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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.

2011

Abstract

The anticipated future changes in temperature, precipitation and snow cover caused by global warming may affect winter survival of autumn sown wheat. More variable weather conditions may cause an increased frequency of periods with alternating freezing and thawing and less stable snow covers. In the present study, the course of plant frost tolerance and growth potential was studied by exposing cold acclimated plants of winter wheat to conditions with alternating periods of freezing and thawing (either -1 °C or +5 °C), and differing durations of snow cover. Tests of frost tolerance and determination of growth potential were performed each time the temperature or snow cover conditions were changed. Periods without snow cover and + 5 °C caused dehardening, with loss of frost tolerance being more pronounced during the first dehardening period than in the second one. The ability to reharden after a dehardening period decreased towards the end of the experimental period. Mild periods during winter also seemed to exhaust plant growth potential, possibly by increasing respiration rate while photosynthesis was still restricted. The results indicate some of the challenges we may face regarding overwintering of winter wheat in a future climate.

Abstract

Four Norway spruce stands treated with single tree selection were studied 11 years after the cuttings. In each of the stands we performed four strengths of cuttings in 0.2 ha plots, with removals ranging from zero to 70 % of the basal area. We investigated accumulated and annual growth, changes in stand structure, tree age and tree damage. 10-20 % of the living trees were still damaged 11 years after the cutting. The diameter distribution displayed a reverse J-curve in all plots both before and after the cuttings. Eleven years later, the curve is only slightly changed. Annual ring widths from 300 increment cores were analysed. Most trees started to increase the growth two or three years after the cutting. This improved growth accelerated the following six or seven years with 20-80 % increase. Both small and large trees reacted, including severely suppressed trees. The initial crown volume and crown vitality after cutting is essential for the increased growth since several years are necessary to build up a larger and better crown. A reduced volume per hectare provided an increased growth for each of the remaining trees and indicates less competition for nutrients and light after cutting. The observed growth during the 11-year post-harvest period was about 10 % less than the estimated yield capacity for even-aged stands.

Abstract

This case study describes reflection, analyses and results obtained from investing in a new saw intake plant with the option to separate pre-sorted logs groups in two sub-sets for increased yield and sawing mini-series of 20-30 logs to maintain high capacity. The new plant was in need of careful trimming and follow-up during a period half a year or more before optimal operation was obtained. Log separation is done based on 3D scaling after debarking. As expected, scaling accuracy was substantially improved. However, scars and damages from the debarker cause some variation in the scaling, and most for 3-dimensional parameters like sweep and taper. Nevertheless, total sawn timber recovery increased by two percent of consumed log volume, equivalent to 2.3 % improvement in the sawmill\"s added value. Sawing two orders simultaneously increased the complexity of planning and sawn timber logistics. Automated sawn timber quality prediction based on observations of barked logs in the 3D scanner has so far not proved successful; one reason for this might be the quality variation within each log. It was concluded that the investment has proven profitable.