Growth and yield for direct seeding and planting at the time of pre-commercial thinning and first thinning : the potential of the regeneration methods to fulfill different production goals

Holmen Skog nyttjar i stor utsträckning både sådd och plantering, varje år används sådd på omkring 20 % av föryngringsarealen. Företaget önskar sig dock mer kunskap om hur tillväxten skiljer sig åt över tiden mellan skogssådd och plantering. Syftet med studien var därför att jämföra tillväxt för skogssådd och plantering inför röjning och inför första gallring samt att undersöka hur väl olika produktionsmål kan uppfyllas genom valet av stamtäthet vid anläggnings- eller röjningstillfället. Studien genomfördes på Holmens Skogs egen mark, distrikt Umeå och Norsjö i Västerbottens län. Sådda bestånd parades med planteringar. Beståndsanläggningstidpunkt, ståndortsegenskaper och geografisk närhet var de viktigaste urvalskriterierna. Beståndstäthet, medel- och högsta höjd, stamvolym och biomassa jämfördes för de två föryngringsmetoderna samt användes för att uppskatta framtida netto vid första gallringen vid stickväg för olika anläggnings- och skötselregimer med olika produktionsmål (stamved (2300 stammar (st) ha-1), kombinationsmål (3500 st ha-1) och biomassamål (7000 st ha-1). Beståndstätheten var generellt högre för sådda bestånd men planterade bestånd uppvisade i medeltal högre värden för höjd, stamvolym och biomassa (dock med få statistiskt säkerställda skillnader). Detta gällde så länge ”normala” omständigheter var rådande, vid exv. höga skadefrekvenser (älg, snö, rostsvampar) kunde förhållandena mellan sådd och plantering skifta. Från röjningstidpunkten till första gallring minskade skillnaden i tallstammar/ha mellan sådda och planterade bestånd från 3 gånger så många ned till ca 40 % fler stammar, på Umeå distrikt. I Norsjö var antalet stammar/ha av tall i sådda bestånd 70 % fler inför röjning och 20 % färre inför gallring, jämfört med planterade bestånd. Sett till utvecklingsbara tallstammar hade sådd något större potential inför första gallring med drygt 40 stammar mer per hektar jämfört med plantering i de dominerande/härskande och medhärskande trädklasserna. Inför röjning var medelhöjden mellan 20 och 30 % högre för plantering på båda distrikten och endast för Norsjö distrikt syntes en liten minskning av skillnaden inför gallring. Även högsta höjden var 20 % högre för plantering och höll sig oförändrad fram till första gallring i Umeå. I Norsjö var högsta höjden 10 % högre för sådd än för plantering. En del av planteringens högre höjd och volym i Umeå distrikt kan tillskrivas ”förädlingseffekten” (max ca 9%) eftersom flera av de planterade bestånden var anlagda med förädlat material. Sådda bestånd hade ca hälften så mycket stamvolym per hektar inför röjning jämfört med plantering, differensen avtog med tiden och inför första gallring hade skillnaden gått ner till ca 30 procent på båda distrikten. Samma avtagande trend märktes för stamvolym och biomassa per stam. Från att planteringar haft mycket större volym och biomassa per stam avtog det till två-tre gånger så stor volym inför första gallring för båda distrikten. Plantering och sådd hade relativt lika årsskottstillväxt och inför gallring hade sådda bestånd enbart elva procents kortare årsskott över senaste femårsperioden. Den skillnad i höjd som fanns mellan plantering och sådd vid anläggningstillfället och etableringsfasen verkar alltså kvarstå fram till gallringen, den relativa tillväxtskillnaden blir dock allt mindre med tiden. En grov ekonomisk kalkyl gjordes för att jämföra olika produktionsmål baserade på sådd och plantering, från anläggning fram till och med första gallring. Plantering inbringade inget positivt netto efter första gallring med traditionell skötselregim för beräknad uttagen volym. Skogssådd gav ett positivt netto för kombinationsmålet (11 680 SEK ha-1) och samtliga alternativ för biomassamålet; såddmix (blandning av beståndsfrö och förädlat frö) inbringade det största nettot (15 060 SEK ha-1). Alla alternativ med positivt netto genomfördes med energivedsuttag enligt en teknik som kan vara operativ först om ett antal år.Holmen Skog is using both planting and direct seeding for forest regeneration. Every year approximately 20 percent of the regeneration area is seeded. The company seeks more knowledge concerning how the growth and yield is differing over time between direct seeding and planting. The objective of this study was to compare growth and yield for direct seeding and planting by the time of pre-commercial thinning (PCT) and first thinning and to investigate how well different production goals could be fulfilled through the selection of stand density at the time of establishment or pre-commercial thinning. The study was performed on Holmen Skog’s own forest land in Umeå and Norsjö district. Seeded stands were paired with planted stands through a range of criteria. Establishing year, site index and geographical closeness were considered to be the most important ones. Stand density, mean- and top height, stem volume and biomass were compared for the two regeneration methods and used to calculate a possible future net value by first thinning for different production goals (stem wood (2300 stems (st) ha-1), combination goal (3500 st ha-1) and biomass goal (7000 st ha-1). Seeded stands had higher stand densities in general while planted stands had higher values for the growth variables (though few significant differences). This was true as long as normal conditions were prevailing but for example with high rates of damage (moose, snow, and rust diseases) the conditions between seeding and planting could be reversed. Seeded stands had 3 times more stems/ha than planted stands at PCT and 40% more stems/ha at first thinning, in Umeå district. In Norsjö the number of pine stems in seeded stands was 70% higher at PCT but 20% less at first thinning, compared to planted stands. Regarding future productive pine stems, seeding entailed about 40 more stems/ha compared to planting in the dominant/co-dominant tree classes. At PCT the mean height was 20 to 30% higher for planted stands on both districts and only in Norsjö a slight decrease in height difference was seen at first thinning. Also the top height was 20% higher for planted stands and kept unaltered until first thinning in Umeå. In Norsjö at first thinning, the seeded stands were 10% higher than the planted ones. Some of the difference (max. 9%) in height and volume in Umeå district could be attributed to the use of orchard plant material in some of the planted stands. Seeded stands had half as much stem volume per hectare before pre-commercial thinning in comparison to planting but the difference was reduced over time to 30% until first thinning in both districts. The same trend was seen in stem volume and biomass per stem. From a very much larger difference at PCT, planted stems contained two to three times more volume/tree, than seeded stems, at thinning in both districts. The annual height growth was rather similar for the two treatments, at first thinning the seeded stands had only 11% lower leader growth. The difference in height between the two regeneration methods seems to be originating mainly from the differences at the time of establishment, however, the relative growth difference is clearly reduced over time. A simple economical analysis was used to compare different production goals, based on direct seeding and planting from the time of establishment until first thinning. Planting did not return a positive net income after first thinning, calculated from extracted volume, with a traditional silvicultural regime. Direct seeding gave a positive net income for the combination goal (11 680 SEK ha-1) and all alternatives for the biomass goal; seeding with an orchard and stand seed mixture gave the highest income (15 060 SEK ha-1). All alternatives with a positive net income were performed with harvest of fuel wood using harvest technology that could be operational first in a few years

