| 1. |
- Arhipova, Natalija, et al.
(författare)
-
Armillaria novae-zelandiae and other basidiomycete wood decay fungi in New Zealand Pinus radiata thinning stumps
- 2015
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 45, s. 298-310
-
Tidskriftsartikel (refereegranskat)abstract
- Two studies were undertaken in a young New Zealand Pinus radiata stand to find a biological control agent for armillaria root disease caused by Armillaria novae-zelandiae. Fresh thinning stumps were inoculated with saprophytic basidiomycete species as wooden dowel cultures or as homogenized aqueous mycelial suspensions, while all stumps were also inoculated with dowel cultures of A.novae-zelandiae. After a period of between one and twoyears, no differences were found among test fungi in the percentage of Armillaria species isolated from stumps. However, inoculation of Stereum sanguinolentum as homogenate, and of Phlebiopsis gigantea, Sistotrema brinkmannii, Hypholoma acutum and Rigidoporus concrescens as dowel cultures, significantly increased their isolation incidence in comparison with stumps not treated by these species. Phlebiopsisgigantea, Resinicium bicolor and R.concrescens were also isolated with greater frequency nearer to their dowel inoculation points. Results suggest that P.gigantea and S.sanguinolentum should be included in further testing. However, a future trial is likely to be more effective if evaluation is directed towards the portion of the stump below the soil surface, particularly the root system.
|
|
| 2. |
|
|
| 3. |
- Bjelke, Ulf, et al.
(författare)
-
Dieback of riparian alder caused by the Phytophthora alni complex: projected consequences for stream ecosystems
- 2016
-
Ingår i: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 61, s. 565-579
-
Forskningsöversikt (refereegranskat)abstract
- 1. Alder trees (Alnus spp.) are key nitrogen-fixing riparian species in the northern hemisphere. Inputs of nitrogen-rich leaf litter from alder into stream food webs can contribute significantly to nitrogen dynamics at local and landscape scales. Alder trees also provide habitats for terrestrial and aquatic organisms, and help stabilize river banks. 2. Recently, substantial declines in alder stands have occurred along streams in Europe, with damages observed in some parts of North America also. A major driver has been the invasive oomycete pathogen Phytophthora alni species complex, which can spread rapidly along stream networks. 3. This review synthesises information on the pathogen, processes of spread and infection, and its impacts on alder. We further address the potential ecosystem-level and management consequences of the decline of alder, and highlight research needs. 4. The alder dieback caused by P. alni is associated with reductions in shade and quality and quantity of leaf litter. A decline in the structural integrity of branches and roots further threatens bank stability. Stream banks dominated by other tree species or no trees at all will result in ecosystem-level changes both above and below the waterline. 5. The P. alni taxonomic complex includes different species with varying phenotypes. An improved understanding of their environmental tolerances, virulence and evolution, along with the processes regulating the spread and impacts of the pathogen, would assist in identification of the riparian and stream systems most vulnerable not only to invasion but also to the heaviest disease outbreaks and ecosystem-level impacts. 6. Within the P. alni complex, the highly pathogenic hybrid species P. x alni is favoured by mild winters and warm, but not excessively hot summer temperatures suggesting possible changes in distribution and level of impact under future global climate change.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Brodde, Laura, et al.
(författare)
-
Diplodia Tip Blight on Its Way to the North: Drivers of Disease Emergence in Northern Europe
- 2019
-
Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Disease emergence in northern and boreal forests has been mostly due to tree-pathogen encounters lacking a co-evolutionary past. However, outbreaks involving novel interactions of the host or the pathogen with the environment have been less well documented. Following an increase of records in Northern Europe, the first large outbreak of Diplodia sapinea on Pinus sylvastris was discovered in Sweden in 2016. By reconstructing the development of the epidemic, we found that the attacks started approx. 10 years back from several isolated trees in the stand and ended up affecting almost 90% of the trees in 2016. Limited damage was observed in other plantations in the surroundings of the affected stand, pointing to a new introduced pathogen as the cause of the outbreak. Nevertheless, no genetic differences based on SSR markers were found between isolates of the outbreak area and other Swedish isolates predating the outbreak or from other populations in Europe and Asia Minor. On a temporal scale, we saw that warm May and June temperatures were associated with higher damage and low tree growth, while cold and rainy conditions seemed to favor growth and deter disease. At a spatial scale, we saw that spread occurred predominantly in the SW aspect-area of the stand. Within that area and based on tree-ring and isotope (delta C-13) analyses, we saw that disease occurred on trees that over the years had shown a lower water-use efficiency (WUE). Spore traps showed that highly infected trees were those producing the largest amount of inoculum. D. sapinea impaired latewood growth and reduced C reserves in needles and branches. D. sapinea attacks can cause serious economic damage by killing new shoots, disrupting the crown, and affecting the quality of stems. Our results show that D. sapinea has no limitations in becoming a serious pathogen in Northern Europe. Management should focus on reducing inoculum, especially since climate change may bring more favorable conditions for this pathogen. Seedlings for planting should be carefully inspected as D. sapinea may be present in a latent stage in asymptomatic tissues.
|
|
| 9. |
- Castaño Soler, Carles, et al.
