Showing papers by "Swedish University of Agricultural Sciences published in 1997"
TL;DR: Measurements of δ15 N might offer the advantage of giving insights into the N cycle without disturbing the system by adding 15 N tracer, as well as giving information on N source effects, which can give insights into N cycle rates.
Abstract: Equilibrium and kinetic isotope fractionations during incomplete reactions result in minute differences in the ratio between the two stable N isotopes, 15N and 14N, in various N pools. In ecosystems such variations (usually expressed in per mil [δ15N] deviations from the standard atmospheric N2) depend on isotopic signatures of inputs and outputs, the input–output balance, N transformations and their specific isotope effects, and compartmentation of N within the system. Products along a sequence of reactions, e.g. the N mineralization–N uptake pathway, should, if fractionation factors were equal for the different reactions, become progressively depleted. However, fractionation factors vary. For example, because nitrification discriminates against 15N in the substrate more than does N mineralization, NH4+ can become isotopically heavier than the organic N from which it is derived.Levels of isotopic enrichment depend dynamically on the stoichiometry of reactions, as well as on specific abiotic and biotic conditions. Thus, the δ15N of a specific N pool is not a constant, and δ15N of a N compound added to the system is not a conservative, unchanging tracer. This fact, together with analytical problems of measuring δ15N in small and dynamic pools of N in the soil–plant system, and the complexity of the N cycle itself (for instance the abundance of reversible reactions), limit the possibilities of making inferences based on observations of 15N abundance in one or a few pools of N in a system. Nevertheless, measurements of δ15N might offer the advantage of giving insights into the N cycle without disturbing the system by adding 15N tracer.Such attempts require, however, that the complex factors affecting δ15N in plants be taken into account, viz. (i) the source(s) of N (soil, precipitation, NOx, NH3, N2-fixation), (ii) the depth(s) in soil from which N is taken up, (iii) the form(s) of soil-N used (organic N, NH4+, NO3−), (iv) influences of mycorrhizal symbioses and fractionations during and after N uptake by plants, and (v) interactions between these factors and plant phenology. Because of this complexity, data on δ15N can only be used alone when certain requirements are met, e.g. when a clearly discrete N source in terms of amount and isotopic signature is studied. For example, it is recommended that N in non-N2-fixing species should differ more than 5‰ from N derived by N2-fixation, and that several non-N2-fixing references are used, when data on δ15N are used to estimate N2-fixation in poorly described ecosystems.As well as giving information on N source effects, δ15N can give insights into N cycle rates. For example, high levels of N deposition onto previously N-limited systems leads to increased nitrification, which produces 15N-enriched NH4+ and 15N-depleted NO3−. As many forest plants prefer NH4+ they become enriched in 15N in such circumstances. This change in plant δ15N will subsequently also occur in the soil surface horizon after litter-fall, and might be a useful indicator of N saturation, especially since there is usually an increase in δ15N with depth in soils of N-limited forests.Generally, interpretation of 15N measurements requires additional independent data and modelling, and benefits from a controlled experimental setting. Modelling will be greatly assisted by the development of methods to measure the δ15N of small dynamic pools of N in soils. Direct comparisons with parallel low tracer level 15N studies will be necessary to further develop the interpretation of variations in δ15N in soil–plant systems. Another promising approach is to study ratios of 15N[ratio ]14N together with other pairs of stable isotopes, e.g. 13C[ratio ]12C or 18O[ratio ]16O, in the same ion or molecules. This approach can help to tackle the challenge of distinguishing isotopic source effects from fractionations within the system studied.
1,518 citations
TL;DR: The most appropriate management practices to increase soil carbon sink capacity vary regionally, dependent on both environmental and socioeconomic factors as discussed by the authors. But, effective mitigation policies will not be based on any single ‘magic bullet’ solutions, but rather on many modest reductions which are economically efficient and which confer additional benefits to society.
Abstract: . Agricultural soils, having been depleted of much of their native carbon stocks, have a significant CO2 sink capacity. Global estimates of this sink capacity are in the order of 20-30 Pg C over the next 50-100 years. Management practices to build up soil C must increase the input of organic matter to soil and/or decrease soil organic matter decomposition rates. The most appropriate management practices to increase soil C vary regionally, dependent on both environmental and socioeconomic factors.
