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
Authors
Fride Høistad Schei Mie Prik Arnberg John-Arvid Grytnes Maren Stien Johansen Jørund Johansen Anna Birgitte Milford Anders Røynstrand Mari Mette TollefsrudAbstract
Climate change and human activities have accelerated the spread of non-native species, including forest pests and pathogens, significantly contributing to global biodiversity loss. Pathogens pose a significant threat to forest ecosystems due to a lack of coevolution with native hosts, resulting in ineffective defence mechanisms and severe consequences for the affected tree species. Ash dieback, caused by the fungus Hymenoscyphus fraxineus, is a relatively new invasive forest pathogen threatening ash (Fraxinus excelsior) with mortality rates in northern Europe reaching up to 80 %. The loss of ash due to dieback has severe ecological implications, potentially leading to an extinction cascade as ash provides crucial habitats and resources for many organisms. Despite this, the consequences of ash dieback on associated communities are largely unknown. To address this, we analysed changes in species richness, vegetation structure, and composition in 82 permanent vegetation plots across 23 Norwegian woodlands. We compared data collected before and 10–14 years after the emergence of ash dieback. In these woodlands, ash significantly declined in cover, leading to changes in tree species composition and facilitating the establishment of other woody tree species like hazel (Corylus avellana) and the invasive species sycamore (Acer pseudoplatanus). Despite these changes in the tree species composition, no significant alterations were observed in the understory plant community, indicating a degree of ecosystem resilience or a lagging community response. At this point, and with our focus on the vascular plants, we do not find support for cascading effects due to ash dieback. However, our findings demonstrate that one invasive species is facilitating the expansion of another, raising concerns about potential ecological imbalance and cascading effects in the future.
Abstract
The study investigated the feasibility for partial phosphate binder replacement with lignin in phosphate bonded paper sludge composites. A central composite experimental design (CCD) was used to optimise the board manufacturing process, wherein the effect of process temperature, as well as lignin content were investigated with respect to board properties based on the ASTM D1037 standard. Moduli of rupture and elasticity of up to 7.2 MPa and 2.8 GPa respectively in the boards with lignin content of 36–43 wt% and formulation temperatures of 118–133 °C were observed. The phosphate binder input, which bears a huge cost in the process was reduced by up to 49% with lignin incorporation. The effect of pine veneer lamination on the strength properties of the composite boards was investigated. Pine veneer lamination improved mechanical properties, with the moduli of rupture and elasticity increasing from 7.2 to 22.1 MPa (67% increase) and 2.8 to 3.6 GPa (22% increase) respectively. The economic viability of the boards produced was also assessed and the results showed that the required selling price for the composite boards is competitive in the local market for inexpensive construction materials, sold at wholesale prices for between R 158/m2 and R 295/m2, depending on product finishing.
Abstract
Lingonberry (Vaccinium vitis-idaea L.) grows in a range of nature types in the boreal zone, and understanding factors affecting the abundance of the plant, as well as mapping its spatial distribution, is important. The abundance of the species can be an indicator of ecosystem changes, and lingonberry can also be a source for commercial utilisation of berry resources. Using country-wide data from 6404 field plots of the Norwegian national forest inventory (NFI), we modelled the relationship between lingonberry cover and airborne laser scanning (ALS) and satellite metrics and bioclimatic variables describing the forest structure, terrain, soil properties and climate using a generalised mixed-effects model with a quasipoisson distribution. The validation carried out with an independent set of 2124 NFI plots indicated no obvious bias in predictions. The most important predictors were found to be interactions between dominant tree species, stand basal area and latitude, as well as the reflectance in the near-infrared band from Sentinel-2 satellite imagery, the dominant height based on the ALS variable and the long-term mean summer (June–August) temperature. The results provide an indicator of the effects of global warming, as well as the possibility of giving forest management prescriptions that favour lingonberry and locating the most abundant lingonberry sites in Norwegian forests.
