Arachnologische Mitteilungen 35

58 S. Buchholz & V. Hartmann according to B ONTE et al. (2003) Pardosa monticola in particular can easily be recorded during sunny days, when females and males are very active. The high number of species at D1 and D4 is caused by the diverse habitat structure being a varied mosaic of open ground, dense vegetation, tall plants, shrubs and in the case of D1 the vicinity to a forest edge (H EUBLEIN 1982, 1983, S CHEIDLER 1990, H ART & H ORWITZ 1991). Low values for diversity and evenness indicate higher dynamics and disturbance in species groups (K RATOCHWIL & S CHWABE 2001) and so reflect the conditions at D2 and D3: the first one is situated on the training area and thus disturbed by the military while D3 is outside the training area, but nevertheless disturbed by mam- mals (e.g. rabbits, sheep). The sites D4 and D5 as well as D6 and D7 have higher evenness values because of their location outside the training area where human impact does not exist. During the investigation period the soil surface of site D1 was removed for habitat management which entailed short-time changes of the habitat structure. Conclusions On the basis of this study we can conclude that it is possible to distinguish spider communities of forested habitats from species groups of open habitats, but there is no uniform spider community which is characteristic for semi-dry grassland. One reason may be that exclusive species are almost missing or rare while eurytopic generalists domi- nate. Furthermore in many parts of the study area the herbal layer of former dry and sandy grasslands is now too dense, probably because dynamics caused by human impact (e.g. military training) or natural disturbances (e.g. wind, erosion) are missing. Thus they almost show ecological conditions of meadows or tall-forb vegetation (e.g. D5). In contrast to this on some patches a very high level of disturbance causes a low diversity and a dominance of pioneer species (e.g. D2). In some places habitat character- istics of semi-dry and dry grassland exist but these patches are often very small (e.g. D3). The small size of the different habitat types seems to be a general problem. Because of the high locomotory activity of spiders many species move from site to site and hence can be found in all habitats of the study area. Acknowledgements We thank Dirk Dreier (Amt für Grünflächen und Um- weltschutz Münster) for enabling the field work, the Bundesanstalt für Immobilienaufgaben and the British Army.We are also grateful toMartin Kreuels for checking the identification of some problematic species, Thomas Fartmann for comments on the text and Lillian Harris for linguistic revision of the manuscript. References B AUCHHENSS E. (1990):Mitteleuropäische Xerotherm- Standorte und ihre epigäische Spinnenfauna - eine autökologische Betrachtung. – Abh. naturwiss. Ver. Hamburg 31/32: 153-162 B AUCHHENSS E. (1995): Die epigäische Spinnenfauna auf Sandflächen Nordbayerns (Arachnida: Araneae). – Zool. Beitr. N. F. 36: 221-250 B ELLMANN H. (1997): Zum Vorkommen dünenspezi- fischer Arthropoden in Mitteleuropa. – Mitt. dtsch. Ges. allg. angew. Ent. 11: 839-842 B EYER R. (1972): Zur Fauna der Laubstreu einigerWald- standorte im Naturschutzgebiet `Prinzenschneise` bei Weimar. – Arch. Naturschutz Landschaftsforsch. 12: 203-229 B ONTE D. & J.-P.M AELFAIT (2001): Life history, habi- tat use and dispersal of a dune wolf spider ( Pardosa group A group B group C species R [%] species R [%] species R [%] Cen_con 100 Hah_ono 100 Mic_her 59 Dra_lut 100 Man_aca 100 Ten_ten 75 Par_agr 99 Zel_ele 88 Mas_sun 85 Xer_min 99 Cne_obs 79 Dic_nig 97 Par_pal 97 Eno_tho 76 Bat_gra 42 Alo_acc 94 Gon_viv 74 Pis_mir 50 Wal_ant 92 Tis_vag 71 Par_hor 36 Par_mon 91 Zel_lat 67 Par_lug 59 Tro_rur 90 Wal_dys 66 Mei_rur 88 Eri_den 63 Rob_liv 87 Tro_ter 35 Pac_deg 76 Phr_fes 74 Xys_ace 73 Cer_pro 70 Alo_pul 69 Tap_pra 69 Hap_sig 68 Xys_koc 68 Stm_lin 63 Xys_cri 62 Par_pra 48 Tab. 4 : Representation values for all species which were included in the PCA.