Mario Oswald


A sample-based survey about the biomass of insects and biodiversity in grass clippings of agriculturally used meadows.

MSc Student
Advisor: Harald Krenn

Unit for Integrative Zoology, Department of Evolutionary Biology
University of Vienna


Rapid intensification and change of agricultural used land are frequently identified as important causes for today’s global biodiversity decline, including insects. Meadows, a typical landscape element of Europe, are nowadays often heavily fertilized and mown several times a year to achieve maximum production output. Although there is a necessity to maximise food production for a growing human population, agriculture practices need to be as biodiversity friendly as possible. This study is therefore realized within the framework of a Federal Ministry funded project in Austria, for the classification of various common mowing techniques regarding their impact on insects in agriculturally differently managed meadows. One of the main aspects is the evaluation of error rates regarding overseen individuals and representativeness of tested classification methods. Furthermore, insect biomass and aspects of biodiversity in freshly cut vegetation of an intensively cultivated meadow and an extensively managed one are compared. The biomass loss due to different mowing techniques on all detected insects larger than three millimetres is examined. Special attention is given to occurring Orthoptera.

First results show that total insect biomass as well as insect diversity are higher for the extensively managed meadow. However, regarding only cut vegetation, there are hardly any differences in detected insect biomass. It is assumed that a few insect species benefit strongly from the intensively mown meadow, achieve high population densities and therefore biomass. Detected orthopteran diversity in extensively versus intensively managed meadow parcels was higher (10 vs. 5 species) as was the number of individuals (39 vs. 8). In almost all cases the error rate of the evaluation technique regarding overseen individuals was 0%.

If error rates among conducted experiments remain low, we will likely conclude that the established evaluation methods show sufficient robustness to allow objective comparisons and classifications. Finally, biomass - in addition to the number of individuals, may also serve as a valid classification parameter.