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- Lindgren, Åsa, 1973-
(author)
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Effects of herbivory on arctic and alpine vegetation
- 2007
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Doctoral thesis (other academic/artistic)abstract
- The distribution of plant species and functional traits in alpine and arctic environments are determined by abiotic conditions, but also by biotic interactions. In this thesis, I investigate interactions among plants and herbivory effects on plant community composition and plant functional traits in three different regions: Swedish Lapland, Beringia (USA/Russia) and Finnmark (Norway). Reindeer grazing was found to be extensive in southern Lapland and had limited effects on plant community composition and seedling germination. However, reindeer presence was found to influence plant functional traits, particularly in the subalpine birch forest. Tall herbs were lower and had lower SLA when reindeer were present, while small herbs showed an opposite pattern. The contrasting effects on the two herb groups are probably explained by a competitive release for small herbs when the tall herbs are suppressed by reindeer. Rodents had the largest relative impact on plant community composition in southern Lapland and this is consistent with the study from Finnmark, where rodents heavily affected dwarf shrubs on predator-free islands. With no predators present, vole densities increased profoundly and almost depleted some dwarf shrub species. These results support the idea that small mammals in arctic and alpine tundra are controlled by predators (i.e. top-down). However, a decrease in the nutritional quality in a sedge after defoliation gives support for the idea that small mammals are regulated by plant quality (i.e. bottom-up). In Beringia, small and large herbivores differed in the relation to plant community composition, since large herbivores were related to species richness and small herbivores were related to plant abundance. Plant functional traits were related only to large herbivores and standing crop of vascular plants.
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| 2. |
- Malmberg Gavelin, Hanna, 1982-
(author)
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Rehabilitation for improved cognition in stress-related exhaustion : cognitive, neural and clinical perspectives
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Stress-related exhaustion disorder (ED) has been associated with concomitant cognitive impairment, perceived by patients to have large impact on everyday life. However, little is known about how to address cognition in stress rehabilitation and how this could influence stress recovery over time. The aim of this thesis was to evaluate the efficacy of additional cognitive and aerobic training for patients with ED who participated in a multimodal stress rehabilitation program. A further aim was to explore the neural correlates of ED. The main focus of this thesis was on cognitive training, the effects of which were studied from a cognitive, neural, and clinical perspective (Study I-III). The final part of this thesis (Study III) broadened the perspective and investigated the long-term effects of cognitive and aerobic training on cognitive and clinical outcomes.Study I and II evaluated the effects of process-based cognitive training immediately following the intervention. The results from Study I showed that generalization of training effects following cognitive training was selective and restricted to tasks similar to those trained. The cognitive training group showed a greater reduction in burnout symptoms, and partial support was given for fewer subjective cognitive complaints compared to stress rehabilitation alone. Study II used functional neuroimaging to explore the neural effects of cognitive training, showing training-related activation increases at high working memory load; however, conclusions were restricted due to the small sample.Study II additionally explored the neural correlates of ED by investigating within-group associations between burnout level and functional neural response during working memory updating. The results revealed that patients with higher levels of burnout showed greater recruitment of working memory-related regions during task execution, potentially reflecting a compensatory mechanism serving to uphold task performance.Study III evaluated the clinical utility of addressing cognitive impairments in stress rehabilitation. Here, the effects of cognitive and aerobic training on several ED-related variables were investigated 1 year after the intervention. Cognitive training was associated with a small and lasting improvement in cognitive performance. Aerobic training yielded improvements in episodic memory immediately following the intervention, but no significant difference was found between the aerobic training group and the control group at 1-year follow-up. For psychological health and work ability, no additional benefits were seen for the added interventions relative to stress rehabilitation alone. However, a long-term improvement in burnout symptoms favouring cognitive training was observed when restricting the analysis to only include patients who had completed the intervention. This highlights the importance of supporting patients in adhering to added treatments.In sum, the papers in this thesis provide initial evidence of neurocognitive plasticity in patients with ED and tentatively suggest that cognitive improvements following cognitive training may translate into alleviated clinical symptoms. These results support the argument that interventions targeting cognitive impairments holds a place in the effective rehabilitation of ED.
