The ecology of saprophagous macroarthropods (millipedes, woodlice) in the context of global change

Biol. Rev. (2010), 85, pp. 881–895. 881doi: 10.1111/j.1469-185X.2010.00138.x

The ecology of saprophagousmacroarthropods (millipedes, woodlice)in the context of global change

Jean-Francois David∗ and Ira Tanya HandaCentre d’Ecologie Fonctionnelle & Evolutive, CNRS, 1919 route de Mende, F-34293 Montpellier cedex 5, France

(Received 02 July 2009; revised 20 March 2010; accepted 24 March 2010)

ABSTRACT

Millipedes (Diplopoda) and woodlice (Crustacea, Isopoda), with a total of about 15000 described species worldwide,contribute substantially to invertebrate biodiversity. These saprophagous macroarthropods, which are key regulators ofplant litter decomposition, play an important role in the functioning of terrestrial ecosystems in tropical and temperateareas. Herein we review current knowledge on the effects of climate, food quality and land cover on millipede andwoodlouse species to explore their potential responses to global change. Essentially similar trends are observed in the twotaxa. Experiments have shown that climate warming could result in higher rates of population growth and have positiveeffects on the abundance of some temperate species. This is consistent with signs of northward expansion in Europe,although the mechanisms of dispersal remain unclear. The generality of this finding is evaluated in relation to the lifehistories and geographical distributions of species. At low latitudes, interactions with more severe droughts are likely andcould affect community composition. Elevated atmospheric CO2 levels and changes in plant community compositionare expected to alter leaf litter quality, a major determinant of macroarthropod fertility via the link with female adultbody size. Although food quality changes have been shown to influence population growth rates significantly, it isproposed that the effects of warming will be probably more important during the coming decades. Land cover changes,mainly due to deforestation in the tropics and land abandonment in Europe, are critical to habitat specialists and couldoverride any other effect of global change. Habitat destruction by man may be the main threat to macroarthropodspecies, many of which are narrow endemics. At the landscape scale, habitat heterogeneity could be a good option forconservation, even at the cost of some fragmentation. Two principal areas are identified which require further work: (i)the effects of climate change across broader geographic ranges, and on species with different ecologies and life histories;(ii) the effects of global change on both macroarthropods and their natural enemies (predators, parasites and pathogens),to improve predictions in field situations.

Key words: climate change, food quality change, habitat loss, abundance, life-history traits, species distribution,biodiversity.

CONTENTS

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 882II. Direct effects of climate change on macroarthropods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 883

(1) Observed changes in distributions: a fingerprint of climate warming? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 883(2) Ecophysiological responses to climate warming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 883(3) Problems of generalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 884(4) Possible interactions with drought . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 885

III. Effects of changes in food quality on macroarthropods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 886(1) The food of saprophages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 886(2) Global change and leaf litter quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 887(3) Responses of macroarthropods to food quality changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 887

* Address for correspondence: E-mail: [email protected]

Biological Reviews 85 (2010) 881–895 © 2010 The Authors. Biological Reviews © 2010 Cambridge Philosophical Society

882 Jean-Francois David and Ira Tanya Handa

IV. Effects of land cover changes on macroarthropods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888(1) Importance of land use for habitat specialists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888(2) Tropical deforestation as a case in point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 889(3) Habitat heterogeneity and biodiversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 889(4) Heterogeneity versus fragmentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 890

V. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 890VI. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 891

I. INTRODUCTION

Saprophagous macroarthropods are large-sized arthropods,mostly in the range 5–50 mm in length, which feedon decomposing plant material. In terrestrial ecosystems,major taxa include millipedes (Diplopoda), woodlice (Crus-tacea, Isopoda) and landhoppers (Crustacea, Amphipoda),although many insects also belong to this group (Schowalter,2006). Whereas landhoppers mainly occur in certain areasof the southern Hemisphere (Friend & Richardson, 1986),millipedes and woodlice occupy nearly all temperate andtropical regions on Earth, from the seashore to high alti-tudes, and from floodplain forests to deserts (Vandel, 1945;Crawford, 1991; Adis & Junk, 2002; Golovatch & Kime,2009). With about 12000 millipede species and 3500 wood-louse species that have been described to date (Schmalfuss,2003; Sierwald & Bond, 2007), they contribute substantiallyto global biodiversity.

These organisms from different animal classes havebroadly similar lifestyles and constitute a well-defined ecologi-cal entity. In contrast to earthworms, the vast majority are nottrue soil-dwellers, but typically occur in the leaf litter and theuppermost soil layers. Throughout their long evolutionaryhistory, macroarthropods have adapted to this environment,which is intermediate between the above-ground and deepsoil environments in terms of climatic severity and resourceavailability (Lavelle & Spain, 2001). These adaptive traitsare reflected in a number of behavioural, physiological, andeven morphological convergences between taxa, such asthe ability to roll up into a ball, which evolved in severalfamilies (Schmalfuss, 1984; Hopkin & Read, 1992). As afunctional group, millipedes, woodlice and other non-socialmacroarthropods have been collectively classified as littertransformers (Lavelle et al., 1997; Wardle, 2002)—as distinctfrom ecosystem engineers (earthworms, termites, ants) thatsubstantially modify the physical structure of the soil profile(Lavelle et al., 1997; Wardle, 2002). Significant trophic differ-ences between both functional groups have been shown bystable isotope analysis, thus confirming the close dependenceof macroarthropods on the litter layer (Pollierer et al., 2009).

