| 1. |
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| 2. |
- Felton, Adam, et al.
(författare)
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The tree species matters : Biodiversity and ecosystem service implications of replacing Scots pine production stands with Norway spruce.
- 2020
-
Ingår i: Ambio. - : Springer. - 0044-7447 .- 1654-7209. ; 49:5, s. 1035-1049
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Forskningsöversikt (refereegranskat)abstract
- The choice of tree species used in production forests matters for biodiversity and ecosystem services. In Sweden, damage to young production forests by large browsing herbivores is helping to drive a development where sites traditionally regenerated with Scots pine (Pinus sylvestris) are instead being regenerated with Norway spruce (Picea abies). We provide a condensed synthesis of the available evidence regarding the likely resultant implications for forest biodiversity and ecosystem services from this change in tree species. Apart from some benefits (e.g. reduced stand-level browsing damage), we identified a range of negative outcomes for biodiversity, production, esthetic and recreational values, as well as increased stand vulnerability to storm, frost, and drought damage, and potentially higher risks of pest and pathogen outbreak. Our results are directly relevant to forest owners and policy-makers seeking information regarding the uncertainties, risks, and trade-offs likely to result from changing the tree species in production forests.
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| 3. |
- Ahlbäck Öberg, Shirin, 1964-, et al.
(författare)
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Akademi utan krisplan
- 2014
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Ingår i: Upsala Nya Tidning. - Uppsala : AB Upsala Nya Tidning. - 1104-0173. ; :6/3, s. 5-5
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 4. |
- Ahlbäck Öberg, Shirin, 1964-, et al.
(författare)
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En högskoleledning i fritt fall
- 2013
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Ingår i: Gefle Dagblad. - Gävle : Gefle Dagblad AB. - 1103-9302. ; :9/3
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 5. |
- Ahlbäck Öberg, Shirin, et al.
(författare)
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Konstitution kan förebygga kris
- 2014
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Ingår i: Upsala Nya Tidning. - Uppsala : AB Upsala Nya Tidning. - 1104-0173. ; :17/3
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 6. |
- Ahlbäck Öberg, Shirin, 1964-, et al.
(författare)
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MOOCs-studenter bildar B-laget
- 2013
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Ingår i: Upsala Nya Tidning. - Uppsala : AB Upsala Nya Tidning. - 1104-0173. ; :17/6
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 7. |
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| 8. |
- Ahlbäck Öberg, Shirin, et al.
(författare)
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Projektsamhället och hoten mot akademin
- 2016
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Ingår i: Det hotade universitetet. - Stockholm : Dialogos Förlag. - 9789175042992 ; , s. 9-26
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 9. |
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| 10. |
- Ammunét, Tea, et al.
(författare)
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Enkla åtgärder kan rädda hästkastanjen
- 2013
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Ingår i: Svampar och insekter : Rapport från Future Forests 2009-2012. ; :2013:5, s. 20-21
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Bokkapitel (populärvet., debatt m.m.)
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| 11. |
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| 12. |
- Bellone, Davide, et al.
(författare)
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Effect of forest stand type on host plant quality and direct and indirect effects on pine sawfly performance
- 2021
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Ingår i: Agricultural and Forest Entomology. - : Wiley. - 1461-9555 .- 1461-9563. ; 23, s. 163-172
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Tidskriftsartikel (refereegranskat)abstract
- Observed lower levels of herbivory in mixed compared with monoculture stands have been hypothesized to depend on top-down forces, through higher predation pressure by natural enemies or through bottom-up mechanisms through plant quality effects on herbivore performance. In this study, we compared the performance measured as host plant induced mortality, cocoon weight, and predation mortality of the European pine sawflyNeodiprion sertifer(Geoffroy) (Hymenoptera, Diprionidae) in mixed and monoculture forest stands. We did not observe a difference in host plant induced mortality, cocoon weight, or predation mortality between mixed and monoculture forest stands. We did find an effect of local conditions around each experimental tree on pine sawfly performance. For example, the nitrogen content of pine needles is negatively affected by the proportion of pine around the experimental tree, which in turn increases the survival of sawfly larvae. The results suggest that local conditions around individual trees are more important for the performance of the European pine sawfly than stand type,i.e.mixed or monoculture plant stands. We conclude that the ongoing trend for diversification within commercial forestry calls for more research where the effects of both bottom-up and top-down effects are studied at several spatial scales.
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| 13. |
- Bellone, Davide, et al.
(författare)
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Habitat heterogeneity affects predation of European pine sawfly cocoons
- 2017
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 7, s. 11011-11020
-
Tidskriftsartikel (refereegranskat)abstract
- Habitat heterogeneity is thought to affect top-down control of herbivorous insects and contribute to population stability by providing a more attractive microhabitat for natural enemies, potentially leading to reduced population fluctuations. Identifying the parameters that contribute to habitat heterogeneity promoting top-down control of herbivorous insects by natural enemies could facilitate appropriate management decisions, resulting in a decreased risk of pest insect outbreaks because of a higher level of predation. In our study, we measured the top-down pressure exerted by small mammals on the cocoons of a notorious pest insect in pine forests, the European pine sawfly (Neodiprion sertifer), which is known to be regulated by small mammal predation. The forest stands used differed in heterogeneity measured in terms of differences in tree diversity and density, understory vegetation height, presence/absence, and density of dead wood. We found higher predation in more dense spots within forest stands. Further, the effect of dead wood on sawfly cocoon predation depended on the pine proportion in forest stands. The addition of dead wood in a manipulation experiment had a slight positive effect on cocoon predation, while dead wood removal caused a clear decrease in predation rate, and the decrease was more pronounced when the proportion of pine increased. Our results show that habitat heterogeneity affects predation by generalist predators on herbivorous insects. This knowledge could be applied to reduce the risk of insect outbreaks by applying management methods that increase heterogeneity in perennial systems such as forests and orchards, thus decreasing the levels of insect damage.
