Bark beetles (Curculionidae: Scolytinae) are among the most damaging pests in forest ecosystems worldwide, but have never been previously recorded in the Icelandic natural environment. We investigated the presence of bark beetles by using pitfall traps in one area (Mógilsá) and searched for potential damage signs in three other forested areas (Heiðmörk, Fossvogsdalur and Öskjuhlíð) in the Reykjavík region over the summers of 2024 and 2025. Bark beetles and signs of them were found in all four forest areas investigated. A total of 159 individuals (adults, larvae, and pupae) were collected. DNA analysis confirmed species identity to be Hylastes cunicularius. A total of 72 adults were captured in pitfall traps throughout the season, with peaks in May 2025 and June 2024. Larval galleries and pupae in Picea logs confirmed successful reproduction and establishment of the species. H. cunicularius establishment in Iceland raises concerns about potential ecological and economic effects, especially in young conifer stands. Ongoing monitoring in other nearby conifer-dominated forests is recommended to evaluate population growth, potential spread, and related risks to Icelandic forests.
Downy birch (Betula pubescens Ehrh) is the only native tree species forming woodland in Iceland and covers around 1.5% of the land area. Historically, birch woodlands have been an important source of fuel, building material and animal fodder. Currently, birch wood production is not economically important, but the species provides other valuable ecosystem services, such as soil conservation and carbon sequestration. Planting of birch increased in the 1990´s, and from 2000 onwards the share of birch has been around 30% of the total annual tree planting. Growth models are essential tools for simulating forest development over time and are widely used in forest management, research, and policymaking. This study presents site index, individual-tree diameter (dbh 1.3 m) increment, and tree height models for even-aged stands of cultivated downy birch in Iceland. The data were collected from the Icelandic National Forest Inventory (NFI) plots measured between 2005 and 2024. In addition, models for aboveground biomass and stem volume were developed using dbh as a predictor. The models can be used in forestry practice and the management optimization of downy birch stands.
Pathological findings in wild birds are rarely reported. This paper reviews gross and histological findings in samples from Icelandic rock ptarmigan (Lagopus muta), obtained through both systematic and lesion-based organ sampling. The study was part of larger project in which ptarmigan were collected and dissected over a 13- year period to study health and population changes. The primary pathological conditions identified were mange and renal tubular oxalosis, with prevalences of 18.3% and 25.3%, respectively. Mange resulted from skin mite infestations, which were more common in juveniles than in adults and more prevalent in females than males. The sex difference was attributed to a higher prevalence in adult females compared to adult males. The prevalence of renal tubular oxalosis did not vary by age or sex, but juveniles exhibited higher average severity scores for the condition than adults. Despite coccidia being found in faecal samples and in histological sections of the intestine, negligible histopathological lesions were seen in the intestinal mucosa. Lesions due to trauma showed a notably high prevalence of 2.6%. The study highlights the importance of histological examination of organs from hunter-collected specimens.
The aim of the study was to update methods for calculating dairy cow enteric methane emissions for the National Inventory in Iceland. The first two phases in our study were: 1) to measure methane emissions in Icelandic dairy herds; 2) to use the data obtained to validate several existing models for predicting enteric methane emissions at the on-farm level. These models are developed from accurate information from planned experiments about feed intake, dietary composition and methane emissions that are not available at the country level. One of the two best performing models in this evaluation was the model used by the Norfor ration optimiser at the time of the study. The two later phases in our study were: 3) to create a database with feed plans simulated by the Norfor ration optimiser, covering a wide range of production levels and feed composition, with methane emissions predicted by Norfor's model tested in phase 2; 4) to fit methane emissions predicted in phase 3 to different combinations of explanatory variables available at the country level and select the most applicable model for predicting methane emissions for the National Inventory in Iceland. Our findings suggest that energy corrected milk yield, amount of concentrates per cow and year, and the content of fatty acids in concentrates are the most important input variables for this purpose. Recommendations are presented regarding: a) how these input variables can be obtained at country level, and b) how to update the operational way of calculation used in the Icelandic National Inventory Report.
