In order to evaluate the impact of agricultural practices on the diversity of terrestrial isopods the preliminary investigations must first include an inventory of species present and their preferred habitat. Paoletti and Hassall (1999) underlined how terrestrial isopods are very widespread, easily identified and form a dominant component of the soil arthropod macrodecomposer community in many temperate habitats (Hassall and Sutton 1977), reaching densities of up to 3000 m^-2 in calcareous grasslands. Isopods were collected using hand search or pitfall trapping; one of the most commonly used methods of sampling ground-dwelling arthropods (Barber 1931, Duelli et al. 1999, Matalin and Makarov 2011).

They are used as surrogates for natural habitats and grassland biodiversity. They are important primary consumers and are an important food source for other animals, often because of their richness in calcium that is more readily absorbable than in molluscs. The species exhibit a lack of tolerance to low or high values of pH.

For example, in Western France, Souty-Grosset et al. (2008) investigated diverse types of habitats in several areas from Poitou-Charentes. The survey was carried out in grasslands (cultivated, temporary or permanent), forests, woods and humid zones, all components of the territory investigated. Humid zones investigated were the margins of ponds and of the Vienne River. Terrestrial isopods were also sampled in connections – either natural or artificial hedges – in order to describe faunal richness in these valuable junctions. Compost heaps and dunghills were also investigated. Sites were randomly prospected with a minimum distance of around 4 km between any two sites. By the end of the survey, 39 different locations were sampled, some of them having several habitats. The study involved 51 habitats. To obtain a correct estimation of isopod diversity, the protocol was simple and reproducible: a hand search method was applied with random sampling for one hour; in order to obtain the same probability of capture, the same three persons were always involved. Armadillidium vulgare, found to be a common species in the region by Legrand (1954), except in forests, was for the first time sampled in oak forests (Figure 2), where the pH is slightly acidic. The species is most prevalent in grasslands rich in monocotyledons, although it has been previously described as preferring dicotyledons (Rushton and Hassall 1983a, b, 1987). No forest harboured A. nasatum Budde-Lund, 1885, a species characterized by having a lower tolerance to pH and tannins than A. vulgare. Grasslands are the typical habitat of the genus Armadillidium by offering suitable pH and humidity. In grasslands, both A. vulgare and A. nasatum can be present whether or not monocotyledons are dominant. Only grasslands with around 50 % of monocotyledons exhibited a prevalence of A. nasatum. The investigation of field boundaries revealed a possible exclusion between A. vulgare and A. nasatum: wild hedgerows provide A. nasatum with higher humidity than do planted hedges; these latter, composed of regularly spaced shrubs with higher temperature and light, harbour particularly A. vulgare. Moreover, A. vulgare was found in all types of compost, especially from corn and withstanding high temperatures. A. vulgare is absent from damp habitats whereas A. nasatum was found near ponds as expected. This species is originally a littoral species which colonized inland habitats by following river valleys (Vandel 1960, 1962).

Figure 2. 

Distribution of isopod species in different types of habitat. A Forest B Grassland C Connections: hedges D Compost E Humid zones. Shannon (H’) and equitability (R’) indices are written below each graph (from Souty-Grosset et al. 2008).

Less abundant species included Oniscus asellus Linnaeus, 1758 and Porcellionides pruinosus (Brandt, 1833). Oniscus asellus is a common species in forests and is a litter feeding macroarthropod, favouring humidity of the soil (Jambu et al. 1987). As the species has no pseudotracheae, it requires a microhabitat with high relative humidity. Moreover, O. asellus has a pH preference of around 5.1 (van Straalen and Verhoef 1997), which explains its occurrence in oak and pine forests. Oniscus asellus was also collected near water, where the water availability is high, allowing it to take up water by mouth and anus (Edney and Spencer 1955). Composts were dominated by P. pruinosus. This species is capable of adaptation to all types of habitats, except those too cold or too humid (Vandel 1962). However, they were absent in grasslands, field boundaries and pond margins. Grasslands and hedges are not favourable because of the high climatic variation and ponds margins are too humid. Composts provide high temperatures to this polyphagous species, allowing high reproductive activity (Juchault et al. 1985).

