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1 Frontiers inecology and the Environment Ecological cross compliance promotes farmland biodiversity in Switzerland Stéphanie Aviron, Heike Nitsch, Philippe Jeanneret, Serge Buholzer, Henryk Luka, Lukas Pfiffner, Stefano Pozzi, Beatrice Schüpbach, Thomas Walter, and Felix Herzog Front Ecol Environ 29; 7, doi:1.189/7197 This article is citable (as shown above) and is released from embargo once it is posted to the Frontiers e-view site ( Please note: This article was downloaded from Frontiers e-view, a service that publishes fully edited and formatted manuscripts before they appear in print in Frontiers in Ecology and the Environment. Readers are strongly advised to check the final print version in case any changes have been made. esa

2 RESEARCH COMMUNICATIONS RESEARCH COMMUNICATIONS Ecological cross compliance promotes farmland biodiversity in Switzerland Stéphanie Aviron 1, Heike Nitsch 2, Philippe Jeanneret 1, Serge Buholzer 1, Henryk Luka 3, Lukas Pfiffner 3, Stefano Pozzi 4, Beatrice Schüpbach 1, Thomas Walter 1, and Felix Herzog 1* In ecological cross compliance, farmers have to meet environmental standards in order to qualify for arearelated direct payments. Because this is a strong financial incentive, cross compliance is a potentially powerful policy instrument. We monitored the effectiveness of cross compliance in promoting biodiversity on grassland and on arable land in Switzerland over 8 years. We observed measurable benefits for flora, butterflies, ground beetles, and spiders, in terms of species numbers and/or community composition. However, populations of threatened species showed no signs of benefit. While cross compliance has been in force in Switzerland for almost a decade, it has only recently been introduced in the neighboring European Union. We argue that provided the environmental standards relating to biodiversity are increased in the future common farmland biodiversity could be enhanced at the continental scale under cross compliance. The Swiss example shows that appropriate cross-compliance standards benefit farmland biodiversity at field and farm scales, while the conservation of threatened species needs to be addressed by specific programs, acting at the scale of agricultural landscapes. Front Ecol Environ 29; 7, doi:1.189/7197 Maintaining the diversity of genes, species, and habitats is essential for sustainable development (UNO 1998). Agricultural policy has a strong impact on land use and, as a consequence, on farmland biodiversity (Mattison and Norris 2). Agri-environmental schemes designed to promote wildlife-friendly farming have been a major policy instrument for the past two decades, and more than 1 programs that aim specifically at improving biodiversity exist in the member countries of the Organisation for Economic Co-operation and Development (OECD 27). Between 2 and 23, the total average annual expenditure on agri-environmental payments was approximately 2.2 billion for the European Union (EU) and US$2. billion for the United States (OECD 23). However, the effectiveness of these payments is often questioned. A review of agri-environmental schemes revealed that, in Europe, only 4% of investigated faunistic and floristic groups exhibited increases in species richness or abundance in response to agri-environmental measures, and 6% exhibited decreases (Kleijn and Sutherland 23). Although the expenditures for agri-environmental schemes are impressive, they represent only % (EU) and 8% (US) of the total budgetary spending on agriculture (OECD 23). The bulk of government subsidies reach 1 Agroscope Reckenholz-Tänikon Research Station ART, Zurich, Switzerland * (felix.herzog@art.admin.ch); 2 Johann Heinrich von Thünen-Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries, Braunschweig, Germany; 3 Research Institute of Organic Agriculture FiBL, Frick, Switzerland; 4 Agroscope Changins-Wädenswil Research Station ACW Nyon, Switzerland farmers through direct payments, production-linked payments, grants for the reduction, control, or cessation of production and indirectly through export subsidies and import tariffs. Linking ecological standards to these subsidies is a potentially powerful lever for achieving environmental objectives, because subsidies contribute substantially to farmers income, whereas agri-environmental schemes provide payments for voluntary environmental services (Baldock et al. 22). The concept of requiring farmers to comply with environmental standards in order to qualify for subsidies is called cross compliance. It was first introduced in the US in 198, mainly to control soil erosion and to prevent farmers from reclaiming wetlands (Hoag and Holloway 1991). Its first application for the promotion of biodiversity in the wider countryside was in Switzerland, where ecological compensation areas (ECAs) had been introduced progressively since 1993, on a voluntary basis, and became conditional cross-compliance