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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2024

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Abstract

The Norwegian Environment Agency has asked VKM to evaluate the risks to biodiversity associated with the import of two species of leeches to Norway, Hirudo medicinalis and H. verbana (so-called medicinal leeches). In addition, they ask that the project group suggest mitigating measures that could reduce any potential risks, should import of the two species be granted. Background Bloodsucking leeches have been employed by humans for millennia. The two species Hirudo medicinalis and H. verbana have dominated the trade in medicinal leeches in Europe. Overcollection combined with loss or degradation of freshwater habitats led to a precipitous decline in European populations by the 1800s and led to a corresponding increase in imports from Turkey, North Africa, Russia and the Middle East. By the turn of the 19th century, the demand for live leeches in Europe had tapered off as contemporary medicine developed, only to have a small resurgence over the last decades as live leeches became recognized as useful for a variety of medical and cosmetic procedures, and to be the source of bioactive molecules of interest to medical researchers. As traditional medicine in Asia also uses a variety of leech products, there is a robust global market for live leeches and leech derivatives that is being met mostly by leech aquaculture, where the live leech trade seems dominated by H. verbana. There is increasing interest in commercializing production and sale of three similar leech species, H. orientalis from Central Asia, H. sulukii from a small region in Turkey, and H. troctina from North Africa. Hirudo medicinalis has been used medicinally in Norway since at least the Middle Ages when they were used by barber-surgeons for bloodletting. Leeches have been dispensed by apothecaries up until the end of the 1950s. Phylogeographic studies have treated the species as native to southern Norway and the Norwegian Biodiversity Information Centre has numerous records of H. medicinalis, with recent records primarily from the eastern coast of southern Norway. The Norwegian Red List for Species categorizes H. medicinalis as being of Least Concern in Norway. Hirudo verbana naturally occurs in southern Europe and has not been observed in Scandinavia so far (see map in Figure 2). Methods for the risk assessment VKM established a small working group with expertise in invertebrates and risk assessment. Our group combed the scientific literature and relevant websites for information on the taxonomy, natural history, ecology, and medical uses of medicinal leeches broadly and H. medicinalis and H. verbana specifically. The project group contacted major leech providers in Europe and North America to learn more about leech production and sale. Using the EICAT (Environmental Impact Classification for Alien Taxa) system developed by the IUCN, The project group identified those mechanisms (“hazards”) through which these two species could affect native biodiversity in Norway should imported specimens become established in Norwegian nature, and characterized the risk related to each of these hazards. The project group then conducted a semi-quantitative risk assessment for the species according to four categories: Low, Medium, Possibly high, and High risk. Hazards: how likely, how impactful, and overall risks In our report, VKM regard H. medicinalis as a native species, since it is so treated by Hirudo experts and is widespread in Norway. The project group regards H. verbana as non-native to Norway. The potential hazards from the EICAT system that could be associated with introducing one or both species include predation and parasitism, competition, disease transmission, and hybridization. ................................ .................................... Conclusions VKM concludes that the overall risk to biodiversity in Norway from importing live H. medicinalis and H. verbana is low.

To document

Abstract

This study aims to analyze the main drivers behind summer farm tourism and the elements of summer farms and the summer farm experience that create value for tourists. The study contributes to the conceptualization of summer farm food consumption. By combining concepts used in the analysis of rural tourism, such as postmodernity and cultural heritage, with the hospitality-oriented Five Aspects Meal Model, we offer a new avenue to understand the drivers behind summer farm tourism. Empirically, the study contributes by bringing a hospitality perspective into research about rural tourism, thus offering new avenues for future research. The results show that intrinsic and extrinsic values (e.g. product-specific and non-product-specific characteristics) of summer farm products, along with a welcoming atmosphere, aspects related to the cultural and biological heritage of summer farms, the scenery, and the possibility of encountering real-life animals, are appreciated elements in creating consumer and tourist value. Tourists appreciate the simple rural experience and wish to preserve the cultural heritage embedded in summer farms. Furthermore, traditional elements of hospitality are highly conditioned by postmodern and cultural heritage values.

Abstract

Forest age structure is one of the most important ecological indicators of forest sustainability in terms of biodiversity, forest history, harvesting potentials, carbon storage, and recreational values. The available information on the forest age is most often stand age from forest management plans or national forest inventories. Depending on the definition, stand age is often not a good indicator for the biological age of the dominant trees in a stand. Here, we used 6,998 increment cores from dominant Norway spruce (Picea abies L.) and Scots pine (Pinus sylvestris L.) sampled on National Forest Inventory (NFI) plots throughout Norway to gain a better understanding of the age structure of Norway spruce and Scots pine stands in Norway, and on the relationship between the recorded stand age and the biological age of dominant trees on the NFI plots. In forest with stand ages indicating that the stand was established after the abandonment of selective harvesting in favor of even-aged management dominated by clear-cutting methods (ca.1940 C.E.), we found no systematic difference between the biological age of the sampled trees and the stand age assessed by the NFI. In older stands, there was a large difference between the stand age and the age of the overstory trees with the sampled age trees occasionally being hundreds of years older than the stand age. Our study also reveals that the area of forest with old Norway spruce and Scots pine trees ≥ 160 years old is considerably higher than the corresponding area estimate based on information derived from the stand age only. These results are important as the stand age is often used to characterize status with respect to forest naturalness, biodiversity, guide protection efforts, and describe the appropriate and allowed management activities.