By comparison, in the Carei Plain natural reserve of north-western Romania, Ferenti et al. (2012) identified 15 species: Haplophthalmus mengii (Zaddach, 1844), Haplophthalmus danicus Budde-Lund, 1880, Hyloniscus riparius (C. Koch, 1838), Hyloniscus transsylvanicus (Verhoeff, 1901), Platyarthrus hoffmannseggii (Brandt, 1833), Cylisticus convexus (De Geer, 1778), Porcellionides pruinosus (Brandt 1833), Protracheoniscus politus (C. Koch, 1841), Trachelipus arcuatus (Budde-Lund, 1885), Trachelipus nodulosus (C. Koch, 1838), Trachelipus rathkii (Brandt, 1833), Porcellium collicola (Verhoeff, 1907), Porcellio scaber (Lamarck, 1818), Armadillidium vulgare and Armadillidium versicolor Stein 1859. The diversity of the terrestrial isopods in this protected area was high due to the diversity of habitats. The highest species diversity was found in wetlands, with the lowest in plantations and forests. Sylvan species were also present in the open wetlands. Unlike marshes, sand dunes harboured only anthropophilic and invasive species.

As a result of modern agricultural practices, calcareous grasslands have been declining both in their extent and quality across Europe. As the abundance of terrestrial isopods was described in grasslands Reynolds et al. (2004), Souty-Grosset et al. (2005a) investigated the diversity of isopods in natural and cultivated grasslands of western France, both as grassland detritivores and further considering that their diversity as grassland detritivores could thus be a potential guide to ecosystem activity in natural and cultivated grasslands. Woodlice diversity was studied in different grassland types at two sites: Fors, with mixed farming (crops and livestock), and Lusignan, with intensive farming. Woodlice were collected by hand in plot centres, borders, and field boundaries. Isopod numbers were higher at Fors than at Lusignan. The total numbers of isopods in plots, their borders, and connections (Figure 3) were clearly lower at Lusignan compared to Fors, regardless of the grassland type. Species assemblages were dominated by Philoscia muscorum (Scopoli, 1763) at Lusignan whereas this species was less numerous at Fors than A. vulgare and A. nasatum. These results also differ with grassland type, with high species diversity or number of individuals in temporary and permanent grasslands.

Figure 3. 

Number of isopods collected by hand-searching in three different types of grasslands in western France. The two sites differ in farming intensity: Lusignan has experienced intensive practices over many years, whereas Fors is in a zone of mixed farming, with a more recent history of intensification. Note the different scales in the y axes (from Souty-Grosset et al. 2005a).

Hedges were important in increasing isopod diversity within plots. The structure of the landscape and its capacity to provide connections between habitats has been found to be important for isopods. The proximity of a suitable habitat for a permanent community of isopods will favour colonization of new habitats. In this study, Souty-Grosset et al. (2005a) showed this influence by the relationship between connections and plots. Thus, hedges are potentially a source of woodlice for grasslands. Therefore, most species present in a plot occur also in the connections. Isopods are highly affected by variations in habitat structure (Davis 1984); while the presence of some species is linked with the degree of openness of the land with some shrubs still present, other species are most common in closed habitats (David et al. 1999). High density of woodlice indicates high habitat quality, as is the case in permanent grasslands. Consequently, some woodlice species may be characteristic of various Atlantic grasslands, and thus are useful as bioindicators of undisturbed and semi-natural conditions. Souty-Grosset et al. (2005b) studied the diversity of woodlice in three types of grasslands: artificial (established for less than 5 years and sown only with leguminous fodder crops), temporary (less than 5 years old, sown with fodder grasses, pure or mixed with leguminous plants) and permanent (sown 6–10 years earlier), in spring, summer, and autumn.

Relative abundance of isopods was different among habitats and the three sampling periods (Figure 4). Associations were dominated by A. vulgare, A. nasatum, and P. muscorum.

Some species were clearly linked to the degree of openness of the land, agreeing with the conclusions by David et al. (1999). The plot level differences were due to differences in management (cutting or grazing). According to Curry (1994), cutting for silage is a major disturbance for soil arthropods in general. Isopods were most abundant in five years old grasslands. Climatic conditions affect the isopod abundance, and the species dominance may change according to season. In permanent grasslands, populations of P. muscorum are most abundant in autumn, A. vulgare in summer and A. nasatum in spring (personal observation).

Figure 4. 

