Nitrogen forms in bark, wood and foliage of nitrogen-fertilized Pinus sylvestris

Cycling of soluble non-protein N compounds is thought to be indicative of the N-nutritional status of trees. We determined the major N forms in bark, wood and foliage and estimated the dependence of prevalent N forms on N availability in Pinus sylvestris L. trees from northern Sweden. Trees subjected to severe N limitation and trees that had been fertilized with an average 64 kg N ha(-1) year(-1) for 25 years were analyzed. Bark and wood samples were collected by tangentially cryo-sectioning the trunk into 30-microm thick sections, from the bark to the functional xylem. Soluble amino compounds were extracted from the sections for analysis. Sap samples from twigs were obtained by centrifugation, and bark samples from twigs were obtained by tissue extraction. In both needles and bark, arginine dominated the amino-N pool. Because arginine concentrations in needles increased with N fertilization, arginine dominance of the amino-N pool in needles was higher in N-fertilized trees than in control trees. In bark, N fertilization resulted in a large increase in glutamine concentration, so that glutamine accounted for a larger proportion of the amino-N pool in bark in N-fertilized trees than in control trees. Glutamine dominated the amino-N pool in wood of control trees. Nitrogen fertilization resulted in an increased proportion of arginine in the wood amino-N pool. We conclude that the composition of the amino-N pools in bark, wood and foliage is highly sensitive to N supply. The composition of the amino-N pools can contribute to the regulation of tree N-nutritional status, which is mediated by shoot to root signalling by long-distance transport of amino compounds.     

Testing and evaluation of natural durability of wood in above ground conditions in Europe – an overview

Natural durability of wood is determined by the European standard EN 252 for specimens in ground contact and EN 113 for basidiomycetes in the laboratory, but no test exists for above ground conditions. For above ground conditions, the European prestandard ENV 12037 and EN 330 are used to determine the durability of treated wood. The most important factors for fungal establishment on the surface and within wood are the moisture content, the surrounding temperature, and the relative humidity. Strength tests are the most sensitive for decay detection, but neither strength tests nor identification of fungi responsible for the decay are included in the standards of above ground durability in field tests. To detect decay, visual examination, pick or splinter tests, and mass loss determination are used. Identifying fungi with traditional methods, e.g., growth on solid medium, is time consuming and complicated. Molecular methods like polymerase chain reaction and sequencing do not require mycological skill for identification to species level, and furthermore the methods do not depend on the subjective judgement like most traditional methods, but are based on the objective information of the target organism (e.g., nucleotide sequences). The next generation of standard field tests will probably consider the drawbacks of standard tests today and be rapid and include both quality tests like molecular identification and nondestructive quantitative tests, e.g., acoustic tests. Laboratory tests can be improved by using fungi identified from field trials and by combining different fungi in the same test and thus simulate degradation in practice.     

The nutrient status of Norway spruce in pure and in mixed-species stands

Atmospheric deposition of N and S appears to have caused nutrient imbalance in Norway spruce stands in southern Sweden. This calls for a change of forest management to procedures that promote nutrient balance. Studies have shown lower soil acidity in Norway spruce/deciduous mixed stands than in spruce monocultures, but the tree nutrient status in such mixtures has not been much investigated so far.

The nutrient status of Norway spruce foliage and top mineral soil chemistry in monocultures and in stands mixed with beech, birch, or oak was investigated through paired comparisons on 30 sites in southern Sweden (27 sites) and eastern Denmark (three sites). In total, 45 mixed stands and 34 pure stands were included in the study.

Spruce needles from mixed stands had higher concentrations and ratios to N of K, P, and Zn than needles from pure spruce stands. Among the mixed stands, the K status appeared to be positively correlated with the percentage of deciduous tree basal area. Soil samples from mixed stands had a higher Mg concentration, base saturation, and BC/Al ratio than soil samples from pure stands. The spruce needle nutrient status was comparable in pure stands on fertile sites and in mixed stands on poor sites. We did not detect any differences in spruce tree growth between pure and mixed stands.

This paper discusses possible reasons for a positive effect on the tree nutrient status in mixed-species stands and the possibility of using mixed-species stands as a forest management procedure to avoid nutrient imbalance.     