requirements in In order to qualify for direct payments, farmers must manage 7% or more of their land as ECAs (Figure 1). Of the 12 ha of ECAs (12% of Swiss farmland), three quarters are extensively managed hay meadows (SFOA 27). Fallows, which are sown with seed mixtures of 2 to 4 herbaceous plant species (wildflower strips) are less extensive in area (3 ha), but are characteristic ECA types for arable regions (SFOA 27). The cross-compliance standards also comprise other restrictions at the farm level that may be beneficial for biodiversity, including balanced nutrient budgets, a minimum diversity of cultivated species involved in crop rotation, and the integrated use of pesticides. Evaluating the effectiveness of cross compliance is of

3 Ecological cross compliance S Aviron et al. Figure 1. In Switzerland, farmers have to manage 7% or more of their land as ecological compensation areas (eg extensively managed meadows or wildflower strip fallows) in order to qualify for government subsidies in the form of direct payments. great importance, because the associated expenditures will only be justified if ecological goals can be reached. Cross compliance has been implemented in Switzerland for almost a decade, but only became obligatory in the EU in 2. We evaluated the effectiveness of cross-compliance regulations in Switzerland with respect to biodiversity by investigating species richness and composition of plants and several invertebrate groups (butterflies, spiders, ground beetles) on ECA farmland as compared to conventionally managed farmland. Based on the results obtained in Switzerland, we discuss the potential effectiveness of this policy instrument for promoting farmland biodiversity at the continental scale. Methods We carried out a long-term assessment to evaluate the effects of cross compliance on species richness in three regions representative of the different farming types (arable, mixed arable grassland, grassland) in central Switzerland (WebPanel 1). Vascular plants, butterflies (Rhopalocera and Hesperidae), ground beetles (Carabidae), and spiders (Aranae) were investigated between 1997 and 24 on ECA and conventionally managed fields. In total, 31 ECA meadows and 216 conventional meadows were sampled in the grassland and mixed arable grassland regions, while 78 wildflower strip ECAs and 72 crop fields were evaluated in the arable region. We analyzed the difference in the numbers of species of vascular plants, butterflies, ground beetles, and spiders between ECA and conventionally managed fields using mixed general linear models. Because we were interested in the effect of ECA rather than in a regional effect, the data from the grassland and the mixed arable grassland regions were pooled (however, the impact of region was investigated). Rarefaction methods (Hurlbert 1971) were used to compute expected numbers of arthropod species for a given abundance level, to correct for each species detectability and sample sizes in each habitat type. The number of vascular plant species derived from presence/absence data were compared between pairs of ECA and conventional fields. Normal log-linear regressions were used to analyze the number of plants and arthropod species. Two separate models were built with management type as explanatory factor, in order to test for differences in species numbers between (1) ECA meadows and conventional meadows and (2) wildflower strip ECAs and crop fields. To take into account their confounding effects, local field conditions, landscape context, the region, and the sampling year were introduced as covariates in the models. See WebPanel 1 for details on methods and analysis. Results ECA meadows contained greater numbers of species of plants, ground beetles, and butterflies, but not of spiders (Table 1; Figure 2). The total expected number of plants, spiders, and ground beetles (as estimated by rarefaction) were also higher in ECAs than in conventional meadows (Table 2). Moreover, ECA meadows harbored plants (3 species), spiders (32 species), ground beetles (1 species), and butterflies (2 species) which were not recorded in conventional meadows. On wildflower strip ECAs, there were between 8% and 6% more species of plants, ground beetles, and spiders than on arable crops (Table 1; Figure 2), and the total expected numbers were higher for plants, spiders, and ground beetles (Table 2). The average species richness of plants and arthropods in ECA meadows varied significantly across regions. Moreover, the diversity of arthropods was also influenced by sampling year and (for spiders and ground beetles) by the relative proportion of ECA or crop fields in the landscape surrounding the fields under investigation (Table 1). However, the effect of ECA management remained substantial after removing the influence of significant covariates. Very few of the plant and arthropod species observed in the three Swiss regions were red-list or rare species (Table 2). Among the 28 plant species recorded on the ECA meadows and wildflower strips, only two were classified as threatened. Seven ground beetle species and six butterfly species were listed in Red Data books, but they represented only 4% and 14% of the total number of observed species. Ten percent of the arachnid species occurring in The Ecological Society of America

