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ASSESSMENT OF SUBALPINE GRASSLAND & HEATH SITES IN HAUTE- SAVOIE USING SYRPHIDAE (DIPTERA) Martin C.D.Speight & Emmanuel Castella SYRPH THE NET: THE DATABASE OF EUROPEAN SYRPHIDAE (DIPTERA) Volume 46 Series Editors: Martin C.D.Speight, Emmanuel Castella, Jean-Pierre Sarthou & Claude Monteil ASSESSMENT OF SUBALPINE GRASSLAND & HEATH SITES IN HAUTE-SAVOIE USING SYRPHIDAE (DIPTERA) M.C.D.Speight Research Branch, National Parks and Wildlife Service, 7 Ely Place, Dublin 2, Ireland E.Castella Laboratoire d'ecologie et de Biologie Aquatique, Université de Genève, 18 chemin des Clochettes, CH GENEVE, SWITZERLAND Syrph the Net: the database of European Syrphidae (Diptera) Volume 46 Speight, M.C.D., Castella, E., Sarthou, J.-P. and Monteil, C. (eds.) 2005 compilation of this database initially received funding from: contract STEP/CT90/0084 (Science and Technology for Environmental Protection), European Commission Acquisition of the 2004 Haute-Savoie data received funding from the French Direction Régionale de l Environnement (DIREN Rhône-Alpes). this publication may be referred to as: Speight, M.C.D. & Castella, E. (2005) Assessment of subalpine grassland and heath sites in Haute-Savoie using Syrphidae (Diptera). In: Speight, M.C.D., Castella, E., Sarthou, J.-P. and Monteil, C. (eds.) Syrph the Net, the database of European Syrphidae, vol. 46, 37 pp., Syrph the Net publications, Dublin. ISSN (Series) Syrph the Net Publications Dublin 2005 M.C.D.Speight 2005 Preface This text is presented as a worked example of a site study. It is an English-language version of Diagnostic de pelouses et landes sub-alpines, à l'aide des Diptères Syrphidae (StN vol. 47) and contains the same material, except that Appendices 3 and 4 of the latter have been omitted. Contents Summary 1. Introduction 2. Materials and Methods 3. Results 3.1. Habitats observed on site 3.2. The syrphids collected by the Malaise trapping programme 3.3. Comparison between predicted and observed species Anterne Carlaveyron Passy 3.4. Species observed but unpredicted 4. Discussion 5. Conclusion Acknowledgements References Appendix 1: results obtained on the Pormenaz site in 2003 Appendix 2: surveillance of invertebrate biodiversity in subalpine/alpine habitats Summary 1. A study of the Syrphidae (Diptera) of three subalpine grassland/heath sites (Anterne, Carlaveyron, Passy) within Natura 2000 reserves in Haute-Savoie was carried out during the summer of The objectives were to: a) evaluate these sites using the syrphid data in conjunction with the Syrph-the- Net database b) contribute to the process of inventorisation of the syrphids of the nature reserves. 2. The syrphid fauna was sampled using 13 Malaise traps, installed on 6 sub-sites (2 traps per sub-site), from which samples were taken from the end of June to mid- September. A total of 59 syrphid species was collected, representing approximately 20% of the known syrphid fauna of Haute-Savoie (the species list for this département is the longest available for any French département). 3. The expected (i.e. predicted) syrphid fauna is poorly represented on all three sites surveyed and for nearly all habitats observed on those sites. 4. In nearly all cases the expected species with larvae feeding in the tissues of herb layer plants are particularly poorly represented. 5. Poor floral diversity of herb layer plants on the three sites is taken to be the primary cause of the poor representation of expected syrphid species. 6. Due to lack of data from other years and other Haute-Savoie sites unimpacted by heavy livestock grazing in the past, it is uncertain whether the impoverishment of the syrphid fauna is due primarily to the extreme weather conditions experienced in Haute-Savoie during 2003, or to chronic heavy grazing experienced in the more distant past by the sites surveyed. 7. If the remaining syrphid biodiversity of these sites is to be maintained it is recommended that livestock grazing is not re-introduced to them. 8. The impoverished character of the present syrphid fauna of these sites suggests that the management priority is biodiversity restoration, not biodiversity maintenance. 9. If there are grounds for assuming the present poor floral diversity of the herb layer on these sites is due to livestock grazing in the past, rather than to the extreme conditions of the summer of 2003, serious consideration needs to be given to the apparent failure of the sites to recover since grazing ceased. 10. Deliberate re-introduction of selected flowering plants that can be presumed to have been lost from these sites by past livestock grazing pressures could be a useful tool to aid in biodiversity restoration at the Anterne and Passy sites. 