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  • 1. Ahonen-Jonnarth, U.
    et al.
    Van Hees, P.A.W.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Finlay, R.D.
    Organic acids produced by mycorrhizal Pinus sylvestris exposed to elevated aluminium and heavy metals concentrations2000In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 146, no 3, 557-567 p.Article in journal (Refereed)
    Abstract [en]

    A cultivation method was developed to enable exposure of ectomycorrhizal plants with intact extramatrical mycelium to solutions containing different concentrations of aluminium or heavy metals. Pinus sylvestris seedlings colonized by Suillus variegatus (two isolates), Rhizopogon roseolus or Paxillus involutus (two isolates) were used. Seedlings were transferred to Petri dishes containing glass beads and exposed to elevated concentrations of Al, Cd, Cu, or Ni in two ways: immediately following transfer; and after allowing mycorrhizal seedlings to develop an extraradical mycelium that colonized the interface between the upper surface of the beads and the metal-containing solution. Production of organic acids in mycorrhizal and non-mycorrhizal systems was measured by withdrawing samples from the solution and analyzing by HPLC. In most experiments, levels of oxalic acid were significantly higher in mycorrhizal treatments than in non-mycorrhizal controls. The measured levels of organic acids were variable, but the results obtained suggest that production of oxalic acid is stimulated by exposure to elevated Al in mycorrhizal seedlings colonized by S. variegatus and R. roseolus. Elevated Al concentrations also increased oxalic acid production by non-mycorrhizal seedlings significantly in two of four Al experiments performed, but the measured concentrations were significantly lower than in corresponding mycorrhizal treatments in both cases. Malonic acid was found in the culture solution of non-mycorrhizal had P. involutus-colonized seedlings, but only trace amounts were found in S. variegatus or R. roseolus-infected seedlings. Citric, shikimic, lactic, acetic, propionic, fumaric, formic, iso-butyric and butyric acid were found in variable concentrations. Production of oxalic acid by seedlings ColoniZed by S. variegatus BL or P. involutus was not stimulated by exposure to 0.44 μM Cd or 17 μM Ni. Exposure to 0.157 mM CU in two separate experiments using P. involutus 87.017 and two strains of S. variegatus (BL and 159) appeared to stimulate production of oxalic acid irrespective of mycorrhizal status or species.

  • 2. Amenitsch, Hans
    et al.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Khan, Ali
    Marques, Eduardo
    La Mesa, Camilo
    Bile Salts Form Lyotropic Liquid Crystals2003In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 213, no 1, 79-92 p.Article in journal (Refereed)
    Abstract [en]

    A reinvestigation of the phase diagrams relative to some conjugated and non-conjugated bile salts in water has demonstrated the formation of lyotropic liquid crystalline phases, in contradiction with generally accepted statements. The phase behaviour is complex and the phase diagrams are unusual, compared to most surfactants and lipids. In particular, coexistence of liquid crystalline phases with crystals has been observed. The formation of liquid crystalline phases requires very long equilibration times and the thermal stability of the lyotropic phases is moderate. The observed structure is tentatively assumed to be of the reverse hexagonal type. Structural relations with currently accepted models for the organisation of bile salts into micelles and solid form have been found.

  • 3. Anderbrant, O
    et al.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Pheromone mating disruption of the pine sawfly Neodiprion sertifer.: Is the size of the area important?2002In: IOBC/WPRS Bulletin, ISSN 1027-3115, Vol. 25, no 9, 111-116 p.Article in journal (Other scientific)
    Abstract [en]

    The success of mating disruption in relation to the area treated is discussed

  • 4. Anderbrant, O
    et al.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Löfqvist, J
    Towards use of Pine Sawfly Pheromones in Forest Protection: Evalution of a Behavioural Antagonist for Mationg Disruption of Neodiprion sertifer1998In: Population Dynamics, Impacts and Integrated Management of Forest Defoliating Insects, 1998, 53-63 p.Conference paper (Refereed)
  • 5. Anderbrant, O
    et al.
    Löfqvist, E
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Development of mating disruption for control of pine sawfly populations1995In: Entomologia Experimentalis et Applicata, ISSN 0013-8703, Vol. 74, no 1, 83-90 p.Article in journal (Refereed)
  • 6. Anderbrant, O
    et al.
    Löfqvist, J
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Baldassari, N
    Baronio, P
    Kolmakova, G
    Lyons, B
    Naito, T
    Odinokov, V
    Simandl, J
    Suptashvili, A
    Tai, A
    Tourianov, R
    Geographic Variation in the Field Response of Male Pine Sawflies Neodiprion sertifer, to Different Pheromone Stereoisomers and Esters2000In: Entomologia Experimentalis et Applicata, ISSN 0013-8703, E-ISSN 1570-8703, Vol. 95, no 3, 229-239 p.Article in journal (Refereed)
  • 7. Anderbrant, O
    et al.
    Löfqvist, J
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Wassgren, A.-B.
    Bergström, G
    Bengtsson, M
    Magnusson, G
    Field Response Of The Pine Sawfly Neodiprion-Sertifer To The Pheromone (2s,3s,7s)-Diprionyl Acetate And Its Stereoisomers1992In: Entomologia Experimentalis et Applicata, ISSN 0013-8703, Vol. 62, no 2, 169-181 p.Article in journal (Refereed)
  • 8. Anderbrant, Olle
    et al.
    Löfqvist, J
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Mating disruption of the Pine Sawfly Neodiprion sertifer (Hymenoptera: Dipionidae): Effects on Pheromone Trap Catch, Sex Ratio, Population Density and Tree Damage1995In: Behavior, population dynamics, and control of forest insects: Proceedings of the International Union of Forestry Research Organizations Joint conference, February 1994, 1995, 415-427 p.Conference paper (Refereed)
  • 9. Anderbrant, Olle
    et al.
    Östrand, Fredrik
    Bergström, Gunnar
    Wassgren, Ann-Britt
    Auger-Rozenberg, Marie-Anne
    Geri, Claude
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Release of sex pheromone and its precursors in the pine sawfly Diprion pini (Hym., Diprionidae)2005In: Chemoecology, ISSN 0937-7409, Vol. 15, no 3, 147-151 p.Article in journal (Refereed)
    Abstract [en]

    The first identification of a sex pheromone of a pine sawfly (Hymenoptera, Diprionidae) dates back almost thirty years. Since then, female-produced pheromones of over twenty diprionid species have been investigated by solvent extraction followed by separation and identification. However, no study has shown what the females actually release. Collection of airborne compounds using absorbtion on charcoal filter as well as solid phase microextraction (SPME) followed by analysis employing gas chromatography combined with mass spectrometry (GC-MS), revealed an unusual system in Diprion pini, in which the pheromone precursor alcohol, 3,7-dimethyl-2-tridecanol, is released together with acetic, propionic, butyric and isobutyric acids. The corresponding acetate, propionate and butyrate esters of 3,7-dimethyl-2-tridecanol were also found in the samples. All esters were electrophysiologically active, and the propionate and isobutyrate were attractive in trapping experiments. Based on these and earlier reported results, it seems that at least in part of its range, the pheromone response of D. pini is not very specific with regard to the functional group, as long as this is an ester.