4 S Aviron et al. Ecological cross compliance ECAs were rare, and the numbers of rare spiders in ECAs were the same as in conventional fields. Discussion Do ECAs promote farmland biodiversity in Switzerland? ECA meadows and wildflower strip ECAs harbored higher overall diversity of vascular plants and arthropods than did conventionally managed fields. The higher diversity of plants in ECAs could be the result of lower fertilizer usage, as the opposite effect the reduction of floristic diversity of grasslands by increased use of fertilizers is well established (Crawley et al. 2). Higher arthropod diversity in ECAs could be interpreted as a consequence of the increased plant diversity and of late cutting, which allows more species to complete their life cycles (Aviron et al. 27). The high diversity of flowering plants in ECAs provides hosts for herbivore arthropods and pollinators, which are, in turn, prey for predators (Marshall et al. 26). For spiders, the absence of an effect of ECA management in meadows might be explained by the similar vertical structure of the two habitat types, as spider diversity is affected more by vegetation structure than by plant species richness (Balfour and Rypstra 1998). The environmental variation linked to site conditions, landscape context, regional factors, and temporal variation can confound the measured effects of agri-environmental schemes if ignored in evaluation studies (Kleijn et al. 26). The majority of Swiss farmers locate ECAs in areas that bear little potential for intensification and which have traditionally been extensively managed. They are therefore more often located on steep hillsides or shaded forest edges than are intensively managed fields (Herzog et al. 2). However, even if the effects of site conditions, landscape context, and regional location are accounted for, the ECA management scheme still had a significant positive effect on biodiversity and added ecological value. The most ambitious objective for agri-environmental measures is to increase the size of populations of threatened species listed in Red Data books. Our results show that ECAs do not benefit red-list or rare species, and that individual species or groups of species reacted differently to ECA management. Among plants and arthropods, only certain groups of species showed increased numbers in ECA meadows (Knop 26). Similarly, although some bird species whose habitats are hedgerows, traditional orchards, or wetlands showed Table 1. Effect of ecological compensation areas (ECAs) and environmental and temporal factors on species richness of vascular plants, butterflies, ground beetles, and spiders. Variable df F value P value Vascular plants Meadows Region ECA management 1.17 <.1 Arable land ECA management <.1 Butterflies Meadows Region <.1 ECA management Year Arable land ECA management <.1 Year Ground beetles Meadows Region <.1 ECA management <.1 Region * ECA management Year Arable land ECA management <.1 Percent cover of crop fields (2-m radius) <.1 Spiders Meadows Region <.1 ECA management Arable land ECA management Year Year * ECA management Percent cover of ECA (2-m radius) Notes: Effects are tested for meadows (ECA and conventional) and arable land (wildflower strip ECAs and crop fields) using mixed general linear models. Degrees of freedom for variables (df), values of the F statistic (F value), and actual significance level (P value) are indicated for each model. population increases as a result of ECAs, threatened bird species showed no increase in numbers (Herzog et al. 2). Thus, increases in the total number of species in ECAs reflect responses of common species, probably because many threatened species no longer occur in the regions investigated. Other evaluation studies on agri-environmental schemes in several European countries also failed to find positive effects of the schemes on threatened species, and Kleijn et al. (26) concluded that their effectiveness for biodiversity conservation is very limited. Efforts must therefore be intensified beyond the mere introduction of agri-environmental schemes (and/or cross-compliance mechanisms) if the ambitious goal of preserving threatened farmland species is to be reached. It has been suggested that biodiversity is enhanced by the ECA scheme beyond the boundaries of individual ECA fields (Albrecht et al. 27), and that species use the ECA network to disperse in the landscape and complete their life cycles (Jeanneret et al. 23). Thus, the restoration of threatened and endangered species might require sufficient connectivity of ECA and other semi-natural habitats in the agricultural landscape.