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| 14. |
- Bennich-Björkman, Li, 1960-, et al.
(författare)
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Dags för Lemne att lämna
- 2015
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Ingår i: Upsala Nya Tidning. ; march 13
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 15. |
- Bergblomma, Marcus, 1979-, et al.
(författare)
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A wireless low latency control system for harsh environments
- 2012
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 9783902823144 ; , s. 17-22
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Konferensbidrag (refereegranskat)abstract
- The use of wireless communication technologies in the industry offer severaladvantages. One advantage is the ability to deploy sensors where they previously could noteasily be deployed, for instance on parts that rotate. To use wireless communication in industrialcontrol loops, demands on reliability and latency requirements has to be met. This in anenvironment that may be harsh for radio communication. This work presents a reliable, lowlatency wireless communication system. The system is used in a wireless thyristor control loopin a hydro power plant generator. The wireless communication is based on Bluetooth radiomodules. The work shows a latency analysis together with empirical hardware based latencyand packet error rate measurements. The background noise of a hydro power plant station isalso investigated. The average latency between the Bluetooth modules for the proposed systemis 5.09 ms. The packet error rate is 0.00288 for the wireless low latency control system deployedin a hydro power plant.
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| 16. |
- Berggren Nieto, Kristina, et al.
(författare)
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Synergistic effects of methyl jasmonate treatment and propagation method on Norway spruce resistance against a bark-feeding insect
- 2023
-
Ingår i: Frontiers in Plant Science. - 1664-462X. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Utilizing plants with enhanced resistance traits is gaining interest in plant protection. Two strategies are especially promising for increasing resistance against a forest insect pest, the pine weevil (Hylobius abietis): exogenous application of the plant defense hormone methyl jasmonate (MeJA), and production of plants through the clonal propagation method somatic embryogenesis (SE). Here, we quantified and compared the separate and combined effects of SE and MeJA on Norway spruce resistance to pine weevil damage. Plants produced via SE (emblings) and nursery seedlings (containerized and bare-root), were treated (or not) with MeJA and exposed to pine weevils in the field (followed for 3 years) and in the lab (with a non-choice experiment). Firstly, we found that SE and MeJA independently decreased pine weevil damage to Norway spruce plants in the field by 32-33% and 53-59%, respectively, compared to untreated containerized and bare-root seedlings. Secondly, SE and MeJA together reduced damage to an even greater extent, with treated emblings receiving 86-87% less damage when compared to either untreated containerized or bare-root seedlings in the field, and by 48% in the lab. Moreover, MeJA-treated emblings experienced 98% lower mortality than untreated containerized seedlings, and this high level of survival was similar to that experienced by treated bare-root seedlings. These positive effects on survival remained for MeJA-treated emblings across the 3-year experimental period. We conclude that SE and MeJA have the potential to work synergistically to improve plants' ability to resist damage, and can thus confer a strong plant protection advantage. The mechanisms underlying these responses merit further examination.
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| 17. |
- Berggren, Åsa, et al.
(författare)
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The distribution and abundance of animal populations in a climate of uncertainty
- 2009
-
Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 118, s. 1121-1126
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Tidskriftsartikel (refereegranskat)abstract
- Current predictions regarding the ecological consequences of climate change on animal populations are generally autecological and species-specific, and/or non-mechanistic extrapolations of recent short-term patterns. To better understand and predict the effects of climate change on the distribution of species and the abundance of populations we offer a novel, broad theoretical framework. Climate-induced changes in trophic structure may actually be more predictable than effects on individual species. The logic is that there are general differences in climatic sensitivity among trophic levels - specifically, that as one moves up trophic levels, there is an increase in the temperature sensitivity of vital rates. More precisely, we provide: (1) a formal mathematical definition of distribution limits that is both operational and conceptual, introducing the concept DL(50), defined as the geographic and climatic isoline representing an equilibrium occupancy of half of the suitable habitats; (2) a matrix of the possible changes in trophic structure from climate change and the general theoretical consequences; and (3) a new idea that predicts broad effects of climatic warming on trophic systems. Our intention is to help meet the challenge of developing and testing general theoretical models that can predict which species will be winners and losers in ecological time, which evolutionary traits will be favoured or selected against, and what will be consequences for ecosystem structure and function.
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| 18. |
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| 19. |
- Birkhofer, Klaus, et al.
(författare)
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Methods to identify the prey of invertebrate predators in terrestrial field studies
- 2017
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 7:6, s. 1942-1953
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Tidskriftsartikel (refereegranskat)abstract
- Predation is an interaction during which an organism kills and feeds on another organism. Past and current interest in studying predation in terrestrial habitats has yielded a number of methods to assess invertebrate predation events in terrestrial ecosystems. We provide a decision tree to select appropriate methods for individual studies. For each method, we then present a short introduction, key examples for applications, advantages and disadvantages, and an outlook to future refinements. Video and, to a lesser extent, live observations are recommended in studies that address behavioral aspects of predator-prey interactions or focus on per capita predation rates. Cage studies are only appropriate for small predator species, but often suffer from a bias via cage effects. The use of prey baits or analyses of prey remains are cheaper than other methods and have the potential to provide per capita predation estimates. These advantages often come at the cost of low taxonomic specificity. Molecular methods provide reliable estimates at a fine level of taxonomic resolution and are free of observer bias for predator species of any size. However, the current PCR-based methods lack the ability to estimate predation rates for individual predators and are more expensive than other methods. Molecular and stable isotope analyses are best suited to address systems that include a range of predator and prey species. Our review of methods strongly suggests that while in many cases individual methods are sufficient to study specific questions, combinations of methods hold a high potential to provide more holistic insights into predation events. This review presents an overview of methods to researchers that are new to the field or to particular aspects of predation ecology and provides recommendations toward the subset of suitable methods to identify the prey of invertebrate predators in terrestrial field research.
