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The aim of this study was to gain a deeper knowledge of the effects of mechanical site preparation on the survival and growth of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and Norway spruce (Picea abies (L.) Karst.) seedlings in southern Sweden. The experiment was conducted on a fresh clearcut at the Asa experimental forest (57° 10′ N). The effects of five different site preparation treatments were investigated: control, patch, mound, invert and mix. In each treatment, 40 seedlings of Norway spruce and 40 of Douglas fir were planted in each of four blocks. Site preparation had little or no effect on the survival and growth of Norway spruce: only a few seedlings died during the first 2 years. For Douglas fir, however, all site preparation treatments increased survival compared with the control, where mortality was high. The most intensive soil preparation treatment, mix, significantly increased root growth and total biomass. Pine weevils caused more severe damage to Douglas fir seedlings than to Norway spruce and targeted different locations in the two species, causing comparatively more damage to the leading shoots of Douglas fir seedlings. © 2012 Institute of Chartered Foresters. All rights reserved. Source

Lokken T.V.,ASA Research
Journal of Natural Gas Science and Engineering | Year: 2013

An investigation of hygrometers for monitoring of water vapour (moisture) in natural gas has been performed, with respect to response on ethylene glycol co-exposure. The tested hygrometers are based on: 1. capacitor sensor, 2. quartz crystal microbalance (QCM), 3. fibre-optic sensor and 4. conversion of water to ethyne, quantified by a gas chromatograph (CaC2-GC). The moisture concentration level in the test gas was 50 μmol/mol during the experiments, corresponding to a frost point of approximately -48 °C (atmospheric pressure). The experiments were performed in the laboratory, using nitrogen as matrix gas. The QCM hygrometer responded with a downward drift of the frost point readings in the presence of traces of ethylene glycol (0.25 μmol/mol and 0.66 μmol/mol, respectively). The drift increased initially when the ethylene glycol concentration increased, and the frost point readings from the QCM hygrometer decreased close to 5 °C during a total of 20 days of ethylene glycol exposure. The QCM hygrometer seemed to recover slowly from the ethylene glycol exposure, indicated by a decreasing upward drift as soon as the ethylene glycol exposure ended. Both tested capacitor hygrometers responded significantly to ethylene glycol exposure. The responses were not uniform, though, with one performing considerably better than the other one. The experiments also demonstrated the insufficiency of chilled mirror techniques for interpreting water frost points or water dew points, with subsequent moisture concentration calculation, in the presence of ethylene glycol, even at trace amounts. This made the chilled mirror technique totally unsuitable for reference measurements after the introduction of ethylene glycol to the test gas. The fibre-optic sensor hygrometer and the CaC2-GC hygrometer showed minor response for ethylene glycol. In general the results from this work demonstrate the need for careful evaluation of individual moisture monitoring applications, before choosing a hygrometer. A well-considered strategy for quality control of the moisture monitoring, regardless of the chosen hygrometer, is of utmost importance to establish a moisture monitoring system with high accuracy. © 2013 Elsevier B.V. Source

Nilsson U.,Swedish University of Agricultural Sciences | Elfving B.,Swedish University of Agricultural Sciences | Karlsson K.,ASA Research
Silva Fennica | Year: 2012

Productivity of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) was studied in 12 paired plots in the interior of northern Sweden. Stands were established between 1928 and 1959; yield plots were established between 1974 and 1983 during precommercial thinning of the stands. Gross stem-wood production was significantly higher for Scots pine than for Norway spruce, stem-wood production by Norway spruce being 29.4% that of Scots pine. The site index for Norway spruce was lower than for Scots pine at all sites except one; the average difference in site index was 4.8 m. The simulated maximum mean annual increment (MAImax) during the rotation was 19% higher than the MAImax estimated with the site index for Scots pine, whereas simulated MAImax and MAImax estimated from the site index was about the same for Norway spruce. The simulations also indicated that MAI peaked about 50 years later for Norway spruce than for Scots pine. More small trees were included in the diameter distribution of Norway spruce than of Scots pine resulting in a lower stem-wood volume for Norway spruce when stands with the same dominant height were compared. This study shows that the difference in growth and rotation length between Scots pine and Norway spruce has implications when choosing which species to grow in the interior of northern Sweden. Source

Elkasabi Y.,U.S. Department of Agriculture | Mullen C.A.,U.S. Department of Agriculture | Pighinelli A.L.M.T.,U.S. Department of Agriculture | Pighinelli A.L.M.T.,ASA Research | Boateng A.A.,U.S. Department of Agriculture
Fuel Processing Technology | Year: 2014

In this paper, we sought to elucidate the relationships between biomass feedstock type and the suitability of their fast-pyrolysis bio-oils for hydrodeoxygenation (HDO) upgrading. Switchgrass, Eucalyptus benthamii, and equine manure feedstocks were pyrolyzed into bio-oil using a continuous fast-pyrolysis system. We also synthesized variations of switchgrass bio-oil using catalytic pyrolysis methods (HZSM-5 catalyst or tail-gas recycle method). Bio-oil samples underwent batch HDO reactions at 320 C under ~ 2100 psi H 2 atmosphere for 4 h, using Pt, Ru, or Pd on carbon supports. Hydrogen consumption was measured and correlated with compositional trends. The resulting organic, aqueous, and gas phases were analyzed for their chemical compositions. Mass balances indicate little coke formation. Switchgrass bio-oil over Pt/C performed the best in terms of hydrogen consumption efficiency, deoxygenation efficiency, and types of upgraded bio-oil compounds. Eucalyptus feedstocks consistently consumed more than twice the normal amount of hydrogen gas per run, primarily due to the elevated syringol content. Catalytically pyrolyzed bio-oils deoxygenated poorly over Pt/C but hydrogenated more extensively than other oils. Although the relative deoxygenation (%DO rel) varied based on feedstock and catalyst, the absolute deoxygenation (%DOabs) depended only on the overall yield. The total extent of upgrading (hydrogenation + deoxygenation) remained independent of feedstock and catalyst. © 2014 Elsevier B.V. Source

Portz G.,University of Sao Paulo | Molin J.P.,University of Sao Paulo | Jasper J.,ASA Research
Precision Agriculture | Year: 2012

Nitrogen management has been intensively studied on several crops and recently associated with variable rate on-the-go application based on crop sensors. Such studies are scarce for sugarcane and as a biofuel crop the energy input matters, seeking high positive energy balance production and low carbon emission on the whole production system. This article presents the procedure and shows the first results obtained using a nitrogen and biomass sensor (N-Sensor ™ ALS, Yara International ASA) to indicate the nitrogen application demands of commercial sugarcane fields. Eight commercial fields from one sugar mill in the state of São Paulo, Brazil, varying from 15 to 25 ha in size, were monitored. Conditions varied from sandy to heavy soils and the previous harvesting occurred in May and October 2009, including first, second, and third ratoon stages. Each field was scanned with the sensor three times during the season (at 0.2, 0.4, and 0.6 m stem height), followed by tissue sampling for biomass and nitrogen uptake at ten spots inside the area, guided by the different values shown by the sensor. The results showed a high correlation between sensor values and sugarcane biomass and nitrogen uptake, thereby supporting the potential use of this technology to develop algorithms to manage variable rate application of nitrogen for sugarcane. © 2011 Springer Science+Business Media, LLC. Source

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