1180 Poster Southampton 14.pptx

Ten Years of Butterfly Monitoring in Switzerland
MATTHIAS PLATTNER, STEFAN BIRRER, MARKUS FLURI, PETRA RAMSEIER, TOBIAS ROTH,
THOMAS STALLING
Biodiversity Monitoring Switzerland BDM by order of the Federal Office for the Environment FOEN. Coordination Office c/o Hintermann & Weber AG, Ecological Consultancy, Planning &
Research, Austrasse 2a, CH-4153 Reinach, Switzerland.
Butterfly monitoring in Switzerland started in 2003 as part of the Swiss biodiversity monitoring programme
(BDM). The main aim of the programme is to survey changes in species richness over time. An analysis of the
data showed no significant changes in total species richness in Switzerland over the last ten years. In contrast,
single species and species groups showed marked trends in abundance and distribution. The results indicate
climate and land use change to be two major drivers of recent changes.
Data collection and butterfly species richness
Day-flying butterflies are surveyed systematically along 2.5km transects within
about 450 square kilometres that are regularly distributed all over Switzerland. The
methodology is an adjusted protocol of the British Butterfly Monitoring Scheme (KSBDM, 2012). On each transect 4–7 surveys (depending on altitude) are made per
flight season. Since 2003 each transect has been surveyed twice with a time lag of
five years.
The current overview of butterfly species richness in Switzerland resulted from the
completion of the second survey cycle (2008–2012; Fig. 1). The mean butterfly
species number in Switzerland is 33 species per square kilometre. Regionally,
however, large differences occur, e.g. the Central Plateau holds on average only
half as many species as the Alps (22 to 39 species). Since 2003, a total of 190
different butterfly species were recorded during the BDM surveys.
Recent changes in species richness and distribution
Total species richness seems to be stable (2003–2012; Fig. 2) or is even slightly
increasing in some regions. Inferring temporal changes in single species or species
groups, however, indicate climate change and land use change to be the two major
drivers of recent changes in butterfly diversity. The population sizes of 22 species
performed significant changes over time. Increasing populations (14 species)
slightly outweighed population declines (8 species). Several Atlantic and
Mediterranean species have extended their distributional ranges in Switzerland
(e.g. the Short-tailed Blue Cupido argiades, Fig. 3a), while some alpine species
seem to suffer from climate change (e.g. the Silky Ringlet Erebia gorge, Fig. 3b).
Overall, however, land use change seems to be of equal importance as a threat of
butterfly species in Switzerland. On the one hand land use in mid-elevation
grassland has been intensified; on the other hand remote and less productive sites
in the Alps have been abandoned (Bühler & Roth, 2011), particularly in the
Southern Alps (Ticino). As a consequence, the Southern Alps are the only region
where we found a significant decrease of butterfly species numbers over the last
decade.
Climate change and land use change as major drivers
The first ten years of butterfly monitoring in Switzerland uncovered a likely climate
and land use driven change from specialists and cold-dwelling butterflies towards
more generalist and warm-dwelling species (Roth et al., 2014), which resulted in an
apparently stable total species richness.
Examples of day-flying
butterflies that occur in
Switzerland (top down):
Small Skipper
(Thymelicus sylvestris),
Short-tailed Blue
(Cupido argiades), Silky
Ringlet (Erebia gorge),
Auspicious Burnet
(Zygaena fausta);
(Photos Th. Marent, Th.
Stalling, F. Altermatt).
Butterfly diversity found in the Swiss Alps is still exceptional. Several butterflies are
endemic to the Alps and Switzerland has major responsibility for helping to maintain
alpine butterfly species in Europe. Climate and habitat change seem to be the two
main threats to biodiversity. While intensification and abandonment of (extensive)
land use and forest encroachment of former open-landscape habitats is doubtlessly
having a negative impact on butterfly diversity, the impact of climate change is more
speculative. Based on model projections, species richness in the Alps could further
increase due to climatic change (Huwyler et al., 2012). It is, however, unclear, if
mostly generalist species expand their range to higher altitudes and how alpine
specialists will react in the long term.
References:.
Birrer S., Fluri M., Plattner M., Ramseier P., Roth T. & Stalling T. 2013. 10 Jahre Tagfaltererhebungen im BDM Schweiz. Interne Publikation der
KS-BDM.
Bühler, Ch.; Roth, T., 2011: Spread of common species results in localscale floristic homogenization in grassland of Switzerland. Diversity
Distrib. 17(6): 1089-1098.
Huwyler, S.; Plattner, M.; Roth, T., 2012: Modellierung der Tagfaltervielfalt im Schweizer Alpenraum: Mehr als ein Drittel der Tagfalter-Hot-Spots
liegt in gesetzlich geschützten Trockenwiesen. Natur und Landschaft 87 (7): 298-304.
KS-BDM, 2012. Anleitung für die Feldarbeit zum Indikator «Z7-Tagfalter». Bern, Bundesamt für Umwelt. http://www.biodiversitymonitoring.ch/
Roth, T.; Plattner, M.; Amrhein, V., 2014: Plants, birds and butterflies: short-term responses of species communities to climate warming vary by
taxon and with altitude. PlosOne 9: e82490 (2014)
Jura
Central
Plateau
Eastern
Alps
Western
Alps
Southern
Alps
Fig. 1. Butterfly species richness in each of the 457 monitored square
kilometres. In the Alps, species-poor sampling areas are located side by
side with very species-rich areas. This wide variety is a result of the
marked relief. In 24 areas, fieldworkers identified at least 60 species,
with the top result of 77 species recorded in a square kilometre in the
Val de Bagnes in southwestern Switzerland. In contrast, the Central
Plateau and the Jura look much more uniform, with a markedly lower
mean number of butterfly species compared to the Alps.
Fig. 2.: Deveclopment of butterfly species numbers in Switzerland
2003–2012. Data source: BDM field surveys (Z7 indicator; May 2013)
Changes in the distribution range of
Cupido argiades
Negative trend in the abundance of
Erebia gorge
Fig. 3a & b.: Two species showing significant trends in abundance are
likely to be influenced by a changing climate. While the warm-dwelling
Short-tailed Blue dramatically expanded its range (left), some typical
Alpine species, e.g. the Silky ringlet (right) show a negative trend in
abundance (Birrer et al., 2013).
Fig. 4a & b.: Intensification of land use and land abandonment are the
main threats to biodiversity in the Alps.

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