The Icelandic goat breed is a closed population consisting of 1875 animals kept in approximately 118 herds. The population has gone through several bottlenecks and has declined below 100 animals at least twice. A detailed analysis of the population was last reported in 2012, showing a 3% annual rate of inbreeding and an effective population size of only 5.1 animals. Here the genetic diversity of the breed was re-estimated using pedigree information of animals born 1962 to 2022, showing a rate of inbreeding per generation in 2016-2022 of 2.8% and an estimated effective population size of 18 animals. The results presented here show that the Icelandic goat population is steadily growing, the rate of inbreeding is decreasing, and the effective population size has increased substantially. Here we discuss some of the population management decisions that have brought about this positive change in a very small and inbred population.
Vegetation cover exerts a strong influence on the rate and severity of soil erosion. In Iceland, soil erosion is a major land management issue, with accelerating rates of degradation since human occupation. Current methods for erosion mapping and monitoring are costly and difficult to employ frequently over large regions. Satellite remote sensing can offer synoptic and systematic information on vegetation conditions useful in environmental monitoring. However, fine-scaled erosive features, such as small deflation patches, may not be easily identifiable in moderate resolution imagery (10-30 m). Here the integration of UnoccupiedAerial Vehicle (UAV), Sentinel-2, and field data is examined to bridge the gap between ground-based and spaceborne monitoring. High resolution (< 5 cm) UAV-based land cover maps are produced for six sites, achieving high overall accuracy (> 90%) compared to ground measurements. These data are upscaled via a regression model estimating bare soil cover, yielding good results (R-2 = 0.81). Using land-monitoring data from the Icelandic National monitoring program Gr & oacute;Lind, erosion severity classes are defined and mapped. This study highlights the potential of multiscale remote sensing for estimating sub-pixel landscape information and improving automated soil erosion mapping.
The breeding goals of the Icelandic sheep breed have focused on fast growth, muscularity and low proportion of fat in lambs at slaughter, and selection has focused on these traits for the past decades. However, the weights of adult sheep and birth weights are also important traits to consider, because of feed and space requirements, and may be affected by selection on growth and body composition. We used data collected at the Hestur research flock from 1999 to 2022 to estimate heritability, genetic correlations and genetic trends for standard reference weight of ewes (SRW), birth weight (BW), and traits related to weight, fat and muscularity of slaughter lambs. The heritability of SRW was 0.65, direct heritability of BW was 0.15, and maternal heritability of BW was 0.30. Genetic correlations and genetic trends indicate that selection for higher weaning weight can lead to increased SRW and BW, while selection for more muscularity at fixed weight has the opposite effect.
The onset of first feeding, the survival, and the growth performance were examined in Arctic charr over 121 days. Group A was fed live enriched artemia for 30 days, with weaning onto dry feed starting on day 20. Group C received preserved marine copepods exclusively for the first 20 days, followed by dry feed. Group D was fed dry feed exclusively. Most juveniles in Groups A and C began exogenous feeding by the first and third day of the experiment, respectively, whereas only about 74% of juveniles in Group D had ingested dry feed by day 15, with the remaining individuals failing to initiate feeding and succumbing to starvation. Fish in Group C were unable to effectively digest the preserved copepods and suffered the lowest growth rate and survival (60%). While early exogenous feeding in Group A improved survival (90%) and growth in the initial rearing stages, using artemia as an alternative to dry feed had no long-term growth benefits.
The aim of the study was to define the mature live weight of Icelandic sheep breed ewes. Data on body condition scores (BCS) and live weight (LW) spanning 22 production years from the Hestur research farm were analyzed to fit the linear relationship LW = a + b x BCS of ewes in different age categories. Ewe live weight continued to increase until 5 years of age. A general estimate of standard reference weight (SRW) of a mature Icelandic ewe is 70.4 f 3.4 kg, standardized at BCS 3. For mature ewes, approximately 8.5 kg LW is needed to raise BCS by one unit. SRW creates opportunities for studies relating mature weight to other important genetic traits and for analysing the independent effects of SRW, degree of maturity, and BCS on animal performance.