In temperate regions, key strategies involve increasing cropping frequency and reducing bare fallow, increasing the use of perennial forages (including N-fixing species) in crop rotations, retaining crop residues and reducing or eliminating tillage (i.e. no-till). In North America and Europe, conversion of marginal arable land to permanent perennial vegetation, to protect fragile soils and landscapes and/or reduce agricultural surpluses, provides additional opportunities for C sequestration.
In the tropics, increasing C inputs to soil through improving the fertility and productivity of cropland and pastures is essential. In extensive systems with vegetated fallow periods (e.g. shifting cultivation), planted fallows and cover crops can increase C levels over the cropping cycle. Use of no-till, green manures and agroforestry are other beneficial practices. Overall, improving the productivity and sustainability of existing agricultural lands is crucial to help reduce the rate of new land clearing, from which large amounts of CO2 from biomass and soil are emitted to the atmosphere.
Some regional analyses of soil C sequestration and sequestration potential have been performed, mainly for temperate industrialized countries. More are needed, especially for the tropics, to capture region-specific interactions between climate, soil and management resources that are lost in global level assessments.
By itself, C sequestration in agricultural soils can make only modest contributions (e.g. 3-6% of total fossil C emissions) to mitigating greenhouse gas emissions. However, effective mitigation policies will not be based on any single ‘magic bullet’ solutions, but rather on many modest reductions which are economically efficient and which confer additional benefits to society. In this context, soil C sequestration is a significant mitigation option. Additional advantages of pursuing strategies to increase soil C are the added benefits of improved soil quality for improving agricultural productivity and sustainability.
720 citations
TL;DR: In this article, the authors found a significant relationship between island area and plant species composition, which was found to be a major factor in determining several ecosystem-level properties of these islands, including standing biomass, plant litter decomposition, nitrogen mineralization, terrestrial carbon partitioning, humus accumulation, and plant nitrogen acquisition.
Abstract: Island area is frequently a major determinant of the species composition of biological communities; community structure, in turn, often has important effects on ecosystem-level properties. Fifty islands of varying area were selected in an archipelago in the northern Swedish boreal forest zone, in which larger islands burn more frequently than smaller ones through wildfire arising from lightning strike, thus inducing a significant relationship between island area and plant species composition. This relationship was found to be a major factor in determining several ecosystem-level properties of these islands, including standing biomass, plant litter decomposition, nitrogen mineralization, terrestrial carbon partitioning, humus accumulation, and plant nitrogen acquisition.
577 citations
TL;DR: In this article, the economic rationale for the spike models and their estimation techniques are discussed, and empirical illustrations are provided, which have some bearing on the continuing debate of the incentive properties of hypothetical surveys and the construction of scenarios in contingent valuation experiments.
Abstract: Spike models allow for a nonzero probability of zero willingness to pay in referendum-style contingent valuation experiments. They include many of the often used models as special cases and allow various analyses that are not possible in standard applications. In this paper, the economic rationale for the spike models and their estimation techniques are discussed, and empirical illustrations are provided. One study suggests that mean willingness to pay is zero, and both studies strongly suggest that median WTP is zero. These results have some bearing on the continuing debate of the incentive properties of hypothetical surveys and the construction of scenarios in contingent valuation experiments.
538 citations
TL;DR: A review of information related to low molecular weight metal chelators isolated from wood decay fungi is presented in this paper, where the presence of the chelator in wood degraded by G. trabeum has been demonstrated by ELISA and TEM immunolabelling studies.
419 citations
385 citations
TL;DR: In this article, the authors address the emissions and possible control of the three greenhouse gases by different managements of organic soils, and present the present trace gas fluxes from these soils, as well as predictions of future emissions under alternative management regimes.
Abstract: . The large boreal peatland ecosystems sequester carbon and nitrogen from the atmosphere due to a low oxygen pressure in waterlogged peat. Consequently they are sinks for CO2 and strong emitters of CH4. Drainage and cultivation of peatlands allows oxygen to enter the soil, which initiates decomposition of the stored organic material, and in turn CO2 and N2O emissions increase while CH4 emissions decrease. Compared to undrained peat, draining of organic soils for agricultural purposes increases the emissions of greenhouse gases (CO2, CH4, and N2O) by roughly 1t CO2 equivalents/ha per year. Although farmed organic soils in most European countries represent a minor part of the total agricultural area, these soils contribute significantly to national greenhouse gas budgets. Consequently, farmed organic soils are potential targets for policy makers in search of socially acceptable and economically cost-efficient measures to mitigate climate gas emissions from agriculture. Despite a scarcity of knowledge about greenhouse gas emissions from these soils, this paper addresses the emissions and possible control of the three greenhouse gases by different managements of organic soils. More precise information is needed regarding the present trace gas fluxes from these soils, as well as predictions of future emissions under alternative management regimes, before any definite policies can be devised.