5 Ecological cross compliance S Aviron et al. Average species richness (± 9% Cl) Average species richness (± 9% Cl) Average species richness (± 9% Cl) Average species richness (± 9% Cl) (a) *** ECA (a) * ECA Vascular plants Conventional Conventional (b) *** Figure 2. Species richness of vascular plants and arthropods within ECAs and conventional fields. Average species richness (± 9% confidence interval) of plants, butterflies, ground beetles, and spiders are displayed for (a) meadows (ECA and conventional) and (b) arable land (wildflower strip ECAs and crop fields). Differences between ECA and conventional fields were tested using mixed general linear models. *** = P <.1, * = P <., ns = not significant. ECA = ecological compensation area; Conventional = conventional field. Will cross compliance promote biodiversity in the European Union? To some extent, Switzerland can be regarded as a laboratory for testing the effectiveness of ecological cross compliance on the European continent. Cross-compliance rules in Switzerland go beyond those in force in most EU ECA Butterflies 4 (b) *** ECA Carabid beetles 2 (a) *** (b) 2 *** (a) ns 1 1 (b) Conventional Conventional ECA Conventional ECA Conventional Spiders ECA Conventional ECA Conventional * member states (WebTable 1), but some member states increase cross-compliance standards by prescribing, for example, buffer strips along hedges and limitations on grassland conversion. Now that the principle of ecological cross compliance has been established in the EU, member countries may follow these examples and increase environmental standards in order to achieve beneficial effects for farmland biodiversity similar to those observed in Switzerland. Although cross compliance is a potentially powerful policy instrument for reaching environmental objectives, it also has drawbacks. Cross compliance in connection with direct payments could lead to tradeoffs between policy objectives (ie securing agricultural income and environmental goods). Ambitious cross-compliance requirements, above and beyond the standards that have already been made mandatory, will tend to limit productivity in order to limit negative externalities or to promote positive externalities, such as biodiversity. This will result in limitation of farm income from the sale of its produce. In a cross-compliance context, the farmer is then free to decide whether he or she (1) considers the direct (compensation) payments to be sufficient and prefers to accept these limitations or (2) considers production limited only by legislated standards to be more advantageous, and prefers to forego the government payments. Cross compliance as a policy instrument will therefore only be effective if a large majority of farmers consider the government payments attractive enough which is certainly the case today in Switzerland, where these payments account for about 2% of farms returns. We argue that, as long as agricultural subsidies remain as high as they presently are in both the EU and the US (OECD 23), environmental cross compliance is a pragmatic way of increasing the provision of public goods (farmland biodiversity) by linking public expenditure for agriculture to ecological requirements. Area-based payments are a relatively nonspecific policy instrument and have been criticized as inefficient in terms of achieving specific environmental objectives. In Switzerland, therefore, they are combined with specific ecological payments for some of the ECA types. Moreover, a result-orientated scheme exists, through which farmers can obtain bonus payments if a minimum number of plant indicator species is present in their ECA meadows (Herzog et al. 2). Similar approaches are being introduced in other The Ecological Society of America

6 S Aviron et al. Ecological cross compliance European countries (eg meadow bird clutch payments in the Netherlands; Verhulst et al. 27). Conclusion and outlook The demand for agricultural commodities will increase in the future, to feed the growing world population and as a source of renewable energy. Meeting these demands without irreversibly damaging our natural resources will be a major challenge of the coming decades (Tilman et al. 22). To cope with the increasing pressure on land, we advocate a nested approach, which targets different qualities of farmland biodiversity on the agricultural field, on the farm, and in the agricultural landscape. Within agricultural fields, novel production systems, such as