Where they are abundant, litter transformers areimportant for the functioning of terrestrial ecosystems, dueto their impacts on decomposition processes (reviews inSchaefer, 1991; Wolters, 2000; Schowalter, 2006). Sometropical species may even be keystone species in theirenvironment (Mahsberg, 1997; Lawrence & Samways, 2003).Saprophagous macroarthropods consume large amounts ofleaf litter and dead wood with highly variable assimilation

efficiencies, and disperse the unassimilated material asfaecal pellets (e.g. Dangerfield & Milner, 1993; David &Gillon, 2002; Zimmer, 2002; Quadros & Araujo, 2008).In addition to direct effects on decomposition throughgut processing, these feeding activities profoundly affectmicrobial activity in the decomposing plant material. Forexample, macroarthropods increase the bacterial-to-fungalratio in their faeces (Hanlon & Anderson, 1980; Hassall,Turner & Rands, 1987; Maraun & Scheu, 1996) andincorporate both fragmented litter and microbial propagulesinto the topsoil layers, where conditions are usually morefavourable for decomposition (Hassall et al., 1987). The faecalpellets of macroarthopods are the seat of intense bioticactivity (Tajovsky et al., 1992) and, as such, an importantfood source for many coprophagous animals, particularlyearthworms (Bonkowski, Scheu & Schaefer, 1998).

Like all living organisms, these invertebrates are facedwith various facets of global change that are stronglyaffecting the natural and human environment (IPCC, 2007a).These include both climate and non-climate drivers, suchas land-use change, pollution and the spread of invasivespecies. Considerable climate changes are occurring due tothe increase in atmospheric greenhouse gas concentrations,mainly CO2 (IPCC, 2007b). Depending on the emissionscenarios, global average temperature is predicted to increaseby 1.8–4.0 ◦C at the end of this century, with most intensewarming at high northern latitudes. Increases in the amountof precipitation are very likely at high latitudes, whiledecreases are likely in most subtropical regions. Theseclimate changes should strongly impact the compositionof plant communities, with far-reaching consequences forecosystems (Walther, 2003; Thuiller et al., 2006). Directeffects of increasing atmospheric CO2 concentrations shouldalso have ecosystem-level consequences, by modifying plantcommunities and the quality of plant tissues to consumers(Korner, 2003). At the regional scale, non-climate driverssuch as land-use changes may be the most important factorsin determining biodiversity changes in terrestrial ecosystems(Wardle, 2002). All these global change phenomena havealready affected and will increasingly affect animal species,especially poikilotherms that feed on plant materials, such asphytophagous insects and saprophagous macroarthropods(Cannon, 1998; Couteaux & Bolger, 2000; Bale et al., 2002).

The aim of this review is to summarize the present knowl-edge on the effects of climate, food quality and land coveron millipedes and woodlice, and to identify what is relevantin terms of their responses to global environmental change.In both taxa, there are insufficient ecological data available


Macroarthropod ecology and global change 883

to use a correlative approach, in which the relationshipsbetween current species distributions and environmentalvariables are modelled, and then used to predict future dis-tributions and extinction risks under global change (Thomaset al., 2004). However, the literature abounds in data onmacroarthropod responses to temperature, moisture, foodquality and land cover, with positive or negative effects ontheir abundance and life-history traits (survival, reproduc-tion, generation time). Such demographic information isinvaluable to predict potential responses to global change,because changes in demography underlie the persistenceor extinction of local populations and thereby the distribu-tion of species (Andrewartha & Birch, 1954; Pulliam, 2000;Hanski, 2005). Basically, depending on whether environ-mental changes result in higher or lower rates of populationgrowth, species are likely to be favoured or threatened, even ifthe outcome also depends on biotic interactions and dispersalability (Davis et al., 1998; Hanski, 2005). The present reviewrests largely on this rationale to explore the implications ofglobal change for saprophagous macroarthropods.

The type of relevant information that can be found in themillipede and woodlouse literature differs markedly depend-ing on the region of the world. Most experimental studies onthe impacts of climate have been conducted on temperatespecies, mainly from Europe, whereas the consequences ofland cover changes have been more extensively studied intropical forests. As the effects of these factors, and in partic-ular their interactions, are likely to vary in different climaticzones (Deutsch et al., 2008; Kearney, Shine & Porter, 2009),significant uncertainties remain regarding the responses ofmacroarthropods to global change. Therefore, only provi-sional conclusions can be reached herein, and we highlighttopics and geographical areas on which more research isneeded.

II. DIRECT EFFECTS OF CLIMATE CHANGEON MACROARTHROPODS

Responses to climatic changes have been much less studiedin millipedes and woodlice than in above-ground insects.Despite a rich background of physiological research onindividual resistance to heat and desiccation (Edney, 1951;Warburg, 1965; Haacker, 1968; Meyer & Eisenbeis, 1985;Davis, 1989), relatively few studies have addressed the effectsof climate on macroarthropods at the population and specieslevel. Existing studies are based either on the examinationof large-scale patterns in nature or on the experimentalstudy of small-scale population dynamics in response tocontrolled environmental changes. Each of these approachesis instructive but has limitations when used in isolation.

(1) Observed changes in distributions: a fingerprintof climate warming?

Difficulties in interpreting large-scale patterns are clearlyillustrated with a study on the poleward expansion of animals

in Great Britain (Hickling et al., 2006). The locations of thenorthern range margin of many species, defined as themean latitude of the ten most northerly occupied 10-kmgrid squares, were compared over a 25-year interval. Themean northward shift of southern species was 74 km formillipedes (six species) and 79 km for woodlice (eight species).Although the consistency of trends across many taxa doessuggest there is range expansion driven by climate warming(Root et al., 2003; Parmesan, 2006), this interpretation isnot necessarily correct for all taxa. The trend may simplyreflect discovery of previously undocumented populations,especially for species not easily sampled (Frey, 2009). Despiteefforts made by Hickling et al. (2006) to standardize fordiffering sampling efforts over time, grid squares were poorlyexplored for millipedes in the first collecting period (P. Lee,personal communication). In addition, apparent expansionsmay involve temporary occurrences of a few individualsbeyond range margins rather than the establishment ofnew populations (Frey, 2009). It is necessary to identify theprocesses involved before we conclude that these observationsare linked to climate warming.

