Effect of Muskox Carcasses on Nitrogen Concentration in Tundra Vegetation

We observed a steep gradient of nitrogen concentration in plants growing around carcasses of four adult muskoxen that had been lying for five or more years on the tundra in the Canadian Arctic. The gradient reached an asymptote at 2 m distance from the carcasses. The carbon-to-nitrogen ratio increased significantly from 1 to 3 m and then stabilized. These results suggest that the effects of carcasses last for several years on the tundra and create nitrogen-rich plant growth in their immediate surroundings. The lush growth around the carcasses in otherwise grazed areas indicated a low level of grazing on the fertilized plants.Nous avons observé un fort gradient de concentration en azote dans les plantes poussant autour de 4 carcasses de bœufs musqués gisant depuis 5 ans ou plus dans la toundra de l'Arctique canadien. Le gradient atteignait une asymptote à 2 m des carcasses. Le rapport carbone/azote augmentait de façon significative de 1 à 3 m, puis se stabilisait. Nos résultats suggèrent que les carcasses créent dans la toundra des micro-communautés de plantes riches en azote dans leur environnement immédiat et que cet effet dure plusieurs années. L'abondance de végétation autour des carcasses, dans des endroits autrement broutés, révélait que les herbivores utilisaient peu les communautés végétales fertilisées

Daniel Bonge : Om lax och laxfångst

In 23 June 1730, Daniel Herman Bonge (1706−1777), born in Oulo in contemporary Finland, defended a thesis about the natural history of the salmon (Salmo salar) at Uppsala University. The thesis, consisting of 28 pages, was written under the presidium of the Professor Lars Roberg. Bonge was apparently familiar with the salmon from his home province and provided many first-hand insights in salmon biology and salmon fishing. He was able to critically discuss the information in ancient sources. In the dissertation, there were also several woodcuts that depict various kinds of gear used by fisher peasants in northern Finland for capturing salmon. Bonge’s dissertation is still of interest for scholars, especially the ethnographic descriptions he gives about the fishing. He also provides local ichthyonyms in Swedish and Finish used in Ostrobothnia. A contemporary writer, Professor Bernd Roling, comments upon Bonge’s dissertation that it is written in ”a very personal and indeed Finnish manner”, and that it gives us insights into the cultural and conditions of Ostrobothnia and Kemi Lappmark in the early eighteenth century. Bonge’s dissertation was followed by other scientifi c descriptions of salmon and salmon fishing in Sweden, also still of historical interest. In 1745, an article by the Tornedalian and astronomer Anders Hellant (1717–1789) about the reproduction of the salmon in northern Swedish rivers, was published in the Proceedings of the Swedish Academy of Sciences. Beside Bonge and Hellant, we can especially mention the provincial physician in Västernorrland Nils Gissler (1715–1771), who in 1751 discusses salmon and salmon fishing in detail in an article in the same journal. The salmon was of course of great local and national economic interest, whichled several scientists to study it in detail from different perspectives

Impacts of moose (Alces alces) at different simulated densities on eco-morphological groups of soil mesofauna

We experimentally tested the impact of browsing, defecation and urination corresponding to four different levels of moose population density on abundance and number of eco-morphological groups of soil mesofauna in a Swedish boreal forest. The study was carried out in three fenced exclosures representing different levels of productivity (from nutrient-rich to nutrient-poor). Moose impact on soil communities was evaluated by analysing abundance, richness and diversity of mesofaunal groups, and by means of a multi-taxa index based on ecomorphological groups, the Biological Soil Quality index (QBS). There was a negative impact of high moose densities on the abundance and richness of soil mesofauna. Furthermore, low-moderate moose densities had a positive impact on abundance and number of eco-morphological groups. We conclude that moose can have a large impact on soil-living mesofauna, and therefore probably soil decomposition processes and biological soil quality, in young boreal forest stands