Number of isopods collected at Fors in three seasons: spring (black bars), summer (grey bars) and autumn (white bars). Habitat abbreviations: CL: clover, AL: alfalfa, TG: temporary grasslands less than 5 years old PG: permanent grasslands more than 5 years old (PG) (from Souty-Grosset et al. 2005b).

Singer et al. (2012) surveyed isopods in the tallgrass prairie ecosystem in Kansas and found the same species as in Western France. Of the four species known in Kansas thus far, all non-native, A. vulgare was the most abundant, accounting for 93 % of all individuals. Armadillidium nasatum, C. convexus, and P. pruinosus were also found and the authors also reported the first record of Porcellio laevis Latreille, 1804 in Kansas. There was no relationship between isopod abundance and either fire frequency or grazing treatment. Plum (2005), reviewing information mainly from Western and Central Europe, showed that isopods are rare in flooded grasslands. The most frequent species is Trachelipus rathkii; all other species occur only occasionally or locally. The most commonly recorded species only occurred in unflooded reference sites (A. vulgare, P. scaber) or were totally absent (O. asellus).

Following the previous study, Souty-Grosset and co-workers (unpublished results) investigated the diversity of terrestrial isopods in a site («Plaine Mothaise»), where changes in agricultural practices led to replacement of more than 25 % of grasslands by crops and poplar plantations within the period 2000–2010 (Figure 5). The approximately 200 ha study area is located between the towns St. Maixent-L’Ecole and La Mothe Saint-Héray (46°22'52"N, 0°06'18"W) in the Poitou Charentes region, central-western France. The localities are connected by the Sèvre Niortaise stream. The area is dominated by croplands (corn), also forest and grassland land uses are represented. This affects habitats, resources and finally the ecosystem services. In order to further integrate restoration management of this area, the impact on terrestrial isopod diversity was first investigated (Table 1).

Figure 5. 

Land cover map with sampling sites in Plaine Mothaise, central-western France. Land cover features of the study site were determined using aerial photographs (Google Earth) and field inspections. Linear characteristics from the landscape were distinguished such as riparian, hedge, continuous and intermittent vegetation. The final categories obtained are Cultivation (crops), Grassland, Poplars, Types of connection, roads and urban. Landscapes were mapped using Arcmap 9.3 (ESRI, 2004) as a main geographical information system. Black dots indicate sites of pitfall trap sampling.

A total of 5 726 isopods were captured representing 15 species and seven families.

The effect of agricultural management on soil arthropod diversity and functioning is often context dependent, e.g. diversity of functionally important taxa such as decomposers may be enhanced by increasing habitat heterogeneity (Diekötter et al. 2010). The role of landscape connectivity in facilitating dispersal between habitat patches has emerged as a key area of research in conservation ecology (Perovic et al. 2010). Arthropod diversity of adjacent agricultural systems can lead to movements of species between them. Thus, even though higher invertebrates are small organisms with specific habitat requirements, at a higher integrative level, diversity evaluation can be based on landscape parameters (Paoletti and Hassall 1999). Several indicators of landscape composition and structure in Plaine Mothaise were calculated. Land cover features of the study site were determined using aerial photographs (Google Earth ^TM) and field inspections. Linear landscape characteristics such as riparian, hedge, continuous and intermittent vegetation were also distinguished. The following final land use categories were then established: cropland, grassland, forest, connection, roads and urban. Landscapes were mapped using Arcmap 9.3 (ESRI 2004) as a main geographical information system and the database was created.

Table 2 shows the correlation between the degree of response (as measured by the diversity of isopods) and the landscape descriptors. Results show that the riparian vegetation and other connecting elements in the landscape provide higher diversity of terrestrial isopods. Although human modifications of landscape have a negative effect on the diversity, those fragmented landscapes still offering either forest or connections, maintained shelters for isopods.

In Greece, generally, organic vineyards and maize were the poorest in Isopoda species, while olive groves, both conventional and organic, were the richest (Hadjicharalampous et al. 2002). Trachelipus squamuliger (Verhoeff 1907b), the only representative of the Trachelipodidae, was the dominant species in olive groves. Armadillidium vulgare, one of the two Armadillidiidae species found in the studied fields, was the second most abundant species, especially in organic olive groves (Hadjicharalampous et al. 2002).