A prerequisite for poleward expansion is dispersal orat least human-mediated transport. Although dispersalability is generally considered to be low in below-ground macroarthropods, that is not true of all species.Wandering is widespread in millipedes and a number ofspecies show occasional migration of entire populations(Cloudsley-Thompson, 1949; Hopkin & Read, 1992). Manymacroarthropod species have been shown to colonize post-mining rehabilitation sites in various geographical areas(Dunger & Voigtlander, 1990; Tajovsky, 2001; Redi, VanAarde & Wassenaar, 2005), which can only be explainedby dispersal. However, in Hickling et al.’s (2006) data, theexpansion rate of millipedes and woodlice was higher than incarabids and butterflies, which are much more mobile taxa.Assuming that macroarthropods have migrated northwardsin Britain, such a high expansion rate is not easy to explain atpresent. There are no indications that recently documentedpopulations occur in particular areas, e.g. suburban areas,which are often hotspots of species introduction for theseanimals (Hornung & Szlavecz, 2003). Genetic studies mightprovide insights into the mechanisms involved and helpto identify potential sources of northern populations. Inprevious studies on cosmopolitan woodlice, the absence ofcorrelation between geographic and genetic distance lentsupport to the hypothesis of long-distance transport by man(Rigaud et al., 1999; Wang & Schreiber, 1999).

(2) Ecophysiological responses to climate warming

To understand the effects of climate warming onmacroarthropods, an important step is to determine theirecophysiological responses to temperature in terms of popu-lation growth rate. In insects, warming is not necessarily ben-eficial to population growth (Bale et al., 2002). For example,the survival of individuals overwintering in diapause maydecrease strongly when temperature increases (Irwin & Lee,2000; Williams, Shorthouse & Lee, 2003). In addition,



because physiological trade-offs constrain arthropodresponses to temperature, individuals may develop faster athigher temperatures but have lower adult mass and fecundity(Atkinson, 1994). To assess an effect in terms of populationgrowth, it is therefore necessary to consider all life-historytraits simultaneously (development rate, survival, growth andfertility) over at least one complete generation. Also, in labo-ratory studies, it is preferable to conduct experiments underseasonal temperature and photoperiod conditions, becausethese seasonally varying factors are important cues for devel-opment and reproduction in macroarthropods (McQueen& Steel, 1980; Mocquard, Juchault & Souty-Grosset, 1989;Iatrou & Stamou, 1990; David, Geoffroy & Celerier, 2003).

A laboratory study meeting the above conditions wasperformed to assess the effects of elevated temperatures onthe life-history traits of the polydesmid millipede Polydesmus

angustus in western Europe (David & Gillon, 2009). Thisspecies has a relatively short life cycle, which is completedin either one or two years depending on the individuals andpopulations (David, Couret & Celerier, 1993). Millipedeswere reared throughout their life cycle under two seasonalregimes of temperature, which differed by 3.3 ◦C on average(Fig. 1). This corresponded to the temperature differencebetween the Atlantic climate of the Paris region, wherethe animals came from, and the Mediterranean climate ofsouthern France, at the edge of the species’ range (Kime,1990). Polydesmus angustus was positively affected by the3.3 ◦C rise (Fig. 1). Development was faster, with a largerproportion of individuals reaching the adult stage beforethe winter. This resulted in earlier reproduction in spring,because adult females are in postdiapause quiescence inlate winter and start laying eggs as soon as temperatureconditions improve (David et al., 2003). At Mediterraneantemperatures, reproduction started in April, 1.3 monthsearlier than at Atlantic temperatures. There was no trade-offbetween development rate and adult body mass; femalesthat developed at elevated temperatures even emerged athigher live mass. These positive effects of temperature ongrowth, which could be a general phenomenon in arthropodsfeeding on detritus (Sinclair & Chown, 2006), may resultfrom greater microbial development in leaf litter and/orbetter exploitation of food by millipedes. The larger bodysize of females at elevated temperatures resulted in higherfertility, which is the rule in macroarthropods (Sutton et al.,1984; David, 1992). Finally, survival was not significantlyaffected by warming.

Overall, the temperature rise resulted in a higherpopulation growth rate, which indicates that the impact ofwarming is positive over large parts of the species’ rangewhen moisture is non-limiting (David & Gillon, 2009).All other things being equal, the abundance of Polydesmus

angustus should tend to increase in established populations.From a metapopulation viewpoint, these populations couldfunction as sources from which individuals could disperse(Hanski, 2005). This is consistent with signs of northwardand eastward expansion of the species in Europe since the

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end of the 20th Century (Meidell & Enghoff, 1993), althoughthe mechanisms of spread remain unclear.

(3) Problems of generalization

To what extent can we extrapolate this positive effect ofwarming to other macroarthropods? Results from earlierlaboratory studies, which were conducted at constanttemperatures, suggest that ecophysiological responses towarming should also be positive for a number of temperatespecies. In North American populations of the millipedePolydesmus inconstans (Polydesmidae) and the woodlousePorcellio spinicornis (Porcellionidae), the highest rates ofpopulation growth are reached at temperatures consistentlyabove 20 ◦C (McQueen & Carnio, 1974; Snider, 1981a, b),which corresponds to a much higher number of degree daysthan current field conditions. In the cosmopolitan woodlouseArmadillidium vulgare (Armadillidiidae), higher temperaturesresult in: (i) earlier reproduction in spring (Mocquard et al.,1989); and (ii) the production of larger offspring, with acascade of positive effects on survival of stress, individualgrowth, and probably fecundity (Hassall et al., 2005). Subjectto unknown effects of elevated temperatures on survival,these studies confirm that higher rates of population growth



can be expected in field populations of A. vulgare living inwarmer environments (Sutton et al., 1984).

However, the response to warming is likely to varywith the life-history characteristics of species. For example,nondiapausing species that breed throughout the year whenkept under favourable conditions, like the paradoxosomatidmillipede Oxidus gracilis in greenhouses (Causey, 1943), shouldalso respond positively to warming. By contrast, species thatdiapause in winter and need a period of chilling to resumedevelopment and reproduce the following summer, like thexystodesmid Parafontaria laminata armigera in Japan (Fujiyama,1996), may be affected negatively by warming. Similarly,species that overwinter for long periods without feeding maybe affected negatively by warming, which may acceleratethe exhaustion of metabolic reserves. For example, in desertsof the southwest USA, the spirostreptid millipede Orthoporus

ornatus overwinters for about eight months of dry season andmoults prior to emergence from the soil (Crawford, Bercovitz& Warburg, 1987). During that prolonged dormancy, thespecies uses its fat reserves, the consumption of whichincreases with temperature (Wooten & Crawford, 1974).

