Publikasjoner
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.
2022
Sammendrag
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Sammendrag
Vi gir i den første delen av denne rapporten en oversikt over dagens skogressurser i Norge og den historiske utviklingen tilbake til 1990. Oversiktene er basert på data fra Landsskogtakseringens permanente prøveflater. Vi presenterer arealfordeling av bonitet og skogtyper i ulike hogstklasser, skogvolum og tilvekst, aldersutviklingen i skog, historisk avvirkning, samt omfang av sluttavvirkning i yngre skog de senere årene, her definert som skog som er yngre enn nedre aldersgrense for hogstklasse 5. Vi dokumenterer også hvor stor andel av skogressursene som står på arealer der det etter sertifiseringsordninger og skoglovgivningen må tas særskilte hensyn ved hogst. I tillegg har vi analysert omfanget av hogst i yngre skog, og som her er definert som avvirkning i skog som er yngre enn nedre aldersgrense for hogstklasse 5. I andre halvdel av rapporten presenterer vi 14 forskjellige prognoser for balansekvantum, med ulike forutsetninger med hensyn til økonomisk drivverdig areal (basert på driftskostnad), skogkulturinnsats, nedre alder ved sluttavvirkning, og for alternative scenarier for prioritering av arealer ved økning av vern av skog. Varierende skogkulturinnsats hadde relativt liten effekt på balansekvantum, men større effekt på tilvekst og volumutvikling samt sammensetningen av framtidig hogstkvantum og skogvolum per treslagsgruppe (gran, furu, lauvtrær). Varierende forutsetninger om nedre aldersgrense for sluttavvirkning hadde også effekt på utviklingen av ressursene og på balansekvantumet. Prognosene der inntil 25 prosent av hogstkvantumet fra sluttavvirkning kan hentes i hogstklasse 4 og resten i hogstklasse 5 gav et høyere balansekvantum enn i prognosene der sluttavvirkning tidligst kan gjennomføres når skogen når nedre aldersgrense for hogstklasse 5. Prognosene uten hogst i hogstklasse 4 gav imidlertid som resultat en større oppbygning av stående volum og tilvekst over tid....
Sammendrag
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Sammendrag
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Sammendrag
The British forestry sector lacks reliable dynamic growth models for stands of improved Sitka spruce, the most important commercial forest type in Great Britain. The aim of this study is to fill this gap by trialling a new modelling framework and to lay the foundations of a future dynamic growth simulator for that forest type. First, we present single tree diameter and height increment models that are climate sensitive and include explicit competition effects. The predictions from the increment models are pooled to project diameter and height at a given age. These projections are then used as inputs to an integrated taper model from which stochastic tree volume predictions are obtained. Retrospective data from over 1400 trees collected in two extensive genetic trials in Scotland and Wales were used for the purposes of this study. Diameter increment and height increment predictions were highly accurate and diameter and height projections proved consistent. The predicted volume at the time of harvesting also exhibited a high degree of accuracy, which shows the robustness of our approach. Further data will be needed in the future to recalibrate the present models and extend their range of validity to the whole of Great Britain.
Forfattere
Antonio Gazol Cristina Valeriano Alejandro Cantero Marta Vergarechea Jesús Julio CamareroSammendrag
There is debate on which tree species can sustain forest ecosystem services in a drier and warmer future. In Europe, the use of non-native timber species, such as Douglas fir (Pseudotsuga menziesii [Mirb.] Franco), is suggested as a solution to mitigate climate change impacts because of their high growth resilience to drought. However, the biogeographical, climatic and ecological limits for widely planted timber species still need to be defined. Here, we study the growth response to climate variables and drought of four Douglas fir plantations in northern Spain subjected to contrasting climate conditions. Further, we measure wood density in one of the sites to obtain a better understanding of growth responses to climate. Correlative analyses and simulations based on the Vaganov–Shaskin process-based model confirm that growth of Douglas fir is constrained by warm and dry conditions during summer and early autumn, particularly in the driest study site. Minimum wood density increased in response to dry spring conditions. Therefore, planting Douglas fir in sites with a marked summer drought will result in reduced growth but a dense earlywood. Stands inhabiting dry sites are vulnerable to late-summer drought stress and can act as “sentinel plantations”, delineating the tolerance climate limits of timber species.
Sammendrag
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Sammendrag
Tree diameter increment (ΔDBH) and total tree height increment (ΔHT) are key components of a forest growth and yield model. A problem in complex, multi-species forests is that individual tree attributes such as ΔDBH and ΔHT need to be characterized for a large number of distinct woody species of highly varying levels of occurrence. Based on more than 2.5 million ΔDBH observations and over 1 million ΔHT records from up to 60 tree species and genera, respectively, this study aimed to improve existing ΔDBH and ΔHT equations of the Acadian Variant of the Forest Vegetation Simulator (FVS-ACD) using a revised method that utilize tree species as a random effect. Our study clearly highlighted the efficiency and flexibility of this method for predicting ΔDBH and ΔHT. However, results also highlighted shortcomings of this approach, e.g., reversal of plausible parameter signs as a result of combining fixed and random effects parameter estimates after extending the random effect structure by incorporating North American ecoregions. Despite these potential shortcomings, the newly developed ΔDBH and ΔHT equations outperformed the ones currently used in FVS-ACD by reducing prediction bias quantified as mean absolute bias and root mean square error by at least 11% for an independent dataset and up to 41% for the model development dataset. Using the revised ΔDBH and ΔHT estimates, greater prediction accuracy in individual tree aboveground live carbon mass estimation was also found in general but performance varied with dataset and accuracy metric examined. Overall, this analysis highlights the importance and challenges of developing robust ΔDBH and ΔHT equations across broad regions dominated by mixed-species, managed forests.
Forfattere
Peter Annighöfer Martina Mund Dominik Seidel Christian Ammer Aitor Ameztegui Philippe Balandier Ieva Bebre Lluis Coll Catherine Collet Tobias Hamm Franka Huth Heike Schneider Christian Kuehne Magnus Löf Any Mary Petritan Ion Catalin Petritan Peter Schall Jürgen BauhusSammendrag
Just as the aboveground tree organs represent the interface between trees and the atmosphere, roots act as the interface between trees and the soil. In this function, roots take-up water and nutrients, facilitate interactions with soil microflora, anchor trees, and also contribute to the gross primary production of forests. However, in comparison to aboveground plant organs, the biomass of roots is much more difficult to study. In this study, we analyzed 19 European datasets on above- and belowground biomass of juvenile trees of 14 species to identify generalizable estimators of root biomass based on tree sapling dimensions (e.g. height, diameter, aboveground biomass). Such estimations are essential growth and sequestration modelling. In addition, the intention was to study the effect of sapling dimension and light availability on biomass allocation to roots. All aboveground variables were significant predictors for root biomass. But, among aboveground predictors of root biomass plant height performed poorest. When comparing conifer and broadleaf species, the latter tended to have a higher root biomass at a given dimension. Also, with increasing size, the share of belowground biomass tended to increase for the sapling dimensions considered. In most species, there was a trend of increasing relative belowground biomass with increasing light availability. Finally, the height to diameter ratio (H/D) was negatively correlated to relative belowground biomass. This indicates that trees with a high H/D are not only more unstable owing to the unfavorable bending stress resistance, but also because they are comparatively less well anchored in the ground. Thus, single tree stability may be improved through increasing light availability to increase the share of belowground biomass.
Sammendrag
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