351 citations
TL;DR: In this article, the effects of different exchange rates of inorganic N with sources and sinks external to the ecosystem (e.g., through de-position and leaching) and different initial ratios of net: gross N mineralization on the responses to an instantaneous doubling of CO2 concen- tration in a 350-yr-old eastern deciduous forest were examined.
Abstract: Ecosystem responses to increased CO2 are often constrained by nutrient limitation. We present a model of multiple-element limitation (MEL) and use it to analyze constraints imposed by N on the responses to an instantaneous doubling of CO2 concen- tration in a 350-yr-old eastern deciduous forest. We examine the effects of different exchange rates of inorganic N with sources and sinks external to the ecosystem (e.g., through de- position and leaching) and different initial ratios of net: gross N mineralization. Both of these factors influence the availability of N to vegetation and, therefore, have important effects on ecosystem responses to increased CO2. We conclude that reliable assessments of ecosystem responses to CO2 will require a better understanding of both these factors. The responses to increased CO2 appear on at least four characteristic time scales. (1) There is an instantaneous increase in net primary production, which results in an increase in the vegetation C:N ratio. (2) On a time scale of a few years, the vegetation responds by increasing uptake effort for available N (e.g., through increased allocation of biomass, energy, and enzymes to fine roots). (3) On a time scale of decades, there is a net movement of N from soil organic matter to vegetation, which enables vegetation biomass to accumulate. (4) On the time scale of centuries, ecosystem responses are dominated by increases in total ecosystem N, which enable organic matter to accumulate in both vegetation and soils. In general, short-term responses are markedly different from long-term responses.
328 citations
TL;DR: In this article, the authors used a mathematical approach in an effort to highlight some facts that might help address this question, such as whether there is a biochemical link between the tocopherol levels and the degree of unsaturation in vegetable oils.
Abstract: The main biochemical function of the tocopherols is believed to be the protection of polyunsaturated fatty acids (PUFA) against peroxidation. A critical question that must be asked in reference to this is whether there is a biochemical link between the tocopherol levels and the degree of unsaturation in vegetable oils, the main source of dietary PUFA and vitamin E. We used a mathematical approach in an effort to highlight some facts that might help address this question. Literature data on the relative composition of fatty acids (16:0, 16:1, 18:0, 18:1, 18:2, and 18:3) and the contents of tocopherols (α-, β-, δ-, and γ-tocopherol) in 101 oil samples, including 14 different botanical species, were analyzed by principal-component analysis and linear regression. There was a negative correlation between α- and γ-tocopherols (r=0.633, P<0.05). Results also showed a positive correlation between linoleic acid (18:2) and α-tocopherol (r=0.549, P<0.05) and suggested a positive correlation between linolenic acid (18:3) and γ-tocopherol.
301 citations
TL;DR: This report shows for the first time that over-expression of the oat phytochrome A gene (PHYA) in a tree significantly changes the critical daylength and effectively prevents cold acclimatization, and indicates that photoperiodic responses in trees might be regulated by the amount of PHYA gene expressed in the plants, and that the amounts of phy tochrome A (phyA) affects the metabolism of GAs and IAA.
Abstract: Survival of temperate-zone tree species under the normal summer-winter cycle is dependent on proper timing of apical growth cessation and cold acclimatization. This timing is primarily based on the perception of daylength, and through evolution many tree species have developed photoperiodic ecotypes which are closely adapted to the local light conditions. The longest photoperiod inducing growth cessation, the critical photoperiod, is inherited as a quantitative character. The phytochrome pigment family is the probable receptor of daylength, but the exact role of phytochrome and the physiological basis for the different responses between photoperiodic ecotypes are not known. This report shows for the first time that over-expression of the oat phytochrome A gene (PHYA) in a tree significantly changes the critical daylength and effectively prevents cold acclimatization. While the critical daylength for elongation growth in the wild-type of hybrid aspen (Populus tremula × tremuloides) was approximately 15 h, transgenic lines with a strong expression of the oat PHYA gene did not stop growing even under a photoperiod of 6 h. Quantitative analysis of gibberellins (GA) as well as indole-3-acetic acid (IAA) revealed that levels of these were not down-regulated under short days in the transgenic plants expressing high levels of oat PHYA, as in the wild-type. These results indicate that photoperiodic responses in trees might be regulated by the amount of PHYA gene expressed in the plants, and that the amount of phytochrome A (phyA) affects the metabolism of GAs and IAA.
