Die Fliegen der palaearktischen Region

Ohne Zusammenfassung     

Erste Ergebnisse der Untersuchungen mit URUS-Mobilseilkran im Schwachholz

Ohne Zusammenfassung Diese Untersuchungen wurden von der Arbeitsgemeinschaft Deutscher Waldbesitzerverb?nde in dankenswerter Weise finanziell gef?rdert.     

Modeling spatial variability in the life-cycle costs of low-volume forest roads

Cost estimation is probably the most decisive factor in the process of computer-aided, preliminary planning for low-volume road networks. However, the cost of construction is normally assumed to be route-independent for a specific project area, resulting in sub-optimal layouts. This is especially true for mountainous terrain and in areas with unstable subsoil. Here, we present a model for more accurately estimating spatial variability in road life-cycle costs, based on terrain surface properties as well as geological properties of the subsoil. This parametric model incorporates four structural components: embankment, retaining structures, pavement, and drainage and stream-crossing structures. It is linked to a geo-database that allows users to derive location-specific parameter values as input. In applying this model, we have demonstrated that variability in costs ranges widely for mountainous areas, with the most expensive construction being approximately five times greater there than on more favorable sites. This variability strongly affects the optimal layout of a road network. First, when location-specific slope gradients are considered, costs are reduced by about 17% from those calculated via currently available engineering practices; when both slope gradient and geotechnical formations are included, those costs are decreased by about 20%. Second, the length of the road network is increased by about 4% and 10% respectively, compared with current practices.     

A NMR study of water distribution in hardwoods at several equilibrium moisture contents

The water state of one tropical (Robinia coccinea) and two temperate (Acer saccharum and Fagus grandifolia) hardwoods was determined at different equilibrium moisture contents (EMC) during desorption at 25°C. NMR technique was used to separate different components of water in wood. The species studied presented different structures, which were apparent on the spin–spin relaxation T₂ values. Three different water components were separated: slow T₂ (liquid water in vessel elements), medium T₂ (liquid water in fiber and parenchyma elements) and fast T₂ (bound or cell wall water). The NMR results showed that even at equilibrated conditions a region exists where loss of liquid water and bound water takes place simultaneously. This region will vary according to the wood structure. Finally, liquid water was present at EMC lower than the fiber saturation point, which contradicts the concept of this point when considered as a bulk property of wood.     

Parental participation in progeny and effective population sizes in experimental seed orchards of wild cherry Prunus avium L. (Batsch)

Parents and progenies genetic diversity, and male and female contributions to the seed crop were assessed in three experimental Prunus avium seed orchards. Collected data were used to compare different effective population sizes, based on phenological, seed crop and paternity analysis. Our results did not show any difference of genetic diversity between parents and progenies. A limited pollen pollution was detected. We showed that distance and coflowering among clones had a significant effect on effective pollination, and a significant effect of the production of flowers was revealed in one of the seed orchards. Our study also revealed a quite low number of effective size of fathers per mother, but high effective sizes of mothers, fathers and parents at the level of the seed orchard. Finally, the calculation of effective size of mothers, fathers and parents was not highly modified when having the complete information based on the paternity analysis.     

Effects of strip wise tillage in combination with liming on chemical and physical properties of acidic spruce forest soils after clear cutting

We investigated the initial effects of strip wise soil loosening (0–35 cm depth) on soil chemical and physical parameters by using a deeply working rotary cultivator in combination with liming and mixing of the dolomite with the soil material of acidic forests. The investigations took place 8 months after the treatment. pH values and contents of exchangeable Ca and Mg increased significantly at the tilled depth whereas the content of exchangeable Al and easily soluble P decreased. The rate of mineralisation increased at this depth which was shown by a loss of Corg, Ntot and short-term loss of NO₃-N. The treatment led to a mobilisation of Mn at the tilled depth. However, the content of exchangeable Pb decreased due to an increased pH value. Below the tillage depth of 35 cm only partly significant changes of exchangeable Mn and NO₃-N were found. The total porosity and bulk density at 10–15 and 40–45 cm depths were not significantly different from those in the control plot, but the rate of infiltration increased significantly.     

Die Verwendung markierter Schnecken zur Populationsdichteabschätzung und zum Studium des Migrationsverhaltens vonArion sp.

Staining the skin of larger slugs with dots of methylene-blue proved to be a simple, reliable and variable marking technique. The marks lasted for about 6 weeks; vitality and activity of marked slugs were not impaired. By use of marked slugs in a capture-recapture experiment the density ofA. rufus in a maize field could be estimated to be about 0.5 slugs/m²; a repetition gave the same result. Registration of marked slugs in artificial refuges showed thatArion rufus is vagrant. An experimental population had left a round area with a diameter of 20 m completely within 12 and 9 days resp., and was replaced by new immigrants. On lawn, singleA. rufus crawled between 3.5 and 12.8 m within one night; on asphalt, they made only between 1.1 and 5.8 m.     

Crinum L. (Amaryllidaceae)

Alkaloids isolated from Crinum species have been reviewed for the period 1985-2000. Non-nitrogenous compounds have been surveyed for the first time. Botanical classification and biological activity are discussed. Spectral data literature sources are listed.