Spatial considerations are also important. Cold-adaptedspecies that live close to summits, e.g. the endemic millipedegenus Pyreneosoma (Haplobainosomatidae) that occur at analtitude of about 2000 m in the Pyrenees (Mauries, 1974), arepotentially threatened by the reduction of their habitable areadue to climate warming. More generally, all species that arecurrently living very close to their upper thermal limits andthat are unable to shift their range are potentially threatened(Parmesan, 2006). Based on ecophysiological models relatingtemperature and population growth rates, Deutsch et al.(2008) predicted that this situation should be much morefrequent for tropical than temperate poikilotherms, even ifglobal warming is less marked in tropical areas. It is howeverunclear whether this latitudinal trend in susceptibility towarming, which is derived from above-ground insect studies,can be generalized to macroarthropods. In buffered, below-ground microhabitats, daily maximum temperatures aremarkedly lower than in the air and increasingly delayed withdepth (Lavelle & Spain, 2001). Tropical macroarthropodsthat are active in hot environments may take advantageof these differences and avoid detrimental temperaturesby diurnal movements between the soil and the surface(Cloudsley-Thompson, 1951; Shachak, Steinberger & Orr,1979). The effectiveness of behavioural thermoregulationunder hot conditions was clearly demonstrated during thesummer feeding season of the desert millipede Orthoporus

ornatus (Wooten, Crawford & Riddle, 1975).In fact, latitudinal trends in macroarthropod responses

to climate change may be more common at the intra-specific level. In widespread species, populations that alreadylive at the warmer edge of the species’ range may beaffected negatively by warming. In these marginal areas,macroarthropods may experience increasing climatic stress,notwithstanding their ability to adapt to local climaticconditions (Castaneda, Lardies & Bozinovic, 2004). Studiesin which insect populations were censused several times

throughout the species’ range have shown that the rate ofpopulation extinction during the last century was greater atlow latitudes (Parmesan, 2006). No such long-term data existfor macroarthropods at the warmer edge of their range, butthe effects of both temperature and drought are likely to beimportant in this respect.

(4) Possible interactions with drought

Elevated air temperatures result in higher saturationdeficits, which increase evapotranspiration and makeregional climates increasingly dependent on rainfall (Begon,Townsend & Harper, 2006). As more severe summer droughtis likely over large areas at low latitudes (IPCC, 2007b), thismay have demographic consequences in animals.

Macroarthropods cope with normal, seasonal periodsof dryness using both behavioural and physiologicalmechanisms (Warburg, 1987; Hopkin & Read, 1992). Thebasic behaviour is to take refuge in deep cavities or toburrow into the soil (Sutton, 1968; Crawford et al., 1987;Bailey & Kovaliski, 1993; Dangerfield, 1998). Burrowingability, which is an important adaptation in this respect,varies among species and, in general, millipedes go deeperin the soil than woodlice (Davis, Hassall & Sutton, 1977;Geoffroy et al., 1981). Accordingly, many millipede speciesremain inactive for long periods during the dry season,unlike certain woodlice that emerge from their retreats toforage at the most favourable times of the day (Paris, 1963;Shachak et al., 1979). Physiological adaptations, such as areduced metabolism, tolerance of increased osmolality, andwater vapour absorption in unsaturated air, allow millipedesto survive such conditions for weeks or months (Crawford,1979; Hopkin & Read, 1992; Wright & Westh, 2006). Quiteoften, dry periods are spent moulting. For example, thewood-feeding spirobolid Narceus americanus in North Americaburrows into logs in late summer, seals the entrance andmoults. O’Neill (1969) showed that this is a response todesiccation, which may protect the animal during the dryseason.

Whether such seasonal adaptations will be sufficient formacroarthropods to withstand more severe droughts dueto climate change remains an open question. Desiccationresistance varies greatly among species, even within acommunity (Haacker, 1968; Meyer & Eisenbeis, 1985; Davis,1989), and the least tolerant species could be negativelyaffected. After exceptional droughts in temperate forests,species of the millipede order Chordeumatida sufferedsignificant population declines (David, 1990; Schallnass,Rombke & Beck, 1992; Geoffroy & Celerier, 1996), inline with their low desiccation resistance in laboratoryexperiments (Haacker, 1968; Meyer & Eisenbeis, 1985).For more tolerant species, predictions are more difficult.In Mediterranean climate areas, juvenile mortality is highin summer for the woodlouse Armadillidium vulgare (Paris,1963) and the glomerid millipede Glomeris balcanica (Iatrou &Stamou, 1991), which might worsen in particularly hot anddry years. However, drought may affect resistant speciesthrough other, non-lethal demographic processes. In a



study along an altitudinal gradient, Read (1985) found thatthe development of the julid millipede Ommatoiulus moreleti

was faster at lower altitudes in winter, probably due tohigher temperatures, but the opposite occurred in summer,suggesting that positive effects of warming on developmentrate were offset by dry summer conditions. In southernGreece, chordeumatidan species that are adapted to severedrought conditions have much longer life cycles than theirtemperate counterparts (Karamaouna, 1990). In general,behaviours that maintain survivorship under prolongedharsh conditions are costly in terms of development rate,growth and reproduction, because they hamper access toenergetic resources (David, 1996; Dangerfield, 1998). Sofar no studies have fully assessed these costs in terms ofpopulation growth in macroarthropods.

Nevertheless, latitudinal patterns of abundance indicatethat the impacts of drought are likely to interact with positiveeffects of warming. For example, a number of millipedespecies that are widespread in western Europe occur asfar south as the Mediterranean region, which is warmwith a dry summer. Their abundance in this region isclosely associated with their desiccation resistance measuredin the laboratory by Haacker (1968) (Fig. 2). Thus, thepoorly resistant Polydesmus angustus is relatively scarce inthe Mediterranean region, except in some humid, riparianforests. In drier forests, it is outnumbered by two moreresistant species, the julid Cylindroiulus caeruleocinctus andthe glomerid Glomeris marginata, the abundances of whichpeak close to their southern range margins (David, 1996).These latitudinal patterns confirm that warming has positiveeffects on temperate millipedes, but also suggest that thecomposition of southern communities is strongly influencedby seasonal drought.

