Freshwater H'etlands anel their sustainable jillure Mossakowski, D. (1970). Ökologische Untersuchungen an epigüischen Co CHAPTER 28 atlantischer Moor- und Heidestandorte. ZeitscllrUi/ ~Visse/ls('llajiliche Zool 233-316 Obrtel, R. (1972). Soil surface Coleoptera in a reeel swanlp. Acta Scientiae EFFECT OF FLOODS ON GROUND BEETLES Brno, 6(6): 1-35 Thiele, H. U. (1977). earl/bill Beet/es in their EIH'ironll/cllt. Springer Verlag, H (CARABIDAE) AND fIAI?VESTMEN (OPILIONES) 369 pp. Tietze, F. (1974). Zur Ökologie, Soziologie und Phänologie der Laufkäfer (Co Carabidae) des Grünlandes inl Süden der DDR. V. Zur Phänologie der Cara L. Klinzes untersuchten GrÜnlandes.llercynia, 11: 47-68 Most spccics of carahids and harvestnlen are epigcic and, thus, their würld is only two-dilncnsional. Adults of both groups usually inhabit the surface earth, litter and the lowest layer of vegetation together \vith their prey, i.e. Diptera larvae, gastropods, Collelllbola spp., spiders, isopods and acarids (Thiele, 1977; Adatns, 1984). Life on the soil surface lnay beconle dangerous because of soil surface disturbances, drying or floods. There are severaI kinds of natural events that 1l1ay rcsuh in tClllporal dcstruction orthc epigcic aniJllal enVirOnl11cnt (Galle ef al., 1982). Flooding is an exalnple of such disturbance. In the Wet Meadows area, the environment of epigeic arthropods is overlaid by up to 0.60 m of water during a flood; this milieu is inhospitable and inlpenetrable for n10st epigeic species. Fate 01' the anilnals is variolls. Many species 01' carabids occllrring in flooded habitats are able to survive under the willcr sllrfaec 1'01' two weeks to two 1110nths (Paln1en, 1945, 1949; HeydeJnann, 1967). Some SpeCil11enS ofcarabids are carried away by the water strealTI, species eapable of flying can escape, together with fast running aniInals living not far fronl elevated places. Many specinlens Inay survive on stenlS of tall herbs and on tree trunks for sonle tilne, and will retunl after the flooel has receded. The populations weakcned by floods, or not surviving at all, can bc supported or rc-cstablishcd by anilnals froln thc neighbollrhood not afTected by the flüod. Only a fcw spceies are weil adapted to flooding. Their adaptations are both physiologieal and/ür bchavioural: a diplopod, Gonographis adisi, from thc Alnazon ßasin, survivcs für IIp to 6 nlonths under watcr, respiring the air stored llnder trec bark (Adis, 1986); sonle speeies of beetle survive long periods near the watcr surface (Innler, 1979) 01' even under it for sonle tinle (Thiele, 1977). Oribaticls can also tClnporarily change their 1l1ierohabitat (Bcck, 1969, 1976) and lnany aniInals escape to tree crowns (Adis, 1981, 1982; Erwin, 1983; Friebe and Adis, 1983; Adis and ScheUer, 1984). SOJne Collenlhola spp. survive flood periods as eggs, i.e. at an ontogenetic stage resistant to a nearly anaerobic environnlcnt. Moreover, flooels aet as Clles breaking the egg donnancy in SOlne spccics (Tan1111, 1984a,b, 1(86). In sonle earabids, survival of larvae subjccted to f100ds is llighcr than that 01' adults (Hcydcrnann, 19(7). In grollnd beetles and harvestInen, the two groups treated in this Chapter, both physiological and behaviouraI adaptations can be expected to occur. Ground 360 361 Fres/nvater H'ctlands alld thci,. sllstaillahle.tittllre E.tlcet (~f.t7oods on grolInd beetles and harvestl1zen beetles are 111arked for their wing polYlnorphisnl (Den Boer, 1971; Den Boer et al., 1980). SOlne species are winged and others are not. SOllle species have both winged and winglcss anilllals in their populations. Pterygote specilllens can take advantage of telnporary habitats such as floodcd areas because they are able (I) to escape frorn the area when the water level is rising, and (2) to recolonize rapidly the defaunated arcas when the tlood is over (Roff, 1990). Most harvestmen prefer l11esic and wet habitats, but they only rarely colonize Shrubs flooded areas. The only, so far, known adaptation of opilionids to tlooding is Meadow behavioural; in the tropics sonle epigeic harvestnlcn cscapc to tree crowns for Pond long periods during floods (Friebc and Attis. 