mixed cropping or agroforestry systems, can potentially increase biomass production while providing environmental benefits (eg Palma et al. 27). At this scale, functional biodiversity that supports pest management and pollination would be the main motivation for biodiversity conservation (Duelli and Obrist 23). Essentially, we expect farmers to be motivated to take advantage of functional biodiversity at the field scale, with societal interventions limited to information, training, and extension activities, to facilitated marketing of, for example, crops from fields sown with seed mixtures, and to adaptations of subsidy schemes to facilitate new agroforestry systems (Graves et al. 27). At the farm level, parts of the land of each farm should be dedicated to traditional, extensive farming practices, similar to the ECA concept in Switzerland. These ECAs would benefit biodiversity at large and help to halt the ongoing decline of farmland biodiversity, preventing additional species from reaching red-list status. At the same time, ECAs should be designed to enhance the functions of biodiversity that support agricultural production (Landis et al. 2). As long as government subsidies make up a substantial part of farmers income in OECD countries, the requirement to dedicate a certain percentage of the farm to wildlife-friendly farming can be part of a cross-compliance catalog of environmental standards. At the landscape level, ECAs need to be complemented with improved agri-environmental schemes, in conjunction with nature protection efforts, in order to target the threatened species which require specific conservation efforts. This requires a concerted effort by a range of economic and societal actors farmers, policy makers, NGOs, landscape planners and should be integrated into biodiversity conservation strategies that are adapted to the specific characteristics and target species Table 2. Total number of species and threatened species of vascular plants, butterflies, ground beetles, and spiders in ecological compensation areas (ECA) and conventional fields Meadows Arable land ECA Conventional ECA Conventional Plants Total species number 118 ± ± ± 12 ± 8 Red-list species 1 2 Butterflies Total species number 36 ± 3 34 ± 1 19 ± 4 19 ± 1 Red-list species 6 4 Ground beetles Total species number 98 ± 4 88 ± 1 8 ± 1 78 ± 3 Red-list species Spiders Total species number 16 ± ± ± 3 14 ± 1 Rare species Notes:The total species richness (± 9% confidence intervals) in ECA and conventional fields in meadows and on arable land was estimated according to rarefaction methods (plants: sample-based; butterflies, ground beetles, spiders: individual-based).threatened species are red-list species (plants, butterflies, ground beetles) or rare species (spiders). Species numbers were derived from 681 sites sampled over years. ECA = ecological compensation area; Conventional = conventional field. of individual regions. Such efforts reach beyond the farming sector and should also integrate forestry and urban development. Acknowledgements The authors thank F Bigler, S Birrer, G Hofer, L Eggenschwiler, O Holzgang, D Kampmann, E Knop, L Kohli, S Pearson, O Roux, and M Spiess for support throughout the project, and P Duelli, D Kleijn, J Marshall, JHN Palma, M Winzeler, and B Osterburg for comments on earlier versions of the manuscript. Part of the funding came from the Swiss Federal Office for Agriculture and the Swiss Federal Office for the Environment. References Aviron S, Jeanneret P, Schüpbach B, et al. 27. Effects of agrienvironmental measures, site and landscape conditions on butterfly diversity of Swiss grassland. Agric Ecosyst Environ 122: Albrecht M, Duelli P, Müller C, et al. 27. The Swiss agri-environment scheme enhances pollinator diversity and plant reproductive success in nearby intensively managed farmland. J Appl Ecol 44: Baldock D, Dwyer J, and Sumpsi Vinas JM. 22. Environmental integration and the CAP. EnvironmentalintegrationandCAP.pdf. Viewed 24 Apr 28. Balfour RA and Rypstra AL The influence of habitat structure on spider density in a no-till soybean agroecosystem. J Arachn 26: Crawley MJ, Johnston AE, Silvertown J, et al. 2. Determinants of species richness in the park grass experiment. Am Nat 16:

7 Ecological cross compliance Duelli P and Obrist MK. 23. Biodiversity indicators: the choice of values and measures. Agric Ecosyst Environ 98: Graves AR, Burgess PJ, Palma JHN, et al. 27. Development and application of bio-economic modelling to compare silvoarable, arable, and forestry systems in three European countries. Ecol Eng 29: Herzog F, Dreier S, Hofer G, et al. 2. Effect of ecological compensation areas on floristic and breeding bird diversity in Swiss agricultural landscapes. Agric Ecosyst Environ 18: Hoag DL and Holloway HA Farm production decisions under cross and conservation compliance. Am J Agric Econ 71: Hurlbert SH The nonconcept of species diversity: a critique and alternative parameters. Ecol Monogr 4: Jeanneret P, Schüpbach B, Pfiffner L, et al. 23. Arthropod reaction to landscape and habitat features in agricultural landscapes. Landscape Ecology 18: Kleijn D and Sutherland WJ. 23. How effective are European agri-environmental schemes in conserving and promoting biodiversity? J Appl Ecol 4: Kleijn D, Baquero RA, Clough Y, et al. 26. Mixed biodiversity benefits of agri-environment schemes in five European countries. Ecol Lett 9: Knop E. 26. Effectiveness of the Swiss agri-environment scheme (PhD dissertation). Zurich, Switzerland: University of Zurich. Landis DA, Wratten SD, and Gurr GM. 2. Habitat management to conserve natural enemies of arthropod pests in agriculture. Annu Rev Entomol 4: S Aviron et al. Marshall EJP, West TM, and Kleijn D. 26. Impacts of an agrienvironment field margin prescription on the flora and fauna of arable farmland in different landscapes. Agric Ecosyst Environ 113: Mattison EHA and Norris K. 2. Bridging the gaps between agricultural policy, land use and biodiversity. Trends Ecol Evol 2: OECD (Organisation for Economic Co-operation and Development). 23. Agricultural policies in OECD countries: monitoring and evaluation. Paris, France: OECD. OECD (Organisation for Economic Co-operation and Development). 27. Inventory of policy measures addressing environmental issues in agriculture. Paris, France: OECD. www2.oecd. org/agr-envdbo/index.asp. Viewed 2 Nov 27. Palma JHN, Graves AR, Burgess PJ, et al. 27. Integrating environmental and economic performance to assess modern silvoarable agroforestry in Europe. Ecol Econ 63: SFOA. 27. Rapport agricole. Berne, Switzerland: Swiss Federal Office for Agriculture. Tilman D, Cassman KG, Matson PA, et al. 22. Agricultural sustainability and intensive production practices. Nature 418: UNO (United Nations Organisation) Convention on biological diversity. New York, NY: Secretariat of the United Nations Organisation. Verhulst J, Kleijn D, and Berendse F. 27. Direct and indirect effects of the most widely implemented Dutch agri-environment schemes on breeding waders. J Appl Ecol 44: The Ecological Society of America

8 S Aviron et al. Supplemental information WebPanel 1. Study area and methods The study areas were each 8 1 km 2. They were located in the Swiss lowlands, in an arable region (8.1 km 2 ; 8 32 N, E; 4 m above sea level [asl]; annual precipitation 9 mm; average annual temperature 8. C), in a mixed arable grassland region (7.2 km 2, N / E, 6 m asl; annual precipitation 9 mm; average annual temperature 8.4 C), and in a grassland region (8.8 km 2 ; 8 7 N / 47 6 E,7 m asl;annual precipitation 14 mm; average annual temperature 6.8 C).The types of ECA and their share (percentage) of the farmland in the three regions were representative of the three larger biogeographic regions in which they were located. Sampling The diversity of vascular plants, butterflies, ground beetles, and spiders was investigated between 1997 and 24 in both ECA and conventionally managed fields (total fields = 681). The number of sampled fields per ECA type and type of conventional field was determined according to the proportion of each type occurring in studied regions (Jeanneret et al. 23). Consequently, ECA meadows and conventional meadows were sampled in the grassland and mixed arable grassland regions, while observations of wildflower strip ECAs and crop fields were limited to the arable region. Only a few fields could be observed throughout the entire period, because crop rotations lead to very dynamic land use in agricultural landscapes. In total, 31 ECA meadows and 216 conventional meadows were investigated in the grassland and mixed arable grassland regions. In the arable region, 78 wildflower strip ECAs and 72 crop fields were evaluated. Vascular plants were recorded every year between 1997 and 23. However, only the records of the last year of observation (23) were analyzed, as we did not observe substantial changes in the plant species richness and composition in ECA and conventional