The dependence of some macroarthropod species onhumid habitats in Mediterranean and sub-arid climate areasmakes changes in community composition very likely underfuture drier conditions. In southwest Australia, for example,several dozens of endemic millipede species are restricted tothe coastal mountain region, which comprises moist sites but

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Fig. 2. Desiccation resistance in dry air (5% RH) of adult femalePolydesmus angustus (N = 12), Cylindroiulus caeruleocinctus (N = 14)and Glomeris marginata (N = 17). Redrawn from Haacker (1968).

is predicted to be severely affected by drought in the comingdecades (Moir, Brennan & Harvey, 2009). Although someof these endemics persisted through previous arid periodsduring the Quaternary, it is likely that local populationswill suffer significant declines if the number of moist refugiadecreases rapidly in this region. At the same time, droughtcould result in a southward shift of more resistant species,e.g. the pool of Antichiropus spp. (Paradoxosomatidae) that liveslightly further north in drier environments (Moir et al., 2009),resulting in substantial changes in community composition.

III. EFFECTS OF CHANGES IN FOOD QUALITYON MACROARTHROPODS

(1) The food of saprophages

Millipedes and woodlice typically feed on decomposing plantmaterial, i.e. leaf litter, dead wood, and the microbiotaassociated with these substrates (Sutton, 1980; Hopkin &Read, 1992). This protein-poor diet is a major constraint onall saprophagous macroarthropods, which prefer leaf littercomparatively rich in nitrogen, with a low carbon:nitrogen(C:N) ratio (Pobozsny, 1978; Gunnarsson, 1987; Davidet al., 2001; Loranger-Merciris et al., 2008). The decreasein C:N ratio during decomposition may partly explain whyleaves of many plant species become progressively morepalatable when ageing (Pobozsny, 1978; Szlavecz, 1985;David & Gillon, 2002). The diet of macroarthropods ishowever more diversified than one might think, becausethey have not only nitrogen requirements but also needmany other nutrients (mainly calcium, phosporus andmagnesium) and carbohydrates (Carefoot, 1984; Scheu &Schaefer, 1998; Zimmer, 2002). This may explain why higherconsumption rates have been reported on litter mixturesthan on single food sources (Ashwini & Sridhar, 2005; DeOliveira, Hattenschwiler & Handa, 2010). Many species alsofeed occasionally on a variety of high-quality food, suchas fallen fruits, seeds, arthropod and mammal faeces, andeven dead invertebrates (Hoffman & Payne, 1969; Warburg,1987; Dangerfield & Telford, 1996; Zimmer & Topp, 2002;Saska, 2008). When macroarthropods are induced to feed onpoor-quality litter material in the laboratory, they generallyshow reduced consumption or even starvation, althoughcompensatory feeding has been reported in some woodlice(Sousa et al., 1998; Catalan, Lardies & Bozinovic, 2008).

The presence of plant defences against herbivores(secondary compounds, toughness) is another characteristicof litter that is important to saprophagous macroarthropods.Deterrent factors must be eliminated for plant litter tobecome palatable, irrespective of its nutritive value (Soma& Saito, 1983; Hassall & Rushton, 1984; Carcamo et al.,2000). This probably explains why relationships betweenconsumption rate and C:N ratio of the food become apparentonly after sufficient leaching and decomposition (David et al.,2001). Fungal colonization may increase the palatability oflitter not only because fungi concentrate easily assimilable



nutrients, but also because of their effects on deterrent factors(Gunnarsson, 1987; Kukor & Martin, 1987).

(2) Global change and leaf litter quality

Alterations to litter quality in the context of global changewill result from either changes to the physical environment,such as elevated atmospheric CO2 concentrations andincreasing levels of solar ultraviolet radiation, or changesin plant community composition. Experiments on the short-term effects of elevated atmospheric CO2 on plant tissuecomposition indicate that chemical changes are much lessmarked in leaf litter than in green plant material (Norbyet al., 2001). However, the litter nitrogen content decreasesslightly—by 7% on average—with a concomitant increasein C:N ratio (Norby et al., 2001). This corresponds to anoverall decrease in food quality for macroarthropods, albeitwith large differences among plant litter species. The effects ofelevated CO2 on the physical and chemical defences of plantsare less clear, but there may be increased concentrationsof phenolics in fresh leaf litter derived from high-CO2conditions (Wardle, 2002; Kasurinen et al., 2007). Changes inlitter chemistry and individual phenolic concentrations canalso occur in response to ultraviolet radiation (Kotilainenet al., 2009).

At the same time, the composition of plant communitiesis progressively changing in response to global warming(Walther, 2003; IPCC, 2007a), and because of differentialgrowth responses of species to CO2 enrichment (Korner,2003). Invasions of exotic plants also occur in a wide rangeof ecosystems (IPCC, 2007a). Ultimately, these changesin community composition may have a greater influenceon litter quality, because (i) differences in nutrients anddeterrent factors among plant species are markedly greaterthan intraspecific variations due to elevated CO2 levels(Norby et al., 2001; Finzi et al., 2001); and (ii) changes inthe composition of a litter mixture can significantly affectits overall quality, due to interactions among componentspecies (Hattenschwiler, Tiunov & Scheu, 2005). However,there is much uncertainty about the rate of changes inplant communities at a continental scale (Neilson et al., 2005;Thuiller et al., 2006). Moreover, the drivers of communitychanges may promote plant species with better or poorerlitter quality for macroarthropods. For example, whileMediterranean tree species are expanding northwards intemperate Europe, which results in litter of lower quality,deciduous tree species are expected to invade coniferousforests in the boreal zone, which should improve litter qualitythere (Koca, Smith & Sykes, 2006; Thuiller et al., 2006).

