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.
2011
Authors
Daniele Castagneri Ken Olaf StoraunetAbstract
A long-term increase in radial tree growth has been reported in tropical (Lloyd & Farquhar 2008), temperate (Spiecker 1996, Voelker et al. 2006), alpine (Rolland et al. 1998) and boreal forests (Hofgaard et al. 1999) over the last decades. Variations in forest growth patterns have been ascribed to different causes, such as longer growing seasons due to climate warming (Hu et al. 2010), changes in land management practices (Hunter & Shuck, 2002), nitrogen deposition (Magnani et al. 2007), and atmospheric CO2 enhancement (Voelker et al. 2006). Tree-ring analyses provide detailed information on the past growth of forests. In order to assess the effect of climate change on forest growth, non-climatic variation should be removed from treering series. The effect of endogenous (inter-tree competition) and exogenous (insects attacks, fires, storms, human influence, etc.) disturbances on tree-ring series can be detected and reduced by considering trees from different sites. Furthermore, as tree-ring width generally decreases as trees grow older and larger, age-related growth trend should be removed, to preserve climatic lowfrequency variability of chronologies. Different detrending methods used to remove non-climatic variations need to be adapted to the objectives of a particular study....
Authors
Kjell Andreassen Bernt-Håvard ØyenAbstract
Fourteen Nordic increment functions have been validated by use of with a test data set from long-term research plots in Norway of even-aged, pure stands of Scots pine, Birch and Norway spruce. In selected functions from Denmark, Finland, Norway and Sweden measures of site productivity, mean tree size and various stand characteristics are represented. Different models display both strengths and weaknesses in their predicting ability. Some measures of precision and bias have been calculated and the functions are ranked due to their performance. Basal area increment models for spruce and pine from Sweden, and a Finish volume increment model for birch has the best fit to the Norwegian test data. Some of the growth models developed outside Norway estimate the growth with about the same accuracy as the models frequently used and developed in Norway. The results indicate that forest conditions and traditional even-aged forest management practice in the Nordic countries seem to have small influence on the relative growth of even-aged stands. By careful recalibration of existing functions from other Nordic countries with data from Norway, a reasonable accuracy could be achieved in Norwegian forest with a reduction of the bias.
Authors
Bruce Talbot Morten NittebergAbstract
In the coastal region of Norway, large volumes of relatively inaccessible plantation timber are maturing for harvest. The economic feasibility of accessing much of this timber has limited the level of harvesting activity considerably. Harvesting planners are faced with the classic dilemma of finding the appropriate level of investment in infrastructure, as against inoptimal transportation. In this paper, we present results from a simple deterministic simulation carried out to illustrate the efficiency frontiers of three transport methods, one of which requires a substantial investment in road upgrading. Results depend on assumptions made, but clearly show that in these conditions, upgrading roads for truck+trailer transport should be evaluated on a cases by case basis. Forest road length and condition, public road distance to conversion site, and investment level all play important roles in the decision structure. In the coastal regions, road upgrades would generally need to be justified by benefits other than timber harvesting alone.
Authors
Bernt-Håvard ØyenAbstract
Sitka spruce (Picea sitchensis (Bong.) Carr) is native to the Pacific North West of America and was introduced to Western Europe in the early 19th century. It is now an important commercial species along the extreme western seaboard of Europe – namely Ireland and Great Britain – and this is where most progress has been made in the area of selection and breeding. Sitka spruce has been the subject of more limited selection and breeding work in some other European countries where it is of secondary or minor significance - Denmark, France, Germany, and Norway. These programmes have now effectively come to a close due to perceived lack of importance. In Sweden Sitka spruce is being planted at an increasing rate and is seen as a species of great potential in the light of climate change. This monograph presents details and statistics relating to Sitka spruce breeding across Europe. It summarises the work carried out to date (plus trees, field testing, orchards), the gains achieved, knowledge of genetic relationships between selection traits, and acts as a conduit to further references for the interested reader.