     

     

  • 10.
    Andersson, E.
    et al.
    Umeå universitet.
    Nilsson, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Temporal variation in the drift of plant litter and propagules in a small boreal river2002In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 47, no 9, 1674-1684 p.Article in journal (Refereed)
    Abstract [en]

    1. Rivers are linear ecosystems across landscapes with an effective transport of organisms, sediment and organic matter. Dispersal is studied mostly during single events and for single species, and there is little knowledge on how the drift of plant litter and propagules varies within and between years for entire communities. 2. We used floating traps for collecting waterborne plant litter and propagules in a small boreal river over 2 years. We installed the traps at four different locations along the river, and emptied them at least once a week during the ice-free season. We analysed propagule content by sorting and identifying species and through germination tests on bare soil. 3. In total, we recorded at least 54 taxa in the samples, and the highest density recorded in one sample was 5000 propagules per 100 g litter (dry weight). Large temporal variations in litter and propagule transport were revealed, both within and between years. 4. The longitudinal pattern was consistent between years, with an increasing mass of litter and number of propagule taxa downstream. The results highlight the importance of the temporal and longitudinal dimensions in river management.

  • 11. Andersson, Elisabeth
    et al.
    Nilsson, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Johansson, M. E.
    Effects of river fragmentation on plant dispersal and riparian flora2000In: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 16, no 1, 83-89 p.Article in journal (Refereed)
    Abstract [en]

    We evaluated the effects of river fragmentation by dams on hydrochory (i.e. plant dispersal by water) and on plant distribution by comparing two adjacent rivers in northern Sweden, one free-flowing and the other regulated. We collected stranded drift material from both rivers in order to quantify the drift material and its species content. We also estimated the floristic continuity along the two rivers by comparing the drift flora with the riparian flora further upstream. The drift amount deposited on the riverbank, its species richness and its contribution to the species pool were higher in the free-flowing than in the regulated river. The floristic continuity was also higher in the free-flowing than in the regulated river.

  • 12. Andersson, Elisabeth
    et al.
    Nilsson, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Johansson, M. E.
    Plant dispersal in boreal rivers and its relation to the diversity of riparian flora2000In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 27, no 5, 1095-1106 p.Article in journal (Refereed)
    Abstract [en]

    Aim The paper has four major objectives: (1) to determine whether diaspore mimics accurately represent dispersal dynamics of real diaspores in a free-flowing river; (2) to estimate distance travelled and reasons for stranding of floating diaspores along a free-flowing river; (3) to test if species composition and seedling recruitment vary with the ability of the riverbank to trap waterborne drift; and (4) to compare diaspore dispersal in a free-flowing river with that in a regulated river where current velocity has been reduced. Location The field work was conducted in two 7th-order boreal rivers in northern Sweden, the free-flowing Vindel River and the regulated Ume River. Methods We performed a series of dispersal experiments. We tested the usefulness wooden cubes of diaspore mimics for performing dispersal experiments by releasing cubes and achenes of Helianthus annuus and compare their dispersal patterns in the free-flowing Vindel River. We used the cubes to identify 50-m long sections along the river with different trapping capacity, i.e. the number of stranded diaspore mimics within a 50-m section. We then related the number of stranded diaspore mimics to the vascular plant flora, the proportions of species with long or short floating times (i.e. more than or less than 2 days, respectively), the number of seedlings, and to environmental variables within the sections. We also released wooden cubes in a run-of-river impoundment to determine the dispersal capacity of diaspores in a regulated river. Results The cubes were useful as diaspore mimics. They dispersed similarly to achenes of H. annuus. The stranding pattern of diaspore mimics was significantly associated with water current. Species richness of vascular plants per 50-m section increased with the number of stranded mimics. Seedling recruitment, and the proportions of species with short-floating and long-floating diaspores, did not vary with the number of stranded mimics. The ability of a river to transport diaspores downstream was strongly reduced by impoundment. Main conclusions We conclude that patterns of species richness of riparian vegetation is in part determined by the ability of the riverbank to trap waterborne diaspores, but differences in floating ability among species did not affect the species composition along free-flowing rivers.

  • 13.
    Andersson, Fredrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Highly stereoselective alkylation of (S)-proline-based chiral auxiliaries2004In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 15, no 16, 2539-2545 p.Article in journal (Refereed)
    Abstract [en]

    Alkylation of the enolates of the propanoylamides of two chiral auxiliaries (S)-(-)-2-(pyrrolidin-2-yl)propan-2-ol 1a and (S)-(-)-2-(2-methoxypropan-2-yl)pyrrolidine 1b, derived from (S)-proline, with benzyl bromide and n-butyl iodide has been studied. The auxiliaries 1a and 1b induced opposite selectivity that is (R)- and (S)-configuration, respectively, at the newly created stereogenic centre. The diastereoselectivities and conversion yields in these alkylations were moderate to excellent. When Cp2ZrCl2 was used as an enolate coordinating agent, benzylation of propanoylated 1b gave an excellent diastereomeric ratio of 99:1. The benzylated diastereomeric products from either propanoylated 1a or 1b were easily separated by liquid chromatography.

  • 14.
    Andersson, Fredrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Synthesis of two (S)-indoline-based chiral auxiliaries and their use in diastereoselective alkylation reactions2006In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 17, no 13, 1952-1957 p.Article in journal (Refereed)
    Abstract [en]

    Two chiral auxiliaries, 2-[(S)-indolin-2-yl]propan-2-ol 1a and (S)-2-(2-methoxypropan-2-yl)indoline 1b, were synthesised from enantiomerically pure (S)-indoline-2-carboxylic acid 3. High diastereoselectivities in alkylations of enolates of the propanoylamides derived from the two auxiliaries are presented. Surprisingly, both auxiliaries induced the same selectivity at the newly created stereogenic centre. The benzyl bromide and n-butyl iodide alkylation reactions showed diastereomeric ratios that were moderate (81:19) to very good (96:4) and with very good yields (86-98%). When LiCl was used as an enolate coordinating agent, in the benzylation of the enolate from propanoylated auxiliary 1a, a very high crude diastereomeric ratio was obtained (99.7:0.3).