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| 20. |
- Björkman, Berit, et al.
(författare)
-
Adult limb and breast amputees' experience and descriptions of phantom phenomena : a qualitative study
- 2010
-
Ingår i: Scandinavian Journal of Pain. - : Walter de Gruyter GmbH. - 1877-8860 .- 1877-8879. ; 1:1, s. 43-49
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Tidskriftsartikel (refereegranskat)abstract
- Background Phantom phenomena – pain or other sensations appearing to come from amputated body parts – are frequent consequences of amputation and can cause considerable suffering. Also, stump pain, located in the residual limb, is in the literature often related to the phantom phenomena. The condition is not specific to amputated limbs and has, to a lesser extent, been reported to be present after radical surgery in other body parts such as breast, rectum and teeth. Multi-causal theories are used when trying to understand these phenomena, which are recognized as the result of complex interaction among various parts of the central nervous system confirmed in studies using functional brain imaging techniques. Functional brain imaging has yielded important results, but without certainty being related to phantom pain as a subjective clinical experience. There is a wide range of treatment methods for the condition but no documented treatment of choice. Aims In this study a qualitative, explorative and prospective design was selected, in the aim to understand the patients’ personal experience of phantom phenomena. The research questions focused at how patients affected by phantom pain and or phantom sensations describe, understand, and live with these phenomena in their daily life. This study expanded ‘phantom phenomena’ to also encompass phantom breast phenomenon. Since the latter phenomenon is not as well investigated as the phantom limb, there is clinical concern that this is an underestimated problem for women who have had breasts removed. Methods The present study forms the first part of a larger, longitudinal study. Only results associated with data from the first interviews with patients, one month after an amputation, are presented here. At this occasion, 28 patients who had undergone limb amputation (20) or mastectomy (8) were interviewed. The focused, semi-structured interviews were recorded, transcribed, and then analyzed using discourse-narrative analysis. Results The interviewees had no conceptual problems in talking about the phenomena or distinguishing between various types of discomfort and discomfort episodes. Their experience originated from a vivid, functioning body that had lost one of its parts. Further, the interviewees reported the importance of rehabilitation and advances in prosthetic technology. Loss of mobility struck older amputees as loss of social functioning, which distressed them more than it did younger amputees. Phantom sensations, kinetic and kinesthetic perceptions, constituted a greater problem than phantom pain experienced from the amputated body parts. The descriptions by patients who had had mastectomies differed from those by patients who had lost limbs in that the phantom breast could be difficult to describe and position spatially. The clinical implication of this study is that when phantom phenomena are described as everyday experience, they become a psychosocial reality that supplements the definition of phantom phenomena in scientific literature and clinical documentation. Conclusions There is a need for clinical dialogues with patients, which besides, providing necessary information about the phenomena to the patients creates possibilities for health professionals to carefully listen to the patients’ own descriptions of which functional losses or life changes patients fear the most. There is a need for more qualitative studies in order to capture the extreme complexity of the pain–control system will be highlighted.
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| 21. |
- Björkman, Berit, 1944-, et al.
(författare)
-
Phantom phenomena – Their perceived qualities and consequences from the patient’s perspective
- 2012
-
Ingår i: Scandinavian Journal of Pain. - : Elsevier. - 1877-8860 .- 1877-8879. ; 3:3, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- Background and aim: The curious phenomenon phantom limbs early became the object of research, and its underlying mechanisms have been discussed over the years. The complex nature of phantom phenom- ena makes interpretation of the results ambiguous, regarding both prevalence and the accompanying suffering. There is a lack of knowledge about how amputees experience the meaning and consequences of phantom phenomena. The present aim, therefore, was to investigate how individuals, in an interview situation, described the qualities of possible perceived phantom phenomena, and how their experience affected their lives one month after the amputation/mastectomy.Methods: Twenty-eight women and men who had undergone a limb amputation or mastectomy were interviewed. The focused, narrative-oriented interviews were transcribed verbatim and the scripts were analysed with content analysis.Results: One month after the amputation the informants described and related their phantom pain and phantom sensations in sensory-discriminative, motivational-affective and cognitive-evaluative dimen- sions. The phantom sensations were experienced mainly as more agonizing than the phantom pain.Despite both the high intensity of and the high annoyance at the phantom pain and phantom sensations, a majority felt that the phantom phenomena were not a hindrance in their attempts to recapture ordinary life. But when the hindrance was evaluated as high, the annoyance was evaluated as the highest possible for both phenomena or for the phantom sensations alone, never for phantom pain alone. The interviewees’ reported attitudes of hindrance were also described and estimated in the light of their sociocultural circumstances. Thus, other preceding and/or co-existent pain conditions as well as factors such as pre- operative information, the respondents’ views on pain treatment, and their knowledge and understanding of phantom phenomena were mentioned and related to the pain-producing situation.Two-thirds of the interviewees had received post-surgical information and for some, the phenomena were well-known from earlier experience. A majority applied some version of the medical explanation model, irrespective of age or level of education. However neither information nor medical explanation, or both, sufficed for them to understand their own phantom phenomena. Thus, differences between the concepts explanation and understanding seemed significant for the annoyance related to the phantom phenomena.Regarding background data: (i) the majority of the interviewees had had pre-amputation pain prob- lems; (ii) the breast-cancer phantoms differed in several ways; (iii) there were some age and gender differences in the descriptions of hindrance.Conclusions and implications: These findings highlight the importance of observing the individual approach to the phenomena as a process of evaluation and selection. In addition, experience and under- standing of the phantoms also have sociocultural aspects. There follows the need for individualized communication and information from the clinician, and for incorporating a socioscientific and meaning- centred approach in future studies. The present insights could also be of value in other iatrogenic pain conditions.
