Effect of shelterbelts on adjoining cultivated fields : Patrolling intensity of carabid beetles (Carabidae) and spiders (Araneae)

The impact of wooded shelterbelts on the patrolling intensity (number of patrolling individuals per trap, per day (NP) - activity density) of spiders and ground beetles was investigated by using pitfall traps placed in parallel rows in shelterbelt centres, along margins of wood and field, and in open wheat fields at a distance of 10 and 50 m from trees. In the shelterbelt - managed areas the biomass of patrolling (BP) arthropods (ground beetles and spiders) was lower inside the fields (F10, F50) than at the field margins and in the shelterbelts. The BP and individual weight increased with the age of strips. However, in the control field with no wood in the vicinity, the BP of carabid beetles was as high as inside the shelterbelts. The highest similarity between the shelterbelts and the field (BP, Morisita's similarity index, diversity index H', individual weight) was found in the field adjoining the youngest (aged 2 years) shelterbelt. It is concluded that similarity between permanent and cultivated ecosystems is important for successful exchange of individuals between them. In the field adjacent to young shelterbelt and in the field with no woods in the vicinity the aeronautic, agrobiont species prevail. In the fields adjacent to older shelterbelts colonization by large body-size species, characteristic for permanent ecosystems was found.