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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.

2026

2025

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Abstract

Seedling emergence constitutes a critical recruitment step, and early growth relates to plant competitive ability. Understanding their drivers has implications for forestry and forest ecosystem conservation, restoration, and adaptation to climate change. We seeded 6984 acorns in an experiment with 97 cases at 45 sites in 15 European countries, encompassing 12 oak species. We tested whether the quality of the acorn batch, site-level weather and soil characteristics, year of seeding, and species’ mean specific leaf area (SLA) affected the emergence and early growth of seedlings after the first summer. Germination potential and acorn dry weight, measured under controlled conditions, were positively associated with emergence and early growth. Seedling emergence was negatively associated with the mean monthly temperature and cumulative winter precipitation, and it was higher in the seedling cohort that was spared from the 2021 drought. Additionally, seedling emergence was positively related to soil nutrient concentration and negatively to increasing soil pH, but not to water-holding capacity, and growth was unrelated to soils. Species-level SLA was not related to either response. The four main study species –Quercus cerris, Q. ilex, Q. petraea, and Q. robur– responded similarly to weather but not to soil conditions. We conclude that, at a continental scale, and assuming that species establish within their current distributions, (a) oak seedling emergence and early growth are associated with acorn quality rather than species identity or SLA, (b) they are highest at sites with low winter precipitation and temperature, (c) emergence is reduced in dry years, and d) soil properties play a secondary role at this early recruitment stage.

Abstract

Background and aims Cover crops are an important measure for carbon (C) sequestration in agriculture. However, little is known about the potential of cover crops to increase C under Nordic conditions and the efficiency of this measure over time. Here, we quantify the potential contribution of different cover crops to soil organic carbon (SOC) and organic matter fractions, and study how this is affected by the origin of the C input (aboveground or belowground residues). Methods We conducted a 13 CO 2 pulse-labelling experiment during the growing season of four cover crops adapted to Nordic conditions, representing different plant functional types. The assimilated 13 C was traced in soil during the following two years. We investigated the fate of cover crop C in two organic matter fractions, Particulate Organic Matter (POM) and Mineral-Associated Organic Matter (MAOM), known to have different persistence in soil. Results Carbon derived from aboveground residues decayed two to three times faster as compared to belowground C. Belowground C inputs were similar among cover crops despite their contrasting root traits and differences in root biomass C. Rhizodeposited-C was consistently the largest belowground C input. Cover crop species affected the quantity of POM-C and MAOM-C, but MAOM-C was preferentially formed from belowground C (ranging from 0.63 ± 0.2 to 0.25 ± 0.1 Mg MAOM-C ha −1 across different cover crops), regardless of the species. Conclusions Cover crop species that can combine large belowground biomass production with root traits that promote physical and physico-chemical protection of OM will contribute most effectively to the long-term SOC pool. These aspects need to be balanced with considerations related to agricultural management.

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Abstract

Climate change is expected to increase the frequency and severity of natural disturbances. In Nordic conifer forests, damage caused by snow accumulation in the canopy is one of the most significant disturbance agents. This study investigates whether adaptive forest management can enhance resistance to snow damage, using a large forest property in southeastern Norway as a case study. To achieve this, we extended the existing scenario analysis tool, GAYA 2.0, integrating new functionality to analyze the risk of snow damage. We performed scenario simulations using a mechanistic critical snow load model to compare two alternative management strategies: standard management and an adapted management approach that reduces stand density in regeneration and tending phases. We analyzed and compared the management effects on snow damage resistance and probability, and on long-term forest production and income. The results indicate that reduced density management leads to a 2.02 % increase in critical snow load (from 74.19 Kg m-2 to 75.68 Kg m-2), and a 10.42 % reduction in yearly damage probability (from 0.345 % to 0.308 %). These findings suggest that adaptive management practices by reducing stand density can effectively enhance resistance and mitigate risks associated with snow damage in Nordic boreal forest ecosystems. The reduced stand density management does not have a significant impact on long-term production and income levels.

Abstract

The objective of this study was to demonstrate how height growth recalculated to periodic site index could be used to monitor and identify climatic drivers for growth variations. We used data from Norway’s National Forest Inventory (NFI), with attention to Norway spruce in the lowlands (<500 m a.s.l.) of southeastern Norway. We recalculated height growth to periodic site index and extracted a time series with annual values. We supplemented this with climatic data, i.e. monthly mean temperature, precipitation and deMartonne aridity index. The results showed that a characteristic two-peaked time series in volume growth in Norway 1994–2020 corresponded well to a time series of periodic site index for Norway spruce in the specific region mentioned above. Statistical analyses showed that for spruce, the periodic site index was higher in cold and moist summers than in warm and dry. Spruce mortality in this region tripled during 2012–22 when June temperature increased considerably, while periodic site index decreased. This corroborates warm and dry weather in June to be a main stress factor for spruce. In conclusion, periodic site index has a potential for being implemented for monitoring site productivity and for identification of climatic drivers.

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Abstract

There is a public debate on how boreal forests can deliver climate change mitigation benefits. While most debates regarding Fennoscandian forests have centered on the contrasting effects of actively managed and old-growth unmanaged forests on carbon uptake and storage, the impact of surface albedo has often been overlooked. According to the new EU forest strategy for 2030, with aim of improving quantity and quality of forests by promoting primary old-growth forests and avoiding clear-cutting, among others, we examined how albedo across a wide age range of boreal Pinus-dominated forests develops over time after wildfire (defined as unmanaged) and clear-cutting (defined as managed). We find that albedo decreases over time after disturbance, but mainly in managed forests. Annual mean albedo in young (<30 years) managed forests (0.36±0.04) is markedly larger than in young unmanaged forests (0.18±0.04). This difference is particularly prominent during winter, when snow-covered ground is present. The mean albedo over the entire unmanaged forest-age gradient (0.17±0.05) is significantly lower (p < 0.05) than that of the managed forest-age gradient (0.23±0.10). Considering the typically higher frequency of clear-cuts compared to wildfires in Fennoscandian forests, these albedo differences would be even larger over long time scales. Our findings reveal the importance of considering the climatic cooling potential of albedo when making decisions on how to optimize future forest management in northern boreal forests to mitigate climate change.

Abstract

The year-to-year variation in the availability of lingonberries (Vaccinium vitis-idaea L.) is a challenge for commercial exploitation. There is also a need to identify the best locations for lingonberry harvesting. Here, we present research that utilized field observations from the Norwegian National Forest Inventory to model and map the association between lingonberry cover and stand characteristics. Additionally, a set of permanent sampling plots were established for annual recording of berry yields in different Norwegian regions, representing variations in slope and forest characteristics. Ultimately, the recorded information on yield from the temporary sample plots were combined with predictions from the cover model, as well as data from remote sensing and climatic data from nearby weather stations (for locations see Figure 1a) to derive: 1) a model for lingonberry yield, and 2) and a yield map covering all forest land in Norway. Variables included in the final berry yield model are main tree species, soil parent material, mean temperature June-August, stand basal area, latitude, slope and distance to coastline (Miina et al., 2024).