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| 22. |
- Björkman, Berit, et al.
(författare)
-
The meaning and consequences of amputation and mastectomy from the perspective of pain and suffering
- 2017
-
Ingår i: Scandinavian Journal of Pain. - : Elsevier. - 1877-8860 .- 1877-8879. ; 14:1, s. 100-107
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe concepts ‘pain’ and ‘suffering’ are frequently treated as synonymous. However, they are clearly distinct phenomena. Phantom phenomena including pain and sensory disturbances are still recognized as long-lasting problems after limb amputation and after mastectomy. The complex nature of phantom phenomena makes the interpretation of its results ambiguous, regarding the prevalence of pain, sensory disturbances and the accompanying suffering. There is clinical experience that suffering is a great burden for the individual but there is a lack of systematic studies of patients’ own evaluations of the suffering caused by their phantom phenomena.ObjectivesThe overall aim of this study was to identify and describe patients’ suffering related to, and as a part, of their post-amputation situation.MethodsThe present study constitutes a part of a prospective, two-year follow up project investigating interviews of 28 men and women in different ages and who have undergone a limb amputation or mastectomy. The reason for amputation or mastectomy varied among the patients and included vascular diseases, cancer (sarcoma and breast-cancer) and trauma. Our ambition was to extract as much variations as possible in different, individualized aspects of the actual pain and suffering producing situation. The participants were, here, invited to open-ended, narrative-oriented interviews one month after the surgery. The interviews were transcribed verbatim and analyzed within qualitative methodology: thematic content analysis.ResultsTwenty-two of 28 interviewees experienced phantom pain and phantom sensations. The two surgical processes amputation and mastectomy meant for a majority of the interviewees a critical event with threatening consequences for everyday life such as loss of function and personal integrity. Nine interviewees felt even stigmatized as a result of their lost body part. Numerous inter-related factors following the amputation/mastectomy, which can inflict severe suffering on the amputee, were uncovered. The context in which the interviewees were informed about the decision to amputate proved to be one such critical and important factor.ConclusionTo understand potential suffering in relation to phantom phenomena, it will never be enough merely to have knowledge of the underlying physiological or neurological mechanisms and/or the intensity of phantom pain and phantom sensations. Rather, it is necessary to find out how the loss of the body part and its everyday consequences are experienced by patients.ImplicationsIt is important to create time for real dialogue with the patients both during pre-operative preparation and post-operative rehabilitation in order to clarify and verbalize elements that constitute the patients individual suffering. Hopefully this strategy can alleviate future chronic pain problems, severe psycho-social distress and suffering. Such an approach ought to have impact also for perceived suffering after other types of surgery or different invasive treatments.
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| 23. |
- Björkman, Christer, et al.
(författare)
-
A rare event – an isolated outbreak of the pine-tree lappet moth (Dendrolimus pini) in the Stockholm archipelago
- 2013
-
Ingår i: Entomologisk tidskrift. - 0013-886X. ; 134, s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- The pine-tree lappet moth, Dendrolimus pini (L.), belonging to the family Lasiocampidae has a wide distribution in Eurasia. In Sweden it is normally found up to 61°N and normally occurs at low densities. In central Europe there have been several reports of outbreaks in historical time. In Sweden the last known outbreak before the one reported here was in 1938-40 in Värmland. In this paper we report a recent severe D. pini outbreak that was discovered in 2012 on the small island Furuskär in the Stockholm archipelago. The distribution of the damage on the island as well as a detailed inventory of larvae and pupae on individual trees is presented. Several photographs are presented to illustrate the damage. In the paper we formulate and try to answer several questions that arose as a natural consequence of this rare event: Why was this particular island hit? What are the causes behind the outbreak? What will happen to the trees and the vegetation on the island? Will the outbreak continue? Will the outbreak spread?
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| 24. |
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| 25. |
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| 26. |
- Björkman, Christer, et al.
(författare)
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Body Size
- 2009. - 2
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Ingår i: Encyclopedia of Insects. - Amsterdam : Elsevier/Academic Press. - 9780123741448 - 9780123741448 ; , s. 114-116
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 27. |
- Björkman, Christer
(författare)
-
Body Size
- 2009
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Ingår i: Encyclopedia of Insects. - 9780123741448 ; , s. 114-116
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 28. |
- Björkman, Christer, et al.
(författare)
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Causes behind insect folivory patterns in latitudinal gradients
- 2011
-
Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 99, s. 367-369
-
Tidskriftsartikel (refereegranskat)abstract
- Summary 1. Adams and Zhang recently published one of the best studies so far of patterns of insect folivory along a latitudinal (climatic) gradient. They show clear negative trends in foliage loss in relation to temperature for certain groups of insect herbivores. 2. Although their suggestion that the plant–herbivore interaction may be more important in cooler climates could be valid, they did not bring up the complementary explanation that interactions between predators and herbivores could also vary with climate. There are indications that insect natural enemies may respond more positively than insect herbivores to an increase in temperature. We argue that higher predator pressure in warmer climates may partly explain the patterns observed by Adams and Zhang. 3. Synthesis. To further develop the important research concerning herbivory in a changing climate, both theoretically and empirically, plant ecologists and entomologists would mutually benefit fromjoining forces. Key-words: climate, herbivory, plant–herbivore interactions, temperature, trophic interactions
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| 29. |
- Björkman, Christer, et al.