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| 3. |
- Larisch, Lisa-Marie
(author)
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Movement behavior and mental health in office workers : Associations and intervention effects
- 2023
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Doctoral thesis (other academic/artistic)abstract
- Mental disorders pose a significant global health challenge. To effectively address this challenge, mental health promotion must be included in various sectors, including workplaces. Various strategies for promoting mental health in the workplace have been suggested, including interventions aimed at improving movement behavior, i.e., sitting less and moving more. Physical activity (PA) and sedentary behavior (SED) are established determinants of mental health. However, there are aspects of the relationship between movement behavior and mental health that are not well understood, for example, the combined effects of all movement behaviors occurring throughout the daily 24-hour cycle, i.e., time in bed, SED, light-intensity physical activity, and moderate to vigorous physical activity (MVPA), on mental health. In addition, only a few well-designed workplace interventions for improving movement and mental health outcomes have been tested. Office workers often spend extensive amounts of time being sedentary and might particularly benefit from such interventions. The aims of this thesis were (1) to investigate cross-sectional associations between 24-hour movement behavior and mental health among office workers and (2) to evaluate the efficacy, acceptability, feasibility, and fidelity of two cluster randomized controlled trial (RCT) interventions for improving movement behavior and mental health using quantitative and qualitative methods.In Paper I, we investigated cross-sectional associations between 24-hour movement behavior and mental health outcomes (symptoms of depression and anxiety, burnout, mental wellbeing, and stress) among office workers (N=345-370). Movement behavior was measured using accelerometers and sleep diaries. Mental health outcomes were assessed using validated questionnaires. Only the proportion of time spent in MVPA, relative to all other behaviors, was positively associated with mental wellbeing. Papers II-IV were based on a three-armed cluster RCT among office workers (N=263). During the 6-month intervention period, the iSED intervention group focused on reducing SED, and the iPA intervention group focused on increasing MVPA compared to a wait-list control group. The multi-level interventions were designed based on ecological models of health behavior, addressing the individual office workers as well as their physical, social, and organizational work environment. Paper II investigated intervention effects on accelerometer-measured 24-hour movement behavior and cardiorespiratory fitness. We considered overall 24-hour movement behavior and movement behavior during work versus non-work time. No intervention effects were found. Paper III was based on a qualitative study that was embedded in the RCT. It investigated the acceptability, feasibility, and fidelity of intervention components that addressed the individual, environmental and organizational level. Interviews and focus group discussions were performed with 38 key stakeholders after the 6-month intervention period. The study included office workers who received the interventions, health coaches who delivered counseling sessions, team leaders who were responsible for implementing group activities, and human resource and higher management staff who provided support at the organizational level. In general, the interventions were well appreciated, and components seemed to work as intended when delivered as intended. Many office workers experienced improvements in movement behavior and wellbeing and ascribed those to the interventions. Acceptability, feasibility, and fidelity of individual-level components were high but reduced for components depending on team leaders, mainly due to challenges associated with recruiting managers as team leaders and forming teams. Manager and team support were considered crucial for promoting more PA and less SED, yet many participants reported a lack of such support. Thus, identified challenges with these components might have reduced overall intervention efficacy. Paper IV investigated intervention effects on mental health outcomes (symptoms of depression or anxiety, mental wellbeing, and stress). In addition, we explored whether changes in mean PA intensity mediated or moderated intervention effects. The interventions improved mental wellbeing for the combined intervention groups and the iSED group but not for the iPA group compared to the control group. The interventions improved mean PA intensity, but mean PA intensity did not mediate intervention effects on any outcome. Mean PA intensity moderated intervention effects on mental wellbeing. Participants who reduced mean PA intensity reduced mental wellbeing compared to participants who did not change mean PA intensity. This highlights the importance of maintaining high levels of PA for mental wellbeing.This thesis contributes to existing knowledge by applying a rigorous investigation of cross-sectional associations between 24-h movement behavior and mental health among office workers and by conducting a comprehensive analysis of intervention effects. It offers valuable insights and considerations that may inform occupational health practitioners, employers, policy makers, and researchers and may contribute to developing future effective interventions.
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