall, Nyffeler, M., Benz, G. (1987): Spiders in natural pest control: a London. review. Journal of Applied Entomology 103: 321–339. Strong, D.R., Lawton, J.H., Southwood, R. (1984): Insects on plants: Pekár, S. (1999): Life-histories and the description of developmental community patterns and mechanisms. Harvard Univ Press, stages of Theridion bimaculatum, Theridion impressum and Cambridge. Theridion varians (Araneae: Theridiidae). Acta Societatis Stratton, G.E., Uetz, G.W., Dillery, D.G. (1979): A comparison of the Zoologicae Bohemicae 63(2): 301–309. spiders of three coniferous tree species. Journal of Arachnology Pekár, S., Brabec, M. (2009): Modern analysis of biological data. 1. 6: 219–226. Generalised Linear Models in R. Scientia, Praha. [in Czech]. Tews, J., Brose, U., Grimm, V., Tielbörger, K., Wichmann, M.C., Pinheiro, J.C., Bates, D.M. (2000): Mixed-effects models in S and S- Schwager, M., Jeltsch, F. (2004): Animal species diversity driven PLUS. New York, Springer Verlag. by habitat heterogeneity/diversity: the importance of keystone Raizer, J., Amaral, M.E.C. (2001): Does the structural complexity of structures. Journal of Biogeography 31(1): 79–92. aquatic macrophytes explain the diversity of associated spider Thunes, K.H., Skarveit, J., Gjerde, I. (2003): The canopy arthropods assemblages? Journal of Arachnology 29: 227–237. of old and mature Pinus sylvestris in Norway. Ecography R Development Core Team (2009): R: A Language and 26: 490–502. Environment for Statistical Computing. Vienna: R Foundation Uetz, G.W. (1991) Habitat structure and spider foraging. , pp 325– for Statistical Computing. Available via http://www.R- 348. In: Bell, S.S., McCoy, E.D., Mushinsky, H.R. (eds.) Habitat project.org. Structure: The Physical Arrangement of Objects in Space. Riechert, S.E., Bishop, L. (1990): Prey control by an assemblage of Chapman and Hall, London, U.K. generalist predators: spiders in garden test systems. Ecology 71: Uetz, G.W., Halaj, J., Cady, A.B. (1999) Guild structure of spiders in 1441–1450. major crops. Journal of Arachnology 27: 270–280. Riechert, S.E., Gillespie, R.G. (1986): Habitat choice and utilization Wise, D.H. (1993) Spiders in ecological webs. Cambridge in web-building spiders. pp 23–48. In: Shear, W.A. (ed) Spiders: University Press, Cambridge. Webs, Behavior and Evolution. Stanford University Press, Stanford. Riechert, S.E., Lockley, T. (1984): Spiders as biological control agents. Annual Review of Entomology 29: 299–320. Riechert, S.E., Tracy, C.R. (1975): Thermal balance and prey availability: bases for a model relating web-site characteristics to spider reproductive success. Ecology 56: 265–285.