(författare)
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Effects of new forest management on insect damage risk in a changing climate
- 2015
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Ingår i: Climate change and insect pests. - 9781780643786 ; 7, s. 248-266
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Bokkapitel (refereegranskat)abstract
- Recent findings suggest that damage by forest insect pests will increase as a consequence of climate warming. Here, we ask whether changes in forest management can alter and possibly mitigate the increased risk of damage and outbreaks. We focus mainly on conditions in northern Europe, particularly Sweden, but conclusions should be valid for northern temperate forests. Three types of insect pests are considered; the regeneration pest,Hylobius abietis(pine weevil), defoliators and the bark beetle,Ips typographus. We compare the expected effect of new management methods with the presently predominant method of even-aged stands, which are thinned two to three times before final harvest by clear-felling. Continuous cover forestry (CCF) is the method most different from the present practice. CCF would lead to a drastic decrease in pine weevils, and also less damage by defoliators, but this latter prediction is uncertain. For the bark beetle, the uncertainty is even greater. In mixed forests, all three insect pest types are expected to become less of a problem. Putative mechanisms involve more abundant and diverse natural enemy fauna, and a more scattered distribution of food resources. A shorter rotation period (including no thinning) is expected to increase the damage by pine weevils, as it will result in more abundant breeding material. For defoliators, it is difficult to foresee the effects. A shorter rotation period will decrease the risk of bark beetle outbreaks, as storm-fellings will be less frequent and young stands more common. The effects of exotic tree species and clonal forestry are complex and will depend on several factors. A general conclusion is that forest management may be used to mitigate the anticipated risk of insect pest damage as a consequence of climate warming, but more research is required to certify these indications
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| 30. |
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| 31. |
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| 32. |
- Björkman, Christer, et al.
(författare)
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Ekologiska risker med nya trädslag
- 2013
-
Ingår i: Svampar och insekter Rapport från Future Forests 2009-2012. ; :2013:5, s. 9-11
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Bokkapitel (populärvet., debatt m.m.)
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| 33. |
- Björkman, Christer
(författare)
-
Fienderna är inte den enda faran
- 2016
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Ingår i: Forskning och framsteg. - 0015-7937. ; , s. 65-66
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Annan publikation (populärvet., debatt m.m.)
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| 34. |
- Björkman, Christer, et al.
(författare)
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Food Conditioning Affects Expression of Insect Resistance in Diploid Willows (Salix spp.)
- 2013
-
Ingår i: American Journal of Plant Sciences. - : Scientific Research Publishing, Inc.. - 2158-2742 .- 2158-2750. ; 4, s. 48-52
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Tidskriftsartikel (refereegranskat)abstract
- The high energy quota and versatility of use make willows (Salix spp.) attractive as bioenergy crops. Insect defoliation constitutes a threat to the profitability of willow growers. Hitherto, the breeding for resistance against the main insect pests has been hampered by the fact that all known resistant willow clones are polyploids, and existing molecular breeding tools work most effectively for diploids. Here, we firstly report diploid willows highly resistant to the main insect defoliator, the leaf beetle (Phratora vulgatissima), offering new opportunities for breeding resistance. Leaf bee-tles exposed to three resistant clones (two S. purpurea one S. eriocephala) laid three to 27 times fewer eggs than fe-males on a susceptible S. viminalis clone. Secondly, we show that beetles laid significantly more eggs on resistant clones if they were fed the susceptible clone prior to the oviposition monitoring test compared to when they pre-fed on resistant clones. Nevertheless, the differences observed between resistant and susceptible clones were pronounced in all cases. The food conditioning effect means that small differences in resistance among clones may be undetected.
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| 35. |
- Björkman, Christer, et al.
(författare)
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High Temperature Triggers Latent Variation among Individuals: Oviposition Rate and Probability for Outbreaks
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Background It is anticipated that extreme population events, such as extinctions and outbreaks, will become more frequent as a consequence of climate change. To evaluate the increased probability of such events, it is crucial to understand the mechanisms involved. Variation between individuals in their response to climatic factors is an important consideration, especially if microevolution is expected to change the composition of populations. Methodology/Principal Findings Here we present data of a willow leaf beetle species, showing high variation among individuals in oviposition rate at a high temperature (20°C). It is particularly noteworthy that not all individuals responded to changes in temperature; individuals laying few eggs at 20°C continued to do so when transferred to 12°C, whereas individuals that laid many eggs at 20°C reduced their oviposition and laid the same number of eggs as the others when transferred to 12°C. When transferred back to 20°C most individuals reverted to their original oviposition rate. Thus, high variation among individuals was only observed at the higher temperature. Using a simple population model and based on regional climate change scenarios we show that the probability of outbreaks increases if there is a realistic increase in the number of warm summers. The probability of outbreaks also increased with increasing heritability of the ability to respond to increased temperature. Conclusions/Significance If climate becomes warmer and there is latent variation among individuals in their temperature response, the probability for outbreaks may increase. However, the likelihood for microevolution to play a role may be low. This conclusion is based on the fact that it has been difficult to show that microevolution affect the probability for extinctions. Our results highlight the urge for cautiousness when predicting the future concerning probabilities for extreme population events
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| 36. |
- Björkman, Christer, et al.
(författare)
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Insect Pests in Future Forests: More Severe Problems?