292 citations
TL;DR: Comparisons between sets of naturally occurring maternal half–sibling collared flycatchers demonstrate that genetic benefits from mate choice can be predicted by the size of a secondary sexual character, and therefore provide direct support for indicator models of sexual selection.
Abstract: Whether females can obtain genetic benefits from mate choice is contentious, and the main problem faced by previous studies of natural populations is that many factors other than paternal genes contribute to offspring fitness. Here, we use comparisons between sets of naturally occurring maternal half-sibling collared flycatchers, Ficedula albicollis, to control for this problem. We show, first, that there are paternal genetic effects on nestling fledging condition, a character related to fitness in this species. Further, the magnitude of the paternal genetic contribution to this character is related to the size of a condition-dependent male secondary sexual character. Our results demonstrate that genetic benefits from mate choice can be predicted by the size of a secondary sexual character, and therefore provide direct support for indicator models of sexual selection.
TL;DR: In this paper, a total of 517 species (148 vascular plants, 131 mosses, 64 hepatics, 142 lichens and 32 wood-inhabiting fungi) from 10 small remnants of boreal old-growth swamp forests were reported.
TL;DR: It is suspected that at least six of the nine cases were caused by gravad or cold-smoked rainbow trout made by producer Y, which is the first rainbow trout-borne outbreak of listeriosis ever reported.
Abstract: An outbreak of listeriosis in Sweden, consisting of nine cases, was investigated by means of molecular typing of strains from patients and strains isolated from suspected foodstuffs, together with interviews of the patients. Listeria monocytogenes was isolated from six of the patients, and all isolates were of the same clonal type. This clonal type was also isolated from a "gravad" rainbow trout, made by producer Y, found in the refrigerator of one of the patients. Unopened packages obtained from producer Y were also found to contain the same clonal type of L. monocytogenes. Based on the interview results and the bacteriological typing, we suspect that at least six of the nine cases were caused by gravad or cold-smoked rainbow trout made by producer Y. To our knowledge, this is the first rainbow trout-borne outbreak of listeriosis ever reported.
TL;DR: Heritability estimates indicate that mutations causing albinism were at least partly of germline origin, and evidence for an increased germline mutation rate was obtained from segregation analysis at two hypervariable microsatellite loci, indicating that mutation events in barn swallows from Chernobyl were two- to tenfold higher than in birds from control areas in Ukraine and Italy.
Abstract: The severe nuclear accident at Chernobyl in 1986 resulted in the worst reported accidental exposure of radioactive material to free-living organisms1. Short-term effects on human populations inhabiting polluted areas include increased incidence of thyroid cancer2, infant leukaemia3, and congenital malformations in newborns4. Two recent studies5,6 have reported, although with some controversy7,8, that germline mutation rates were increased in humans and voles living close to Chernobyl, but little is known about the viability of the organisms affected9. Here we report an increased frequency of partial albinism, a morphological aberration associated with a loss of fitness, among barn swallows, Hirundo rustica, breeding close to Chernobyl. Heritability estimates indicate that mutations causing albinism were at least partly of germline origin. Furthermore, evidence for an increased germline mutation rate was obtained from segregation analysis at two hypervariable microsatellite loci, indicating that mutation events in barn swallows from Chernobyl were two- to tenfold higher than in birds from control areas in Ukraine and Italy.
TL;DR: Analysis of radial distribution pattern of indole-3-acetic acid in the stem of hybrid aspen indicates that IAA has a role in regulating not only the rate of physiological processes such as cell division, but also the duration of developmental processessuch as xylem fiber expansion, suggesting that I AA functions as a morphogen, conveying positional information duringxylem development.