Studies in other continents show that a drought-tolerant species, such as A. vulgare, could have colonised croplands from field margins and boundaries: In Argentina, since the late 1990s A. vulgare has been an abundant and frequent species in agricultural land colonizing broad areas (Trumper and Linares 1999, Saluso 2004, Faberi et al. 2011, Villarino et al. 2012, Faberi et al. 2014). Armadillidium vulgare is also found in agricultural lands in Illinois and Kansas, USA (Byers et al. 1983; Johnson et al. 2012) and in the Gauteng Province of South Africa (Tribbe and Lube 2010). Porcellio scaber and Balloniscus sellowii Brandt, 1833 are found although less frequently, the latter recorded only in Entre Rios Province, Argentina (Saluso 2004). Other very common species in agricultural lands are Australiodillo bifrons (Budde-Lund, 1885) in New South Wales, Australia (Paoletti et al. 2008), and Trachelipus rathkii in Pennsylvania, USA (Byers and Bierlein 1984), respectively.

In general, untilled agricultural soils are similar to grassland soils since the absence of tillage allows the accumulation of litter on the soil surface, reducing erosion, modifying the soil surface and topsoil environmental characteristics by reducing soil aeration, stronger mechanical resistance to root penetration, smaller soil temperature amplitudes and thus creating a more favourable microhabitat for soil organisms (Hendrix et al. 1990). In Argentina, as in other parts of the world, during the 1970´s, an intensification of agriculture process took place as agriculture has become more profitable than cattle farming (Studdert 2003, Manuel-Navarrete et al. 2005). Increasing cultivation involved aggressive tillage using moldboard and/or disk ploughs (i.e., conventional tillage - CT). Intense use of CT practices accelerates soil erosion and other degradation processes through its impact on the physical, chemical, and biological factors related to soil quality. In response to these problems, farmers have adopted a conservation tillage system such as no-tillage (NT) as a soil-protecting measure (Studdert and Echeverría 2000, García-Préchac et al. 2004). Under NT, litter and soil organic matter tend to concentrate in the upper 5 cm layer of soil (Dominguez et al. 2005). Since the soil is less disturbed NT practice improves soil aggregation (Carter 1992; Beare et al. 1994) decreases litter decomposition rate (Sánchez et al. 1996, Creus et al. 1998) and reduces organic matter loss (García-Préchac et al. 2004), is. Additionally, in NT systems soil erosion by water and wind is reduced (Fabrizzi et al. 2005, Hobbs et al. 2008).

The litter layer under NT systems enhances habitat conditions favourable for isopods. These include reducing soil temperature and moisture extremes and provisioning of food and shelter (Stinner and House 1990, Wolters and Ekschmitt 1997). On the other hand, soil disturbance in CT has direct and indirect effects on isopod populations. Direct effects are related to injury or mortality of individuals and indirect effects are related to habitat destruction (Wallwork 1976, House and Parmelee 1985, Hendrix et al. 1990, Stinner and House 1990, Holland and Reynolds 2003, Estrade et al. 2010, Errouissi et al. 2011).

According to Paoletti and Hassall (1999), when NT is adopted, isopod biomass and diversity increases compared to CT. In Argentina A. vulgare individuals are found both in CT and NT fields. However, this species has taken on considerable importance in agricultural land under NT systems (Trumper 2001, Faberi et al. 2011). Its abundance is higher in NT with respect to CT in winter-spring and in summer-autumn seasons (Manetti et al. 2013). In addition, this species represents a high proportion of the total abundance of arthropods in NT systems, reaching up to 45.5%, while under CT systems it represents approximately 1–9 % of the total abundance of macro-arthropod decomposers (Manetti et al. 2013). The other isopod species, P. scaber and B. sellowii colonizing agricultural land, were always found under NT systems.

In France, agriculture has changed much during the past 50 years, with the transition from small farms to large farms and the overuse of pesticides causing decreases in biodiversity. In Western France, Deschamps et al. (2011) investigated the diversity of isopods with the return of more environmentally friendly agriculture. With this aim, a group of farmers compiled practices about Major Economic Crops. From 2008 to 2010, the relevance of these modifications of practices was tested. A study was initiated in collaboration with 18 farmers located in Poitou-Charentes and Indre aiming to evaluate the impact of changing farming practices on macrofaunal diversity. Terrestrial isopods have been sampled as bioindicators of the quality of agroecosystems. The abundance of terrestrial isopods is the highest in wheat and agro-ecological infrastructures (AEI). Armadillidium vulgare is dominant in wheat, grass strips, and grasslands. Philoscia muscorum is dominant in hedges and secondary in woods. Armadillidium nasatum is the most abundant in grassland and generally less often present than A. vulgare. The diversity of isopods is also higher in wheat and agro-ecological infrastructures. In AEI, A. vulgare made up 99 % of the total sampling in wheat.