1 1. Introduction As part of ongoing action, on biodiversity and management of Haute Savoie areas proposed for inclusion in the Natura 2002 network, sites in the Massif Arbe Giffre were selected by the Comité Scientifique des Réserves Naturelles de Haute-Savoie, for survey of their syrphid (Diptera: Syrphidae) fauna during This study was defined as follows: Etude des Diptères Syrphidae des réserves naturelles de Haute-Savoie. Cette étude sera menée sur des placettes de suivi des pelouses subalpines. Elle comprend six sites de suivi qui seront inventoriés de juin à septembre. La capture se fait par l'intermédiaire de pièges passifs. Les Diptères Syrphidae capturés seront déterminés à l'espèce. Le peuplement de chaque site sera analysé et interprété en fonction des espèces présentes et potentielles. Cette analyse s'appuiera sur la base de données Syrph the Net, the Database of European Syrphidae . La liste des espèces par habitat sera établie et l'interprétation des peuplements comprendra l'écologie des espèces, leur sensibilité et les caractéristiques des habitats. Des propositions de gestion seront faites àasters. Les collections d'insectes triés et déterminés dans le cadre de cette convention seront remises au Muséum d'histoire Naturelle de Genève. Les prélèvements non triés seront remis au Muséum d'histoire Naturelle de Genève. La détermination des autres taxons pourra ainsi être accessible aux experts référents. The Syrphidae are a family of Diptera well represented in Haute Savoie, where more than 260 species are known (Speight & Castella, 2004a). The species exhibit a wide range of different types of life history and between them make use of nearly all natural habitats and most structural components of habitats, from the grass-root zone of the soil to the canopy layer of trees. These and other characteristics make them potentially valuable tools in environmental interpretation/evaluation studies (see Speight, 1986, 2000, 2005, Sarthou & Speight, 2005). This has encouraged databasing of relevant biological information about them, to make them more accessible to analysis (see Speight, 2004; Speight & Castella 2004b; Speight et al, 2004). In the Alps there are 72 syrphid species known to be associated with unimproved, montane grassland and 106 syrphid species known to be associated with unimproved, alpine grassland (Speight et al, 2004). As shown in Figure 1, 82% and 77%, respectively, of these species are known to occur in Haute-Savoie, so the montane/subalpine grasslands of this part of France could potentially play a significant role in maintenance of the syrphid biodiversity of these habitats, not only in the French Alps, but also in central Europe in general. But the study reported on here appears to be the first carried out specifically on syrphids of montane/subalpine habitats in Haute-Savoie, apart from that of Aubert et al (1976), which was located exactly on the frontier between Haute-Savoie and Valais (Switzerland). 2 montane, unimproved grassland alpine, unimproved grassland France / Alps Haute-Savoie / Alps Haute-Savoie / France Figure 1: the representation of central European syrphids associated with montane, unimproved grassland and alpine, unimproved grassland in France and Haute-Savoie. 3 2. Materials and Methods Malaise traps were installed on the sites selected by the Comité de Gestion (Plate 1), following the general approach to Malaise trap survey for syrphids advocated by Speight et al (2000). Habitats present at each sampling station were noted and recorded photographically. Two, or sometimes three, Malaise traps were installed at each sampling station and sample bottles containing c90% industrial alcohol were attached during June (July at Carlaveyron, where bad weather retarded commencement of the sampling programme). Once in place on the traps, sample bottles were removed and replaced at intervals of two weeks until September (see Table 1). Damage to traps by grazing livestock (sheep) that arrived during August then made continuation of trapping at Carlaveyron impossible, so no sample data are available from that site for September and some of the samples from the second half of August are truncated. In consequence, Anterne and Passy each yielded 24 Malaise trap samples, but Carlaveyron yielded 20, three of them damaged/incomplete. An attempt to obtain data from all three sites by direct collecting (hand net), for comparison with the Malaise trap results, during a period selected as optimal (the second week in July), had to be abandoned due to bad weather - including late snowfall at Carlaveyron. On removal each sample bottle was labelled with individual provenance details. Site Sampling station Trap June July Aug. Sept. Ist half 2nd half Ist half 2nd half Ist half 2nd half 1st half Anterne Caricion ferruginae A (*) * * * * * * c 1800m B (*) * * * * * * Caricion davallianae A (*) * * * * * * B (*) * * * * * * Passy Seslerion A (*) * * * * * * c2000m B (*) * * * * * * heath with Azaleas A (*) * * * * * * B (*) * * * * * * Carlaveyron siliceous grassland + Carex curvula A * * * * c2200m B * * * * heath /siliceous grassland A * * * * B * * * * C * * * * Table 1: Malaise trapping programme conducted Blank areas indicate samples unavailable due to environmental