  • 15. Andersson, J
    et al.
    Biasoletto-Tjellström, G
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Reduced pulmonary oxygen uptake during apnea in resting humans: European Underwater and Baromedical Society (EUBS) meeting Copenhagen2003Conference paper (Other academic)
  • 16. Andersson, Johan
    et al.
    Linér, Mats
    Fredsted, Anne
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans2004In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 96, no 3, 1005-1010 p.Article in journal (Refereed)
    Abstract [en]

    The effect of the diving response on alveolar gas exchange was investigated in 15 subjects. During steady-state exercise (80 W) on a cycle ergometer, the subjects performed 40-s apneas in air and 40-s apneas with face immersion in cold (10degreesC) water. Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (-22% compared with eupneic control) and was further reduced during apnea with face immersion (-25% compared with eupneic control). The plasma lactate concentration increased from control (11%) after apnea in air and even more after apnea with face immersion (20%), suggesting an increased anaerobic metabolism during apneas. The lung oxygen store was depleted more slowly during apnea with face immersion because of the augmented diving response, probably including a decrease in cardiac output. Venous oxygen stores were probably reduced by the cardiovascular responses. The turnover times of these gas stores would have been prolonged, reducing their effect on the oxygen uptake in the lungs. Thus the human diving response has an oxygen-conserving effect.

  • 17.
    Andersson, Johan P.A.
    et al.
    Department of Animal Physiology, Lund University.
    Linér, Mats H.
    Lund University Hospital.
    Rünow, Elisabeth
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Diving response and arterial oxygen saturation during apnea and exercise in breath-hold divers2002In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 93, no 3, 882-886 p.Article in journal (Refereed)
    Abstract [en]

    This study addressed the effects of apnea in air and apnea with face immersion in cold water (10°C) on the diving response and arterial oxygen saturation during dynamic exercise. Eight trained breath-hold divers performed steady-state exercise on a cycle ergometer at 100 W. During exercise, each subject performed 30-s apneas in air and 30-s apneas with face immersion. The heart rate and arterial oxygen saturation decreased and blood pressure increased during the apneas. Compared with apneas in air, apneas with face immersion augmented the heart rate reduction from 21 to 33% (P < 0.001) and the blood pressure increase from 34 to 42% (P < 0.05). The reduction in arterial oxygen saturation from eupneic control was 6.8% during apneas in air and 5.2% during apneas with face immersion (P < 0.05). The results indicate that augmentation of the diving response slows down the depletion of the lung oxygen store, possibly associated with a larger reduction in peripheral venous oxygen stores and increased anaerobiosis. This mechanism delays the fall in alveolar and arterial Po2 and, thereby, the development of hypoxia in vital organs. Accordingly, we conclude that the human diving response has an oxygen-conserving effect during exercise.

  • 18. Andersson, Johan
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Diving response and apneic time in humans. 1998In: Undersea & Hyperbaric Medicine, ISSN 1066-2936, Vol. 25, no 1, 13-19 p.Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to compare apneic time with the human diving response, defined as heart rate (HR) reduction and reduced skin blood flow, in groups with varying degrees of breath-hold diving experience. Apneic time and HR reduction at apneas in air and apneas with face immersion in cold water were thus recorded in nine groups. Skin capillary blood flow was recorded in six of the groups. All subjects received the same information on maximizing apneic duration, and no information about their progress during the apneas. The longest apneas and the most pronounced cardiovascular adjustments were found in the young, trained divers. It was found that apneic time was significantly correlated to HR reduction among the nine groups (r = 0.94, P < 0.001), and to skin capillary blood flow reduction among the six groups where the parameter was measured (r = 0.82, P < 0.05). The correlation between HR reduction and skin capillary blood flow reduction was also significant (r = 0.85, P < 0.05). When the difference in HR reduction and apneic time between apneas in air and apneas with face immersion were compared in the nine groups, it was found that all groups reacted with a more pronounced HR reduction during apneas with face immersion. All groups without prior breath-hold diving experience were found to perform shorter apneas with face immersion than apneas in air, or apneas of the same duration in both conditions, which has been reported in other studies. However, in all groups with diving experience, the apneic time was prolonged during apneas with face immersion. The results of this study suggest an oxygen-conserving effect of the diving response in trained apneic divers

  • 19. Andersson, Johan
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effects of lung volume and involuntary breathing movements on the human diving response1997In: European Journal of Applied Physiology, ISSN 1439-6319, Vol. 77, no 1/2, 19-24 p.Article in journal (Refereed)
    Abstract [en]

    The effects of lung volume and involuntary breathing movements on the human diving response were studied in 17 breath-hold divers. Each subject performed maximal effort apnoeas and simulated dives by apnoea and cold water face immersion, at lung volumes of 60%, 85%, and 100% of prone vital capacity (VC). Time of apnoea, blood pressure, heart rate, skin capillary blood flow, and fractions of end-expiratory CO 2 and O 2 were measured. The length of the simulated dives was the shortest at 60% of VC, probably because at this level the build up of alveolar CO 2 was fastest. Apnoeas with face immersion at 100% of VC gave a marked drop in arterial pressure during the initial 20?s, probably due to high intrathoracic pressure mechanically reducing venous return. The diving response was most pronounced at 60% of VC. We concluded that at the two larger lung volumes both mechanical factors and input from pulmonary stretch receptors influenced the bradycardia and vasoconstriction, resulting in a non-linear relationship between the breath-hold lung volume and magnitude of the diving response in the near-VC range. Furthermore, the involuntary breathing movements that appeared during the struggle phase of the apnoeas were too small to affect the diving response

  • 20. Andersson, Johan
    et al.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Gislén, Anna
    Holm, Boris
    Cardiovascular responses to cold water immersions of the forearm and face, and their relationship to apnoea2000In: European Journal of Applied Physiology, ISSN 1439-6319, Vol. 83, no 6, 566-572 p.Article in journal (Refereed)
    Abstract [en]

    Apnoea as well as cold stimulation of the face or the extremities elicits marked cardiovascular reflexes in humans. The purpose of this study was to investigate whether forearm immersion in cold water has any effect on the cardiovascular responses to face immersion and apnoea. We recorded cardiovascular responses to cold-water immersions of the forearm and face in 19 (part I) and 23 subjects (part II). The experimental protocol was divided in two parts, each part containing four tests: I1, forearm immersion during eupnoea; I2, face immersion during eupnoea; I3, forearm and face immersion during eupnoea; I4, face immersion during apnoea; II1, apnoea without immersion; II2, forearm immersion during apnoea; II3, face immersion during apnoea; and II4, forearm and face immersion during apnoea. The water temperature was 9–11 °C. Cold-water immersion of either the forearm or face was enough to elicit the most pronounced thermoregulatory vasoconstriction during both eupnoea and apnoea. During eupnoea, heart rate responses to forearm immersion (3% increase) and face immersion (9% decrease) were additive during concurrent stimulation (3% decrease). During apnoea, the heart rate responses were not affected by the forearm immersion. The oxygen-conserving diving response seems to dominate over thermoregulatory responses in the threat of asphyxia. During breathing, however, the diving response serves no purpose and does not set thermoregulatory adjustments aside