Shannon indices and species evenness (Table 3) showed the highest values in grasslands and hedges, secondly in wheat.

In the case of wheat plots, Philoscia muscorum is encountered in the cultivated plot when a hedge and /or a border is present on the side of the plot (Figure 6).

The size of the plots also affects the number of Philoscia muscorum (R² = 0.2954, 29 % of the presence of P. muscorum in cultivated plots is explained by the size of the plots). The presence of P. muscorum in wheat is correlated both with the presence of agro-ecological infrastructures bordering the plot (the higher the numbers in the hedge, the higher the numbers in the plot) and with the size of the plot (the smaller the plot, more species in the center of the plot are from a nearby field margin).

Figure 6. 

Sampling Philoscia muscorum in wheat (pitfall traps). Importance of hedges and woods for inducing the presence of the species in the studied plots. Key: Dark bar: P. muscorum in the plot. Light gray bar: P. muscorum in the borders of the plot (hedges/wood). Codes were expressed for each plot: the first three letters corresponded to the name of the location, the two following numbers to the French department (16: Charente; 86: Vienne; 79: Deux Sèvres; 36 (1 and 2): Indre).

This study shows the importance of refuge habitats like grass strips, hedges and woods for terrestrial isopod populations. Results on A. vulgare in wheat were analysed according to tillage, size of the plot, and presence of pebbles (Table 4). PCA analyses showed that the more the soil is tilled, the fewer A. vulgare are obtained in samples; also the size and the number of pebbles are not related with the abundance of A. vulgare (Souty-Grosset, unpublished data).

Isopod abundance and diversity are related to the type of cultivation, the practices (Tillage and use of phytosanitary products (herbicides, nematocides, and fungicides) expressed by TFI i.e., Treatment Frequency Index, calculated also without Herbicides TFIH-), the size of the plot, the presence of agro-ecological infrastructure (AEI) and its quality AEI+) (Table 5).

Isopods are omnivorous and they have a tendency to shift their food source (Warburg 1993). The capacity of isopods to switch between feeding on dead and green living tissues, i.e., herbivorous feeding, in the field has been demonstrated for several decades. Different isopod species have been observed feeding on green living tissues of several plants even if they have another food source as a choice (Paris and Sikora 1965, Byers et al. 1983, Szlávecz and Maiorana 1990, Hopkin 1991, Benetti et al. 2002; Morisawa et al. 2002; Paoletti et al. 2008; Farmer and Dubugnon 2009; Tierranegra-Garcia et al. 2010, Faberi et al. 2011, Miller 2011, Johnson et al. 2012, Faberi et al. 2014, 2017). In addition, more recently isopods have been reported to exhibit granivory, i.e., feeding on seeds of weeds and crop plants, of some typical plants in agroecosystems (Saska 2008; Koprdová et al. 2012, Salvio et al. 2012).

The preference for or selection of green tissues over decayed leaf litter can be related to the higher N content of green tissues (Szlávecz and Maiorana 1990), or the level or lack of chemical anti-herbivore defense compounds on living plants, e.g. the jasmonate signal pathway (Farmer and Dubugnon 2009) and phenolics (Wood et al. 2012). For example, parallel laboratory experiments identified P. scaber and A. vulgare as being capable of predation on intact plants. Their feeding was strongly facilitated in jasmonate-deficient Arabidopsis and rice plants and revealed potentially detritivore-sensitive, jasmonate-protected Achilles’ heels in these architecturally different plants (petioles and inflorescence stems in Arabidopsis, and lower stem and mesocotyl in rice). The work addresses the question of what stops both species from attacking living plants and provides evidence that it is, in part, the jasmonate signal pathway. Additionally, when isopod populations increase in agroecosystems intra-specific competition among isopods is induced and in consequence may result in consumption of live plant material as is observed in A. vulgare (Paris and Sikora 1965, Trumper 2001, Saska 2008, Johnson et al. 2012, Faberi et al. 2014) and in Australiodillo bifrons (Paoletti et al. 2008).

