Against a background of increasing land use intensification on favorable agricultural areas and land abandonment on less arable areas in the Alps, the aim of this investigation was to detect whether and how 10 differently used types of grassland can be distinguished by site factors, plant species composition, and biodiversity. By using a very large number of vegetation surveys (936) that were widely distributed in the Central Alps, site parameters and species composition of the different land use types were compared by discriminant analyses and various biodiversity indices. Results showed that land use is a significant factor affecting the development of different grassland communities with site factors playing a subordinate, yet important role. The 10 land use types studied can be clearly differentiated from one another by single species as well as by species composition. Our study found that the number of plant communities along with the number of species decreases constantly and significantly with increasing land use intensity and on abandoned land. For example, on average, extensively used meadows have more than three times as many species as intensively used meadows. Further, the most even distribution of species (Evenness index) is reached in intensively used meadows, whereas on pastures and abandoned land, some species become dominant forcing other species to recede. The results confirm that due to current trends in agriculture, such as land abandonment and land use intensification, plant diversity in the Alps is decreasing considerably.

No abstract

No abstract

The marble trout, a lineage of the Salmo trutta complex, is endemic to the Southern Alpine region. Although it is endangered throughout its entire distribution range, population genetic data were lacking for the central area, including the upper Etsch/Adige River system (South Tyrol, Northern Italy). A total of 672 Salmo trutta specimens, comprising phenotypic marble trout and phenotypic brown trout, from 20 sampling sites throughout South Tyrol were analysed by sequencing the complete mitochondrial DNA control region. Thirteen distinct haplotypes were identified, which clustered within three major genetic lineages: the Marmoratus (MA), the Atlantic (AT) and the Danubian (DA) lineage. 41.7% of the investigated individuals carried haplotypes of the MA lineage, 47.9% of the AT lineage and 10.4% of the DA lineage. It is noticeable that AT haplotypes were present at all sampling sites and no ''pure'' marble trout population with exclusively MA haplotypes was found. This points to a considerable impact of stocking with allochthonous brown trout, given that there is no evidence for natural colonisation by individuals of the AT lineage. However, our data indicate, for at least four localities, a limited gene flow between the native marble trout and hatchery-reared strains. Future conservation and rehabilitation measures will thus have to concentrate on the identification of remnant pure marble trout individuals from such mixed populations.

Long-term hypoxia is a general phenomenon on the Italian Adriatic coastline, and is mainly caused by continuous eutrophication. The sensitivity of sole Solea solea to long-term hypoxia was investigated. Healthy S. solea obtained from trawls were kept at l g°C in aquana for at least 2 mo. The fish were exposed to hypoxia after a preacclimation penod of 30 h at normoxia Oxygen levels dunng normoxla were kept constant at 80% air saturahon (16.6 kPa, 6 . 4 mg I-' OZ); during hypoxia oxygen levels were set at 60, 40, 20, 12 or 6 % air saturation (4.8, 3.2, 1.6, 1.0, 0.5 m g I-'). During the expenment oxygen consumption was measured continuously. At the end of each experiment, blood samples were taken from anaesthetized specimens. Oxygen consumption patterns were statistically analyzed. A novel technique is described for the determination of the standard metabolic rate and the scope for activity of free-slulmmng animals. The resting metabolic rate and the scope for activity showed significant changes at reduced oxygen levels Activ~ty levels declined progressively starting at 40 % air saturation Restlng levels remained constant between 80 and 20 % air saturation, but fell below the standard metabohc rate at 12 and 6 % Blood lactate levels were increased at 12 and 6 % , indicating anaerobic metabolism. Data show that 40% air saturation should be considered as a limiting level, while the incipient lethal level lies between 12 and 20%.