  • 21. Andreasson, B
    et al.
    Forsström, Jennie
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Wågberg, Lars
    Determination of fibre pore structure: influence of salt, pH and conventional wet strength resins2005In: Cellulose (London), ISSN 0969-0239, Vol. 12, no 3, 253-265 p.Article in journal (Refereed)
    Abstract [en]

    It has been shown, in the present investigation, that the two methods used to investigate the pore size distribution of unbleached chemical pulps, i.e. inverse size exclusion chromatography (ISEC) and nuclear magnetic resonance (NMR), give different average pore radius for the pores inside the fibre wall. This is due to the way in which these experiments are performed and the sensitivity of the methods to different types of pores in the cell wall. It was also shown that the two methods gave different results when changing the pH and the ionic strength of the pulp suspension. The pore radius, as detected with ISEC, decreased with both increasing ionic strength and decreasing pH, indicating a loose structure of the exterior of the fibrillar network. However, the pore radius as detected with NMR, was virtually unaffected when increasing the ionic strength, indicating a very rigid structure of the interior of the fibre wall. Decreasing pH though, lead to a decrease in pore radius indicating that upon protonation of the carboxylic groups in the fibre wall, the electrostatic repulsion is diminished and the average pore radius decreases. The NMR technique was also used to study wet strength aid penetration into the fibre wall. It was shown that wet strength aids with a small molecular weight, penetrated the fibre wall, as detected by a decrease in pore radius. It was also shown that addition of different wet strength aids increased the tensile index of the sheet and decreased the fibre strength, measured as zero span-strength of the sheets.

  • 22. Andreasson, Bo
    et al.
    Forsström, Jennie
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Wågberg, Lars
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The porous structure of pulp fibres with different yields and its influence on paper strength2003In: Cellulose, ISSN 0969-0239, Vol. 10, no 2, 111-123 p.Article in journal (Refereed)
    Abstract [en]

    The porous structure of the interior of papermaking fibres is a well-known important property of the fibres. Changes of this structure will influence tensile and burst strength of paper formed from the fibres and a change in pore size of the pores within the fibre wall is also important for the ability of molecules to diffuse in and out of the fibre wall. Relevant examples of this latter effect are the removal of lignin during cooking and the addition of performance chemicals during papermaking. In this paper, pore sizes and the pore size distribution of unbleached softwood fibres have been studied. A well-characterised fibre material consisting of laboratory cooked spruce and pine pulp of various lignin contents was used. Pore size and pore size distribution were measured by studies of the relaxation behaviour of 2H in fibres saturated with 2H2O. Beside this the total and surface charge of the fibres were also measured together with strength properties of papers from unbeaten fibres. For both pulps, there is a maximum in pore radius at a yield around 46%. Calculations of fibre wall volume from water retention values and yield levels show that there is a discontinuity in pore radius as a function of the fibre wall volume around a yield of 51%. It is suggested that this discontinuity is caused by the breakdown of the hemicellulose/lignin matrix within the fibre wall at this yield level. The strength of the papers formed from the fibres shows a correlation with the surface charge of the fibres. Based on the change in surface charge with yield and the change in total charge with yield, this correlation is suggested to be due to an opening up of the external part of the fibre wall. This stresses the importance of the chemical composition and physical structure of the outer layer of the fibre wall.

  • 23.
    Andreasson, Ulrika
    et al.
    SCA Packaging Research, Sundsvall, Sweden.
    Wågberg, Lars
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ink release from printed surfaces: new methodology and initial insights to the true mechanisms behind ink detachment2001Report (Other academic)
  • 24. Andzane, Jana
    et al.
    Tobin, Joseph M.
    Li, Zhonglai
    Prikulis, Juris
    Baxendale, Mark
    Olin, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Holmes, justin D
    Erts, Donats
    Selection of Application Specific Single and Multi Walled Carbon Nanotubes by In Situ Characterization of Conductive and Field Emission Properties2007In: AZojono - Journal of Nanotechnology onlineArticle in journal (Refereed)
    Abstract [en]

    The conductive and field emission properties of individual single and multi-walled carbon nanotubes, grown by chemical vapour and supercritical fluid deposition techniques, have been assessed using an in-situ transmission electron microscope-scanning tunnelling microscope (TEM-STM) technique. The conductivity and field emission measurements were obtained from nanotube-electrode distance and contact observations. Experimental field emission characteristics for all carbon nanotubes investigated fitted well to the Fowler-Nordheim equation when different work functions were applied. Differences in field emission and conductive properties are analysed and related to the structure of the carbon nanotubes. The method presented here is suitable for in situ selection of CNT with desired properties for particular electronic applications.

  • 25.
    Angelstam, Per
    et al.
    SLU, Skinnskatteberg.
    Jonsson, Bengt Gunnar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Törnblom, Johan
    SLU, Skinnskatteberg.
    Uppföljning av 1997 års bristanalys för bevarande av biologisk mångfald olika skogsmiljöer i Sveriges naturregioner: Vad har hänt på tio år?2007Report (Other academic)
  • 26.
    Aronsson, Andreas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Vedaska från biobränslen: resurs eller avfall?2004In: Finlands Natur, ISSN 0356-4509, Vol. 63, no 1, 15-17 p.Article in journal (Other scientific)
  • 27.
    Aronsson, Andreas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ekelund, Nils
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Biological effects of Wood Ash Application.2004In: Journal of Environmental Quality, ISSN 0047-2425, Vol. 33, no 5, 1595-1605 p.Article in journal (Refereed)
    Abstract [en]

    The Swedish National Board of Forestry recommends recycling of wood ash for two main reasons: 1) to avoid depletion of essential soil nutrients, and 2) to reduce the harmful effects of acidification of surface waters. There is no doubt that recycling of wood ash to boreal forests will become a major industry in the near future. Much research is conducted regarding the effects of wood ash application on forest growth. Present studies show that, generally speaking, forest growth can be increased on wood ash-ameliorated peatland rich in nitrogen. On mineral soils, however, no change or even decreased growth has been reported. The effects on ground vegetation are not very clear, as well as the effects on fungi, soil microbes and soil decomposing animals. The discrepancies between different studies are for the most part explained by abiotic factors such as variation in fertility among sites, different degrees of stabilization and wood ash dosage used, and different time scales among different studies. The lack of knowledge in the field of aquatic ecosystems and their response to ash application is an important issue for future research. The few studies conducted have mainly considered changes in water chemistry. The biotoxic effects of ash application can roughly be divided into two categories: primary and secondary. Among the primary effects is toxicity deriving from compounds in the wood ash and cadmium is probably the worst among these. The secondary effects of wood ash are generally due to its alkaline capacity and a release of ions into the soil and soil water, and finally, watercourses and lakes. The present review aims to summarize current knowledge in the topic of wood ash application to boreal forest and aquatic ecosystems, and the different effects derived from these actions. ABBREVIATIONS: WAA, Wood ash application; MT, metric tonnes