Abstract: The radial distribution pattern of indole-3-acetic acid (IAA) was determined across the developing tissues of the cambial region in the stem of hybrid aspen (Populus tremula L. x Populus tremuloides Michx). IAA content was measured in consecutive tangential cryo-sections using a microscale mass spectrometry technique. Analysis was performed with wild-type and transgenic trees with an ectopic expression of Agrobacterium tumefaciens IAA-biosynthetic genes. In all tested trees IAA was distributed as a steep concentration gradient across the developing tissues of the cambial region. The peak level of IAA was within the cambial zone, where cell division takes place. Low levels were reached in the region where secondary wall formation was initiated. The transgenic trees displayed a lower peak level and a wider radial gradient of IAA compared with the wild type. This alteration was related to a lower rate of cambial cell division and a longer duration of xylem cell expansion in the transgenic trees, resulting in a decreased xylem production and a larger fiber lumen area. The results indicate that IAA has a role in regulating not only the rate of physiological processes such as cell division, but also the duration of developmental processes such as xylem fiber expansion, suggesting that IAA functions as a morphogen, conveying positional information during xylem development.
TL;DR: More than 200 angiosperms, distributed in 25 genera, develop root nodule symbioses (actinorhizas) with soil bacteria of the actinomycetous genus Frankia as mentioned in this paper.
Abstract: summary
More than 200 angiosperms, distributed in 25 genera, develop root nodule symbioses (actinorhizas) with soil bacteria of the actinomycetous genus Frankia. Although most soils studied contain infective Frankia, cultured strains are available only after isolation from root nodules. Frankia infects roots via root hairs in some hosts or via intercellular penetration in others. The nodule originates in the pericycle. The number of nodules in Alnus is determined by the plant in an autoregulated process that, in turn, is modulated by nutrients such as nitrogen and phosphate. Except in the genera Allocausarina and Casuarina, Frankia in nodules develops so-called vesicles where nitrogenase is localized. Sporulation of Frankia occurs in some symbioses. As a group, actinorhizal plants show a large range of anatomical and biochemical adaptations in order to balance the oxygen tension near nitrogenase. In symbioses with well aerated nodule tissue like Alnus, the vesicles have a multilayered envelope composed mainly of lipids, bacterio-hopanetetrol and their derivatives. This envelope is assumed to retard the diffusion of oxygen into the nitrogenase-containing vesicle. In symbioses like Casuarina, the infected plant cells themselves, rather than Frankia, appear to retard oxygen diffusion, and high concentrations of haemoglobin indicate an infected region with a low oxygen tension. At least in Alnus spp., ammonia resulting from N2 fixation is assimilated by glutamine synthetase in the plant. The carbon compound(s) used by Frankia in nodules is not yet known. Nitrogenase activity decreases in response to a number of environmental factors but recovers upon return to normal conditions. This dynamism in nitrogenase activity is often explained by loss and recovery of active nitrogenase and has been traced to loss and recovery of the nitrogenase proteins themselves. Recovery is partly due to growth of Frankia and to development of new vesicles in the Alnus nodules. In the field, varying conditions continuously affect the plants and the measured rate of N2 fixation is a result not only of the conditions prevailing at the moment but also of the conditions experienced over preceding days. N2 fixed by actinorhizal plants is substantial and actinorhizal plants have great potential in soil reclamation and in various types of forestry. Several species are also useful in horticulture.
TL;DR: It is concluded that most ectomycorrhizas formed by the 44 investigated species should be recognized by comparison with this dataset, if the mycorrhIZas are sampled from a site located in Fennoscandia, but in datasets from even larger geographical areas encompassing a higher degree of intraspecific variation in the ITS region, it might be necessary to include local reference species.
Abstract: Interspecific and intraspecific variation in the internal transcribed spacer (ITS) region of rDNA of ectomycorrhizal fungi of 44 species in 17 genera were examined using the restriction fragment length polymorphism (RFLP) method. For each species, two to five herbarium vouchers (mainly basidiocarps), collected throughout Fennoscandia, were examined. The ITS region was amplified using the polymerase chain reaction (PCR) and the universal primers ITS1 and ITS4, and subjected to RFLP analysis with three endonucleases. Intraspecific polymorphisms in the ITS region were found in seven species (in nine of the 132 herbarium vouchers). Polymorphisms were due to length mutations, ranging from 5 to 15 bp in four of the seven polymorphic species and mutations in endonuclease restriction sites in six species, mostly affecting only one endonuclease, but in two species two endonucleases. Using a single endonuclease, a unique RFLP pattern could be obtained for more than half the investigated species. By combining different endonucleases, 34 (77%) of the species could be distinguished from another. The remaining RFLP types occurred in one genus. On the basis of the low intra- but high interspecific variation in the ITS region, it is concluded that most ectomycorrhizas formed by the 44 investigated species should be recognized by comparison with this dataset, if the mycorrhizas are sampled from a site located in Fennoscandia. However, in datasets from even larger geographical areas encompassing a higher degree of intraspecific variation in the ITS region, or when mycorrhizas from several sites distant from each other are compared, it might be necessary to include local reference species.
