Eignung unterschiedlicher Monitoring-Methoden als Grundlage zum Risk Assessment für Agrarsysteme : am Beispiel einer biozönologischen Reihenuntersuchung und einer Einzelfallstudie

Abstract

Two field trial approaches were conducted to show different aspects of Risk Assessment and to derive conclusions for monitoring of biodiversity in arable landscapes. The first study was part of a research project concerning Risk Assessment of genetically modified maize. The second study was complementary to a research project to evaluate the impact of pesticides in arable landscapes.Study 1: Effects of cultivation of genetically modified Bt maize on epigeic arthropods (Araneae; Carabidae). A field study was conducted in Germany to determine the possible effects of transgenic maize cultivation on nontarget epigeic predator organisms. During the growing period of 2001-2003, the activity abundances of spiders and carabid beetles were recorded with pitfall traps and box traps and compared in three treatments: (1) Bt-maize (Mon 810) expressing the Cry1ab protein from Bacillus thuringiensis (Berliner), (2) an isogenic variety, and (3) the isogenic variety treated with insecticide. The results were evaluated using statistical and descriptive methods to address and appraise possible effects of treatments. Significantly different activity abundances in Bt plots compared with isogenic control plots were observed both for spiders and carabid beetles during 2001. However, in 2002 and 2003, no changes in community structure were detectable in any of the treatments. The change in the first year may have been caused by the influence of a massive cornborer infestation and accompanying large changes in microclimatic factors. Therefore the effect can not be classified as a detrimental effect of Bt-maize on non-target arthropods. Independent from this result, a clear shift in community structure could be found as a result of the exclusive cultivation of maize over the study period.Study 2: Classification of beetle mite coenoses (Acari, Oribatida) in grassy field margins of the habitat type ruderalised tall oat grass meadow´Complementary to an ecological serial investigation the Oribatid-community in the habitat “ruderalised Arrhenatheretum” was surveyed. Three different arable areas in Germany (1) Jülicher Börde (2) Leipziger Tieflandsbucht and (3) Mainfranken were selected. The aim was to link and combine the coenoses of oribatid mites synecologically with those of plants and other arthropod groups (Araneae, Carabidae) and to typify joint biocoenose/site units. 67 oribatid mite species with different positions in the community could be identified. As a result of the synoptical qualitative ecological evaluation with all taxa 17 biocoenose/site units could be classified. For the classification of the units 27 differential groups and nine fundamental groups were used. Therefrom 18 groups of species contained oribatid mites. The typified biocoenoses were significantly correlated with edaphic parameters i.e. soil typ, nutrition content, moisture as the dominant factors. Other determining factors were differences in climate and modality of land use. The results of the qualitative evaluation could be supported with multivariate statistical analyses. The distribution of oribatid mites within the gradient of environmental parameters was similar to those of Carabids and Aranees. A significantly different annidation to those of epigeic predators could not be found. According to the legal regulation, the ecological requirements for monitoring communities in arable landscapes were described. The requirements were derived from the results of the conducted studies. With the two different approaches - ecological serial investigation and plot design - were generated two different sets of data. The advantages and disadvantages of these qualitative different data types for Risk Assessment were evaluated. The good ecological status should be used as a reference to assess detrimental changes of biodiversity. The definition of this status for the different arable land-types is one of the key issues for further development of monitoring for Risk Assessment. Furthermore the utmost importance of combination of retrospective and prospective Risk Assessment is shown. The challenge is to discover detrimental effects within the natural variance of species and communities in the field. Against this background, it was discussed which methods and endpoints of coenoses in arable landscapes are suitable to demonstrate the relevance of detrimental effects on coenoses best. The definition of good ecological status provide a reference for the assessment of impairments in arable biotopes suitable for all different fields of Risk Assessment. It was proposed to harmonise the approaches for the different topics, i.e. introduction and monitoring of GMOs and pesticides, Environmental impact assessment, etc. The possibility to percept relevant effects is of utmost importance and should be the central point in Risk Assessment