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The arthropods of grassy field margins (off crop) and the consequences for impact assessment of pesticides on terrestrial ecosystems:

The R & D project focused on recording and classifying the biocoenosis of grassy field margins (off crop) in agricultural landscapes. The main objective of this biocoenological investigation was to identify species with a high significance on biocoenosis (e.g. key species) and species which indicate a damage of the community by their lack of presence or by their unusually high dominance, respectively. Depending on these results, those test species were examined which are currently used in the execution of the pesticides law and the respective EU directive, in order to show whether these are suitable as surrogate species of the analyzed biocoenosis.

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Research method

823 plant and animal species were recorded on the chosen fields. On the basis of a qualitative-ecological evaluation method, 25 distinct groups of species were identified which helped to divide the "tall oat grass meadows" into two major variants and the "ruderalized tall oat grass meadows" into 15 variants. In order to differentiate the biocoenosis properly, essential factors such as mowing, pH-value, calcium content, soil type, soil humidity, continentality as well as the structures variety were determined for correlation with the identified groups. Besides the qualitative-ecological method also a mathematical-statistical evaluation (CA, CCA) method was performed. The results of both methods were identical to a large extent. However, the qualitative-ecological evaluation method has the advantage that concrete "bio-indication species" are identified.

Ackerrandstreifen

Results of the biocoenological classification

823 plant and animal species were recorded on the chosen fields. On the basis of a qualitative-ecological evaluation method, 25 distinct groups of species were identified which helped to divide the "tall oat grass meadows" into two major variants and the "ruderalized tall oat grass meadows" into 15 variants. In order to differentiate the biocoenosis properly, essential factors such as mowing, pH-value, calcium content, soil type, soil humidity, continentality as well as the structures variety were determined for correlation with the identified groups. Besides the qualitative-ecological method also a mathematical-statistical evaluation (CA, CCA) method was performed. The results of both methods were identical to a large extent. However, the qualitative-ecological evaluation method has the advantage that concrete "bio-indication species" are identified.

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Consequences for ecotoxicity testing:

The environmental variety of the investigated biocoenosis made a more detailed assessment necessary. The "ruderalized tall oat grass meadow" in an agricultural landscape tends to develop grassy stands of dominance. This structural change of biocoenosis will lead in an indirect way to a damage in the flower-visting arthropods, e.g. due to a loss of dicotyledonous plants. It can´t be ruled out with certainty in agricultural landscapes that the stands of dominance will increase and the biocenosis is continuously changed by the use of pesticides as an additive stress factor. Currently used ecotoxicity test methods make use of some typical and representative species of the "ruderalized tall oat grass meadow" community of off crops. But the biodiversity of the biocoenosis was found to be not represented by the test species in a sufficient way. Among the main test species are pioneer species with a high recovery potential(e.g. Aphidius), which play a marginal role in biocoenosis of grassy field margins. Such pioneer species appear not to be suitable for representing a biocoenosis which is subject to a more stable competitive relationship.

Publication

Roß-Nickoll M, Lennartz G, Fürste A, Mause R, Ottermanns R, Schäfer S, Smolis M, Theißen B, Toschki A, Ratte HT (2004): Die Arthropodenfauna von Nichtzielflächen und die Konsequenzen für die Bewertung der Auswirkungen von Pflanzenschutzmitteln auf den terrestrischen Bereich des Naturhaushaltes. Umweltbundesamt (UBA), FKZ 20063403.

Your contact:

Dr. Gottfried Lennartz

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