Black cottonwood (Populus balsamifera ssp. trichocarpa) was initially introduced to Iceland in 1944 from the Kenai Peninsula in Alaska and has been widely planted in shelterbelts and afforestation projects since the 1980s. There is currently much interest in increasing the planting of black cottonwood, especially in carbon sequestration projects, because of its rapid growth at an early age. Growth models simulate the growth of a forest over time and are important tools for forest managers, researchers, and policymakers. This study presents, for the first time, site index, individual-tree diameter increment and tree height models for even-aged black cottonwood stands in Iceland. The data were collected from Icelandic national forest inventory (NFI) plots and from three plots from a network of permanent sample plots (PSP). The NFI data were collected during 2005-2022, and the PSP data were collected between 2009 and 2022. The model of McDill and Amateis was selected for predicting site index and dominant height development, and the model of Schumacher was selected for predicting tree height. For diameter increment modelling, an optimization-based modelling approach was found to be more suitable than non-linear regression analysis. The models developed in this study can be used in forestry practice and in optimization studies for thinned black cottonwood stands. The models produced simulation results that corresponded to measured stand development.
Horses have a well-developed mucosal-associated lymphoid tissue in the naso-oropharynx for immunological defence and the development of immunological tolerance. The different components of this lymphoid tissue have been documented, but not all areas of the equine oral cavity have been investigated. In the present study, samples for histological and immunohistochemical examinations were collected from slaughtered horses of different ages, focusing on the rostral part of the oral cavity. Dense lymphatic tissue was found in the mucosa covering the bar area of the mandibles and the floor of the oral cavity, and it was present in horses of different ages. The most prominent lymphatic tissue, with large aggregates of lymph nodules, was present on either side of the lingual frenulum. The rostral location of this lymphatic tissue in horses renders support for application of antigens in allergen-specific immunotherapy via the oral mucosa.
Sitka spruce has been one of the most planted tree species in Iceland since the mid-twentieth century. Here, we use different dendrochronological methods to identify the controlling climatic factors of its growth and possible changes in their influence over time. We develop annually resolved and absolutely dated measurements of tree-ring width (TRW) from 21 trees and oxygen (delta 18O) and carbon (delta 13C) stable isotopes from six trees to evaluate growth trends and climate sensitivity in Iceland's Hallormsstaour National Forest over the past 54 years (1965-2018). Warmer and wetter summers in the last few decades have resulted in significantly increasing radial growth. While TRW and delta 13C reflect strong July-August temperature signals, with the highest correlation for July, delta 18O is mainly controlled by the temperature in March. The occurrence of negative pointer years in TRW decreases with increasing temperature in July but increases with excessive precipitation in August. Our study shows great continued potential for Sitka spruce cultivation in Iceland.