Production of the bioactive compound eritadenine by submerged cultivation of shiitake (Lentinus edodes) mycelia

Fruit bodies and mycelia of shiitake mushroom ( Lentinus edodes) have been shown to contain the cholesterol-reducing compound eritadenine, 2( R),3( R)-dihydroxy-4-(9-adenyl)butyric acid. In the search for a production method for eritadenine, shiitake mycelia were investigated in the present study. The mycelia were cultivated both in shake flasks and in bioreactors, to investigate the effects of pH, stirring rate, and reactor type on the production and distribution of eritadenine. Both the biomass and the culture broth were examined for their eritadenine content. In the shake flasks, the final concentration of eritadenine was 1.76 mg/L and eritadenine was equally distributed between the mycelia and the growth media. In the bioreactors, the shiitake mycelia were found to contain eritadenine in relatively low levels, whereas the majority, 90.6-98.9%, was detected in the growth media. Applying a stirring rate of 250 rpm during bioreactor cultivation resulted in the highest eritadenine concentrations: 10.23 mg/L when the pH was uncontrolled and 9.59 mg/L when the pH was controlled at 5.7. Reducing the stirring rate to 50 rpm resulted in a decreased eritadenine concentration, both at pH 5.7 (5.25 mg/L) and when pH was not controlled (5.50 mg/L). The mycelia in the shake flask cultures appeared as macroscopic aggregates, whereas mycelia cultivated in bioreactors grew more as freely dispersed filaments. This study demonstrates for the first time the extra- and intracellular distribution of eritadenine produced by shiitake mycelial culture and the influence of reactor conditions on the mycelial morphology and eritadenine concentrations.     

Effects of nutritional status on the drought resistance in Norway spruce

Many studies have dealt with the links between nutrient supply and tree growth. High N availability usually leads to increased growth but it may also be a stress factor and may affect the ability of the tree to take up both water and nutrients. We measured the nutritional status of the trees and estimated their tolerance to drought by examining the flushing of new shoots and needle loss. The studies were carried out on trees grown under different N and water supply in a field experiment using a 25–30 year old Norway spruce (Picea abies) in SW Sweden. The treatments included in this study were ammonium sulphate (NS) where 100 kg N ha^?1 was applied yearly, N-free fertiliser (V) where P, K, Ca, Mg and S but no N was applied, and also the combinations of ammonium sulphate and drought (ND) and N-free fertiliser and drought (VD). The NS treatment caused increased N but decreasing P/N, K/N and Mg/N ratios in the needles whereas the N-free fertiliser resulted in increased P/N and Ca/N ratios. In ND and VD, nutrient ratios remained relatively unchanged compared with NS and V. Thus, trees keep a stable internal nutrient balance. However, as a response to the drought, ND seemed to stop the flushing of new shoots to a higher degree than VD. In conclusion, this study showed that nutrient status did affect drought resistance which could be seen as differences in the flushing of new shoots rather than changes in nutrient ratios in the needles.     

Sample pooling for real-time PCR detection and virulence determination of the footrot pathogen <Emphasis Type="Italic">Dichelobacter nodosus</Emphasis>

Dichelobacter nodosus is the principal cause of ovine footrot and strain virulence is an important factor in disease severity. Therefore, detection and virulence determination of D. nodosus is important for proper diagnosis of the disease. Today this is possible by real-time PCR analysis. Analysis of large numbers of samples is costly and laborious; therefore, pooling of individual samples is common in surveillance programs. However, pooling can reduce the sensitivity of the method. The aim of this study was to develop a pooling method for real-time PCR analysis that would allow sensitive detection and simultaneous virulence determination of D. nodosus. A total of 225 sheep from 17 flocks were sampled using ESwabs within the Swedish Footrot Control Program in 2014. Samples were first analysed individually and then in pools of five by real-time PCR assays targeting the 16S rRNA and aprV2/B2 genes of D. nodosus. Each pool consisted of four negative and one positive D. nodosus samples with varying amounts of the bacterium. In the individual analysis, 61 (27.1%) samples were positive in the 16S rRNA and the aprV2/B2 PCR assays and 164 (72.9%) samples were negative. All samples positive in the aprV2/B2 PCR-assay were of aprB2 variant. The pooled analysis showed that all 41 pools were also positive for D. nodosus 16S rRNA and the aprB2 variant. The diagnostic sensitivity for pooled and individual samples was therefore similar. Our method includes concentration of the bacteria before DNA-extraction. This may account for the maintenance of diagnostic sensitivity. Diagnostic sensitivity in the real-time PCR assays of the pooled samples were comparable to the sensitivity obtained for individually analysed samples. Even sub-clinical infections were able to be detected in the pooled PCR samples which is important for control of the disease. This method may therefore be implemented in footrot control programs where it can replace analysis of individual samples.     

