Matthias Dolek

Conserving biodiversity on calcareous grasslands in the Franconian Jura by grazing: a comprehensive approach

Calcareous grasslands, as extraordinarily species-rich and diverse habitats of northern and central Europe, need some management for their long-term conservation. Traditionally, they have been used as pastures, mainly with sheep, but goats are important, because they mainly browse and climb rocks. This study presents a comprehensive approach to the conservation of these sites, including the requirements of shepherds, which were obtained by a questionnaire, together with autecological information on the habitat requirements of species. Grazing is a central option, which has to be regulated in timing, intensity and spatial distribution, to gain optimum results. Nevertheless, local regulations must consider the requirements of the shepherds regarding infrastructure and social conditions, so that grazing remains practicable. Additionally, sheep-farming on conservation sites is presently unprofitable and therefore needs financial support. This support is supplied by state subsidies in Bavaria (Vertragsnaturschutzprogramm), and in the study area by a lamb-meat sales premium, which allows the shepherds to charge higher prices for lamb-meat produced under the premium regulations. The success of the overall strategy is only possible given a well adjusted interplay of influencing factors.

Influence of management on butterflies of rare grassland ecosystems in Germany

Traditional hay-meadows in the Alps and fens at the edge of the Alps are habitats for many rare and endangered butterfly species. Conservation efforts aim at preserving these species, but the biotopes depend on regular mowing, which in turn requires intensive financial support. The feasibility of substituting mowing of these sites by grazing is discussed and considered as a more cost effective management type which produces agriculturally valuable goods as well. In this study the butterfly fauna of mown and grazed sites were compared. Species composition, species number, and the occurrence of rare species under the two management types were in most cases rather similar for both grassland ecosystems. Nevertheless, there are hints that for single rare species this might not be true. Additionally, at one site, grazing intensity on a former hay-meadow was too high to preserve the species-rich community. Overall the results are encouraging: grazing does not have to be as detrimental as formerly thought, although details (compartments of pastures, intensity) still have to be confirmed. Experimental grazing management of aban-doned grasslands of the studied types should be started.

Ants on oaks: effects of forest structure on species composition

The ant fauna of oak forest canopies in Northern Bavaria was studied by canopy fogging on 45 trees in August 2000 and May 2001. The study focused on a comparison of several different forestry management practices resulting in several types of canopy cover. Forests surveyed were: (1) high forest (high canopy cover), (2) coppice with standards (low canopy cover), (3) forest pasture with mostly solitary trees (very low canopy cover) and (4) transitional forest from former coppice with standards to high forest (approaching high canopy cover). This comprised a full gradient of canopy coverage. On the 45 oak trees sampled, a total of 17 ant species were found. Species composition was dependent on the different forestry management practices. The total number of species and the number of species listed in the Red Data Books of both Germany and Bavaria were much higher in the forest pasture and the coppice with standards, as compared to the high forest. The transitional forest was at an intermediate level. The highest number of ant species was found in the forest pasture. This can be explained by the occurrence of species of open habitats and thermophilous species. In the coppice with standards, forest dwelling and arboricolous species dominated, whereas the high forest showed much lower frequencies of arboricolous species like Temnothorax corticalis, Dolichoderus quadripunctatus and Temnothorax affinis. A multivariate analysis revealed that canopy cover (measured as “shade”, in percentage intervals of canopy cover) was the best parameter for explaining species distribution and dataset variation, and to a lesser extent the amount of dead wood, canopy and trunk diameter. Thus ant fauna composition was mostly driven by structural differences associated to the different forestry management practices. Many ant species clearly preferred the more open and light forest stands of the coppice with standards as compared to the dense and shady high forest.

Modelling in the light of uncertainty of key parameters: a call to exercise caution in field predictions of Bt-maize effects

Perry et al . [[1][1]] developed a model to simulate the field exposure and adverse effects for three European non-target Lepidoptera species ( Inachis io L., Vanessa atalanta L., and Plutella xylostella L.) to pollen of the Bacillus thuringiensis ( Bt ) maize MON810 containing lepidopteran-

Distribution of Maculinea rebeli and hostplant use on sites along the river Danube

Maculinea rebeli (or Glaucopsyche rebeli, according to Nassig, 1995) is one of the species listed in the Red Data Book of Bavaria in the highest category (Geyer and Bucker, 1992) and requires special attention in management. The larval foodplant for M. rebeli is Gentiana cruciata and the host ant, Myrmica schencki, so these two species are a basic requirement for its occurrence. The availability of hostplant and host-ant species determines the quality of potential habitats. However, in many other butterfly species it has been shown that the food plant has to grow under certain environmental conditions to be suitable for oviposition and larval development (e.g. Thomas, 1983, 1991; Thomas et al., 1986; Warren, 1992; Bourn and Thomas, 1993; Geyer and Dolek, 1995; Vogel, 1995). For management this knowledge is of major importance and the following questions arise:

Introducing time-lapse cameras in combination with dataloggers as a new method for the field study of caterpillars and microclimate

We used time-lapse cameras, in combination with dataloggers for microclimate (air humidity and temperature), in an insect field study to analyse behaviour of caterpillars over several larval stages and determine mortality reasons in relation to microclimate. We studied caterpillars of instar 1–3 of the Moorland Clouded Yellow (Colias palaeno, Linnaeus, 1761), that is from hatching from the egg until hibernation. The observation by time-lapse cameras enabled us to gather data on several caterpillars simultaneously over longer time periods. Especially, the combination with dataloggers collecting microclimatic data gives interesting insights in the life, mortality causes and behaviour of the observed caterpillars in relation to microclimatic conditions. To our knowledge, time-lapse or automatic cameras combined with dataloggers collecting microclimatic data have not been used in field studies on phytophagous insects, but only in defined experimental settings or to observe pollinators visiting flowers. Therefore, we summarize our experiences on opportunities and limitations in this communication. If the observed insect is not moving too far and is most of the time visible on the upper surface of the leaf this method can be used for several research questions under very different conditions.