PowerPointPrsentation

1
Spatial and temporal variation of grasshopper
assemblages recorded in 1981-83 and 2002-03 in
Grindelwald, Swiss Alps
M. Hohl1, Jeanneret P.1, Wal0ter T.1, Lüscher A.1
and Gigon A.2 1Agroscope FAL Reckenholz, Swiss
Federal Research Station for Agroecology and
Agriculture, 8046 Zurich, Switzerland 2Geobotanica
l Institute, ETH Zurich, 8092 Zurich, Switzerland

• Aims
• Investigate the influence of altitude and slope
  on the composition of grasshopper assemblages.
• Asses the temporal change of the grasshopper
  assemblages between 1981-2003.
• Relate the observed changes to altered grassland
  management.

Background Over the last decades, changes in
grassland management were presumed to continue in
mountain regions. Grasshoppers are good
indicators for land use changes. Historical
grasshopper data are useful for investigating the
temporal change of grasshopper diversity and in
assessing the extent of land use change over time.
Investigation area and Methods Grasshoppers were
recorded in 1981-83 and in 2002-03 on the same
twenty plots in Grindelwald, using the same
transect method. The plots were situated in the
lower montane zone (LM), in the upper montane
zone (UM) and in the subalpine zone (SA) between
900 m and 2000 m a.s.l. Slope varied in each zone
(0-70).
E. brachyptera
Results
Analysis of the species loss between 1981-2003

• In 2002-03, 21 grasshoppers were found in
  Grindelwald. The most species rich grasslands
  were observed in the upper montane zone (Tab.1).
  The grasshopper assemblages differ significantly
  among the three altitudinal zones and slope (Fig.
  1).
• All species of 1981-83 were found again in
  2002-03. The analysis indicated a significant,
  but very small species loss (Fig. 1).
  Grasshoppers disappeared only locally between
  1981-83 and 2002-03.
• In 2002-03, grasshopper species sensitive to
  intensified grassland management (e.g. E.
  brachyptera) are still numerous in all the
  assemblages.

Table 1. Total number of grasshopper species in
the lower montane zone (LM), the upper montane
zone (UM) and in the subalpine zone (SA) as well
as mean species number per plot observed in
2002-03.
Fig. 1 Ordination diagram showing the pooled
assemblages of 1981-83( ) and 2002-03 ( ) in
the three altitudinal zones (LM, UM, SA). The
species loss in the assemblages between 1981-83
and 2002-03 is very small, indicated by the
distance between the pooled assemblages of
1981-83 and 2002-03. In the lower montane (LM)
the species loss was largest, shown by an arrow.
Grasshopper species, shown in the diagram are
strongly related to the investigated factors.
(Species abbreviations Tettignonia cantans
Stenobothrus lineatus Decticus verrucivorus
Chorthippus biguttulus Euthystira brachyptera
Omocestus viridulus Metrioptera brachyptera)
Conclusions
3. For setting conservation priorities, focus
should be given to steep grasslands in the upper
montane zone because in here the species
diversity is highest. The future development of
grassland management in the lower montane zone
should be monitored.
2. The study shows that the agricultural
management, practised in Grindelwald, plays an
important role in maintaining this grasshopper
diversity. A general land use change over the
last two decades could not be observed.
1. The Grindelwald region is a hotspot for
grasshopper diversity. The twenty plots harbour
about 20 of the Swiss Orthoptera fauna. Five
species are rated vulnerable and two are
endangered according to the Red List of northern
Switzerland.