- 2011
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Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 2, s. 474-485
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: A common concern is that damage by insects will increase in forests as a consequence of climate change. We are assessing the likelihood of this predicted outcome by examining how other factors (especially changes in forest management practices) may interact with effects of climate change. Here we describe the strategies for improving understanding of the causes of insect outbreaks and predicting the likelihood of insect-mediated damage increasing in the future. The adopted approaches are: (i) analyses of historical data, (ii) comparison of life history traits of outbreak and non-outbreak species, (iii) experiments along climatic gradients to quantify the strength of trophic interactions, and (iv) modeling. We conclude that collaboration by researchers from many disciplines is required to evaluate available data regarding the complex interactions involved, to identify knowledge gaps, and facilitate attempts to progress beyond speculation to more robust predictions concerning future levels of insect damage to forests
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| 37. |
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| 38. |
- Björkman, Christer
(författare)
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"Jag brukar alltid" (bildinsändare)
- 2009
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Ingår i: Göteborg : Offside press, Reportagebörsen.. - 1404-6822. ; , s. 20-
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Annan publikation (populärvet., debatt m.m.)
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| 39. |
- Björkman, Christer
(författare)
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Nonadditive interactions between trophic levels bias the appraisal of the strength of mortality factors
- 2012
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Ingår i: Population Ecology. - : Wiley. - 1438-3896 .- 1438-390X. ; 54, s. 125-133
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Tidskriftsartikel (refereegranskat)abstract
- The role of bottom-up and top-down factors in determining the abundance of organisms is still often evaluated in terms of the nominal (i.e., apparent) cause of death. To determine whether estimates of mortality can be influenced by nonadditive multitrophic interactions, we generated both marginal (i.e., the entirety of mortality attributable to a given factor, including its obscured fraction) and nominal estimates of the trophic forces acting on an herbivore. This was accomplished by comparing mortality rates of the willow leaf beetle Phratora vulgatissima on willows affected or relatively unaffected by local growing conditions, in the presence or absence of natural enemies. Marginal estimates indicated that bottom-up and top-down mortality factors interacted in a synergistic or compensatory way, with the nature of the interaction varying in response to the time elapsed since the last harvest of willow plantations. In contrast, nominal estimates could not discriminate synergistic and compensatory interactions from top-down influence. Combined with recent evidence of compensatory mortality between trophic forces in another system, this study suggests that nonadditive effects between bottom-up and top-down mortality factors may be common, offering an explanation through which the contrasting evidences previously presented by proponents of the bottom-up and top-down views can be understood.
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| 40. |
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| 41. |
- Björkman, Christer, et al.
(författare)
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Outbreaking forest insect drives phase synchrony among sympatric folivores: Exploring potential mechanisms
- 2020
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Ingår i: Population Ecology. - 1438-3896 .- 1438-390X. ; 62, s. 372-384
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Tidskriftsartikel (refereegranskat)abstract
- We explore a common feature of insect population dynamics, interspecific synchrony, which refers to synchrony in population dynamics among sympatric populations of different species. Such synchrony can arise via several possible mechanisms, including shared environmental effects and shared trophic interactions, but distinguishing the relative importance among different mechanisms can be challenging. We analyze interannual time series of population densities of the larch budmoth,Zeiraphera griseana(Lepidoptera: Tortricidae), along with six sympatric larch-feeding folivores from a site in the European Alps 1952-1979. These species include five lepidopterans,Exapate duratella,Ptycholomoides aeriferana,Spilonota laricana,Epirrita autumnataandTeleiodes saltuum, and one hymenopteran sawflyPristiphora laricis. We document that the highly regular oscillatory behavior (period 9-10 years) ofZ.griseanapopulations is similarly evident in the dynamics of most of the sympatric folivores. We also find that all of the sympatric species are phase synchronized withZ.griseanapopulations with half of the sympatric species exhibiting nonlagged phase synchrony and three of the species exhibiting 2-5 year lags behindZ.griseanapopulations. We adapt a previously developed tritrophic model ofZ.griseanadynamics to explore possible mechanisms responsible for observed phase synchronization. Results suggest that either shared stochastic influences (e.g., weather) or shared parasitoid impacts are likely causes of nonlagged phase synchronization. The model further indicates that observed patterns of lagged phase synchronization are most likely caused by either shared delayed induced host plant defenses or direct density-dependent effects shared withZ.griseana.
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| 42. |
- Björkman, Christer
(författare)
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Phenotypic Plasticity in a Willow Leaf Beetle Depends on Host Plant Species: Release and Recognition of Beetle Odors
- 2015
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 40, s. 109-124
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Tidskriftsartikel (refereegranskat)abstract
- Aggregation behavior of herbivorous insects is mediated by a wide range of biotic and abiotic factors. It has been suggested that aggregation behavior of the blue willow leaf beetle Phratora vulgatissima is mediated by both host plant odor and by odor released by the beetles. Previous studies show that the beetles respond to plant odors according to their prior host plant experiences. Here, we analyzed the effect of the host plant species on odor released and perceived by adult P. vulgatissima. The major difference between the odor of beetles feeding on salicin-rich and salicin-poor host plants was the presence of salicylaldehyde in the odor of the former, where both males and females released this compound. Electrophysiological studies showed that the intensity of responses to single components of odor released by beetles was sex specific and dependent on the host plant species with which the beetles were fed. Finally, behavioral studies revealed that males feeding on salicin-rich willows were attracted by salicylaldehyde, whereas females did not respond behaviorally to this compound, despite showing clear antennal responses to it. Finally, the ecological relevance of the influence of a host plant species on the plasticity of beetle odor chemistry, perception, and behavior is discussed.
