Untersuchungen zum Überleben der Heuschrecken (Caelifera et Ensifera) in der Überschwemmungsaue der Elbe bei Dessau (Sachsen-Anhalt)
AbstractFischer, N.; Witsack, W.: Studies on the survival of the grasshoppers (Caelifera et Ensifera) in the
flooded meadows of the Elbe near Dessau (Saxony-Anhalt). – Hercynia N.F. 42 (2009): 255 – 304.
The populations of grasshoppers were investigated in flooded meadows of „Biosphärenreservat Mittelelbe“
in 2005 and 2006. The focus of the study was on differences in the composition of species
due to flooding conditions, furthermore, the possibilities of survival for each stage of development and
the different seasons were reviewed. On plots of four flood-affected areas, two meadows with no flood
and seven plots in a transect through the meadows 6500 grasshoppers in 22 species were found. It was
shown, that there are high similarities between flood-plains und non-flood-plains. The abundance and
dominance of each species was more connected to the type of meadow (wide open meadows or meadows
surrounded by forests). Even the dry and wet subunits show marginal differences in the dominance-identity.
Thermophilic grasshoppers, as Chorthippus biguttulus, were present on non-flooded areas and the
dryer parts of the flooded meadows. Hygrophile species, such as Stethophyma grossum or Conocephalus
dorsalis, were detected in the moist parts of the flood-plains. For most grasshoppers the only possibility
to survive a flood is in the egg phase. The species of the flood plots successfully survived the spring
floods in 2005 and 2006 in the egg stage. In summer floods the larvae and most imagines drown. But still
occurring eggs of the preceding year can ensure the survival of the species at this time. This is shown by
the young hatched larvae in late June and July. Females of the new generation with eggs appear in July
in years without flood. The eggs of these females can save the population from summer floods (from
middle of July to beginning of August) to the next year. The overlapping of the egg-generation ensures
that the grasshopper populations can survive in this way floods during all times of summer. Macropter
grasshoppers are also able to escape a flood by flying. The grasshopper Chorthippus parallelus is
but also occurs in macropter morphs. As such it was detected on the investigated meadows,
but just in low numbers and randomly distributed. However, macropter animals could repopulate areas
after a flood. Investigations after the Elbe floods in the spring of 2005 and 2006 and in August 2002 suggest
that the stage for maintaining the population is mostly the egg stage.
Key words: Caelifera, Ensifera, ecology, phenology, survival on flood, flooded meadows, Elbe meadows,
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