Commercial forest fertilization causes long-term residual effects in ground vegetation of boreal forests

Due to an increasing demand of forestry products, nitrogen (N) fertilization of coniferous forests may in the future become a standard silvicultural practice in parts of the boreal region that is not too remotely situated. Beside positive effects on productivity, forest fertilization may induce changes in species composition of the ground vegetation. More information on the magnitude of such side effects is needed to evaluate whether commercial forest fertilization is in accordance with principles of sustainable forestry and preservation of biodiversity.     

Can Graphical Vector Analysis be Used to Identify Micro Nutrient Deficiency?

Initial analysis of needle nutrient status and visible symptoms suggested that a declining Norway spruce (Picea abies L. Karst.) stand in south Sweden was suffering from B and Cu deficiency. Effects of addition of 1000 kg ha^-1 of a commercial N-free fertilizer containing macro nutrients plus B, Cu, and Zn were investigated. B concentrations and B/N ratios were increased significantly in needles from fertilized trees compared to the control, to levels well above critical levels of deficiency and optimum nutrient ratios. In contrast, the treatment did not change the low needle Cu status and there was no effect on growth measured as needle mass after one growing season. Graphical vector analysis together with the absence of change in needle mass suggested a luxury uptake of B. Application of the concepts for critical levels of deficiency and optimum nutrient ratios in relation to N suggested B and Cu deficiency were contributing factors to the observed forest damage in the area. Graphical vector analysis requires a rapid response in needle mass, in combination with improved needle nutrient status in order to identify nutrient deficiencies. The applicability of the technique appears to be limited to primarily growth-promoting nutrients.     

Associations between use,activities and characteristics of the outdoor environment at workplaces

Today, office work in western societies is more sedentary and more mentally demanding than ever before. This way of working plays a role in the increase in lifestyle diseases related to sedentary routines and stress. Green outdoor environments have been found to motivate physical activity and reduce stress levels. In this study, we therefore considered these environments to have a positive affect on work force health and wellbeing. However, research on the workplace outdoor environment is still limited. To investigate how and why the workplace outdoor environment is used by office workers and the impact of these environments on office workers’ health and wellbeing, five research questions were formulated. The questions addressed the use of the outdoor environments; the outdoor activities; encouragement and impediments for going outdoors; characteristics of the outdoor environment, and the impact of workplace outdoor environments on employees’ health, job satisfaction and work performance. In order to answer these research questions, we conducted a web-based questionnaire, completed by (N) 402 office workers from six Danish companies. The results show that 37.8% of the respondents spent time outdoors during their working day, and that the proportion of men spending time outdoors was higher than the proportion of women. Eight outdoor activities were identified, and significant relationships between the outdoor activities and perceived sensory dimensions (PSD) of the outdoor environment were found, indicating that the presence of the dimension ‘serene’ increased the odds for respondents going outdoors and that five of the eight activities would be performed. Only few significant relationships between outdoor environment use and employee health, job satisfaction and work performance were identified.     

Use of Small Public Urban Green Spaces (SPUGS)

During recent years, the use of urban green space (UGS) has received increased attention within several research fields, as well as politically, especially in relation to the benefits it provides for human health. Much research on larger green areas has shown that they are beneficial to people's health, physically, socially and mentally. However, because of densification tendencies in cities in Western countries, large green areas are a limited resource and many people live in city areas where the distance to larger green areas reduces the possibility for frequent use. Small Public Urban Green Spaces (SPUGS) in dense city areas might contribute to satisfy the need for everyday experiences of outdoor areas, but research on SPUGS is limited. In this paper, we describe how nine SPUGS in Copenhagen are used by the citizens based on data from 686 respondents who completed on-site questionnaires during their visit. The results show that SPUGS are primarily used for ‘socialising’ and ‘rest and restitution’. Furthermore, they are mainly used by well-educated people between the ages of 30 and 49. For ‘socialising’, SPUGS are primarily used on the way home. For ‘rest and restitution’, SPUGS are primarily used ‘en route’ or on the way home. More than half of the respondents reported living more than 1000 m from the SPUGS, and more than half of the respondents reported that they travel more than 500 m to get to the SPUGS. People aged 50–65 are more likely to visit the SPUGS for ‘rest and restitution’ than the younger age groups. Furthermore the older people are, the less likely they are to visit SPUGS to socialise. These results show that SPUGS are an important asset in citizen's everyday lives, and the results may provide inspiration for landscape architects, city planners and policy makers for the future planning of dense city areas.