Zettel Jürg
Planning a migration corridor for the highly endangered grasshopper Chorthippus pullus (Orthoptera, Acrididae) in the Rottensand (Pfynwald, VS): biodiversity aspects
Project Number: CH-5000
Project Type: |
Master |
Project Duration: |
04/01/2006 - 08/31/2007 project completed |
Funding Source: |
other , |
Leading Institution: |
Universität Bern, Zoologisches Institut |
Project Leader: |
Prof. em. Jürg Zettel Biologe Speichergasse 8 3150 Schwarzenburg Phone: +41 31 971 34 44
|
Research Areas:
Disciplines:
Keywords:
Pfynwald, C. pullus, migration corridor, Orthoptera, Heteroptera, Sphecidae, Myrmeleonidae, diversity, habitat quality, reflector marking
Abstract:
At Pfynwald (VS, Switzerland) an investigation to the habitat management of a relic population of the grasshopper Chorthippus pullus (Acrididae, Gomphocerinae) was carried out, which is situated at Rottensand, in a shrinking and unsuitable habitat. A breaching of the dike caused by a flood in 1993 created a large, gravelly area ca. 700 m away from the population. This plain, which is particularly poor in vegetation, would represent a suitable habitat for C. pullus. From earlier observations it is known that C. pullus is able to emigrate, if a path exists. The present population should be connected with the floodplain through a corridor, to enable a colonisation of the new habitat. A current migration of C. pullus is impossible, because the vegetation is too dense. The structure of the corridor should cover the needs for reproduction, which includes an open passage containing a large proportion of bare soil and rather sparse vegetation. Since the area lies in a region of high entomological value and vegetation unique for Switzerland, the consequences of a corridor must be valued carefully. The investigated area was divided into 7 zones with regard to the following parameters : vegetation (occurring species, cover, height, density), soil (fraction of bare soil, moss cover, stones, gravel, sand, litter) and exposure to wind and insolation. Linear transects were chosen in the zones and plots were defined where particular soil conditions predominated. The steppe flora was dominated by Artemisia campestris, Astragalus onobrychis and Stipa pennata. A biological inventory of selected species of the taxa Orthoptera, Heteroptera, Sphecidae, Coleoptera and Myrmeleonidae was carried out, by a combination of visual search and sweep-netting.
On average 236 grasshoppers (belonging to 4 families), 30 true bugs (beonging 8 families), 21 beetles (belonging to 11 families), 20 digger wasps (6 selected species) and 252 ant lions (one species only) was found on 6 visits from June to August. The digger wasp Bembecinus tridens and the ant lion Myrmeleon bore are of special faunistic interest. A large diversity of insects was found on Scabiosa triandra, Verbascum thapsus, Centaurea vallsiaca and Acinos arvensis, allf o them indicators of extreme drought.
To analyse the mobility of C. pullus, the animals were marked with an individual color code and a reflecting tag. At night the area was scanned with a head lamp. 48 adult C. pullus (28 males, 20 females) were marked, 41 animals were found at leat twice, having covered maximal distances up to 32 m (male) and 17 m (female) respectively; the average distance covered was 0.9 m per day. 10 animals were found always at the same place (5 males).
Leading questions:
Regarding the area where the corridor will be proposed, which animals are occurring?Based on their ability to move and on their incapability to evade: Which species must be protected whilst constructing the corridor? And where is it absolutely impossible to place the corridor, due to locally present species?
Publications:
Kurth S. 2007. Planning a migration corridor for the highly endangered grasshopper Chorthippus pullus (Orthoptera, Acrididae) in the Rottensand (Pfynwald, VS): biodiversity aspects. Zoologisches Institut, Abteilung Synökologie, Universität Bern
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Last update: 7/18/17
Source of data: ProClim- Research InfoSystem (1993-2024)
Update the data of project: CH-5000
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