Authors
Felix Herzog Katalin Balázs Peter Dennis Tetyana Dyman Wendy Fjellstad Jürgen Friedel Salah Garchi Philippe Jeanneret Rob Jongman Maximilian Kainz Gerardo Moreno Charles Nkwiine Maurizio Paoletti Philippe Pointereau Jean-Pierre Sarthou Siyka Stoyanova Davide ViaggiAbstract
Farmland biodiversity is an important component of Europe’s biodiversity. More than half the continent is occupied by agricultural lands. They host specific habitats and species, which - in addition to their conservation values they provide - perform vital ecological functions. Indicators are needed to enable the monitoring of biodiversity at the farm level for the purpose of assessing the impacts of farming practices and of agricultural policies. Our research aims at identifying farmland biodiversity indicators which are scientifically sound, operational and relevant for stakeholders. We screened the literature for farmland biodiversity indicators and, in an iterative process with stakeholders, we identified 28 candidate indicators for genetic, species and habitat diversity. Those selected biodiversity indicators, as well as 14 management indicators that are known to relate to biodiversity, were assessed in 12 case study regions across Europe. Each case study region represents a typical production system (i.e. specialist field crops, horticulture and permanent crops; specialist grazing with cattle and other livestock types; mixed crop and livestock farming). In each region, 8-20 farms were randomly selected, mostly within the two groups of organic and non-organic farms, to obtain a gradient of farming intensity. Indicators were measured applying standardized sampling procedures and farm interviews. Sampling effort was recorded in order to assess the cost of indicator measurement. For each case study region, biodiversity indicators are presently being evaluated in conjunction with management indicators. Surrogate indicators will be proposed when possible and indicators will be prioritized taking into account their validity, practicality, cost and priority for stakeholders. Based on preliminary results, the presentation will focus on the specific challenges of farm level monitoring, addressing issues of sampling design within the farms and up-scaling from plot to farm to region. Part of this research was funded by the EU FP7 contract KBBE-2B-227161. For more information consult www.biobio-indicator.org
Abstract
Understanding the driving forces affecting species occurrences is a prerequisite for determining the indicator suitability of crenic plants. We analysed 18 environmental variables in a two-step approach, evaluating their ability to explain the species composition of 222 springs on five siliceous mountain ranges, in central Germany and north-west Czech Republic (49.9°–50.8°N, 10.6°–12.8°E). First, we identified the significant environmental variables in three subsets of spatial, hydrophysical and hydrochemical variables using a forward-selection procedure. We then performed a partial canonical correspondence analysis (pCCA) to estimate the influence of each subset alone, as well as in combinations. We also used a multiple response permutation procedure (MRPP) to compare the five regions with respect to the dissimilarity of their vegetation composition and environmental variables. Hydrochemical factors played a fundamental role in determining the plant community of the investigated springs. Spatial factors, in particular altitude, were correlated with the hydrochemical factors, but were less important. Hydrophysical factors played only a marginal role. More precisely, species occurrence was mainly driven by a gradient of nutrient availability, which in turn reflected the acidity status. This gradient was primarily represented by high Al, Cd, and Mn concentrations in acidic crenic waters, high Ca and Mg concentrations were encountered in circumneutral springs. By comparing the five regions we could show that there are spatial patterns in the vegetation of springs, which provide valuable ecological information on the water quality. We therefore suggest that biomonitoring approaches to vegetation are suitable for revealing the acidity status of springs and their forested catchments.
Authors
Peder GjerdrumAbstract
Scaling accuracy is of utmost importance to obtain optimal yield in log breakdown. In this paper we have combined sawmill experience, a review of available publications and supplementary observations to analyse the accuracy of roundwood scaling for Norway spruce and Scots pine. The influence of ovality, bark thickness variation and bark damage were analysed for scaling in one-directional and two- directional shadow scanners, and for three-dimensional (3D) reflected beam scanners. The overall accuracy for diameter under bark can be calculated by adding the variances for each independent term. For unbarked logs, shadow scanners with two perpendicular directions are most accurate. Results show that 3D scanners are most accurate, provided used for barked logs. For a case study, transferring from scaling unbarked logs in a two-dimensional shadow scanner to a full 3D scan of barked logs reduced annual roundwood consumption by 2.0%.
Authors
Helmer BelboAbstract
The theoretical potential for increased efficiency in early thinning by using accumulating harvester heads was investigated through simulation. Thinning was performed in corridors perpendicular to the strip road in 75 artificially generated stands with varying average tree size and density. The work pattern and work time in the crane work for five sizes of heads, with grapple diameters in the range of 10 to 50 cm, was estimated by the simulation model. The efficiency increased rapidly when the grapple diameter increased from two to four times the average diameter in the harvested stand, reducing the work time per tree by 15 to 50 percent compared to the single tree handling harvester head. Further increases in grapple dimension also increased the efficiency, but not at the same rate. In real work, the efficiency increase by an accumulating harvester head will probably be slightly lower due to less optimal harvesting conditions, operator skills and other non-productive work tasks that are not affected by work method.
Abstract
Forest regrowth in rural districts of Norway is currently leading to extensive landscape changes. We aim to quantify and understand the future impact of outfield forest regrowth following land-use abandonment on red-listed vascular plant species which are supposedly threatened by regrowth in Norway, i.e. species classified to habitats within the semi-natural landscape. Vascular plant species were defined by the Norwegian Red List and presence data was downloaded from the Norwegian GBIF-node, Artskart. A newly developed spatially explicit model of deforested semi-natural heaths and meadows in Norway was used to evaluate the vulnerability of red-listed plants to future forest regrowth. The results show that some red-listed species may be greatly affected, since they have most of their known populations within the modelled areas of future forest regrowth. The study also revealed that there are many methodological challenges in using museum databases for hypothesis testing. However, the use of such databases was clearly hypothesis generating, giving us many ideas for future studies.
– Changes in landscape and vegetation heterogeneity of rural Norway
Lars Østbye Hemsing, Anders Bryn
Abstract
Extensive landscape and vegetation changes are apparent within rural districts of Norway, especially as forest regrowth on abandoned agricultural land. Forest regrowth changes the landscape and vegetation heterogeneity, thus affecting management issues related to, for example, biodiversity and landscape aesthetics. By comparing up-to-date actual vegetation maps (AVMs), interpreted previous vegetation maps (IPVs), and potential natural vegetation maps (PNVs), we assess and quantify structural changes on a landscape level which are important for biological diversity and also the tourism industry. Our findings indicate that landscapes in rural districts of Norway have changed and that changes will continue in the future. The landscapediversity did not decrease from the 1970s until 2009. Further forest regrowth however, will lead to reduced landscape heterogeneity, while landscape connectivity will increase.