19X3). In Ccntral Europe. silnilar Corltour hehaviour has not yct hCCIl ohscrvcd. Tltus. pefllWlll'lll popubliolls ofltarvesIIlH.'1l line are likely 10 bc l'oulld only in habilals \vhich are llo1 affcc1cd by flooding or Streams which are tloodcd only for a short period. If the fauna at a site is either partly 01' cOl1lpletely dal11aged by a tlood, a Fields recolol1ization proccss folIows. Not only different species but also sexes of individual species differ in their ability to spread. According to Fisher's theory (1930) the sex ratio (Illale:fclnale) should be about I: I, because it is beneficial Figure 28.1 Location 01' the sanlpling sites in the Wet Meadows area near TIebon (fuH for outbreeding equilibriuln populations to renlo,:e sIllall deviations fronl this circles); the site of the clin1ate station is indicated by an open circle ratio (Trivers, 1985). This is also true for carabids (Sustek, 1984). In a population which has just been established, one can expect deviations in the sex ratio biased Table 28.1 Basic characteristics of the sanlpling sites situated at different elevations towards I1lales which are nlore 1110bilc and, thus, able to colonize new habitats above 111ean water level in Roznlberk fishpond earlier than females. Populations closc to extinction should bias their sex ratio towards feInales that are nlore tolerant of stress factors (Sustek, 1984). Samp/ing sites It is ahnost ilnpossible to predict the long-tenn dynalnics 01' individual Ahhrel'iatiol1 UD sc AP CG RO populations in the Wet Meadows because or the unpredictable effects of tloods. But it is clear that the water level and probably also other environnlental factors Habitat Rudcral stand Shrub. I1lcadow Mown shorc Wctland Fishpond correlated with it or with soil Inoisture content, tluctuate less widely on drier Elcvation IcmJ 39 IX 16 12 3 sites than near the fishpond shores. This relationship ShOltld be reflected in the Dominant plants Urtica dioica + Sahx pentandra A/opccurus Carcx grad/is Glyccria nUlnber of species with deviated sex ratios. 'Thcreforc, it can be expected that: Sahx cillcrea + Deschampsia pratcllsis + C. l'esicaria maxima (1) the proportion of winged specinlens of canlbicls is greater on tlooded sites, c{)c.\pitosa (2) persisting populations of harvestnlen are found only on sites not subjected to flooding and (3) the proportion of species with deviated sex ratio is greater on frequently flooded sites than in steady-state habitats. winter season. Adults of carabids and both adults and juveniles of harvestmen were included in this study. The nOlnenclature ofcarabid beetles follows Freude elol. (1976), that of harvestnlen Martens (1978). MATERIAL AND METHODS The investigations took place in the Wet Meadows between the town ofli"ebon RESULTS and Rozmberk fishpond (see Chapter 13) froln 1985 to 1986. Five ~cologically differing sites were explored in 1985 and foul' in 1986 (Figure 28.1 and Table The nunlbers of specinlens of carabids and harvestillcil caught on individual 28.1). On each sanlpling site, six pitfall traps of Xenl in dialneter were placed at sites in Wet Meadows arc given in Tablc 28.2. Total nUlnber of carabids, the centre of each site, the other five traps, each 01' 4.5 cm in dialneter, were belonging to 53 species, was 4203. Total number ofharvestmen was 1460; they placed in the corners of a pentagon so that the neighbouring traps were about were represented by 6 species (Table 28.3). The number of captured specimens 2 In apart. The traps were Inade of glass and fillcd up to one third with 6% increased in the second year 01' our investigations in both grollps and on all sites formaldehyde solution. The saIllples were collected lnonthly, except for the exccpt the Ineadow (AP), where the nunlbers of carabids slightly decreased 362 363 Freslnvater l-vetlands and their sustainahle jilture E.tt'ect qjj700ds 011 groulld heet/es lind harvest/11en Table 28.2 Pitfall trap catches ofcarabid bcclles anel harvestnlen in the Wet Meadows Table28.3 Survcy ofcarabid bcctles and harvestlnen frOI11 pitfall traps and relationship in the period 1985-1986 bctween the nUlnbers of nlacropterous anel brachypterous carabids (nl!b); * significant 2 diffcrencc bctween ycars (chi , p < 0.05). Sec Table 28.1 for abbreviations Sitl' Sill' UD SC AP ce RO UD SC AP CG RO Year 1985 1986 1985 1986 1985 1986 1985 1986 1985 Year 1985 1986 1985 1986 1985 1986 1985 1986 1985 Total Carabidae Agonum jilliginosum 184* 53* 85* 47* 5 77 56* 79* d Carabidac A. moestul1l 14* 2 2 24 36 13 m Spccimcns IIX4 934* 196 317* 413 360 152 334* 313 42()3 A.ohsc"r"l11 85* 31* 3 I d Spl'l'il's .'X .'5 15 10 23 22 10 13 IX 53 Amara COllll1l11l1is 71 (li 4 III Ill/b ().-t 0.5 0.7 3.6* 1.5 104 4.2 4.1 3.1 1.12 27* m Bemhidion assimile °l>iliones 152* 144* 29 151* 112* 140* 10 136* 41 d Carahus granulatus Adults 162 570* 24 7* 6 11* I1 69* 2 862 44 3 84 30 2 2 b Dyschirills gioboslis I Juveniles 199 231 13 42* 9* 38 66* 598 Elaphrus ClipreliS 3 I 48 m Species 5 5 3 3 4 5 3 3 2 6 Loricera pilicornis 9 18 14 33 48 6 3 m Oodes helopioides 6 15 1 8 2 I 15 35 19 m Poecilus \'ersicolor 5* 8 14* 35* III Pterostidllls diligells 93 30 6 12 4 2 14* 9 d P.minor I 2 9* 10 12 35* 32 l1l crabk 2X.3). Thc incrcasing trend 01' capturcd Spccilllcns on thc sites conlpared P.nigrita 2 8* 39 51* 13 12 7 9 19 m followed the elevation gradient in both arthropod groups studied (RO < SC, P.