conditions (see text). Asterisks indicate sample collected.. Partial samples (due to climatic conditions) are indicated by asterisks in brackets. Sample bottles were then topped up with alcohol, where necessary (loss due to evaporation can be significant during a two-week period), and stored until required for sorting. The syrphids were subsequently sorted into separate tubes, each carrying the same provenance details as the parent sample. The sorted material was then determined, a record of the determinations being kept both on paper and electronically. Literature used for determinations was as recommended in Speight (2004). The nomenclature used follows Speight et al, Sixt / Anterne Sixt / Anterne Caricion davallianae Caricion ferruginae Carlaveyron siliceous grassland + Carex curvula Carlaveyron heath /siliceous grassland Passy Passy heath with Azaleas Seslerion Plate 1 The six sites studied in 2004 in the Haute-Savoie nature reserves 5 Interpretation of the species lists derived from the samples was carried out using the StN database (Speight et al, 2004). The procedure used for generating, from the database, lists of the species predicted to occur in association with a site, habitat or microhabitat is detailed by Speight (2000). This procedure, and its application in biodiversity-related studies, are further elaborated in Speight (2000), Speight and Castella (2001) and Speight et al (2002). The basic procedure is illustrated in Figure 2, taking generation of list of species predicted to occur on a site in Haute-Savoie as an example. The species coded into the database are first filtered using macrohabitat/species association data for the macrohabitats (habitats sensu CORINE/Habitats Directive) observed on-site, so that the species associated with macrohabitats not represented on-site are excluded, and then filtered a second time so that species not known from Haute-Savoie are excluded. Once the list of species predicted to occur on a site has been generated it may then be compared with the list of species observed on that site. In the present report the objective of comparison was to gauge performance levels of the various components of each site, in respect of the ecosystem biodiversity maintenance function (BDMF). The species is taken as the unit of biodiversity and biodiversity maintenance is taken to be maximal when observed and predicted species lists co-incide. Comparison between predicted and observed lists of species was first conducted at Macrohabitat level, to identify any habitats underperforming in comparison with other habitats present, or in comparison with specified target levels. This phase of the procedure is shown diagrammatically in Figure 3. Because there is no absolute measure of BDMF performance, standard performance measures are shown in Figure 3: if less than 50% of the species expected (i.e. predicted) for a habitat are observed it is regarded as underperforming; if 50-74% are observed its BDMF performance is regarded as reasonable and if 75% or more are observed its BDMF performance is regarded as good/very good. This simple system of BDMF measures was employed in categorising the habitats and microhabitats considered in the present text. Habitats identified as underperforming were then investigated further, to establish which parts of them (i.e. which microhabitats) could be identified as performing least well. The procedure conducted with the database at microhabitat level is essentially the same as that conducted at macrohabitat level, as indicated by Figure 4, though in considering the results more attention is given to how badly microhabitats are performing, in comparison with one another. Finally, for certain microhabitats identified as underperforming, the traits balance of the predicted and observed faunas was considered, as shown in Figure 5. At this level the comparative performance of different traits was again given particular consideration. 6 Figure 2: diagrammatic representation of the process of generating a list of the species predicted to occur on a site in Haute-Savoie. The on-site habitats are used to filter out species in the database known only from other habitats and the Haute-Savoie species list is then used to filter-out species not known from Haute-Savoie. 7 Figure 3: diagrammatic representation of the use of the predicted and observed lists of species for a site, in identification of habitats under-performing in respect of the biodiversity maintenance function (BDMF). Comparison between the predicted and observed lists of species for a habitat demonstrates the percentage of the expected species found. Representation of 50% or more of the expected species is taken as reasonable. A habitat for which less than 50% of the expected species are observed is taken to be under-performing and requiring further investigation. 8 Figure 4: diagrammatic representation of the use of predicted and observed species lists for a habitat, here called habitat 1 , in identification of microhabitats under-performing in respect of the biodiversity maintenance function. 