  • 28.
    Aronsson, K. Andreas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effects of wood ash on freshwater organisms and aquatic forest ecosystems2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wood ash application (WAA) has been recommended mainly for two reasons; i) to avoid depletion of minerals in the soil due to whole tree harvest in the forestry and ii) to mitigate harmful effects of acidification of soil and surface waters. In conclusion, the effects on terrestrial ecosystems and, especially, tree growth, can be attributed to the properties of the ash, the dose applied and the specific site at which the ash is applied. The research conducted on the effects of WAA on limnological ecosystems is very limited, and the major purpose of the present thesis was to gain knowledge of the effects of wood ash to different freshwater organisms, and the more comprehensive, limnological effects of WAA in the first stream in Bispgården, Sweden.

    Effects of wood ash solutions on the unicellular alga Euglena gracilis Klebs, the amphipod Gammarus pulex L., and the moss Fontinalis antipyretica Hedw. were investigated under laboratory conditions. Common in all three species was the decline in performance (growth/velocity/respiration/oxygen evolution) when the concentration of wood ash exceeded 5 g/l and no adjustment of pH was done (alkaline solution). In contrast, different movement parameters (motility, upwards swimming and velocity) in E. gracilis (neutral conditions), and increased growth of F. antipyretica with increased concentrations of wood ash indicated that nutrients in the ash was bioavailable for these organisms. There was no evidence of toxic effects on the organisms from metals or other compounds as a result from exposure to wood ash solutions in the present studies.

    The field study was conducted in a forest area close to Bispgården, about 100 km NW from Sundsvall, Sweden. The catchment area (50 ha) of the stream Fanbergsbäcken was treated with wood ash in September of 2004 (3,000 kg/ha;selfhardened crush-ash). In general, both biological (diatoms) and chemical (pH, alkalinity, and aluminum (Al) measurements) indicators have shown no significant effect on acidification parameters from the addition of wood ash. There was, however, evidence of an increased pH during spring flood, accompanied with a decrease in the frequency of low pH values (<5.6) during spring flood. In addition to this, alkalinity was significantly higher in the period 2005-2006, compared to that of 2003. High concentrations of toxic forms of Al repeatedly occured in the stream Fanbergsbäcken, and the WAA did not affect the frequencies of high concentrations of toxic Al forms (<50 μg/l). Both the moss F. antipyretica and the leaves from Alnus incana displayed increased potassium (K) concentrations, although other nutrients did not increase from WAA. In conclusion, no evidence of WAA being effective in restoring or improving the ecological status of freshwater environments has been established, either in the literature or in the present field study. On the other hand, there were no indications of harmful effects due to WAA, either. However, we still do not know the effects of wood ash on several organisms (predominantly invertebrates) inhabiting small ponds and other, temporary or permanent, freshwater ecosystems. In the context of WAA, these environments and organisms have not attended any attention in the research published to date, and future studies are strongly encouraged.

  • 29.
    Aronsson, K. Andreas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ekelund, Nils
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effects on growth, photosynthesis and pigments of the freshwater moss Fontinalis antipyretica Hedw. after exposure to wood ash solution2006In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 372, no 1, 236-246 p.Article in journal (Refereed)
    Abstract [en]

    The application of wood ash from biofuel sources to the forest has been suggested as a source of nutrients for trees and for restoration of acidified soils and surface waters. Studies on the effects of wood ash on aquatic organisms and ecosystems are, however, few. This study investigated the effects of wood ash (0.1 - 10 g l-1) on the freshwater moss Fontinalis antipyretica Hedw., which has previously been shown to be a sensitive test organism for assessing environmental pollution. After nine weeks of treatment with wood ash, a significant effect of enhanced stem growth was observed at the higher concentrations (1 � 10 g l-1). The concentration of wood ash was also correlated to the growth of secondary branches. Photosynthesis (oxygen evolution after 4 h of exposure to wood ash) was significantly lower in the alkaline treatments (no pH adjustment) compared to the treatments with neutral wood ash solutions (pH adjusted to 7.5). Furthermore, photosynthesis in the alkaline wood ash treatments was significantly lower compared to the control. The ratio between the optical density value before and after acidification (OD665/665a) was higher for all wood ash concentrations compared to the control. The OD665/665a values ranged from 1.52 to 1.61 and there was a difference, however not significant, between the alkaline and the neutral treatment at 10 g l-1 wood ash. This study clearly demonstrated that wood ash may be beneficial for F. antipyretica at moderate concentrations (0.5 - 5 g l-1), particularly when sudden increase in pH is avoided.

  • 30.
    Aronsson, K. Andreas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ekelund, Nils
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effects on Motile Factors and Cell Growth of Euglena gracilis After Exposure to Wood Ash Solution: Assessment of Toxicity, Nutrient Availability and pH-Dependency2005In: Water, Air and Soil Pollution, ISSN 0049-6979, Vol. 162, no 1-4, 353-368 p.Article in journal (Refereed)
    Abstract [en]

    Wood ash application (WAA) to the forest has been suggested as a resource of nutrients for trees and for restoration of acidified soils and surface waters. However, studies of the effects of WAA on aquatic systems are few. This study investigated the effects of wood ash (1-25 g L-1) on the unicellular flagellate Euglena gracilis, which has been proved to be a sensitive test organism for assessing environmental change. Long-term (7 days) growth studies and short-term (direct, 24 and 48 h) studies of different motile factors, using the automatic biological test system Ecotox, were conducted. The results show no indication of biotoxic effects due to wood ash (adjusted to neutral) treatments. However, when no adjustments of pH in wood ash solutions were made, inhibitory effects on motile factors and cell growth were observed at higher concentrations of wood ash (10-25 g L-1) due to high pH (> 8). In tests with pH adjusted to neutral, enhanced motility was observed. These results indicate that high concentration of WAA could affect freshwater environments.

