Nyberg M.,Uppsala University |
Heidorn T.,Postboks 115 As |
Lindblad P.,Uppsala University
Journal of Biotechnology | Year: 2015
Nitrogenase based hydrogen production was examined in a δhupW strain of the filamentous heterocystous cyanobacterium Nostoc PCC 7120, i.e., cells lacking the last step in the maturation system of the large subunit of the uptake hydrogenase and as a consequence with a non-functional uptake hydrogenase. The cells were grown in a developed flat panel photobioreactor system with 3.0L culture volume either aerobically (air) or anaerobically (Ar or 80% N2/20% Ar) and illuminated with a mixture of red and white LED. Aerobic growth of the δhupW strain of Nostoc PCC 7120 at 44μmolar photons m-2s-1 PAR gave the highest hydrogen production of 0.7mL H2 L-1h-1, 0.53mmol H2 mg chlorophyll a-1h-1, and a light energy conversion efficiency of 1.2%. Anaerobic growth using 100% argon showed a maximal hydrogen production of 1.7mLL-1h-1, 0.85mmol per mg chlorophyll a-1 h-1, and a light energy conversion efficiency of 2.7%. Altering between argon/N2 (20/80) and 100% argon phases resulted in a maximal hydrogen production at hour 128 (100% argon phase) with 6.2mL H2L-1h-1, 0.71mL H2 mg chlorophyll a-1h-1, and a light energy efficiency conversion of 4.0%. The highest buildup of hydrogen gas observed was 6.89% H2 (100% argon phase) of the total photobioreactor system with a maximal production of 4.85mL H2 L-1h-1. The present study clearly demonstrates the potential to use purpose design cyanobacteria in developed flat panel photobioreactor systems for the direct production of the solar fuel hydrogen. Further improvements in the strain used, environmental conditions employed, and growth, production and collection systems used, are needed before a sustainable and economical cyanobacterial based hydrogen production can be realized. © 2015 Elsevier B.V.
Ohm M.,Thunen Institute of Organic Farming |
Schuler M.,Thunen Institute of Organic Farming |
Fystro G.,Postboks 115 As |
Paulsen H.M.,Thunen Institute of Organic Farming
Landbauforschung Volkenrode | Year: 2015
Limited knowledge is available on inner farm nutrient transfer from organic grassland to arable land in organic farms. This study quantifies the phosphorus (P) mobilization of permanent grassland and different arable crops for inner farm P transfer and discusses in how far P reserves in grassland soils can be a component of sufficiency P management in organic farming. A North German organic dairy farm with sufficient soil P supply is analyzed. Over three years its P balance showed an average deficit of 7.9 kg ha-1 yr1 in permanent grassland and 10.9 kg ha-1 yr1 in arable land. Maize (30.5 kg P ha-1 yr1), grass-clover (23.9 kg P ha-1 yr1) and mixed faba bean and oats (19.8 kg P ha-1 yr1) had the highest P uptake in cropland. At grassland, grazing intake of P by livestock was 15.9 kg P ha-1 yr1 and via storage feed and manure it directly fed arable land with 64 kg P yr1 (average 1 kg P ha-1 yr1). Especially on grassland, soil P mining does not endanger soil fertility yet, according to sufficient available P-contents in the soils (CAL-extract averages [mg 100 g-1 P]: grassland 14.7, arable land 6.7). Generally, the inclusion of unexploited grassland sites with high soil P contents in farm nutrient flows (via feed conserves for livestock or biogas) would address unused soil P reserves for redistribution.
Kassi P.,Natural Resources Institute Finland |
Kankanen H.,Natural Resources Institute Finland |
Niskanen O.,Natural Resources Institute Finland |
Lehtonen H.,Natural Resources Institute Finland |
Hoglind M.,Postboks 115 As
Biosystems Engineering | Year: 2015
Cattle feeding in Northern Europe is based on grass silage, but grass growth is highly dependent on weather conditions. If ensuring sufficient silage availability in every situation is prioritised, the lowest expected yield level determines the cultivated area in farmers' decision-making. One way to manage the variation in grass yield is to increase grass production and silage storage capacity so that they exceed the annual consumption at the farm. The cost of risk management in the current and the projected future climate was calculated taking into account grassland yield and yield variability for three study areas under current and mid-21st century climate conditions. The dataset on simulated future grass yields used as input for the risk management calculations were taken from a previously published simulation study. Strategies investigated included using up to 60% more silage grass area than needed in a year with average grass yields, and storing silage for up to 6 months more than consumed in a year (buffer storage). According to the results, utilising an excess silage grass area of 20% and a silage buffer storage capacity of 6 months were the most economic ways of managing drought risk in both the baseline climate and the projected climate of 2046-2065. It was found that the silage yield risk due to drought is likely to decrease in all studied locations, but the drought risk and costs implied still remain significant. © 2015 IAgrE.