9 Figure 5: diagrammatic representation of the use of predicted and observed species lists in identification of traits poorly represented in the fauna of a microhabitat, shown as microhabitat 1 . 10 3. Results The results are presented at site level and habitat level. No attempt has been made to consider the individual sample stations or sub-sites in comparison with one another, since the objective is to engender recommendations for management at site level that would accommodate the needs of the habitats observed on each site, wherever on-site those habitats might be located. 3.1.Habitat Survey The habitats observed on each site were as follows: Anterne A1: calcareous, montane/subalpine, unimproved grassland (Caricion ferrugineae) with flushes (Caricion davallianae), CORINE 36.41, 36.51, 38.3: sub-site Collet d'anterne/sub-site Anterne. A2: alpine heath (Rhododendron/Vaccinium) with flushes, CORINE 31.4: sub-site Collet d'anterne A3: montane/subalpine tall herb communities (Adenostylion), CORINE 37.8: sub-site Collet d'anterne/sub-site Anterne. A4: alpine Alnus viridis scrub with open, grassy areas, CORINE : sub-site Anterne. Carlaveyron C1: acidophilous, alpine, unimproved grassland (Caricion curvulae), CORINE 36.34: sub-site Caricion C2: alpine heath (with Azalea/Vaccinium: landine ), CORINE 31.4: sub-site Caricion/sub-site Gradient Passy P1: calcareous, alpine, unimproved grassland (Seslerion), CORINE 36.4: sub-site Seslerion. P2: acidophilous, alpine, unimproved grassland (Nardion strictii)/alpine heath (Loiseleurion) mosaic, CORINE 36.31/ CORINE 31.4: sub-site Azalées. P3: calcareous moraine and scree: sub-site Seslerion/subsite Azalées The Syrphidae collected by the Malaise trapping programme The number of specimens of each syrphid species collected by Malaise trap on the three sites is shown in Table 2. The Malaise trap samples collected a total of 979 individuals, belonging to 59 species - approximately 20% of the Haute-Savoie syrphid fauna. All of the species collected were already known to occur in Haute-Savoie. 11 Species Anterne Carlaveyron Passy Arctophila bombiforme (Fallen), Baccha elongata (Fabricius), Cheilosia derasa Loew, Cheilosia grisella Becker, Cheilosia impudens Becker, Cheilosia melanura Becker, Cheilosia montana Egger, Cheilosia nivalis Becker, Cheilosia rhynchops Egger, Cheilosia scutellata (Fallen), Cheilosia vangaveri Timon-David, Cheilosia vicina (Zetterstedt), Chrysotoxum fasciatum (Muller), Chrysotoxum fasciolatum (de Geer), Chrysotoxum festivum (L.), Criorhina berberina (Fabricius), Dasysyrphus pinastri (DeGeer), 1776 sensu Doczkal, Epistrophella euchroma (Kowarz), Episyrphus balteatus (DeGeer), Eristalis pertinax (Scopoli), Eristalis similis (Fallen), Eristalis tenax (L.), Eupeodes corollae (Fabricius), Eupeodes latifasciatus (Macquart), Eupeodes luniger (Meigen), Eupeodes nielseni (Dusek & Laska), Eupeodes nitens (Zetterstedt), Lapposyrphus lapponicus (Zetterstedt), Melanostoma dubium (Zetterstedt), Melanostoma mellinum (L.), Melanostoma scalare (Fabricius), Meligramma cincta (Fallen), Meliscaeva auricollis (Meigen), Merodon rufus Meigen, Paragus haemorrhous Meigen, Paragus punctulatus Zetterstedt, Parasyrphus lineolus (Zetterstedt), Parasyrphus macularis (Zetterstedt), Parasyrphus vittiger (Zetterstedt), Pipiza noctiluca L, Platycheirus albimanus (Fabricius), Platycheirus angustatus (Zetterstedt), Platycheirus angustipes Goeldlin, Platycheirus clypeatus (Meigen), Platycheirus manicatus (Meigen), Platycheirus melanopsis Loew, Platycheirus nielseni Vockeroth, Platycheirus splendidus Rotheray, Scaeva pyrastri (L.), Scaeva selenitica (Meigen), Sphaerophoria fatarum Goeldlin, Sphaerophoria interrupta (Fabricius), Sphaerophoria scripta (L.), Syrphocheilosia claviventris (Strobl), Syrphus ribesii (L.), Syrphus torvus Osten-Sacken, Volucella bombylans (L.), Xanthandrus comtus (Harris), Xylota jakutorum Bagatshanova, total number of species collected total number of individuals collected Table 2: numbers of individuals of each syrphid species collected by Malaise trap on the three sites sampled. 12 As shown in Table 3, none of the species collected during this Malaise trapping campaign are recognised as threatened at European level, or in France (Speight et al, 2004). A few of them are endemic to Europe, but widely distributed in the continent. None of them would be regarded as European endemics with a restricted range. Anterne Carlaveyron Passy threatened at European level threatened in France restricted European endemic European endemic Table 3: the number of observed species on each site in different range and status categories restricted European endemic = a species endemic to Europe and found in a restricted part of Europe, e.g. the Alps; European endemic = a species endemic to Europe, but widely distributed in Europe 3.3.Comparison between predicted and observed species
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