Abstract
In densely populated areas, roadside verges
often provide the last semi-natural habitats available. Their
ecological value is often stressed by bio survey results. Yet
insect summer surveys potentially misjudge the value of a
biotope (roadside or otherwise) since the occurrences of
species may only be seasonal, or even transient. To effectively
ascertain the importance of a site for insects, species
must be shown to complete their life cycle there or at least be
shown to successfully accomplish critical life stages, such as
reproduction or overwintering. To confirm overwintering of
arthropods in roadsides, sods were cut in late winter in a
verge where several years of summer survey data were
available. The sods were placed in transparent semi-permeable
cages and kept alive during subsequent spring,
summer and autumn. All emerging arthropods were caught
inside the cages using pitfall and funnel traps and identified
to order or family level. Most of the terrestrial arthropod
phyla and orders occurring in NW-Europe appeared to
be represented. Several groups were further identified to
the species level: Carabidae (Coleoptera), Curculionidae
(Coleoptera), Araneae, Orthoptera, Apidae (Hymenoptera),
Syrphidae (Diptera) and Dephacidae/Cercopidae (Hemiptera).
Particularly for the Carabidae, Araneae and Curculionidae,
many species recorded in summer were also found to
overwinter; species overlap amounted to approximately
67%. Rarefaction of the summer sample or excluding possible
summer vagrants, raised this overlap to as much as 88%
for the Carabidae. Many of the species successfully overwintering
in the roadside verge were generalists, but less
common, more stenotopic species were present as well.
Not only species hibernating as adults were involved, but
also species overwintering in immature stages, indicating
reproduction also takes place in the roadside verge. Apparently
the roadside occurrence of many arthropod species,
including stenotopic and declining ones, is not merely seasonal
or incidental, and roadside verges do not necessarily
act as a sink only. The ecological importance often attributed
to roadside verges should clearly be taken seriously.
Original language | English |
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Pages (from-to) | 511-522 |
Journal | Journal of Insect Conservation |
Volume | 16 |
Issue number | 4 |
DOIs | |
Publication status | Published - 2012 |
Keywords
- species composition
- beetles coleoptera
- conservation value
- carabid beetles
- abundance
- assemblages
- hymenoptera
- dispersal
- corridors
- diversity