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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

Abstract

An overview of the European Heathland Network, its history, purpose and role in connecting research, management and policy across Europe. The presentation also highlighted past workshops, current management challenges and priorities for strengthening the network in the future.

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Abstract

Insect pollinators are important drivers of fruit quality and yield in horticultural systems. The global reduction in wild bee populations has increased the demand for managed honeybees, despite honeybees relatively low pollination efficiency. Here, we assessed how bee communities, bee behaviour, and orchard design in Norwegian apple orchards affects apple pollination success, an important determinant of apple quality. We placed pan and vane traps in 18 apple orchards, in six distinct locations, within the two main apple growing regions in Norway. We also tracked individual bees (honeybees, bumblebees, and solitary bees) throughout the apple flowering season, and recorded their flower handling time, number of flower visits, stigma contact, and movement between apple flowers. Finally, we calculated the seed set rate (ovules developed into seeds / total number of ovules) from 908 harvested apples to estimate pollination success. Our key finding is that pollination success was driven by the abundance of wild bees and overall orchard planting design. We found lower pollination success in block design orchards where a single cultivar is planted continuously over a large area, compared to orchards with an integrated design where compatible cultivars are planted within the orchard. We also found that stigma contact decreased as apple flowering progressed, and that solitary bees visited fewer flowers per foraging event but were potentially more thorough foragers. Our results highlight the importance of promoting wild bees in apple orchards while also ensuring there is compatible pollen in the orchards for optimal pollination.

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Abstract

Extreme climate events are increasingly impacting Central European forests. The 2018 drought and heat wave intensified tree mortality and bark beetle outbreaks. We examined how these disturbances altered water, organic-matter (OM), and nutrient fluxes in mixed beech (Fagus sylvatica)–maple (Acer pseudoplatanus) forests and Norway-spruce (Picea abies) stands on shallow, calcareous soils in central Germany. From 2018–2020 we collected bi-weekly samples of throughfall, stemflow, and free-draining lysimeter samples from different soil depths. The samples were analysed for pH, electrical conductivity (EC), dissolved and particulate organic carbon (DOC; POC), total dissolved nitrogen (DN), and nutrients. Linear mixed-effects models revealed strong species responses: mixed beech-maple exported more DN and calcium to deeper soil layers than spruce stands, whereas spruce had significantly higher DOC fluxes at all depths. Radiocarbon signatures indicated that spruce DOC is dominated by recent carbon inputs, while beech/maple DOC incorporates older, previously more stabilized OM. Drought-induced premature leaf fall, subsequent re-wetting events, bark-beetle infestation, and canopy opening contributed to amplify export of OM and nutrients to deeper soil horizons. Bark-beetle infestation of spruce stands mobilized phosphorus from the organic layer. Tree species, the post-drought monitoring phase, and soil depth together explained more than 65% of the variance in water, DOC, DN, Ca, pH, and EC fluxes, confirming that species-specific controls dominate post-drought biogeochemical dynamics. These findings underscore the vulnerability of common Central European forests to the combined pressures of drought and biotic stressors and highlight the importance of incorporating species-specific considerations into forest management adaptations.

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Abstract

Spatially explicit information on forest resources and structure is essential for sustainable forest management and evidence-based policy-making. In the Nordic region, large-scale forest mapping often relies on integrating National Forest Inventory (NFI) field plots with airborne laser scanning (ALS) data. However, infrequent nationwide ALS campaign coverage limits their use for continuous monitoring. Satellite imagery, with its high temporal and spatial resolution, provides a promising alternative. We evaluate UNet-based deep learning models trained on wall-to-wall ALS-derived forest resource maps for predicting volume and Lorey’s height in Norway using optical (Sentinel-2) and SAR (Sentinel-1, PALSAR-2) data. The UNet models, trained on both Finnish and Norwegian ALS maps, are benchmarked against extreme gradient boosting (XGB) models. Transfer learning is further explored by finetuning models using Norwegian NFI plots. Model accuracies are assessed using 541 reserved test NFI plots and 44 independent forest stands, representing high‑volume mature boreal forests (>200 m3 ha−1). The UNet model trained on Norwegian ALS‑based data achieved R2 values of 0.59 for both volume and Lorey’s height when evaluated on NFI plots, and 0.70 and 0.59 for forest stands, respectively, outperforming the XGB models. Finetuning improved model transferability, yielding gains of up to 0.13 in R2 for volume and 0.46 for Lorey’s height when adapting the Finnish model to Norwegian conditions. Utilizing SAR data alongside optical data enhanced model accuracy. Overall, our findings demonstrate the potential of UNet models trained on wall-to-wall ALS maps for forest resource mapping across Nordic countries.

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Abstract

Non-destructive and rapid analysis of adhesive penetration in engineered wood products ensures bond integrity, enabling the development of novel adhesives and quality manufacturing. The present study evaluated the X-ray densitometry method for studying the adhesive penetration in birch plywood. In this approach, it was quantified as a function of distance by measuring the X-ray density profile section where the adhesive bond-line density was above the baseline wood density. Accordingly, untreated and esterified birch veneers were pressed into plywood using both liquid and solid-type phenolic adhesives, resulting in four types of five-layered plywood of 7-8 mm in thickness. Optimization of X-ray beam attenuation through the plywood was done by preliminary trials and identified the specimen dimensions as 50 mm in height and 25 mm in width using a scanning speed of 0.5 mm min $$^{-1}$$ . The X-ray densitometry measured densities of cured phenolic adhesive to be 1150 ± 50 kg m $$^{-3}$$ and esterification-modified birch plywood to be 750 ± 25 kg m $$^{-3}$$ . These density values are consistent with gravimetric density measurements. Density profile observations indicate that both liquid and solid forms of phenolic adhesives exhibited similar levels of adhesive penetration in plywood. X-ray densitometry analysis determined a total interphase thickness ranging from 0.50 to 0.75 mm, encompassing the central adhesive bond-line and the effective adhesive penetration into both adjacent veneers. These values are comparable with those measurements obtained from microscopy imaging analysis. Therefore, X-ray densitometry could be a swift method for quantifying adhesive penetration, although further studies are needed to validate its accuracy and reliability.