Risk and Prognostic Factors of Low Back Pain: Repeated Population-based Cohort Study in Sweden

Study Design. Prospective longitudinal cohort study. Objective. To determine the associations for workload and health-related factors with incident and recurrent low back pain (LBP), and to determine the mediating role of health-related factors in associations between physical workload factors and incident LBP. Summary of Background Data. It is not known whether the risk factors for the development of LBP are also prognostic factors for recurrence of LBP and whether the associations between physical workload and incident LBP are mediated by health-related factors. We used data from the Swedish Longitudinal Occupational Survey of Health study. Those responding to any two subsequent surveys in 2010 to 2016 were included for the main analyses (N = 17,962). Information on occupational lifting, working in twisted positions, weight/height, smoking, physical activity, depressive symptoms, and sleep problems were self-reported. Incident LBP was defined as pain limiting daily activities in the preceding three months in participants free from LBP at baseline. Recurrent LBP was defined as having LBP both at baseline and follow-up. For the mediation analyses, those responding to three subsequent surveys were included (N = 3516). Methods. Main associations were determined using generalized estimating equation models for repeated measures data. Mediation was examined with counterfactual mediation analysis. Results. All risk factors at baseline but smoking and physical activity were associated with incident LBP after adjustment for confounders. The strongest associations were observed for working in twisted positions (risk ratio = 1.52, 95% CI 1.37, 1.70) and occupational lifting (risk ratio = 1.52, 95% CI 1.32, 1.74). These associations were not mediated by health-related factors. The studied factors did not have meaningful effects on recurrent LBP. Conclusion. The findings suggest that workload and health-related factors have stronger effects on the development than on the recurrence or progression of LBP, and that health-related factors do not mediate associations between workload factors and incident LBP.Peer reviewe