Anton-Fernandez C.,Postboks 115 As |
Froese R.E.,Michigan Technological University
Canadian Journal of Forest Research | Year: 2015
We present a revised estimator for the sampling error of local competition variables that builds on the conceptual framework given by Stage and Wykoff (Stage, A.R., and Wykoff, W.R. For. Sci. 44(2): 224–238, 1998). Accurate estimation of the sampling error of local competition variables is a requisite for most approaches that correct the effects of measurement error in model fitting and application. Our revision addresses the bias inherent in Stage and Wykoff’s estimator due to the overlapping of random samples that are constrained to include a subject tree. We also argue that the adjustment that Stage and Wykoff used to account for the absence of treeless plots (zero truncation) is unnecessary. We illustrate the performance of the new estimator and the estimator of Stage and Wykoff through simulation. For a hypothetical Poisson forest (800 trees·ha−1; mean diameter at breast height, 9.8 cm), bias is negligible for the new estimator, and variance is reduced by 92%. © 2015, National Research Council of Canada, All rights reserved.
Hoibo O.,Norwegian University of Life Sciences |
Hansen E.,Oregon State University |
Nybakk E.,Postboks 115 As
Canadian Journal of Forest Research | Year: 2015
As societies urbanize, a growing proportion of the global population and an increasing number of housing units will be needed in urban areas. High-rise buildings and environmentally friendly, renewable materials must play important roles in sustainable urban development. To achieve this, it is imperative that policy makers, planners, architects, and construction companies understand consumer preferences. We use data from urban dwellers in the Oslo region of Norway to develop an understanding of material preferences in relation to environmental attitudes and knowledge about wood. We emphasise wood compared with other building materials in various applications (structural, exterior, and interior) within urban apartment blocks. We use 503 responses from a web panel. Our findings show that Oslo area consumers tend to prefer materials other than wood in various applications in apartment blocks, especially structural applications. Still, some respondent prefer wood, including some applications in apartment blocks where wood is currently not commonly used. The best target for wood-based urban housing includes younger people who have strong environmental values. As environmental attitudes evolve in society and a greater proportion of consumers search out environmentally friendly product alternatives, the opportunities for wood to gain market share will most likely increase. © 2015, National Research Council of Canada, All Rights Reserved.
Woolliams J.A.,Roslin Institute |
Berg P.,Postboks 115 As |
Dagnachew B.S.,Norwegian University of Life Sciences |
Meuwissen T.H.E.,Norwegian University of Life Sciences
Journal of Animal Breeding and Genetics | Year: 2015
Genetic contributions were first formalized in 1958 by James and McBride (Journal of Genetics, 56, 55-62) and have since been shown to provide a unifying framework for theories of gain and inbreeding. As such they have underpinned the development of methods that provide the most effective combination of maximizing gain whilst managing inbreeding and loss of genetic variation. It is shown how this optimum contribution technology can be developed from theory and adapted to provide practical selection protocols for a wide variety of situations including overlapping generations and multistage selection. The natural development of the theory to incorporate genomic selection and genomic control of inbreeding is also shown. © 2015 Blackwell Verlag GmbH.
Breidenbach J.,Postboks 115 As |
McRoberts R.E.,U.S. Department of Agriculture |
Astrup R.,Postboks 115 As
Remote Sensing of Environment | Year: 2016
Due to the availability of good and reasonably priced auxiliary data, the use of model-based regression-synthetic estimators for small area estimation is popular in operational settings. Examples are forest management inventories, where a linking model is used in combination with airborne laser scanning data to estimate stand-level forest parameters where no or too few observations are collected within the stand. This paper focuses on different approaches to estimating the variances of those estimates. We compared a variance estimator which is based on the estimation of superpopulation parameters with variance estimators which are based on predictions of finite population values. One of the latter variance estimators considered the spatial autocorrelation of the residuals whereas the other one did not. The estimators were applied using timber volume on stand level as the variable of interest and photogrammetric image matching data as auxiliary information. Norwegian National Forest Inventory (NFI) data were used for model calibration and independent data clustered within stands were used for validation. The empirical coverage proportion (ECP) of confidence intervals (CIs) of the variance estimators which are based on predictions of finite population values was considerably higher than the ECP of the CI of the variance estimator which is based on the estimation of superpopulation parameters. The ECP further increased when considering the spatial autocorrelation of the residuals. The study also explores the link between confidence intervals that are based on variance estimates as well as the well-known confidence and prediction intervals of regression models. © 2015.
Anton-Fernandez C.,Postboks 115 As |
Mola-Yudego B.,Postboks 115 As |
Dalsgaard L.,Postboks 115 As |
Astrup R.,Postboks 115 As
Canadian Journal of Forest Research | Year: 2016
The present study aims to develop biologically sound and parsimonious site index models for Norway to predict changes in site index (SI) under different climatic conditions. The models are constructed using data from the Norwegian National Forest Inventory and climate data from the Norwegian meteorological institute. Site index was modeled using the potential modifier functional form, with a potential component (POT) depending on site quality classes and two modifier components (MOD): temperature and moisture. Each of these modifiers was based on a portfolio of candidate variables. The best model for spruce-dominated stands included temperature as modifier (R2 = 0.56). In the case of pine- and deciduous-dominated stands, the best models included both modifiers (R2 = 0.40 and 0.54 for temperature and moisture, respectively). We illustrate the use of the models by analyzing the possible shift in SI for year 2100 under one (RCP4.5) of the benchmark scenarios adopted by the Intergovernmental Panel on Climate Change for its fifth assessment report. The models presented can be valuable for evaluating the effect of climate change scenarios in Norwegian forests. © 2016, National Research Council of Canada. All rights reserved.