TL;DR: In this paper, the authors present management options for three major site types in boreal Sweden which mimic natural dynamics better than traditional forestry, including Scots pine forest, deciduous or Norway spruce dominated forest, and Norway Spruce forest regenerated by so-called gap dynamics.
TL;DR: The low microsatellite density in the genome in general and on the microchromosomes in particular imposes an obstacle for the development of marker-rich genetic maps of chicken and other birds, and for the localization of quantitative trait genes.
Abstract: A better insight into the occurrence of microsatellites in a range of taxa may help to understand the evolution of simple repeats. Previous studies have found the relative abundance of several repeat motifs to differ among mammals, invertebrates, and plants. Absolute numbers of microsatellites also tend to correlate positively with genome size. We analyzed the occurrence, frequency, and distribution of microsatellites in birds, a taxon with one of the smallest known genome sizes among vertebrates. Dot-blot hybridization revealed that about half of 22 different di-, tri-, and tetranucleotide repeat motifs were clearly more common in human than in three species of birds: chicken, woodpecker, and swallow. For the remaining motifs no clear difference was found. From searching avian database sequences we estimated there to be 30,000-70,000 microsatellites longer than 20 bp in the avian genome. The number of (CA) > or = 10 would be around 7000-9000 and the number of (CA) > or = 14 about 3000. The calculated density of avian microsatellites (total, one every 20-39 kb; (CA) > or = 10, one every 136-150 kb) is much lower than that estimated for the human genome (one every 6 and 30 kb, respectively). This may be explained by the fact that the avian genome contains relatively less noncoding DNA than most mammals and that avian SINE/LINE elements do not terminate in poly(A) tails, which are known to provide a resource for the evolution of simple repeats in mammals. We found no association between microsatellites and SINEs in birds. Primed in situ labeling suggested fairly even distribution of (CA)n repeats over chicken macrochromosomes and intermediate chromosomes, whereas the microchromosomes, a large part of the Z and W chromosomes, and most telomeres and centromeres had very low concentrations of (CA)n microsatellites. The scarcity of microsatellites on the microchromosomes is compatible to these regions likely being unusually rich in coding sequences. The low microsatellite density in the genome in general and on the microchromosomes in particular imposes an obstacle for the development of marker-rich genetic maps of chicken and other birds, and for the localization of quantitative trait genes.
TL;DR: In this article, the authors evaluated the health and productivity of Sweden's forests by posing a number of specific questions, and synthesized information from the extensive research in Sweden on N deposition, fertilization and forest growth.
TL;DR: The aim has been to crystallographically demonstrate substrate binding and to locate the two effector-binding sites of RNR R1, and to conclude that the general allosteric effector site, located far from the active site, appears to regulate subunit interactions within the holoenzyme.
TL;DR: In this paper, the authors outline a standard methodology for comparing the greenhouse gas balances of bioenergy systems with those of fossil energy systems, focusing on a careful definition of system boundaries, and give some recommendations on how bio-energy systems should be optimized from a greenhouse gas emissions point of view.
Abstract: In this paper, which was prepared as part of IEA Bioenergy Task XV (“Greenhouse Gas Balances of Bioenergy Systems”), we outline a standard methodology for comparing the greenhouse gas balances of bioenergy systems with those of fossil energy systems. Emphasis is on a careful definition of system boundaries. The following issues are dealt with in detail: time interval analysed and changes of carbon stocks; reference energy systems; energy inputs required to produce, process and transport fuels; mass and energy losses along the entire fuel chain; energy embodied in facility infrastructure; distribution systems; cogeneration systems; by-products; waste wood and other biomass waste for energy; reference land use; and other environmental issues. For each of these areas recommendations are given on how analyses of greenhouse gas balances should be performed. In some cases we also point out alternative ways of doing the greenhouse gas accounting. Finally, the paper gives some recommendations on how bioenergy systems should be optimized from a greenhouse-gas-emissions point of view.
TL;DR: The molecular evolution of the gene CHD, which is present on the Z and W sex chromosomes of birds, appears to be male driven—a situation that supports a neutral model of molecular evolution.