Authors
Klemens Schadauer Rasmus Astrup Johannes Breidenbach Jonas Fridman Stephan Gräber Michael Köhl Kari T. Korhonen Vivian Kvist Johannsen Francois Morneau Risto Päivinen Thomas RiedelAbstract
No abstract has been registered
Authors
Mingkai Jiang Belinda E. Medlyn David Wårlind Jürgen Knauer Katrin Fleischer Daniel S. Goll Stefan Olin Xiaojuan Yang Lin Yu Sönke Zaehle Haicheng Zhang He Lv Kristine Y. Crous Yolima Carrillo Catriona Macdonald Ian Anderson Matthias M. Boer Mark Farrell Andrew Gherlenda Laura Castañeda-Gómez Shun Hasegawa Klaus Jarosch Paul Milham Raúl Ochoa-Hueso Varsha Pathare Johanna Pihlblad Juan Piñeiro Nevado Jeff Powell Sally A. Power Peter Reich Markus Riegler David S. Ellsworth Benjamin SmithAbstract
The importance of phosphorus (P) in regulating ecosystem responses to climate change has fostered P-cycle implementation in land surface models, but their CO2 effects predictions have not been evaluated against measurements. Here, we perform a data-driven model evaluation where simulations of eight widely used P-enabled models were confronted with observations from a long-term free-air CO2 enrichment experiment in a mature, P-limited Eucalyptus forest. We show that most models predicted the correct sign and magnitude of the CO2 effect on ecosystem carbon (C) sequestration, but they generally overestimated the effects on plant C uptake and growth. We identify leaf-to-canopy scaling of photosynthesis, plant tissue stoichiometry, plant belowground C allocation, and the subsequent consequences for plant-microbial interaction as key areas in which models of ecosystem C-P interaction can be improved. Together, this data-model intercomparison reveals data-driven insights into the performance and functionality of P-enabled models and adds to the existing evidence that the global CO2-driven carbon sink is overestimated by models.
Authors
Mingkai Jiang Kristine Y. Crous Yolima Carrillo Catriona A. Macdonald Ian C. Anderson Matthias M. Boer Mark Farrell Andrew N. Gherlenda Laura Castañeda-Gómez Shun Hasegawa Klaus Jarosch Paul J. Milham Rául Ochoa-Hueso Varsha Pathare Johanna Pihlblad Juan Piñeiro Jeff R. Powell Sally A. Power Peter B. Reich Markus Riegler Sönke Zaehle Benjamin Smith Belinda E. Medlyn David S. EllsworthAbstract
The capacity for terrestrial ecosystems to sequester additional carbon (C) with rising CO2 concentrations depends on soil nutrient availability1,2. Previous evidence suggested that mature forests growing on phosphorus (P)-deprived soils had limited capacity to sequester extra biomass under elevated CO2 (refs. 3,4,5,6), but uncertainty about ecosystem P cycling and its CO2 response represents a crucial bottleneck for mechanistic prediction of the land C sink under climate change7. Here, by compiling the first comprehensive P budget for a P-limited mature forest exposed to elevated CO2, we show a high likelihood that P captured by soil microorganisms constrains ecosystem P recycling and availability for plant uptake. Trees used P efficiently, but microbial pre-emption of mineralized soil P seemed to limit the capacity of trees for increased P uptake and assimilation under elevated CO2 and, therefore, their capacity to sequester extra C. Plant strategies to stimulate microbial P cycling and plant P uptake, such as increasing rhizosphere C release to soil, will probably be necessary for P-limited forests to increase C capture into new biomass. Our results identify the key mechanisms by which P availability limits CO2 fertilization of tree growth and will guide the development of Earth system models to predict future long-term C storage.