grasslands over the period of study (Buholzer et al. 2). Presence/absence of plant species was sampled in a 1-m 2 plot centred in each field. Observations in crop fields and wildflower strips were made after crop bloom (ie between late June and early July), while observations in meadows were made in late May, before the first cut. Observations of butterflies were repeated biennially between 1998 and 24. Butterflies were observed between May and August in a.2-ha surface area within sampled fields for five periods of 1 minutes each. Observations were conducted between 9: am and 6: pm, under sunny weather conditions, with no or light wind and a minimum temperature of 18 C (Pollard 1977). The five censuses per field were pooled for analysis. Ground beetles and spiders were also observed bi-annually between 1997 and 23. Ground beetles and spiders were collected using three pitfall traps located in the center of each field and spaced 3 m apart from one another. The traps consisted of funnel traps of 1.-cm diameter, containing 2 cm of 9% alcohol/water solution.trapping was conducted during the first 3 weeks of May and the last 2 weeks of June (Duelli 1997) to optimize the number of catches per unit of sampling effort. Traps were emptied once per week. The three pitfall traps and the weeks were pooled for analysis. Threatened species of plants, butterflies, and ground beetles were identified by means of national Red Data books. Red-list species of spiders have not been inventoried in Switzerland, and their rarity status was used instead (Pozzi et al. 1998). Local field conditions were described by soil type, field orientation, and field slope, which might affect plant and arthropod diversity. Soil type was characterized for each field using geological maps of study areas and categorized into 13 classes following nomenclatures of soil types in Switzerland. Field orientation (south versus non-south facing) and slope (less than 3 versus more than 3 ) were derived from a digital elevation model. Land-cover maps of study areas were digitized from aerial photographs and topographic maps using a geographic information system (Arcview 8.1, ESRI). Each region was visited annually and all fields categorized according to their use. For each sampled field and every year, landscape context was described by the percent cover of ECA (wildflower strip ECAs, ECA meadows, ECA hedges, ECA orchards), of conventional meadows, of crop fields, and of woody elements (non-eca hedges and forest) in a 2-m radius circle around the field.the extent of seminatural habitat and cultivated fields is positively related to biodiversity (Schmidt et al. 2). A 2-m radius size was selected because the study was designed to consider effects of the neighboring landscape and not to test possible effects of landscape features over a wide range of spatial scales. The Euclidian distance from sampled fields to the nearest forest edge was also calculated, to account for the potentially biased location of ECAs, which are more often on unproductive sites along shaded forest edges (Herzog et al. 2). Data transformation and statistical analysis We analyzed the difference in species richness (ie number) of vascular plant, butterfly, ground beetle, and spider species between ECA and conventionally managed fields. Counts of observed species cannot be directly compared between different habitat types, as the number of individuals varies within and between each kind of habitat, leading to variable sampling efficiency (Gotelli and Colwell 21).The number of species found in a given area also increases with the number of sampling sites. We therefore corrected for the varying detectability of species in habitat types and for the different sample sizes in each habitat type by computing the expected number of spider, ground beetle, and butterfly species for a given number of sampled individuals according to the rarefaction method (Hurlbert 1971).The total number of arthropod species expected for the four management types (ECA meadow, wildflower strip ECA, conventional meadow, and crop field) and expected number of arthropod species for each sampled field were estimated using the vegan community ecology statistical package for R (Oksanen et al. 2). Because only presence/absence data were recorded for vascular plants, expected numbers of plant species for a given number of sampled individuals could not be derived. The total number of plant species expected for the four management types was instead computed for a given number of samples (sampled fields), according to rarefaction method (Hurlbert 1971), and sample sizes were reduced for the statistical comparisons between ECA and conventional