  • 31.
    Aronsson, K. Andreas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ekelund, Nils
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Respiration measurements can assess the fitness of Gammarus pulex (L.) after exposure to different contaminants: experiments with wood ash, cadmium and aluminum2005In: Archiv für Hydrobiologie, ISSN 0003-9136, Vol. 164, no 4, 479-491 p.Article in journal (Refereed)
    Abstract [en]

    Wood ash application has been suggested as a means to mitigate acidification of surface waters. However little is known about the effects of wood ash to freshwater organisms. A Clark-type oxygen electrode was used to investigate the effects of wood ash, cadmium and aluminum on the respiration of the freshwater amphipod Gammarus pulex (L.). Harmful effects following wood ash addition were primarily found to be explained by elevated pH. At high concentrations (> 1 g/l) of wood ash the respiration of G. pulex decreased when no adjustment of pH was made, a response that was negatively correlated to the elevated pH (r = -0.43). An ion-related response was also detected in the pH-adjusted (pH 7) tests, although it was not statistically significant. Cadmium proved to be sublethal in the range of 0.2-0.4mg/l in a 24-h exposure. Mortality was 100% at 0.5 and 1.0mg Cd/l. No effects were detected after exposure to Al, due to the high pH (pH 7-8) of the solutions and the subsequently low concentrations of labile monomeric Al. We demonstrate that the method described in this paper could be a useful probe for the detection of sublethal concentrations of contaminants in freshwater ecosystems.

  • 32. Aune, Karin
    et al.
    Jonsson, Bengt-Gunnar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Moen, Jon
    Isolation and edge effects among woodland key habitats in Sweden: making fragmentation into forest policy?2005In: Biological Conservation, ISSN 0006-3207, Vol. 124, no 1, 89-95 p.Article in journal (Refereed)
    Abstract [en]

    Fragmentation of natural forests is a major threat to forest biodiversity. In areas with a long history of forestry, the remaining patches of old forests constitute only a minor part of the landscape. In such situations small stands may be valuable and important for conservation. However, as they may suffer from strong edge effects and isolation, their value may be lower than anticipated. In Sweden a national inventory of woodland key habitats (WKHs) has identified about 1% of the forest landscape as sites where red-listed species occur or may occur. Most are small (national median 1.4 ha) and isolated stands within an intensively managed landscape. The present analyses calculate WKH core area based on a range of depths of edge influence, and isolation based on both distance to nearest WKH and a weighted isolation measure that includes all neighboring WKHs and protected forest. These analyses are done on the WKHs in Norrbotten County in northern Sweden and include almost 5000 stands. The actual core area in the WKHs is about 30% given a 50 m edge influence. The degree of isolation is species dependent but the results indicate that only species with high dispersal abilities may effectively utilize the network of WKHs. For species with effective dispersal distances of less than 2 km the network is probably insufficient. The results emphasize the need to create buffer zones, to increase reserve areas and to manage the matrix so that species dispersal is promoted. This likely includes a necessity to aggregate biodiversity efforts on the landscape scale.

  • 33.
    Backlund, Hans-Olof
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Höglund, Hans
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Gradin, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Study of tangential forces and temperature profiles in commercial refiners2003In: 2003 International Mechanical Pulping Conference, 2003, 379-388 p.Conference paper (Refereed)
  • 34.
    Batchelor, Warren J.
    et al.
    Monash University, Australia.
    Westerlind, B. S.
    SCA Graphic Research, Sundsvall.
    Hägglund, R.
    SCA Packaging Research, Sundsvall.
    Gradin, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effect of test conditions on measured loads and displacements in zero-span testing2006In: TAPPI Journal, ISSN 0734-1415, Vol. 5, no 10, 3-8 p.Article in journal (Refereed)
    Abstract [en]

    Single fiber mechanical properties play a critical role in determining sheet mechanical properties, but fiber mechanical properties are rarely measured, because of the time-consuming nature of the tests. Zero-span strength is commonly used as a measure of fiber strength, but the results can vary with the test conditions. Modeling has shown that the load displacement curves are influenced by the thickness-to-span ratio, as there is a heterogeneous stress field in the thickness direction of the sample.

    This paper presents data on the effect of grammage on the loads and displacements in zero-span tests. Clamps were designed and made for a displacement-control led load frame. These clamps can test up to 10 plies of papers with,a span length from 0 to 3 mm. For the sake of comparison, tests were made using a commercial zero-span tester, which is load controlled but limited in span length and thickness of the tested material. Both machines were found to give comparable results. Isotropic 65 g/m(2) handsheets, 36 g/m(2) aluminum foil, and 42 g/m(2) greaseproof paper were tested as functions of sheet grammage. An intrinsic zero-span strength was defined as the y-axis intercept of a plot of zero-span strength versus grammage.

    Application:This paper demonstrates that the measured zero-span strength is always less than the intrinsic zero-span strength. The results show that, for best results, the grammage of the material tested should be minimized to obtain a measured value that is as close to the intrinsic value as possible.

  • 35.
    Berg, Jan-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effect of impact velocity on the fracture of wood as related to the mechanical pulping process2001In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 35, no 4, 343-351 p.Article in journal (Refereed)
    Abstract [en]

    The fibre separation step in refining is crucial for energy consumption in subsequent refining where the pulp properties are developed. The size reduction of chips during refining is dependent on refining intensity and chip strength. Factors affecting these two parameters are discussed in a literature review. The impact strength of chips and the break down of chips to separate fibres are also discussed. Specifically the effect of impact velocity on the fracture of wood has been studied by use of a falling weight impact tester. Samples were prepared from a freshly cut log of Norway spruce, Picea abies, and the impact strength was measured using an instrumented falling weight impact tester. An increase in impact velocity from about 2.7 to 4.8 m/s resulted in an increase in impact strength of about 50%.

     

  • 36.
    Berg, Jan-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Fracture Behaviour of Wood and Fibres as Related to the Mechanical Pulping Process1996Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    The fibre separation step in refining is crucial to energy consumption

  • 37.
    Berg, Jan-Erik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Gradin, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effect of Temperature on Fracture of Spruce in Compression Using Acoustic Emissions1995In: AECM-5, Fifth International Symposium on Acoustic Emission From Composite Material, Columbus, OH, USA: The American Society for Nondestructive Testing, Inc. , 1995, 139-148 p.Conference paper (Refereed)
  • 38.
    Berg, Jan-Erik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Gradin, Per A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    A Micromechanical Model of the Deterioration of a Wood Fibre1999In: Journal of Pulp and Paper Science, ISSN 0826-6220, Vol. 25, no 2, 66-71 p.Article in journal (Refereed)
    Abstract [en]

    A simple analytical model is presented in this paper for the prediction of the stiffness degradation and the damage state in a wood fibre, loaded in uniaxial tension or shear. The model is based on an assumed displacement field together with the minimum total potential energy theorem. For the damage development, an energy criterion is employed. The model is applied to a specific example and the relevant stiffness coefficients are calculated as a function of the damage state. The damage development as a function of the applied loads is also given. The results from a specific example considered indicate that a tensile load affects the stiffness degradation to a larger extent than does a shear load.