During 2008 to 2016, five polar bears (Ursus maritimus) swam from the East Greenland population to Iceland and were shot soon after walking ashore. Each bear was dissected. Ectoparasites were searched for in their ears and fur, helminths in the gastrointestinal tract and Trichinella larvae in muscles. Protozoan cysts, oocysts and helminth eggs were also searched for in faecal samples. No ectoparasites were detected. Two bears (40%) hosted fourth stage larvae of the nematode Contracaecum osculatum (strain B) in the stomach. Characteristic scars, noted as craters in the rectum wall, indicated previous acanthocephalan infection in one bear. Three polar bears were infected by the nematode Trichinella nativa. No protozoan parasites were detected in faecal samples, but cysts of the heterokontophyte Blastocystis sp. were found in faeces of two bears (40%). This is the first report of C. osculatum, Blastocystis sp. and an acanthocephalan infection in free-living polar bears. Keywords: Iceland, parasites, Ursus maritimus, polar bear, vagrant, new host records
Environmental monitoring by aluminium smelters in Iceland has included fluoride analysis of sheep and horse mandibles. Statistical modelling was done retrospectively on fluoride analyses of sheep and horses from 2007 to 2019. Relationships between the fluoride concentration in bone tissue and the age and the regional origin of the animals were investigated, along with the effect of proximity to aluminium smelters. Furthermore, the development of fluoride accumulation in sheep mandibles through the years and pathological changes were explored. A positive correlation was found between age and fluoride concentration, with a decline after a certain age. Fluoride concentration was highest in areas with aluminium smelters, in sheep in the Southwest and East of Iceland and in horses in the Southwest. Fluoride concentration in lambs around a Southwest smelter decreased significantly during 2007-2014. Pathological changes compatible with fluorosis were seen in the tooth enamel of sheep from around the smelter, in connection with an accidental burst of emissions in August 2006. Keywords: Domestic animals, environmental monitoring, fluorosis, herbivores, Iceland, pathology
This paper reports three trials that evaluated the effects of pelleting hay upon feed intake, digestibility, growth rate and energy utilisation of 7-9 month old, castrated male lambs. In the first trial, hay and pellets were compared on three feeding levels. The second study had a similar arrangement of treatments and an additional comparison of two types of hay. The third trial had three treatments with different combinations of whole hay and pellets ad libitum. In the first two trials the lambs were individually fed, and in vivo digestibility was measured. In the third trial, feed intake was measured on a group basis. Pelleting increased ad libitum feed intake by 40-75%. Digestibility was negatively affected by pelleting, but the overall effect of pelleting on growth rate was positive. Measurements of energy retention indicate that the negative effect of pelleting on digestibility was compensated by better utilisation of digestible energy into net energy.
The prediction of tree biomass and stem volume is necessary for monitoring and assessing of national forest biomass, carbon stock and sustainable forest management. Such predictions of biomass or carbon stocks are generated by using either allometric models or applying biomass expansion factors (BEFs), where the former is a better method. Volume models are generated by using allometric models. The data for development of the new volume and biomass models for Iceland presented in this paper were collected between years 2000-2021, from 48 locations in even aged stands that were planted between 1942-1983. Because of the young age of forest plantations in Iceland, existing biomass and volume models need to be updated regularly as trees get older and larger. The new models use the same independent variables as the previous ones for Iceland but use a wider approach and have a different form than the older ones. Using the previous Icelandic models outside their data range results in underestimation for both aboveground biomass and stem volume.
Lodgepole pine (Pinus contorta subsp. contorta) is one of the most important tree species planted in Iceland. The current plantation area is 7100 ha, the first plantations being 80 years old. This study presents models for simulating the development of Icelandic lodgepole pine plantations on an individual-tree basis. The model set consists of a site index model, tree height model, and diameter increment model. Data were collected in 35 permanent sample plots with measurement intervals ranging from 3 to 14 years. The total number of diameter increment observations was 3664. Regression analysis was used in site index and height modelling, and both regression analysis and optimization were tested in diameter increment modelling. An optimization-based model was evaluated to be the most suitable for growth simulations. The use of the developed model set was demonstrated in management optimizations, where the rotation length and cutting schedule were optimized for two young sample plots, one representing poor sites and the other good sites. The optimizations showed that planting is not profitable on poor sites if the discount rate is 4% or higher. The mean annual stem wood harvest was 2.7–4.1 m3ha-1a-1 on the poor site and 8.3–11.7 m3ha-1a-1 on the good site.
The distribution of Ceramica pisi has been expanding in Iceland after 1990, concurrent with a recent rise in mean annual temperature. A previous study showed that the winter survival of C. pisi is primarily related to pupal mass. We monitored the development of C. pisi larvae over cool, mild, and warm summers in southern Iceland and calculated the total mass-related survival of C. pisi larvae/pupae through pupation and winter. A significant positive relationship was found between a) summer growing degree days and the proportion of larvae that reached critical mass for winter survival, and b) larval mass and likelihood of pupation. We conclude that increased summer temperature is the primary cause of the distribution range shift of C. pisi in Iceland, and this has facilitated increased population density of the species, in combination with increased availability of food resources due to host shift over to Nootka lupin.