Isopod population outbreaks and their diet switching between dead and live plant material have two possible consequences in agroecosystems. On the one hand, Saska (2008) and Koprdová et al. (2012) suggested that the predation of isopods on weed seeds and seedlings may contribute to biological control of weeds. On the other hand, at really high abundances, isopods themselves can become crop pests.

Rapid biodiversity assessment (RBA): RBA has been proposed by Obrist and Duelli (2010). It is an affordable indicator for monitoring local species richness of arthropods and sustainability of related ecosystem services. The indicator is based on strictly standardised sampling procedures and the identification of parataxonomic units (morphospecies) instead of species identification. Over a period of eight years, annual mean numbers of morphospecies were assessed in Switzerland in 15 agricultural habitats, in 15 managed forests, and in 12 unmanaged habitats ranging from protected lowland wetlands to Alpine meadows. The annual RBA-trend in unmanaged habitats is used for assessing the influence of climate and weather on biodiversity, and as a reference for measuring the relative influences of recent management changes in agriculture and forestry. The average number of morphospecies per sampling station per year depends on temperature, and was only marginally significantly increasing over time in agriculture, but not in forestry or unmanaged areas. Three RBA indices considered to be relevant for maintaining ecosystem services were calculated from the average number of morphospecies per location per year: (1) an indicator for ecological resilience and sustainability (all morphospecies), (2) an indicator for pollinator diversity (taxa with a majority of pollinators) and (3) an indicator for biocontrol diversity (ratio between carnivore and herbivore guilds).

A synthetic index of biological soil quality (IBQS) was developed by Ruiz et al. (2011) studying soil macro-invertebrate community patterns to assess soil quality in 22 sites representing the diversity of agroecosystems encountered in France. Using hierarchical classification, sites could be separated into four homogeneous groups and using the ‘indicator value’ method, 46 indicator taxa characteristic of one or another of these groups were identified. They used a formula that takes into account the abundance of indicator species and their respective indicator values to score soils from 1 to 20. IBQS was able to detect the effects of management practices on soil quality. Soil quality varied from 6 to 20 in forests, 7 to 9 in pastures, and 2 to 9 in crops respectively. Indicator species, such as T. pusillus and O. asellus had an indicator value of 73 % and 60 %, respectively. Both species are tolerant to soil acidity and their abundances were strongly correlated with soil water-holding capacity (van Straalen and Verhoef 1997).

The research must be now conducted in two ways. First, it is necessary to know why isopod population outbreaks occur and what intrinsic or extrinsic factors drive the shift in their feeding behaviour. Second, we need to understand isopod density/crop damage relationships in order to know the lowest population density that each crop can tolerate and then reach agroecological equilibrium. According to Moonen and Barberi (2008), in order to frame the importance of biodiversity in agroecosystems, three main questions were addressed: (1) What does biodiversity mean in natural and agricultural ecosystems; (2) How is the concept of functionality used in relation to biodiversity; and (3) Which biodiversity measures are currently used to express agriculture/biodiversity relationships?

Analysis of the literature was also performed by Moonen and Barberi (2008) and resulted in a framework consisting of three steps. First, the objectives of biodiversity research and policies have to be defined. Three options can be foreseen here: (a) species, community, habitat or overall biodiversity conservation regardless of its functions, (b) biodiversity conservation to attain production and environmental protection services, and (c) use of bio-indicators for agroecosystem monitoring. For example, studying the bioindicator A. nasatum at a regional scale, Masson et al. (2014) have developed microsatellite markers as the most efficient markers for studying the influence of landscape features and agricultural practices on genetic structure and demographic history of A. nasatum populations. In the second step the appropriate target elements for conservation have to be chosen based on an agroecosystem approach. Finally, the third step involves selection of adequate biodiversity measures of composition, structure and function for each target element. In conclusion, functional biodiversity is important in relation to the provision of specific agroecosystem services. The study of functional biodiversity should start with the definition of agroecosystem functional groups comprising all elements that interact with the desired service, and the subsequent determination of the role of diversity within these functional groups for the fulfilment of the agroecosystem service. Therefore, a more precise definition of ‘functional biodiversity’ was proposed by Moonen and Barberi (2008) as ‘that part of the total biodiversity composed of clusters of elements (at the gene, species or habitat level) providing the same (agro)ecosystem service, that is driven by within-cluster diversity’.