Abstract
Aim Seedling recruitment is a vital process for forest regeneration and is influenced by various factors such as stand composition, climate, and soil disturbance. We conducted a long-term field experiment (18 years) to study the effects of these factors and their interactions on seedling recruitment. Location Our study focused on five main species in boreal mixed woods of eastern Canada: trembling aspen (Populus tremuloides), paper birch (Betula papyrifera), white spruce (Picea glauca), balsam fir (Abies balsamea), and white cedar (Thuja occidentalis). Methods Sixteen 1-m2 seedling monitoring subplots were set up in each of seven stands originating from different wildfires (fire years ranging from 1760 to 1944), with a soil scarification treatment applied to every other subplot. Annual new seedling counts were related to growing-season climate (mean temperature, growing degree days and drought code), scarification, and stand effects via a Bayesian generalized linear mixed model. Results Soil scarification had a large positive effect on seedling recruitment for three species (aspen, birch and spruce). As expected, high mean temperatures during the seed production period (two years prior to seedling emergence) increased seedling recruitment for all species but aspen. Contrary to other studies, we did not find a positive effect of dry conditions during the seed production period. Furthermore, high values of growing degree days suppressed conifer seedling recruitment. Except for white cedar, basal area was weakly correlated with seedling abundance, suggesting a small number of reproductive individuals is sufficient to saturate seedling recruitment. Conclusion Our findings underscore the importance of considering multiple factors, such as soil disturbance, climate, and stand composition, as well as their effects on different life stages when developing effective forest management strategies to promote regeneration in boreal mixed-wood ecosystems.
Authors
Mika Helene Kirkhus Håvard Kauserud Vigdis Vandvik Ella Thoen Ane Vollsnes Aud Helen Halbritter RechsteinerAbstract
The boreal, alpine, and arctic heaths and forests are dominated by dwarf-shrubs along with their symbionts, ericoid mycorrhizal fungi. Dwarf-shrubs are sensitive to climate change and are already affected in large-scale diebacks. It remains to explore how their mycorrhizal symbionts mitigate damages, since little is known about these plant-fungal interactions. Ericoid mycorrhizal fungi are known to aid the host plant with nutrient uptake, but little research exists on their dealings with drought, suggesting a major knowledge gap. A better overview of belowground ericoid fungi at different drought levels might help predict future climate-change induced damage. In our study we aim to find out if and how drought affects ericoid mycorrhizal fungal communities, and pinpoint key species related to drought mitigation.
Authors
Mika Helene Kirkhus Håvard Kauserud Vigdis Vandvik Ella Thoen Ane Vollsnes Aud Helen Halbritter RechsteinerAbstract
The boreal, alpine, and arctic heaths and forests are dominated by dwarf-shrubs along with their symbionts, ericoid mycorrhizal fungi. Dwarf-shrubs are sensitive to climate change and are already affected in large-scale diebacks. It remains to explore how their mycorrhizal symbionts mitigate damages, since little is known about these plant-fungal interactions. Ericoid mycorrhizal fungi are known to aid the host plant with nutrient uptake, but little research exists on their dealings with drought, suggesting a major knowledge gap. A better overview of belowground ericoid fungi at different drought levels might help predict future climate-change induced damage. In our study we aim to find out if and how drought affects ericoid mycorrhizal fungal communities, and pinpoint key species related to drought mitigation.
Abstract
Uneven-aged forests set certain challenges for cut-to-length harvesting work. It is a challenge to cost-effectively remove larger trees while leaving a healthy understory for regrowth. The study’s aim was to evaluate productivity and costs of harvesting two-storied silver birch (Betula pendula Roth) and Norway spruce (Picea abies (L.) H. Karst.) stands by creating time consumption models for cutting, and using existing models for forwarding. Damage to the remaining understory spruce was also examined. Four different harvesting methods were used: 1) all dominant birches were cut; 2) half of them thinned and understory was preserved; compared to 3) normal thinning of birch stand without understory; and 4) clear cutting of two-storied stand. Results showed the time needed for birch cutting as 26–30% lower when the understory was not preserved. Pulpwood harvesting of small sized spruces that prevent birch cutting was expensive, especially because of forwarding of small amounts with low timber density on the strip roads. Generally, when taking the cutting and forwarding into account, the unit cost at clear cuttings was lowest, due to lesser limitations on work. It was noted that with increasing removal from 100 to 300 m3 ha–1, the relative share of initial undamaged spruces after the harvest decreased from 65 to 50% when the aim was to preserve them. During summertime harvesting, the amount of stem damage was bigger than during winter. In conclusion, two-storied stands are possible to transit to spruce stands by accepting some losses in harvesting productivity and damages on remaining trees.