All these changes in plant species and communities alsomodify the composition of microbial communities in thedecomposing material, even if these processes are complexand not yet fully understood (Bardgett, Freeman & Ostle,2008). As litter microbiota are an essential component ofthe food of saprophagous macroarthropods (Bignell, 1989;Zimmer, 2002), probably with a strong influence on litterpalatability (Gunnarsson, 1987; Ihnen & Zimmer, 2008), the

entire litter substrate including its microbial populations isconsidered in the following discussion.

(3) Responses of macroarthropods to food qualitychanges

The effects of elevated atmospheric CO2 concentrationson litter consumption rates were studied in temperatewoodlice, in which two types of responses were identified.When woodlice were fed on plant litter species known tobe unpalatable before undergoing decomposition, such asbeech (Fagus sylvatica), oak (Quercus myrtifolia) and certain grassspecies, elevated-CO2 litter was consumed slightly morethan ambient-CO2 litter, irrespective of the nutrient content(Hattenschwiler, Buhler & Korner, 1999; David et al., 2001;Cotrufo, Drake & Ehleringer, 2005). The latter authorshypothesized that, in these litter types, deterrent factorscould be lost more rapidly during the decomposition ofelevated-CO2 material (David et al., 2001; Cotrufo et al.,2005). This interpretation has found support in resultsindicating that CO2 enrichment increases leaching of poorlydegradable organic matter from leaf litter, particularly duringthe initial leaching phase (Hagedorn & Machwitz, 2007).A different type of response was observed when woodlicewere fed on plant litter species without deterrent factors,i.e. highly palatable to macroarthropods in the first stagesof decomposition, such as ash (Fraxinus excelsior) and certainforbs. In these cases, the nutrient content of the food wasthe most important factor, and elevated-CO2 litter with ahigher C:N ratio was consumed less than ambient-CO2 litter(Cotrufo, Briones & Ineson, 1998; David et al., 2001).

Food quality not only affects consumption rates butalso has a considerable influence on life-history traits ofmacroarthropods, mainly growth and reproduction (Rushton& Hassall, 1983; Striganova & Prishutova, 1990; Zimmer& Topp, 2000; Lardies, Carter & Bozinovic, 2004). WhenBlower (1974) reared the julid millipede Ophyiulus pilosus

from egg to maturity on dead sycamore leaves alone, adultfemales did not lay eggs. Upon dissection, only half-sized eggswere found, presumably due to a nutrient deficiency. FemalePolydesmus angustus that were reared from egg to maturity on amixture of leaf litter did reproduce, but their fertility was verylow. However, when a pinch of yeast was added monthlyto the leaf litter, female fertility was 4.3 times as high andsimilar to the fertility of adult females from the field (David &Celerier, 1997). Similarly, in laboratory-reared Armadillidium

vulgare, the reproductive allocation of females was increasedby 21% under conditions of higher food quality, i.e. whena mixture of dicotyledonous leaves was added to dried grass(Hassall et al., 2005). Moreover, these effects can influence thedynamics of field populations, since Hassall & Dangerfield(1990) showed that the addition of high-quality food tofield enclosures significantly increased the individual growthrate of A. vulgare, which is the major determinant of femalefecundity. These authors concluded that the availability ofhigh-quality food was probably the most important factorregulating the density of this woodlouse population.



Since low-quality food has negative effects onmacroarthropod demography, the question is whether sucheffects, in the context of global change, can offset the positiveinfluence of climate warming on population growth rate.David & Gillon (2009) compared the effects of elevatedtemperatures and reduced litter quality on the life-historytraits of Polydesmus angustus. Millipedes were reared under eachtemperature regime on two types of leaf litter: (i) Atlantic leaflitter including hornbeam (Carpinus betulus), chestnut (Castanea

sativa) and hazel (Corylus avellana); and (ii) Mediterranean leaflitter including downy oak (Quercus pubescens), sorb (Sorbus

torminalis) and holm oak (Quercus ilex), which proved to bepoorer in nitrogen. This choice made it possible to explorethe effects of a higher C:N ratio in the food, while simulatingthe ultimate stage of litter changes associated with a 3.3 ◦Crise in temperature. All components of the population growthrate were affected negatively by the switch from Atlantic toMediterranean leaf litter, and deteriorating food conditionsamply offset the effects of warming (compare Figs. 1 and3). When both treatments were applied in P. angustus, therewere no significant changes in development rate, survival,adult live mass, and age at first reproduction (Fig. 3). Fertilitywas more responsive to food quality than to warming anddecreased significantly when both factors were combined(Fig. 3). Therefore, from an ecophysiological point of view,a reduction in litter quality can offset the positive effects ofwarming on saprophages (David & Gillon, 2009). This resultsupports the general pattern observed in insect herbivores(Zvereva & Kozlov, 2006).

It is important to stress, however, that the drasticchange in leaf litter composition that was simulated inthis experiment—a switch from Atlantic to Mediterraneanleaf litter—is unlikely to occur in the near future. Thereplacement of dominant plant species by locally rare speciesor new migrants from low latitudes may require decades orcenturies, especially in forests (Neilson et al., 2005). If changesin leaf litter composition lag behind climate warming,temperate macroarthropods should retain the opportunity offeeding on high-quality plant species. In addition, the meandecrease in food N content resulting from the replacement ofAtlantic species by Mediterranean species was of the orderof 18–28% depending on the season (David & Gillon, 2009).These values are much higher than the mean decrease of7% reported by Norby et al. (2001) for intraspecific plantresponses to elevated CO2 levels. These considerationssuggest that temperate macroarthropods are likely to befavoured by climate warming during the coming decades,even in areas where litter quality tends to deteriorate.