  • 39.
    Berg, Jan-Erik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Gradin, Per A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Effect of Temperature on Fracture of Spruce in Compression, Investigated by Use of Acoustic Emission Monitoring2000In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 26, no 8, 294-299 p.Article in journal (Refereed)
    Abstract [en]

    Acoustic Emission (AE) monitoring during compression of wood has been used to investigate the fracture history with specific emphasis on its dependence on temperature, moisture content, strain and loading direction. The wood was compressed in both the lateral and longitudinal directions in order to select preferred modes of deformation to achieve desired irreversible changes in the wood structure. The elastic modulus, the compressive strength and the cumulated number of AE events decreased with increasing temperature. It was concluded that the most efficient loading direction is longitudinal in order to introduce flaws in wood under compression and that a longitudinal compression of 24%, corresponding to a specific energy input of 3 kWh/ton, is needed in order to achieve substantial changes in the wood structure. The compression should be carried out at temperatures well below 120°C in order to introduce many failure sites.

  • 40. Bergelin, A.
    et al.
    van Hees, P. A. W.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Wahlberg, O.
    Department of Chemistry, Royal Institute of Technology, .
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The acid-base properties of high and low molecular weight organic acids in soil solutions of podzolic soils2000In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 94, no 2-4, 223-235 p.Article in journal (Refereed)
    Abstract [en]

    The acid properties of the organic acids and identified low molecular weight (LMW) organic acids in soil solutions of podzolic soils were determined using proton affinity spectra, based on EMF titration data, and Gran titrations. The proton affinity spectra showed apparent pKa values of 2.6, 4.1, 5.4 and 6.7 for the dissolved organic material. The LMW organic acids had similar pKa values. The average specific buffer capacity as determined by Gran titrations was 8.8±0.5 μmol H+/mg DOC. The specific buffer capacity for the identified low molecular acids was 40±2 μmol H+/mg DOC.

  • 41.
    Berglund, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Edman, Mattias
    Dept of Ecology and Environmental Science, Umeå University.
    Ericson, Lars
    Dept of Ecology and Environmental Science, Umeå University.
    Temporal variation of wood-fungi diversity in boreal old-growth forests: Implications for monitoring2005In: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 15, no 3, 970-982 p.Article in journal (Refereed)
    Abstract [en]

    Monitoring programs that supply reliable and sufficient information on numbers and types of organisms are essential for following changes in biodiversity. In boreal Fennoscandia, forest-dwelling species are threatened in managed forest landscapes and, thus, are of particular concern for conservation strategies. Wood fungi represent key ecological components in the boreal forest that are sensitive to forestry and widely used as indicators in large-scale forest inventories for identifying valuable forest habitats. Knowledge of their natural dynamics is required for designing monitoring programs to assess the adequacy of conservation strategies. We studied the occurrence of corticoids (Corticiaceae) and polypores (Polyporaceae) over time at different spatial scales in unexploited boreal old-growth forests. Data from 70 downed logs followed during an eight-year period showed that the lifespan of fruit bodies of most species was shorter than four years. Even perennial species followed this pattern, although fruit bodies of some species (e.g., Phellinus spp.) remained vital throughout the eight years studied. Both species richness and species composition on individual logs changed markedly over the eight years due to deterministic succession of species paralleling the wood decay. By contrast, data from the stand scale, i.e., seven 0.1-ha plots, showed that species richness and species composition of polypores did not undergo any major changes during a six-year period. A majority of all recorded polypore species (80%) were already present at the first inventory. However, although species richness remained constant at the stand scale, corticoid species composition differed between years, reflecting their short-lived, annual fruit bodies. This study suggests that monitoring should be performed at stand scale and focus on species with durable fruit bodies, e.g., polypores. This will provide data that can be used both to detect future changes in biodiversity in old-growth spruce forests and to evaluate conservation strategies.

  • 42.
    Berglund, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Jonsson, Bengt Gunnar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Nested plant and fungal communities: the importance of area and habitat quality in maximizing species capture in boreal old-growth forests2003In: Biological conservation, ISSN 0006-3207, Vol. 112, no 3, 319-328 p.Article in journal (Refereed)
    Abstract [en]

    Knowledge of the distribution of rare species is crucial for species conservation in fragmented habitats. Species communities often exhibit nestedness, i.e. species in species-poor sites comprise a subset of richer ones. Thus, rare species are confined to species-rich sites. We evaluate whether plant and fungal communities in 46 old-growth spruce forest patches (0.17–12 ha) exhibit nestedness. The question whether a single large patch or several small patches capture most species (i.e. the SLOSS-issue) is evaluated in combination with species saturation analyses. All species groups exhibited significant nestedness. Area was generally related to nestedness, i.e. rare species were over-represented in the largest patches. Species saturation analysis indicated that large patches accumulated more Red-list species in patch interiors than small patches. Thus, rare and Red-list species were best captured in large patches. However, nestedness also emerged in equal sized sample plots, i.e. rare species were over-represented in high quality habitats. Thus, small habitats of high quality should not be neglected in a conservation perspective.

  • 43.
    Berglund, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Jonsson, Bengt Gunnar
    Umeå Univ, Dept Ecol & Environm Sci, SE-90187 Umeå, Sweden .
    Predictability of plant and fungal species richness of old-growth boreal forest islands2001In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 12, no 6, 857-866 p.Article in journal (Refereed)
    Abstract [en]

    The fragmentation and deterioration of old-growth forest habitat by modern forestry have become a major threat to species diversity in Fennoscandia. In order to develop a conservation strategy for the remaining diversity it is essential to identify the existing diversity and to develop appropriate conservation and monitoring programs. For these purposes indicators of conservation value for administrative prioritization are required. This study examines the predictability of plant and fungal species richness on two spatial scales on 46 isolated old-growth forest islands (0.17-12 ha) in a forest-wetland mosaic. We explore (1) to what extent area, isolation and stand structure variables can explain the variation in species richness and (2) if richness patterns of individual species groups correlate. Isolation showed no relation to species richness. Area explained 50-70% of the variation in total species richness and was positively related to the density of crustose lichens and Red-list species in island interiors. Stand structure variables explained 28-66% of the residual variation in total species richness after controlling for island size, and 15-73% of the variation in density of species in island interiors. The highest predictability of species richness was found among substrate-specific fungi and Red-list species. Different stand structure variables were found to explain richness in the different species groups, and only among a few species groups species richness correlated. Thus, species richness of one single species group is unlikely to be a good indicator for total biodiversity. The results show that measurements of stand size and stand structure variables may be a strong complementary tool. and sometimes a substitute to extensive species inventories when one aims to estimate and monitor plant and fungal species diversity in old-growth Picea abies forests.