Favoritism Toward Foreign and Domestic Brands: A Comparison of Different Theoretical Explanations

Five theoretical approaches can predict favoritism toward domestic and foreign brands. This article applies a contrastive perspective to examine social identity, personal identity, cultural identity, system justification, and categorical cognition theories and their attendant constructs. The authors propose a set of main-effects hypotheses as well as hypotheses related to both product and country moderation effects on attitudes toward and loyalty to domestic and foreign brands. They test the hypotheses on a sample of Chinese consumers with respect to salient brands from 12 product categories. The results indicate that three of the theoretical approaches examined can explain only one side of favoritism—most commonly favoritism toward domestic brands—but not favoritism toward both domestic and foreign brands. Consumer xenocentrism, a concept rooted in system justification theory, seems to provide more consistent predictions for both domestic- and foreign-brand bias

It's giving me the blues: A fixed-effects and g-formula approach to understanding job insecurity, sleep disturbances, and major depression

Research suggests that work-related factors like job insecurity increases the risk of major depression (MD), although it is unclear whether the association is causal. Research further suggests that job insecurity increases sleep disturbances, which is also a risk factor for MD. Based on current knowledge, it is possible that job insecurity operates through sleep disturbances to affect MD, but this pathway has not been examined in the literature. The current study extends the literature by using two complementary, counterfactual approaches (i.e., random- and fixed-effects regression and a mediational g-formula) to examine whether job insecurity causes MD and whether sleep disturbances mediate the relationship. A methodological triangulation approach allowed us to adjust for unobserved and intermediate confounding, which has not been addressed in prior research. Findings suggest that the relationship between job insecurity and MD is primarily direct, that hypothetically intervening on job insecurity (in our g-formula) would reduce MD by approximately 10% at the population level, and this relationship operates via sleep disturbances to some degree. However, the indirect pathway had a high degree of uncertainty

Long working hours, anthropometry, lung function, blood pressure and blood-based biomarkers : cross-sectional findings from the CONSTANCES study

Background Although long working hours have been shown to be associated with the onset of cardiometabolic diseases, the clinical risk factor profile associated with long working hours remains unclear. We compared the clinical risk profile between people who worked long hours and those who reported being never exposed to long hours. Methods A cross-sectional study in 22 health screening centres in France was based on a random population-based sample of 75 709 participants aged 18-69 at study inception in 2012-2016 (the CONSTANCES study). The data included survey responses on working hours (never, former or current exposure to long working hours), covariates and standardised biomedical examinations including anthropometry, lung function, blood pressure and standard blood-based biomarkers. Results Among men, long working hours were associated with higher anthropometric markers (Body Mass Index, waist circumference and waist:hip ratio), adverse lipid levels, higher glucose, creatinine, white blood cells and higher alanine transaminase (adjusted mean differences in the standardised scale between the exposed and unexposed 0.02-0.12). The largest differences were found for Body Mass Index and waist circumference. A dose-response pattern with increasing years of working long hours was found for anthropometric markers, total cholesterol, glucose and gamma-glutamyltransferase. Among women, long working hours were associated with Body Mass Index and white blood cells. Conclusion In this study, men who worked long hours had slightly worse cardiometabolic and inflammatory profile than those who did not work long hours, especially with regard to anthropometric markers. In women, the corresponding associations were weak or absent.Peer reviewe

Job insecurity and risk of coronary heart disease : Mediation analyses of health behaviors, sleep problems, physiological and psychological factors