IV. EFFECTS OF LAND COVER CHANGESON MACROARTHROPODS

(1) Importance of land use for habitat specialists

Although climate together with the physical and chemicalproperties of the soil largely determine the distribution andabundance of millipedes and woodlice (Kime & Wauthy,

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Fig. 3. Combined effects of increasing temperature by 3.3 ◦C (TAtl to TMed) and reducing litter quality (LAtl to LMed) on developmenttime, age at first reproduction, adult live mass and fertility of female Polydesmus angustus reared in the laboratory. Values are means +S.E.M. (N = 7 broods). TAtl, Atlantic temperatures; TMed, Mediterranean temperatues; LAtl, Atlantic leaf litter; LMed, Mediterraneanleaf litter (see text for composition). Redrawn from David & Gillon (2009).



1984; Warburg, Linsenmair & Bercovitz, 1984; Branquartet al., 1995; Judas & Hauser, 1998; Judd & Horwitz, 2003),land use is equally important. It is important at the site scale,where land cover and the level of disturbance are majorsite characteristics for these macroarthropods (Davis, 1984;Wolters & Ekschmitt, 1997; Wardle et al., 2001; Paoletti et al.,2007), and at the landscape scale, where land use determinesthe level of spatial heterogeneity among sites (Dauber et al.,2005). Management practices that alter microhabitats withinsites, e.g. by modifying the amount of coarse woody debris inforests, also influence communities (Judd & Horwitz, 2003;Topp et al., 2006).

In temperate, tropical or mountain areas, specialistmacroarthropod species are clearly associated with landcover, such as forest, grassland, or mixed habitats withscattered trees and shrubs (Vandel, 1960; Pedroli-Christen,1993; Hornung & Warburg, 1995; Kime, 2004; Hamer,Slotow & Lovell, 2006). Within those habitats, some specieshave a further specialization on microhabitats, especiallyin forests (O’Neill, 1967; Enghoff, 1992; Judd & Horwitz,2003). Although self-evident, it should be emphasized thathabitat loss is critical to habitat specialists and can overrideany positive effects of climate warming (Hanski, 2005).For example, in Great Britain, although many butterflieswere predicted to thrive because of ameliorating climaticconditions, range reduction occurred for a number of speciesat the end of the 20th Century (Warren et al., 2001). Habitatspecialists were much more affected than habitat generalists,suggesting that habitat loss was the most important factor.There have been no such studies for millipedes and woodlice,but there is some evidence that they are also affected byhabitat loss.

(2) Tropical deforestation as a case in point

Deforestation is likely to be critical to forest specialists,especially in tropical zones. Macroarthropod communitiesin old-growth forests are often rich in species, possibly inrelation to the high diversity of tree leaf litter, since ‘‘single-tree patterns’’ in their distribution have been reported(Vohland & Schroth, 1999; Loranger, Ponge & Lavelle,2003). Small-scale differences in litter standing crop and litterquality are important determinants of arthropod abundanceand diversity in the forest floor (Sayer et al., 2010). Theimmediate impact of deforestation (clearcutting or slashburning) on tropical macroarthropods is strongly negative(Mathieu et al., 2005). Forest specialists are eliminated anddo not reinvade sites subsequently used as grassland. Evenless-destructive methods like selective logging considerablyalter the composition of communities, as was shown forwoodlice in Malaysia (Hassall et al., 2006).

The replacement of old-growth forests by managed,low-diversity tree plantations does not restore the originalhabitats. In tropical plantations of eucalypt, rubber, cocoa,etc., macroarthropod abundance may remain high butspecies richness may be markedly reduced. For example,in Ivory Coast, Bourdanne (1997) compared millipedecommunities in a humid tropical forest and three nearby

plantations. Out of 31 species found in the forest, sevenwere absent from plantations, and a further five were ata strongly reduced population density. By contrast, onlythree species had systematically higher population densitiesin plantations—with an outbreak of the native spirostreptidAulonopygus aculeatus. Overall, even taking into account a fewspecies found only in plantations, total millipede richnessdecreased by 8 to 13 species depending on the plantation,i.e. by 26–42% in comparison with the old-growth forest(Bourdanne, 1997). Similar results were obtained earlier byAouti (1978).

Can tropical secondary forests on abandoned lands,which are more diversified than plantations, provide suitablehabitats for all old-growth forest specialists? It is doubtful,according to data obtained for ants and dung beetles (Bihnet al., 2008; Gardner et al., 2008), but different taxa mayshow different responses to changes in habitat (Lawton et al.,1998). There are few data for millipedes and woodlice,with those that exist mainly from young or very youngsecondary forests (Hofer et al., 2001; Nakamura, Proctor &Catterall, 2003). This hinders comparisons with old-growthforests because macroarthropod communities are knownto change considerably with the age of regenerating forestsites (Redi et al., 2005). In an Amazonian secondary forest,however, although the biomass of millipedes and woodlicewas much lower than in primary forest and plantations,community composition was more similar to that in primaryforest, suggesting a trend towards the restoration of thebelow-ground macroarthropod fauna (Hofer et al., 2001).

(3) Habitat heterogeneity and biodiversity

Other species are open-habitat specialists and the extensionof closed-canopy woodland in Europe, due to theabandonment of extensive grazing and coppicing, alsoaffects macroarthropod diversity. Julid millipedes such asCylindroiulus arborum, which typically occurs in open woodlandin central Europe (Spitzer et al., 2008), and Ommatoiulus

rutilans, which typically occurs in grazed grassland in westernEurope (David et al., 1999), are negatively affected by habitatclosure.

Fine-scale studies in habitat mosaics have shown thatthe composition of macroarthropod communities changeswith land cover over very short distances (Dunger &Steinmetzger, 1981; David et al., 1999). This results in ahigh overall species richness (γ−diversity) at the landscapescale, because mosaics contain typical species of each habitatpatch—grassland, woodland, shrubland—and, possibly,ecotonal species specialized on edges (David et al., 1999).Presumably, a degree of land cover heterogeneity ismore favourable to macroarthropod diversity than uniformhabitats covering large areas, as in many arthropod groups(Tews et al., 2004; Eggleton et al., 2005; Samways, 2007).In Greece, the number of woodlouse species recordedon Mediterranean islands was strongly related to habitatdiversity (Sfenthourakis, 1996), and in Hungary, millipedespecies richness in nature reserves was found to be more



dependent on land cover heterogeneity than on reserve size(Baldi, 2008).

