The chotts in Algeria are temporary salt lakes recognized as important wintering sites of water birds but neglected in terms of the diversity of the insects living on their banks. Around a chott in the wetland complex in the high plains near Constantine (eastern Algeria), more than half of the species of plants are annuals that dry out in summer, a situation that prompted us to sample the vegetation in spring over a period of two years. Three zones were identified based on an analysis of the vegetation and measurements of the salt content of the soils. Surveys carried out at monthly intervals over the course of a year revealed temporal and spatial variations in biodiversity and abundance of grasshoppers. The inner zone is colonized by halophilic plants and only one grasshopper species (Dericorys millierei) occurs there throughout the year. Two polyphagous species of Calliptamus, which can feed on halophilic plants migrate from adjacent areas into the inner zone in August to feed on the plants growing there. The other species of grasshoppers remain in outer zones as they are unable to feed on halophilic plants. The greatest abundance of grasshoppers from August to winter was recorded in the inner zone and in spring and early summer in the outer zones. The dependence of D. millierei on bushes of Amaranthaceae and its moderate flight ability, features of the family Dericorytidae, limit this species ability to colonize neighbouring chotts., Sarah Mahloul, Abboud Harrat, Daniel Petit., and Obsahuje bibliografii
We investigate orthopteran communities in the natural landscape of the Russian Far East and compare the habitat requirements of the species with those of the same or closely related species found in the largely agricultural landscape of central Europe. The study area is the 1,200 km2 Lazovsky State Nature Reserve (Primorsky region, southern Russian Far East) 200 km east of Vladivostok in the southern spurs of the Sikhote-Alin Mountains (134°E/43°N). The abundance of Orthoptera was recorded in August and September 2001 based on the number present in 20 randomly placed 1 m2 quadrates per site. For each plot (i) the number of species of Orthoptera, (ii) absolute species abundance and (iii) fifteen environmental parameters characterising habitat structure and microclimate were recorded. Canonical correspondence analysis (CCA) was used first to determine whether the Orthoptera occur in ecologically coherent groups, and second, to assess their association with habitat characteristics. In addition, the number of species and individuals in natural and semi-natural habitats were compared using a t test. A total of 899 individuals of 31 different species were captured, with numbers ranging between 2 and 13 species per plot. Species diversity was higher in semi-natural habitats than natural habitats. There was a similar but non-significant pattern in species density. Ordination analysis indicated four orthopteran communities, which were clearly separable along a moisture and vegetation density gradient. The natural sites in the woodland area of the Lazovsky Zapovednik are characterized by species-poor and low-density orthopteran assemblages compared to the semi-natural sites. But, the natural sites have a higher diversity of habitat specialists. Our findings corroborate the hypothesis that intermediate habitat disturbance levels support particularly species-rich animal communities at high densities. Under such regimes, orthopterans presumably mostly profit from the high diversity in plant species, which generates great structural and microclimatic heterogeneity.
Whereas the classification of plant communities has a long tradition that of animal assemblages remains poorly developed. Here we propose a classification scheme for orthopteran communities based on regional "character species", "differential species" and "attendant species" at different levels of habitat complexity, which is also applicable to other insect groups. In this context there are three main points of special importance: (i) the geographical reference area, (ii) the hierarchical spatial level (e.g. habitat complex, habitat and microhabitat) and (iii) precise constancy criteria for the definition of character species and differential species. We develop this new approach using a study on orthopteran communites of central German semi-dry calcareous grasslands. Within this habitat, we describe seven structural types that are characterized by specific orthopteran communities. For the arrangement of the structural types several environmental parameters (e.g. height and density of vegetation) were collected. Orthopteran densities were sampled at 80 sites using a biocoenometer (box quadrat). Regional character species of semi-dry grasslands include Myrmeleotettix maculatus, Metrioptera brachyptera, Stenobothrus lineatus and Tetrix tenuicornis. Within this habitat, Chorthippus parallelus, Metrioptera roeselii, Omocestus viridulus, Pholidoptera griseoaptera and Tettigonia viridissima were designated as differential species for particular structural types. Furthermore, Tettigonia cantans and Tettigonia viridissima act as altitudinal differential species. Chorthippus biguttulus is the only attendant species with high constancy values in all structural types. This classification is a powerful tool for arthropod conservation, since it allows one to determine community completeness of very important and threatened habitats, like semi-dry calcareous grasslands.