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| 43. |
- Björkman, Christer
(författare)
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Phenotypic plasticity in host plant preference of the willow leaf beetle Phratora vulgatissima: the impact of experience made by adults
- 2014
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Ingår i: Agricultural and Forest Entomology. - : Wiley. - 1461-9555 .- 1461-9563. ; 16, s. 417-425
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of the plasticity of Phratora vulgatissima (Colepotera: Chrysomelidae) behavioural responses to cues of its willow host plants is essential for understanding host affiliations of this species and for developing management strategies. We investigated how the experience obtained by adult P. vulgatissima with two different willow species shapes olfactory, feeding and oviposition preferences in the laboratory. The willow species differed in their leaf odours and phenolic glycoside contents. Females that had experienced Salix viminalis (Salicaceae) neither discriminated between odours of S. viminalis and Salix dasyclados, nor between blends of green leaf volatiles (GLV) that mimic quantitatively those released by S. viminalis and S. dasyclados. However, when females had experienced S. dasyclados, they preferred the experienced odour of S. dasyclados and the respective GLV blend to the odour of S. viminalis or its GLV blend. By contrast, regardless of their experience obtained in the adult stage, females preferred S. viminalis over S. dasyclados for feeding and oviposition. Exposure of beetles to odour of stands with various willow species might affect the experience-induced olfactory preference for a single species and thus impair host location success.
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| 44. |
- Björkman, Christer, et al.
(författare)
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Spatial distribution of interacting insect predators: Possible roles of intraguild predation and the surrounding habitat
- 2011
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Ingår i: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 12, s. 516-522
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Tidskriftsartikel (refereegranskat)abstract
- Predator foraging behaviour affects the outcome of enemy enemy interactions. Using a combination of fieldwork and laboratory experiments, we show that intraguild predation may be important in the field distribution of generalist predators that share a common prey: the eggs (and larvae) of the leaf beetle Phratora vulgatissima, a major insect pest in coppicing willow plantations. We focused on a species from the hoverfly genus Parasyrphus (Syrphidae), which may exhibit large temporal and spatial variation in density. Predator and prey densities were quantified in 40 field plots in willow plantations. The likelihood of finding hoverfly eggs declined with increasing densities of two predatory minds, Orthotylus marginalis and Closterotomus fulvomaculatus, which exhibit less mobile behaviour similar to that of hoverfly larvae. The density of a more mobile predatory bug species, the anthocorid Anthocoris nemorum, was not associated with hoverfly occurrence. These results corroborate the hypothesis that less mobile predators should be stronger intraguild predators than mobilepredators. Further partial support for this hypothesis was obtained in the laboratory study where individual predators were presented with clutches of P vulgatissima eggs containing one hoverfly egg: the less mobile C. fulvomaculattts and O. marginalis tended to consume the hoverfly egg more readily than the more mobile A. nemorum. However, most individuals of all three bug species consumed the egg of the potential competitor - the syrphid - within 24 h. The field study also showed that hoverfly occurrence was positively associated with the density of their prey and with the presence of nearby forests. We conclude that intraguild predation, abundance of prey and the surrounding habitat affect the distribution of hoverflies in this system and should be considered when developing biological control methods.
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| 45. |
- Björkman, Christer, et al.
(författare)
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Stand structure of Monocotyledons and Dicotyledons in different successional stages in Corcovado National Park, Costa Rica
- 2011
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Ingår i: Bois Et Forets Des Tropiques. - 0006-579X. ; , s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- The two major groups of angiosperms, monocotyledons and dicotyledons, differ in several of their life history traits. Despite the obvious differences between the two groups, there are few studies elaborating on how these may relate to their ecological succession. The study compares the relative densities of these two fundamental groups of plants with different evolutionary histories in forests in two different successional stages at the Sirena station in Costa Rica's Corcovado National Park, in Central America. The hypothesis was that the monocotyledons/dicotyledons ratio would decrease in later successional stages. A total of 40 right-angled triangular plots ((5 x 5 m)/2) were sampled and the plants were divided into four crown size classes, as well as into monocotyledons and dicotyledons. Plant densities and crown size class distribution were analysed using ANOVA with the general linear model (GLM) procedure. The mean overall plant density in the secondary forest was significantly greater than in the primary forest (P < 0.001). The structure of the crown size class distribution, however, was similar for both monocotyledons and dicotyledons, and for the primary and secondary forest types. There was no significant difference between the two forests in the monocotyledons to dicotyledons ratio (P = 0.99). The crown size class distribution results indicate that there is a similar distribution trend in monocotyledon and dicotyledon succession, although there are always more dicotyledons than monocotyledons. These results led to conclude that a larger difference between successional stages is necessary to perceive the difference anticipated in this study.
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| 46. |
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| 47. |
- Boberg, Johanna, et al.
(författare)
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Skadegörarna utmanar skogen
- 2014
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Ingår i: Future Forests Syntes.
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Annan publikation (populärvet., debatt m.m.)abstract
- Invasiva skadegörare är främmande arter som som hamnat i en ny miljö och därigenom ofta orsakar stor skada. Skadegörare i skog består till största delen av olika insekter och svamp-patogener som orsakar sjukdomar. Introduktionen av invasiva skadegörare till Europas skogar har mer än fördubblats under de senaste 100 åren. De invasiva skadegörarna sprids effektivt via handeln med växter och växtmaterial, men även i förpackningsmaterial, som lastpallar. Svamppatogener introduceras oftast genom import av levande plantor medan skadliga insekter som barkborrar och nematoder oftast transporteras med trä och träprodukter. Den potentiella kostnaden orsakade av invasiva skadegörare är enorm. Att hantera almsjukan, en patogen som påverkat ett trädslag med liten utbredning i Sverige, har uppskattats kosta 20-54 miljoner kronor per år. Inkluderas värdeförluster ökar kostnaden med upp till 37 gånger! Skulle de dominerande trädslagen gran eller tall hotas av en invasiv art på liknande sätt som almen skulle kostnaderna snabbt kunna blir mycket stora. Dessutom går stora värden i kulturlandskapet och i biologisk mångfald förlorade.
