Effects of forest-dune ecotone management on the endangered heath grasshopper, Chorthippus vagans (Orthoptera: Acrididae)

Abstract

Dry, oligotrophic ecosystems are highly threatened in Europe due to massive changes in land use and eutrophication. The conservation of these xeric habitats has received much attention, whereas the ecotones between xeric habitats and other habitat types are often disregarded. One species which mainly inhabits the transition zone between pine forests and adjacent xeric habitats is the heath grasshopper, Chorthippus vagans. This species is endangered in large parts of Europe. One of the largest populations in northern Germany is found on a degraded inland dune near Hanover. This population is threatened by dense growth of deciduous trees and litter accumulation. We analyzed changes in the distribution of this population after the implementation of conservation measures (thinning out the forest and removal of leaf litter). Moreover, we examined dispersal distances of the species in order to assess its colonization potential. We also studied the microhabitat preferences of C. vagans to assess key factors influencing its local distribution. Our data show a substantial growth in population size, which might be a consequence of the conservation measures. New patches on the dune were colonized, promoting dispersal between the subpopulations. We propose that restoration of forest-dune ecotones should be considered more often in landscape planning and conservation management.

Orthoptera assemblages of beech stand plots during early succession stages after clearcutting -

“…We suggest that the rather high species numbers already in the first year after clearcutting may be explained by the fact that several Orthoptera species (e.g. P. griseoaptera, M. thalassinum and species of the genus Tetrix) occur in differently managed forests (open canopy forests, closed canopy forests, young forests) and their ecotones (Detzel 1998;Hochkirch et al 2008;Diekötter et al 2009; our unpublished data from the forests surrounding clearcuts). Furthermore, we may suppose that in formerly closed and dark forests, some insect stages are able to survive in diapause under unfavourable environmental conditions (e.g.…”

“…In the second year of the clearcut succession, the typical indicator species was well-flying P. falcata (typical of high herbs and shrubs) recorded also by Marini et al (2009a), Fartmann et al (2012) in early and intermediate succession stages of grasslands. In the second year, typical was also higher abundance in terricolous C. vagans (preferring light forests and bare ground) characteristic of deforested plots (Hochkirch et al 2008). The formation of grasslands in the second year developed along with increased abundance of the graminicolous species E. brachyptera and C. parallelus characteristic mainly for grassland assemblages (Guido, Gianelle 2001;Jenni et al 2007;Fabriciusová et al 2011).…”

Response of Orthoptera to clear-cuts in beech forests

“…We also thought that clear-cuts would be first colonized by species that naturally occur in forest clearings (Kati et al, 2003;Theuerkauf & Rouys, 2006) and are good flyers, e.g. Chorthippus vagans (Hochkirch et al, 2008), Chorthippus brunneus (Laußmann, 1993;Jenni et al, 2007) TABLE 3. Relative importance of 19 species based on the DFA (the lower the value of Wilks' , the more important the species) and standardized coefficients of the canonical roots.…”

“…Diekötter et al, 2005Diekötter et al, , 2009. Of the Caelifera group, the most frequent species in all age categories of clear-cuts was the long-winged species C. vagans, which is an inhabitant of forest edges and sparse forests (Hochkirch et al, 2008). Colonization by some long-winged species of Caelifera, e.g.…”

“…In the case of insects capable of flight, even more distant habitats can act as sources of colonizers (Buchweitz, 1993;Detzel, 1998). These pioneer species are good dispersers and are able to colonize quickly newly created habitats (Picaud & Petid, 2007;Hochkirch et al, 2008). However, even the colonization by short-winged or less mobile species can be quite rapid (Jenni et al, 2007).…”