Job insecurity has been linked to increased risk of coronary heart disease (CHD), but underlying mechanisms remain uncertain. Our aim was to assess the extent to which this association is mediated through life style, physiological, or psychological factors. A total of 3917 men and women free from CHD provided data on job insecurity in the Whitehall II cohort study in 1997-1999. The association between job insecurity and CHD was decomposed into a direct and indirect effect mediated through unhealthy behaviors (smoking, high alcohol consumption, physical inactivity), sleep disturbances, 'allostatic load', or psychological distress. The counterfactual analyses on psychological distress indicated a marginally significant association between job insecurity and incident CHD (hazard ratio (HR) 1.32; 95 % confidence interval (CI) 1.00-1.75). This association was decomposed into a direct (HR 1.22, 95 %CI 0.92-1.63) and indirect association (1.08, 95 %CI 1.01-1.15), suggesting that about 30 % of the total relationship was mediated by psychological distress. No mediation was indicated via health behaviors, sleep disturbances, or allostatic load, although job insecurity was related to disturbed sleep and C-reactive protein, which, in turn were associated with CHD. In conclusion, our results suggest that psychological distress may play a role in the relation between job insecurity and CHD.Peer reviewe

Work stress, anthropometry, lung function, blood pressure, and blood-based biomarkers : a cross-sectional study of 43,593 French men and women

Work stress is a risk factor for cardio-metabolic diseases, but few large-scale studies have examined the clinical profile of individuals with work stress. To address this limitation, we conducted a cross-sectional study including 43,593 working adults from a French population-based sample aged 18-72 years (the CONSTANCES cohort). According to the Effort-Reward Imbalance model, work stress was defined as an imbalance between perceived high efforts and low rewards at work. A standardized health examination included measures of anthropometry, lung function, blood pressure and standard blood-based biomarkers. Linear regression analyses before and after multivariable adjustment for age, socioeconomic status, depressive symptoms, health-related behaviours, and chronic conditions showed that work stress was associated with higher BMI, waist circumference, waist-hip ratio, alanine transaminase, white blood cell count and lower high-density lipoprotein cholesterol in men, and with higher BMI and white blood cell count in women (differences 0.03-0.06 standard deviations, P <0.05 between individuals with and without work stress). No robust associations were observed with lung function, haemoglobin, creatinine, glucose levels or resting blood pressure measures. This indicates that work stress is associated altered metabolic profile, increased systemic inflammation, and, in men, poorer liver function, which is a marker of high alcohol consumption.Peer reviewe

Characteristics of Workplace Psychosocial Resources and Risk of Diabetes: A Prospective Cohort Study

OBJECTIVE: To examine whether characteristics of workplace psychosocial resources are associated with the risk of type 2 diabetes among employees. RESEARCH DESIGN AND METHODS: Participants were 49,835 employees (77% women, aged 40-65 years, and diabetes free at baseline) from the Finnish Public Sector cohort study. Characteristics of horizontal (culture of collaboration and support from colleagues) and vertical (leadership quality and organizational procedural justice) psychosocial resources were self-reported. Incident type 2 diabetes (n = 2,148) was ascertained through linkage to electronic health records from national registers. We used latent class modeling to assess the clustering of resource characteristics. Cox proportional hazards models were used to examine the relationship between the identified clusters and risk of type 2 diabetes during 10.9 years of follow-up, adjusting for age, sex, marital status, educational level, type of employment contract, comorbidity, and diagnosed mental disorders. RESULTS: We identified four patterns of workplace psychosocial resources: unfavorable, favorable vertical, favorable horizontal, and favorable vertical and horizontal. Compared with unfavorable, favorable vertical (hazard ratio 0.87 [95% CI 0.78; 0.97]), favorable horizontal (0.77 [0.67; 0.88]), and favorable vertical and horizontal (0.77 [0.68; 0.86]) resources were associated with a lower risk of type 2 diabetes, with the strongest associations seen in employees at age ≥55 years (Pinteraction = 0.03). These associations were robust to multivariable adjustments and were not explained by reverse causation. CONCLUSIONS: A favorable culture of collaboration, support from colleagues, leadership quality, and organizational procedural justice are associated with a lower risk of employees developing type 2 diabetes than in those without such favorable workplace psychosocial resources