Abstract: Assuming that new mutations arise mainly during DNA replication, sequence evolution in mammals has been seen as 'male driven' (ref. 1) because of the many more cell divisions in spermatogenesis than in oogenesis. Molecular support for this idea has been obtained from the observation of higher substitution rates in genes on the Y than on the X chromosome of primates and rodents, which are species with male heterogamety, but has not been confirmed by the reciprocal analysis of organisms with female heterogamety. The recent suggestion that an intrinsic reduction in the X-chromosome mutation rate may be confounded with male effects in previous comparisons, and the paradoxical finding of low levels of polymorphism on the primate Y chromosome indicate that the idea of male-biased mutation rate needs to be re-examined. We have analysed the molecular evolution of the gene CHD, which is present on the Z and W sex chromosomes of birds. The substitution rate at synonymous positions, as well as in intron DNA, was considerably higher on the Z chromosome than on the female-specific W chromosome, with an estimated male-to-female bias in mutation rate (alpha m) of 3.9-6.5. Thus, evolution appears to be male driven in birds--a situation that supports a neutral model of molecular evolution.
TL;DR: The effects of outdoor rearing and sire breed on carcass composition and technological and sensory meat quality in pigs were studied in a trial with 102 crossbred slaughter pigs.
TL;DR: This paper aims to demonstrate the efforts towards in-situ applicability of EMMARM, the objective of which is to provide real-time information about the response of the immune system to drought.
Abstract: Swedish University of Agricultural Sciences, Department of Conservation Biology, Section of Conservation Botany, Box 7072, 750 07 Uppsala, Sweden; University of Oulu, Department of Biology, Linnanmaa, 90 570 Oulu, Finland, and University of Lund, Department for Theoretical Ecology, Ecology Building, 223 62 Lund, Sweden; University of Lund, Department for Theoretical Ecology, Ecology Building, 223 62 Lund, Sweden
TL;DR: A method of classification of broiler foot-health status was developed to estimate the prevalence of foot-pad dermatitis in Swedish broilers and found that flocks reared in houses equipped with small water cups had significantly (P < 0.05) higher prevalences ofFoot health in commercial broiler flocks at slaughter was affected by rearing conditions and equipment.
TL;DR: In this paper, a stepwise regression model was used to investigate the role of soil temperature in methane emissions in Swedish landfills, finding that soil temperature was negatively correlated with biological methane oxidation, which strongly suggests that biological oxidation is an important regulating factor.
TL;DR: It is suggested that the white forehead patch of male collared flycatchers may function as a badge of status that is also used in sexually selected contests over resources when alternative vacant sites exist in the neighbourhood.
TL;DR: There is a causal, positive relationship between male tail length and paternity and this study shows that female choice is a component of selection for larger male ornaments.
Abstract: Previous studies of the socially monogamous barn swallow (Hirundo rustica) have shown that males that most frequently engage in extrapair copulations and whose partners are least involved in copulations with extrapair males are those with long tail ornaments. In this study, through the use of three highly polymorphic microsatellite markers, we analyze the relationships between length of tail ornaments of male barn swallows and proportion of nestlings fathered in own broods, number of offspring fathered in broods of other pairs, and total number of offspring fathered, using both a correlational and an experimental approach. Consistent with our predictions, we show that males with either naturally long or experimentally elongated tails have higher paternity (proportion of biological offspring in own broods), and they produce more biological offspring during the whole breeding season than males with naturally short or experimentally shortened tails. Males with naturally long tails also had more offspring in extrapair broods than short-tailed males, but the effect of tail manipulation on the number of offspring fathered in extrapair broods, although being in the predicted direction, was not statistically significant. Cuckolded males that did not fertilize extrapair females had smaller postmanipulation tail length than cuckolders. We conclude that there is a causal, positive relationship between male tail length and paternity. Since female barn swallows have extensive control over copulation partners and heritability of tail length is high, this study shows that female choice is a component of selection for larger male ornaments. Benefits from extrapair fertilizations to females may arise because they acquire "good" genes for sexual attractiveness or high viability for their offspring.
TL;DR: In this article, the effects of clearcutting and shelterwood cutting of mature Norway spruce peatland forests were compared regarding the effects on the forest flora, and it was concluded that shelterwood regimes may preserve species preferring shaded and moist conditions, whereas those species decreased after clearcutting.