9 Supplemental information S Aviron et al. WebPanel 1. (Continued) meadows (n = 49 pairs) and between wildflower strip ECAs and crop fields (n = 22 pairs). The differences in vascular plant, butterfly, ground beetle, and spider species numbers between ECA and conventionally managed fields were tested using mixed general linear models (GLM) within the statistical program SAS (SAS Institute Inc). Normal log-linear regressions were used to analyze numbers of plant and arthropod species. Two separate models were built, with management type as explanatory factor (ECA versus conventional), in order to test differences in species numbers between (1) ECA meadows and conventional meadows in the grassland and mixed arable grassland regions and (2) wildflower strip ECAs and crop fields in the arable region.to take into account their confounding effects, local field conditions (type of soil, orientation, and slope), landscape context (percent cover of land uses in 2-m radii, distance to forest), and the region (in cases in which two regions were involved) were introduced as covariates in the models. Sampling year (in the case of arthropods) was also entered as a random variable in the models, to account for yearly variations. Data were square-root or log transformed to overcome departure from normality. References Buholzer S, Jeanneret P, and Bigler F. 2. Arthropodes dans les surfaces de compensation écologique du Plateau. In: Herzog F and Walter T (Eds). Evaluation des mesures écologiques domaine biodiversité. Zurich, Switzerland: Agroscope FAL Reckenholz. Duelli P Biodiversity evaluation in agricultural landscapes: an approach at two different scales. Agric Ecosyst Environ 62: Gotelli NJ and Colwell RK. 21. Quantifying biodiversity: procedures and pitfalls in the measurement and comparison of species richness. Ecol Lett 4: Herzog F, Dreier S, Hofer G, et al. 2. Effect of ecological compensation areas on floristic and breeding bird diversity in Swiss agricultural landscapes. Agric Ecosyst Environ 18: Hurlbert SH The nonconcept of species diversity: a critique and alternative parameters. Ecol Monogr 4: Jeanneret P, Schüpbach B, Pfiffner L, et al. 23. The Swiss agrienvironmental programme and its effects on selected biodiversity indicators. J Nature Conserv 11: Oksanen J, Kindt R, and O Hara RB. 2. Vegan: community ecology package version Viewed 24 Apr 28. Pollard E A method for assessing changes in the abundance of butterflies. Biol Conserv 12: Pozzi S, Gonseth Y, and Hänggi A Evaluation de l entretien des prairies sèches du plateau occidental Suisse par le biais de leur arachnologique (Arachnida, Araneae). Rev Suisse Zool 1: Schmidt MH, Roschewitz I, Thies C, and Tscharntke T. 2. Differential effects of landscape and management on diversity and density of ground-dwelling farmland spiders. J Appl Ecol 42: The Ecological Society of America

10 S Aviron et al. Supplemental information WebTable 1. Cross compliance in Switzerland and the European Union Minimum Minimum Wildlife- Immediate Quantitative Retention share of maintenance friendly restrictions on minimum Constraints of existing landscape of grassland cutting of conversion of standards on nutrient and landscape elements/ beyond yearly set-aside permanent for crop pesticide inputs elements 1 buffer strips mulching 2 grassland grassland 3 rotation (above legislation) Austria On certain locations Belgium Wallonia Denmark On fallow Finland France (3%) Regional rules Regional rules On ECA Germany Greece ( ) Ireland Italy Regional rules Unless for renewal Luxembourg Netherlands Portugal Spain Unless for On fallow renewal Sweden On fallow England On unculti- On buffer vated and strips semi-natural land Switzerland (7%) For ECA For ECA Notes: Selected requirements with biodiversity impacts, which farmers have to fulfil in order to qualify for direct payments in EU-1 (EC 1782/23,Annex IV) and for area payments in Switzerland. From Alliance Environnement. 27. Evaluation of the application of cross compliance as foreseen under Regulation 1782/23. agriculture/eval/reports/cross_compliance/index_en.htm.viewed 3 Jun Biodiversity related (eg hedges, groups of trees, wetlands); 2 eg limit on mulching or grazing required or removing of vegetation; 3 or only after official authorization.