The effect of local anthropogenic habitat heterogeneity on assemblages of carabids (Coleoptera, Caraboidea) endemic to the Alps

Abstract

We assessed the response of a guild of endemic medium and large-bodied carabid species to the local (fine-grained) habitat heterogeneity induced by man. The study was conducted by means of trapping (without killing and preservative agents) and radiotracking methods (to collect data on the spatial ecology of the endangered species Carabus olympiae Sella). Habitat differentiation induced by man (a mosaic of beech forests, alpen rose shrubberies and pastures) affected species richness and abundance of the guild, which were significantly higher in forests and/or shrubberies than in pastures. Most species preferred forests and shrubberies, with the only exception of Carabus concolor Fabricius, which preferred open areas. Species distribution was also affected by stone density and cattle grazing intensity. In particular, petrophilous species peaked on the roadside because of the high stone density there (stones amassed during road construction), while species abundances significantly lowered in overgrazed pastures. The compactness of the paths made by C. olympiae individuals (evaluated through a tortuosity index) was significantly higher in beech forests than in alpen rose shrubberies, indicating movements in the latter habitat type were bound by the spatial distribution of shrubs, which imposes a limit on path tortuosity. Our findings suggest that local ground beetle species diversity strongly depends on small-scale anthropogenic variables (namely habitat type, stone density and grazing intensity), and that habitat modifications (namely from forest to shrubbery) may significantly affect species movement patterns. General and local conservation management suggestions are given in conformity with these results.

The effect of local environmental heterogeneity on species diversity of alpine dung beetles (Coleoptera: Scarabaeidae)

“…Several studies have shown that habitat heterogeneity is associated with an increase in overall animal diversity (Beaufoy et al, 1994;Pain & Pienkowski, 1997;Laiolo et al, 2004;Negro et al, 2007;Zahn et al, 2007). These results agree with the so called habitat heterogeneity hypothesis, which predicts that more animal species will occur in vegetation where different forms and species of plants provide greater structural heterogeneity (Hart & Horwitz, 1991;Dennis et al, 1998).…”

The impact of forest ski-pistes on diversity of ground-dwelling arthropods and small mammals in the Alps

“…The two areas, despite their relative proximity, greatly differenced in arthropod species composition, due to environmental and historical events (Casale and Vigna Taglianti 1993). Nevertheless, the results were similar at two sites and showed that mean abundance, Negro et al 2007Negro et al , 2008. The relationship between brachyptery and endemic status of montane forest dwelling carabids in the Alps has been examined closely in Brandmayr (1991).…”

“…Ski-pistes might potentially prevent or reduce movements between adjacent forest patches. This is of particular concern in the case of carabid endemic species, such as Pterostichus flavofemoratus, P. muntipunctatus, Carabus depressus (all identified by IndVal as typical forest species), which were precinctive to more or less restricted alpine areas (Negro et al 2007). Certain carabids and spiders rarely cross large roads (Mader 1984;Koivula and Vermeulen 2005), which are known to lead to significant intraspecific genetic differentiation in flightless carabids (Keller et al 2004a).…”

Habitat use and movement patterns in the endangered ground beetle species, Carabus olympiae (Coleoptera: Carabidae)

“…In a previous study we pointed out that most species were more abundant in forest and/or shrubberies than in pastures. Only one species (Carabus concolor Fabricius, 1792) presented a reversed habit, being trapped more frequently in pastures than in the other two habitats (Negro et al, 2007).…”

“…Pitfall trapping is one of the oldest, lowest cost and simplest of all invertebrate sampling techniques, which has been widely used to obtain information on the effects of urbanisation (Niemelä et al, 2002) and habitat change (Assmann & Janssen, 1999;Magura et al, 2001), life cycle (Khobrakova & Sharova, 2005) and habitat selection (Niemelä et al, 1992;Negro et al, 2007) on invertebrate abundance and diversity. Carabid beetles are usually sampled using pitfall traps with killing and preservative agents.…”