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NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.

2024

Sammendrag

Forests are a key plank of European policies to mitigate and adapt to climate change and to promote biodiversity. These policies are starting to become more nuanced with respect to the account of their impacts on carbon storage, considering the effect of long-lived wood products and value of conserving old-growth forests, along with indirect land-use change impacts. However, a CO2-focused perspective means that many processes are still omitted for the quantification of the true extent of climate effects. Emissions of the greenhouse gases nitrous oxide and methane, short-lived climate forcers and effects from albedo changes and heat fluxes are also relevant. These processes are interconnected and influence the climate mitigation of forests in a complex way and need to be considered. The CLImate Mitigation and Bioeconomy pathways for sustainable FORESTry (CLIMB-FOREST) Horizon Europe project that runs until 2027 uses a holistic approach to estimate the climate impacts of various management alternatives. The foundation of CLIMB-FOREST is the use of European-wide empirical data, as well as an advanced coupled vegetation and earth-system modelling framework that includes biodiversity indicators and the interaction of forestry stakeholders in a global trade system. This framework is used to model management, forest tree species and climate on short- to long-term in Europe. We present first results of the climate effects and ecosystem functioning for a range of management alternatives in boreal, temperate, and Mediterranean forests. For example, introducing broadleaved trees in a coniferous forest promotes resilience and increased cooling from higher solar light scattering and latent heat flux of broadleaved trees. On the other hand, higher evapotranspiration might lead to an accelerated soil moisture depletion and reduced monoterpene emissions. The latter would have a warming effect because terpenes produce atmospheric particles, which are effective cooling agents through their involvement in cloud formation. Consequently, understanding these complex climate effects is key for appropriate climate-smart-forestry policies and approaches. The main outcomes and impacts of CLIMB-FOREST are to suggest alternative pathways for the forest sector to mitigate climate change in entire Europe, create attitude change in the policymaking process and influence foresters to adopt to new forest management strategies.

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Sammendrag

Heat treatment increases the decay resistance of wood by decreasing its hygroscopicity, but the wood material remains degradable by fungi. This study investigated the degradation of heat-treated wood by brown rot fungi, with the aim of identifying fungal-induced hygroscopicity changes that facilitate degradation. Scots pine sapwood samples were modified under superheated steam at 200 and 230 °C and then exposed to Coniophora puteana and Rhodonia placenta in a stacked-sample decay test to produce samples in different stages of decay. Sorption isotherms were measured starting in desorption from the undried, decaying state to investigate their hygroscopic properties. Although there were substantial differences in degradative ability between the two fungi, the results revealed that decay by both species increased the hygroscopicity of wood in the decaying state, particularly at high relative humidity. The effect was stronger in the heat-treated samples, which showed a steep increase in moisture content at low decay mass losses. The reference samples showed decreased hygroscopicity in absorption from the dry state, while the heat-treated samples still showed an increase at low mass losses. Near infrared spectroscopy showed that the early stages of decay were characterised by the degradation of hemicellulose and chemical changes to cellulose and lignin, which may explain the increase in hygroscopicity. The results provide a new perspective on brown rot decay and offer insight into the degradation of heat-treated wood.

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In boreal forests, turnover of biomass and necromass of ectomycorrhizal extraradical mycelia (ERM) are important for mediating long-term carbon storage. However, ectomycorrhizal fungi are usually not considered in ecosystem models, because data for parameterization of ERM dynamics is lacking. Here, we estimated the production and turnover of ERM biomass and necromass across a hemiboreal Pinus sylvestris chronosequence aged 12 to 100 years. Biomass and necromass were quantified in sequentially harvested in-growth bags, and incubated in the soil for 1–24 month, and Bayesian calibration of mathematical models was applied to arrive at parametric estimates of ERM production and turnover rates of biomass and necromass. Steady states were predicted to be nearly reached after 160 and 390 growing season days, respectively, for biomass and necromass. The related turnover rates varied with 95% credible intervals of 1.7–6.5 and 0.3–2.5 times yr−1, with mode values of 2.9 and 0.9 times yr−1, corresponding to mean residence times of 62 and 205 growing season days. Our results highlight that turnover of necromass is one-third of biomass. This together with the variability in the estimates can be used to parameterize ecosystem models, to explicitly include ERM dynamics and its impact on mycorrhizal-derived soil carbon accumulation in boreal forests.

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Automated sorption balances are widely used for characterizing the interaction of water vapor with hygroscopic materials. These instruments provide an efficient way to collect sorption isotherm data and kinetic data. A typical method for defining equilibrium after a step change in relative humidity (RH) is using a particular threshold value for the rate of change in mass with time. Recent studies indicate that commonly used threshold values yield substantial errors and that further measurements are needed at extended hold times as a basis to assess the accuracy of abbreviated equilibration criteria. However, the mass measurement accuracy at extended times depends on the operational stability of the instrument. Published data on the stability of automated sorption balances are rare. An interlaboratory study was undertaken to investigate equilibration criteria for automated sorption balances. This paper focuses on the mass, temperature, and RH stability and includes data from 25 laboratories throughout the world. An initial target for instrument mass stability was met on the first attempt in many cases, but several instruments were found to have unexpectedly large instabilities. The sources of these instabilities were investigated and greatly reduced. This paper highlights the importance of verifying operational mass stability of automated sorption balances, gives a method to perform stability checks, and provides guidance on identifying and correcting common sources of mass instability.

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The purpose of this review is to report on the state-of-the-art on the interaction of moisture with natural materials and fabricated biomimetic functional materials, with an emphasis upon the hygro-responsive behaviour of wood. The primary objective is to examine how water sorption affects dimensional behaviour and how knowledge of this property in natural plant-based (mainly, but not exclusively wood) materials can be used to inform biomimetic design of moisture-responsive materials and devices. The study examines the literature on natural and bio-inspired materials, concentrating upon sorption kinetics, water migration and location of the sorbed water in the materials and their microstructure and mechanical response of the microstructure and how this affects molecular mobility of the sorbate translating to macrostructural changes. Also included within this review, it is an overview of the main experimental techniques which have been used to investigate the interaction of water with these materials at molecular length scales and how modern techniques can resolve the response of these materials at the cell wall level.

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Despite their relevance in building stock modeling, building lifetimes are poorly understood and tend to form the weakest link in forecasting energy use, greenhouse gas (GHG) emissions, waste generation, and resource use. Here, we develop a methodology to trace building lifetimes for cohorts in two central areas built up after fires in the 1840s. Using Geographical Information System (GIS) data of the current building stock and archival material, we determined yearly hazard rates for buildings within the cohort 1841–1845 in the historical center of Trondheim, Norway. We find that hazard rates are very sensitive to events ranging from global to hyperlocal scales and that demolition rates have slowed down significantly since the 1980s when municipal preservation policies came into effect. In contrast, age-based lifetime approaches fail to capture the effects of such events as they only account for the delay between construction and demolition. We discuss the use and limitations of hazard rates to better reflect changes in demolition that are not correlated with building age. Our study underscores that building lifetimes are a property of a wider system rather than an attribute of individual structures. In that sense, hazard rates are a more suitable approach to capture spatiotemporal changes of building stocks and could be further used in scenarios in dynamic models.