(4) Heterogeneity versus fragmentation

An excess of habitat heterogeneity may turn intofragmentation, which could be detrimental to biodiversity(Tews et al., 2004). On theoretical grounds, highlyfragmented habitats are generally considered to increasethe risk of extinction, especially for species that lack dispersalability (Hanski, 2005). In empirical studies, however, theeffects of fragmentation on arthropods are highly variableacross taxa and among studies (Fahrig, 2003; Ewers &Didham, 2006). At what point does habitat heterogeneitybecome fragmentation for below-ground macroarthropods?A quasi-experiment was conducted in a eucalypt forest inAustralia, where a large area was clearcut to be plantedto pines, except on forest remnants of different sizes. Overa nine-year period following clearing, abundance decreasedfor landhoppers in the smaller remnants (Margules, Milkovits& Smith, 1994) but not for millipedes (Baker, 1998). Amongthe most common species, a paradoxosomatid (Somethus

sp.) was not affected by fragmentation and a dalodesmid(Gephyrodesmus sp.) became more abundant, especially inthe smaller remnants (Fig. 4). The mechanisms drivingthese changes in abundance are unclear, but the resultsillustrate that there is little evidence for negative effects offragmentation on millipedes. This is confirmed by the factthat, in Poland, normally abundant and rich communitieshave been described on lake islets only a few hectares in area(Wytwer & Zalewski, 2005). Likewise, in South Africa, a largenumber of forest specialists—including large-bodied speciesup to 200 mm long—occupy remnants of less than 1 km2

(Hamer & Slotow, 2000). Woodlice do not seem to be moresensitive to fragmentation. Pitfall-trapping in 40 urban shrubhabitat fragments in California (range 0.3–91 ha) revealedno negative effects of fragmentation on the abundanceof Armadillidium vulgare and Porcellio laevis (Bolger et al.,

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2000). Although litter-dwelling macroarthropods exhibittraits that are expected to increase species’ vulnerabilityto fragmentation, i.e. large body size, low mobility andlow population abundance (Ewers & Didham, 2006), moststudied species seem to be unaffected. It may be becausethe critical fragment size is very small for these animals, orbecause they are better dispersers than generally thought.

Although conservation issues are beyond the scope ofthis review, these data suggest that a number of specialistmacroarthropod species with shrinking habitats can survivein relatively small conservation areas, especially if these arenot too isolated. Of course, this will not be a cure for allills. Small remnants may preserve faunal richness at givensites (α−diversity), but if species turnover is high amongsites (β-diversity), many species may remain threatened.This is the case in areas with considerable numbers of siteendemics, like Madagascar, South Africa and certain oceanicislands (Enghoff & Baez, 1993; Hamer et al., 2006; Wesener,2009). Many specialist species that survive only at a verylimited number of small sites, such as giant pill millipedes(Sphaerotheriidae) in Malagasy forests (Wesener, 2009), areat risk of extinction if habitat conservation efforts do notencompass large territories.

V. CONCLUSIONS

(1) In terms of impacts of global change on saprophagousmacroarthropods, we tentatively conclude that: (a)climate warming could have a positive effect on theabundance of some temperate species, with a possiblepoleward expansion of their range; (b) the warmingeffect could be offset by a drastic reduction of leaflitter quality in certain areas, but this is unlikely tooccur in the near future; (c) decreasing rainfall at lowlatitudes could alter the composition of communities byfavouring drought-resistant species in many regions;(d) land cover changes, mainly due to deforestationin the tropics and land abandonment in Europe,could override any other factor for habitat specialists;and (e) landscape heterogeneity could be positive formacroarthropod conservation, even at the cost of somefragmentation. The emerging picture is that climatechange per se may be less harmful to macroarthropodsthan habitat loss resulting from increasing humanpressure—although their joint impact might beadditive (Samways, 2007). For example, the ability oftropical species to withstand warming by behaviouralmeans may depend on the availability of shade(Kearney et al., 2009), which depends critically onland use.

(2) There is a relative paucity of data on millipede andwoodlouse ecology. Most conclusions herein are basedon short-term studies involving a limited number ofspecies, mainly from Europe. Little is known aboutthe physiological ecology of most species, i.e. howthey respond to abiotic factors in terms of population



growth. More ecophysiological studies are needed overbroader geographical ranges, including species withdifferent ecologies and life histories. This is particularlyimportant for tropical species, in order to test thepredicted decrease in their population growth rates inresponse to climate warming (Deutsch et al., 2008).

(3) Only a few components of global change have beenincluded in this review. Interactions with other factorsmay occur, with possible implications for macroarthro-pod ecology. For example, the ecological consequencesof nitrogen deposition may interact strongly with thoseof CO2 enrichment in terrestrial ecosystems (Wardle,2002). Elevated CO2 levels reduce the water con-sumption of certain tree species, which may result inslower drying of the forest soil (Korner, 2003). Thefrequency of extreme events (heat wave, drought, fire,flooding. . . ) can also have direct and indirect effects onbelow-ground macroarthropods, even though they arebetter protected than their above-ground counterparts(York, 1999; Adis & Junk, 2002; Paoletti et al., 2007).Further studies are required on all these factors.

(4) Despite growing evidence of the demographic impactsof diseases, parasitism and predation on field popula-tions of millipedes and woodlice (Sunderland & Sutton,1980; Federici, 1984; Baker, 1985a, b; McKillup,Allen & Skewes, 1988; Krooss & Schaefer, 1998),no studies have investigated so far the effects of globalchange on both macroarthropods and their naturalenemies. As pathogens, parasites and predators arealso affected directly and indirectly by environmentalchange, biotic interactions may result in varied butpervasive effects on the abundance and distribution ofspecies (Tylianakis et al., 2008) . These effects mightexplain some inconsistencies between the expectedresponses to climate change in temperate woodliceand the population dynamics observed in the field(Zimmer, 2004). Both ecophysiology and biotic inter-action studies will be necessary to understand fully theeffects of global change on macroarthropods.

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The ecology of saprophagous macroarthropods (millipedes, woodlice) in the context of global change