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| 48. |
- Bommarco, Riccardo, et al.
(författare)
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Insecticides Suppress Natural Enemies and Increase Pest Damage in Cabbage
- 2011
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Ingår i: Journal of Economic Entomology. - 0022-0493 .- 1938-291X. ; 104, s. 782-791
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Tidskriftsartikel (refereegranskat)abstract
- Intensive use of pesticides is common and increasing despite a growing and historically well documented awareness of the costs and hazards. The benefits from pesticides of increased yields from sufficient pest control may be outweighed by developed resistance in pests and killing of beneficial natural enemies. Other negative effects are human health problems and lower prices because of consumers' desire to buy organic products. Few studies have examined these trade-offs in the field. Here, we demonstrate that Nicaraguan cabbage (Brassica spp.) farmers may suffer economically by using insecticides as they get more damage by the main pest diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), at the same time as they spend economic resources on insecticides. Replicated similarly sized cabbage fields cultivated in a standardized manner were either treated with insecticides according common practice or not treated with insecticides over two seasons. Fields treated with insecticides suffered, compared with nontreated fields, equal or, at least in some periods of the seasons, higher diamondback moth pest attacks. These fields also had increased leaf damage on the harvested cabbage heads. Weight and size of the heads were not affected. The farmers received the same price on the local market irrespective of insecticide use. Rates of parasitized diamondback moth were consistently lower in the treated fields. Negative effects of using insecticides against diamondback moth were found for the density of parasitoids and generalist predatory wasps, and tended to affect spiders negatively. The observed increased leaf damages in insecticide-treated fields may be a combined consequence of insecticide resistance in the pest, and of lower predation and parasitization rates from naturally occurring predators that are suppressed by the insecticide applications. The results indicate biological control as a viable and economic alternative pest management strategy, something that may be particularly relevant for the production of cash crops in tropical countries where insecticide use is heavy and possibly increasing.
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| 49. |
- Chen, Yayuan, et al.
(författare)
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Comparing Exogenous Methods to Induce Plant-Resistance Against a Bark-Feeding Insect
- 2021
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Exogenous application of the plant hormone methyl jasmonate (MeJA) can trigger induced plant defenses against herbivores, and has been shown to provide protection against insect herbivory in conifer seedlings. Other methods, such as mechanical damage to seedlings, can also induce plant defenses, yet few have been compared to MeJA and most studies lack subsequent herbivory feeding tests. We conducted two lab experiments to: (1) compare the efficacy of MeJA to mechanical damage treatments that could also induce seedling resistance, (2) examine if subsequent insect damage differs depending on the time since induction treatments occurred, and (3) assess if these induction methods affect plant growth. We compared Scots pine (Pinus sylvestris) seedlings sprayed with MeJA (10 or 15 mM) to seedlings subjected to four different mechanical bark damage treatments (two different bark wound sizes, needle-piercing damage, root damage) and previous pine weevil (Hylobius abietis) damage as a reference treatment. The seedlings were exposed to pine weevils 12 or 32 days after treatments (early and late exposure, hereafter), and resistance was measured as the amount of damage received by plants. At early exposure, seedlings treated with needle-piercing damage received significantly more subsequent pine weevil feeding damage than those treated with MeJA. Seedlings treated with MeJA and needle-piercing damage received 84% less and 250% more pine weevil feeding, respectively, relative to control seedlings. The other treatments did not differ statistically from control or MeJA in terms of subsequent pine weevil damage. For the late exposure group, plants in all induction treatments tended to receive less pine weevil feeding (yet this was not statistically significant) compared to control seedlings. On the other hand, MeJA significantly slowed down seedling growth relative to control and all other induction treatments. Overall, the mechanical damage treatments appeared to have no or variable effects on seedling resistance. One of the treatments, needle-piercing damage, actually increased pine weevil feeding at early exposure. These results therefore suggest that mechanical damage shows little potential as a plant protection measure to reduce feeding by a bark-chewing insect.
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| 50. |
- Chen, Yayuan, et al.
(författare)
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Seasonal timing and recurrence of methyl jasmonate treatment influence pine weevil damage to Norway spruce seedlings
- 2021
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Ingår i: New Forests. - : Springer Science and Business Media LLC. - 0169-4286 .- 1573-5095. ; 52, s. 431-448
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Tidskriftsartikel (refereegranskat)abstract
- Defense can be induced in conifer seedlings to reduce pine weevil (Hylobius abietis) damage, by treatment with the plant hormone methyl jasmonate (MJ). Few studies have addressed important practical issues regarding the use of MJ such as treatment incidence and timing, seedling age and its compatibility with plant nursery practices. We examined if levels of pine weevil damage depend on seasonal timing and recurrence of MJ treatment, and if the observed effects depend on plant age. Norway spruce (Picea abies) seedlings from two age cohorts (1 year and 1.5 years old) received four MJ treatments: MJ application before winter storage in the previous year, after winter storage but before spring/summer planting, repeated MJ application (both before winter storage, and before planting) or no MJ application at all. Pine weevil damage was evaluated in a lab and field experiment. We found that the timing and recurrence of MJ treatment affected the amount of damage inflicted by pine weevils in different ways, but these effects were consistent among age cohorts. MJ application before winter storage provided the most effective protection, and this reduction in damage was comparable to that provided by a currently used physical protection method against pine weevil feeding. Our results indicated that MJ can be applied in line with nursery practices (before winter storage) and provides adequate protection for two growing seasons.
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