  • 44.
    Berglund, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Jonsson, Bengt Gunnar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Verifying an extinction debt in north Swedish boreal forests2005In: Conservation biology, ISSN 0888-8892, Vol. 19, no 2, 338-348 p.Article in journal (Refereed)
    Abstract [en]

    Destruction and fragmentation of natural habitats results in small species populations that face increased risk of extinction. A time delay may be involved in the regional extinction of species, and the number of species that eventually may go extinct in the future is called the "extinction debt." In boreal Sweden, we examined whether the number of epiphytic crustose lichens and wood-inhabiting fungi in old-growth forest remnants diverges from species richness levels in forest patches that have been naturally isolated for millennia. An excess of species in forest remnants could indicate the presence of an extinction debt. Observed species richness in 32 old-growth forest remnants (also called woodland key habitats [WKHs]) was compared with predicted species richness. To predict species richness we used regression models based on data from 46 isolated old-growth forest patches in a forest-wetland matrix. The reference landscape is ancient and assumed to reflect the conditions of insular floras in dynamic equilibrium. Stand factors constituted predictive variables in the models. The observed number of lichen species was higher than expected (i.e., an extinction debt among lichens may exist). By contrast, there was no significant difference between observed and expected species richness among wood-inhabiting fungi. The species richness of wood-inhabiting fungi has adjusted to the changes in forest and landscape structure more rapidly than the species richness of lichens. Differences in substrate dynamics between epiphytes on living trees and species growing on decaying logs might explain the difference between species groups. The results also indicate that population densities of red-listed species were low, which may result in continuing extinctions of red-listed species. The importance of WKHs might be overvalued because species may be lost if conservation efforts consider only protection and preservation of WKHs.

  • 45.
    Berglund, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ryvarden, Leif
    Botany Department, University of Oslo, Blinderu, Oslo, Norway.
    Oligoporus norrlandicus nov sp2000In: Cryptogamie Mycologie, ISSN 0181-1584, E-ISSN 1776-100X, Vol. 21, no 3, 145-146 p.Article in journal (Refereed)
    Abstract [en]

    Oligoporus norrlandicus is described as new and compared with similar white resupinate species.

  • 46.
    Berglund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Holocene shore displacement and chronology in Ångermanland, eastern Sweden, the Scandianvian glacio-isostatic uplift centre2004In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 33, no 1, 48-60 p.Article in journal (Refereed)
    Abstract [en]

    The shore displacement during the Holocene in southeastern Ångermanland, Sweden, has been investigated by means of radiocarbon-dating of isolation intervals in sediment cores from a total of nine new basins. Results from earlier investigations have been used in complement. There is a forced regression in the area from c. 9300 BP (c. 10 500 cal. yr BP) until c. 8000 BP (c. 9000 cal. yr BP), on average c. 8 m/100 years, after which there is a gradually slowing regression of c. 2.5-1.0 m/100 years up to the present time. The most rapid regression occurs during the later phase of the Ancylus Lake stage, 9500-9000 cal. yr BP. There is no evidence of halts in the regression. Crustal uplift in the area since deglaciation is c. 310 m. The deglaciation of southeastern Ångermanland took place c. 9300 BP (c. 10 500 cal. yr BP); this is c. 900 years earlier than the age given by clay varve dating. The shore displacement curve provides a means of estimating the difference between the clay varve time scale and calibrated radiocarbon dates, by comparison with varve-dated altitudes of alluvial deltas of the River Ångermanälven. From c. 2500 to c. 8000 cal. BP there is a deficit in clay varves of some 300 years; further back in time this discrepancy increases significantly. The main explanation for the discrepancy is most likely lacking varves in the time-span 8500-10 200 cal. yr BP, located along the upper reaches of River Ångermanälven below the highest shore level

  • 47.
    Berglund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The Holocene shore displacement of Gästrikland, eastern Sweden: A contribution to the knowledge of Scandinavian glacio-isostatic uplift2005In: Journal of Quaternary Science, ISSN 0267-8179, Vol. 20, no 6, 519-531 p.Article in journal (Refereed)
    Abstract [en]

    The shore displacement in Gästrikland, east-central Sweden, has been investigated by means of AMS radiocarbon dating of sediment cores from isolated basins. Twenty dates from 11 sites are presented. Pollen and diatom analyses, and archive material from the Geological Survey of Sweden, have been used to identify isolation intervals in the cores and as chronological support to the 14C dates. An important pollen stratigraphical time-marker is a distinct mid-Holocene increase in Tilia. For the mid-Holocene, pollen stratigraphy is used rather than the 14C dates for the age determination. The deglaciation of Gästrikland, according to the new 14C dates, took place ca. 11 000 cal. yr BP (ca. 9500 14C yr BP). Through the Holocene the shore displacement is regressive. The regression was initially rapid (on average ca. 3.5 m per 100 yr 11 000-7500 cal. yr BP, probably much more rapid at the earliest stage), then slowed down considerably and was from ca. 5000 cal. yr BP (probably already from 7000 cal. yr BP) relatively constant, ca. 0.8-0.9 m per 100 yr. There are important differences between the shore level curve from Gästrikland and curves from other areas, indicating some irregularities in the regional glacio-isostatic rebound.

  • 48. Berglund, P.
    et al.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hult, K.
    Controlling lipase enantioselectivity for organic synthesis: Meeting abstract2000In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 2000, Vol. 219, U219- p.Conference paper (Refereed)
  • 49. Berglund, P
    et al.
    Vörde, Carin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Esterification of 2-Methylalkanoic Acids Catalysed by Lipase from Candida rugosa: Enantioselectivity as a Function of Water Activity and Alcohol Chainlength1994In: Biocatalysis and Biotransformation, ISSN 1024-2422, Vol. 9, 123-130 p.Article in journal (Refereed)
  • 50.
    Berglund, Per
    et al.
    Department of Biotechnology, Royal Institute of Technology, SE-100 44 Stockholm.
    Christiernin, M
    Department of Biotechnology, Royal Institute of Technology, SE-100 44 Stockholm.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Enantiorecognition of Chiral Acids by Candida rugosa Lipase: Two Substrate Binding Modes Evidenced in an Organic Medium2001In: Applied Biocatalysis in Speciality Chemicals and Pharmaceuticals, 2001, 263-273 p.Conference paper (Refereed)
    Abstract [en]

    We have identified the existence of different modes of binding the enantiomers of 2-methyl-branched carboxylic acids to a lipase active site by rational substrate engineering. Similar to hydrolysis, previously investigated, we have now evidence for differential binding modes in the Candida rugosa lipase-catalyzed esterifications in cyclohexane. The relevance of considering two different binding modes to understand lipase enantiorecognition is demonstrated by introducing bulky substituents on a chiral carboxylic acid which impose a different orientation of the substrate acyl chain in the active site of Candida rugosa lipase. With this substrate engineering approach based on molecular modeling it is thus possible to markedly alter the enantioselectivity of the lipase. Examples from hydrolysis and new results from esterifications in an organic solvent are presented and discussed.

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