No abstract

The dispersal of an endangered beetle, Osmoderma eremita, that lives in tree hollows, was studied by mark-release-recapture with pitfall traps. As only a small proportion of all dispersals is observed by this method, a simulation model was constructed to estimate the dispersal rate per individual. The model results suggest that 15% of the adults leave the original tree for another hollow tree, and consequently most individuals remain in the same tree throughout their entire life. This suggests that each hollow tree sustains a local population with limited connection with the populations in surrounding trees. It supports the view that O. eremita has a metapopulation structure, with each tree possibly sustaining a local population, and with the population in an assemblage of trees forming a metapopulation. Low dispersal rate and range make the species vulnerable to habitat fragmentation, probably at a scale of only a few hundred meters.

We review species richness in major organism groups, mainly using examples from northern Europe. A high proportion of these species is forest living, and large numbers are dependent on decaying wood. Biodiversity can be assessed at various scales using two different principles. One is to use features, such as ancient and dead trees, known to be important for a large number of species. The other method is to choose species or groups of species known to indicate high biodiversity or presence of many red-listed species. We argue that any serious biodiversity assessment method should include the most species rich organism groups, for example insects. In the present paper we point out the most important features for high biodiversity (old trees and large dead trees), and review the quantities of these features in near-virgin forests. The natural disturbance regime of a region should be the basis for defining a suitable scale and the appropriate features for biodiversity assessment. Possible indicator species for high biodiversity in northern Europe are suggested, based on previous investigations. Among epiphytic lichens and wood-living beetles there are many potentially useful species in addition to vascular plants in the nemoral forest. Among vertebrates, woodpeckers and grouses seem to be the most useful. Validation tests for indicator structures and species are largely lacking but urgently needed. The implications of possible delayed local extinctions are important to bear in mind when managing for sustainable forestry. The knowledge of forest history is useful when developing cost-efficient measures.

[1] We present results of in situ measurements of charged nanoparticles, electrons, and positive ions obtained during a sounding rocket flight in October 2004 from Kiruna, Sweden, under nighttime conditions. The particle measurement reveals positive charge signatures in the altitude range between 80 and 90 km corresponding to peak charge number densities of $100 e/cm 3 at around 86 km. Aerodynamical analysis of the sampling efficiency of our instrument reveals that the particles must have been larger than 2 nm assuming spherical particles with a density of 3 g/cm 3 . The plasma environment of the observed particles is dominated by negative and positive ions, with only few free electrons. A calculation of the mean particle charge expected for particles in a plasma consisting of electrons and positive and negative ions shows that the presence of sufficiently heavy and numerous negative ions (i.e., m n > 300 amu and l ! 50) can explain the observed positive particle charge. Citation:

Many insects living in ancient trees are assumed to be threatened as a result of habitat loss and fragmentation. It is generally expected that species in habitats with low temporal variability in carrying capacity have lower degree of dispersal in comparison to those in more ephemeral habitats. As hollow trees are long-lived, species in that habitat are expected to be sensitive to habitat fragmentation, due to a low capacity to establish new populations far from present ones.Using radio telemetry, we studied the dispersal for a beetle, Osmoderma eremita, living in hollow trees. O. eremita exhibited philopatry and only dispersed over short ranges. 82-88 % of the adults remained in the tree where they were caught. All observed dispersal movements ended up in nearby hollow trees and 62 % in the neighbouring hollow tree. These results corroborate the suggestion that habitat fragmentation may be detrimental to insects living in temporally stable but spatially variable habitats. In order to preserve such species, we propose that conservation efforts should be focused on maintaining or increasing the number of suitable trees in and near presently occupied stands.