Of goats and spines : a feeding experiment

This is the postprint version of the article.Spines in plants have evolved to reduce mammalian herbivory, and their main function may be to protect twigs more than photosynthetic tissue. Type and frequency of spines vary in different scales. We hypothesised that different types of spines affect animal foraging through different mechanisms. We studied feeding behaviour by twig browsing goats in relation to two types of spines of Acacia tortilis using experimental manipulation of the occurrence of spines. Feeding time, number of biting actions, number and diameter of bites on trees (post-trial) and total intake were recorded. The removal of either long straight spines or short hooked spines resulted in no feeding responses by goats. The removal of both types of spines tended to increase feeding time resulting in more and larger bites with larger bite diameters and in increased total intake and utilisation compared to control branches. The removal of spines gave no effects on feeding rate, expressed as biting actions/minute, number of twigs bitten/minute or intake rate (g/minute). Both types of spines reduced total intake and utilisation of browse, but the functional mechanisms were different with the long straight spines mainly influencing bite size and short hooked spines mainly affecting number of bites

Increased summer temperature is associated with reduced calf mass of a circumpolar large mammal through direct thermoregulatory and indirect, food quality, pathways

Climate change represents a growing ecological challenge. The (sub) arctic and boreal regions of the world experience the most rapid warming, presenting an excellent model system for studying how climate change afects mammals. Moose (Alces alces) are a particularly relevant model species with their circumpolar range. Population declines across the southern edge of this range are linked to rising temperatures. Using a long-term dataset (1988–1997, 2017–2019), we examine the relative strength of direct (thermoregulatory costs) and indirect (food quality) pathways linking temperature, precipitation, and the quality of two important food items (birch and freweed) to variation in moose calf mass in northern Sweden. The direct efects of temperature consistently showed stronger relationships to moose calf mass than did the indirect efects. The proportion of growing season days where the temperature exceeded a 20 °C threshold showed stronger direct negative relationships to moose calf mass than did mean temperature values. Finally, while annual forb (freweed) quality was more strongly infuenced by temperature and precipitation than were perennial (birch) leaves, this did not translate into a stronger relationship to moose calf weight. The only indirect path with supporting evidence suggested that mean growing season temperatures were positively associated with neutral detergent fber, which was, in turn, negatively associated with calf mass. While indirect impacts of climate change deserve further investigation, it is important to recognize the large direct impacts of temperature on cold-adapted species

The scope of science for the International Polar Year, 2007-2008

The International Polar Year 2007““2008 will be the largest internationally coordinated research programme in 50 years. It will be an intensive period of interdisciplinary science focused on the Arctic and the Antarctic. IPY 2007““2008 research activities were assembled from the ideas of researchers in more than 60 countries. A total of 228 projects have been endorsed by the ICSU/WMO Joint Committee for IPY 2007““2008. These projects have a strong interdisciplinary emphasis and address the six themes as well as education and outreach objectives. IPY projects will exploit new technological and logistical capabilities and strengthen international coordination of research. They aim to attract, engage and develop a new generation of researchers and raise the awareness, interest and understanding of polar residents, educators, students, the general public and decision makers worldwide. IPY projects will collect a broad-ranging set of samples, data and information which will be made available to an unprecedented degree. IPY 2007““2008 aims to leave a legacy of enhanced observational systems, facilities and infrastructure. The observational networks to be established during IPY include integrated ocean observing systems in both the Arctic and Southern Oceans, coordinated acquisition of satellite data products from multiple space agencies and observational systems for astronomy, sun““earth physics, atmospheric chemistry, meteorology, ecosystems, permafrost, glaciers and geophysics. Many observing systems within IPY will be developed within the framework of existing international global observing systems

SHOOT GROWTH OF BETULA PENDULA AND B. PUBESCENS IN RELATION TO MOOSE BROWSING

Birches are important food plants for moose in Sweden. Of the two closely-related species Betula pendula Roth and B. pubescens Ehrh. Moose prefer B. pendula during the winter. This study compared the shoot growth and architecture of the two species for both unbrowsed and browsed birches. Unbrowsed B. pendula generally produced heavier current annual shoots than unbrowsed B. pubescens. After browsing both species responded by producing shoots which were longer, thicker, heavier and more often branched. In addition, browsing, caused shoot growth to occur at lower heights. The responses to browsing were more pronounced in B. pendula. Moose bites occurred most frequently between 1.0-2.0 m in height. Within this interval moose encountered on previously browsed B. pendula, about three time more biomass of current annual shoots, than on unbrowsed trees of the same age