(författare)
-
Rainfall homogenizes while fruiting increases diversity of spore deposition in Mediterranean conditions
- 2019
-
Ingår i: Fungal Ecology. - : Elsevier BV. - 1754-5048 .- 1878-0083. ; 41, s. 279-288
-
Tidskriftsartikel (refereegranskat)abstract
- There is a lack of knowledge regarding the main factors modulating fungal spore deposition in forest ecosystems. We have described the local spatio-temporal dynamics of fungal spore deposition along a single fruiting season and its relation with fruit body emergence and rainfall events. Passive spore traps were weekly sampled during autumn and analysed by metabarcoding of the ITS2 region in combination with qPCR. There were larger compositional changes of deposited spores across sampling weeks than amongst sampling plots. Spore diversity and abundance correlated with mushroom emergence and weekly rainfall. Spore compositional changes were related to rainfall, with lower spatial compositional heterogeneity across plots during weeks with higher rainfall. Soil saprotrophs, and amongst them, puffball species, showed the strongest positive correlation with rainfall across fungal guilds. We saw high fine-scale temporal changes of deposited spores, and both mushroom emergence and rainfall may be important factors driving airborne spore deposition. (C) 2019 Elsevier Ltd and British Mycological Society. All rights reserved.
|
|
| 10. |
- Eriksson, Louise, 1973-, et al.
(författare)
-
Invasive forest pathogens in Europe : Cross-country variationin public awareness but consistency in policy acceptability
- 2019
-
Ingår i: Ambio. - : Springer Netherlands. - 0044-7447 .- 1654-7209. ; 48:1, s. 1-12
-
Tidskriftsartikel (refereegranskat)abstract
- Political action can reduce introductions of diseases caused by invasive forest pathogens (IPs) and public support is important for effective prevention. The public’s awareness of IP problems and the acceptability of policies aiming to combat these pathogens were surveyed in nine European countries (N = 3469). Although awareness of specific diseases (e.g., ash dieback) varied, problem awareness and policy acceptability were similar across countries. The public was positive towards policies for informational measures and stricter standards for plant production, but less positive towards restricting public access to protected areas. Multilevel models, including individual and country level variables, revealed that media exposure was positively associated with awareness of IP problems, and strengthened the link between problem awareness and policy acceptability. Results suggest that learning about IPs through the media and recognizing the associated problems increase policy acceptability. Overall, the study elaborates on the anthropogenic dimension of diseases caused by IPs.
|
|
| 11. |
- Keskitalo, E. Carina H., 1974-, et al.
(författare)
-
Implementing Plant Health Regulations with Focus on Invasive Forest Pests and Pathogens : Examples from Swedish Forest Nurseries
- 2018
-
Ingår i: The Human Dimensions of Forest and Tree Health. - Cham : Palgrave Macmillan. - 9783319769554 - 9783319769561 ; , s. 193-210
-
Bokkapitel (refereegranskat)abstract
- International trade and climate change have increased the movement potential for invasive alien species (IAS), including invasive pests and pathogens (IPPs), to the point where biological invasions are considered one of the major threats to biodiversity. However, practical implementation of plant health with regard to IAS and IPPs is difficult: regulative responsibilities are commonly spread across different authorities, and resources on the ground are often limited. Based on a legislative and literature review and semi-structured qualitative interviews (N = 7), the present study examines the possibilities and potential risks of monitoring and detection of forest invasive species in Sweden, with a particular focus on forest plant nurseries. The study thus adds practical implementation aspects concerning possibilities to limit the spread of invasive species in the plant trade.
|
|
| 12. |
- Klapwijk, Maartje, et al.
(författare)
-
Invasiva arter i en föränderlig värld
- 2013
-
Ingår i: Svampar och insekter Rapport från Future Forests 2009-2012. ; :2013:5, s. 12-13
-
Bokkapitel (populärvet., debatt m.m.)
|
|
| 13. |
- Mola-Yudego, Blas, et al.
(författare)
-
The invasive forest pathogen Hymenoscyphus fraxineus boosts mortality and triggers niche replacement of European ash (Fraxinus excelsior)
- 2020
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Determining the impacts of invasive pathogens on tree mortality and growth is a difficult task, in particular in the case of species occurring naturally at low frequencies in mixed stands. In this study, we quantify such effects by comparing national forest inventory data collected before and after pathogen invasion. In Norway, Fraxinus excelsior is a minor species representing less than 1% of the trees in the forests and being attacked by the invasive pathogen Hymenoscyphus fraxineus since 2006. By studying deviations between inventories, we estimated a 74% higher-than-expected average ash mortality and a 13% slower-than-expected growth of the surviving ash trees, indicating a lack of compensation by the remaining ash. We could confidently assign mortality and growth losses to ash dieback as no mortality or growth shifts were observed for co-occurring tree species in the same plots. The mortality comparisons also show regional patterns with higher mortality in areas with the longest disease history in Norway. Considering that ash is currently mostly growing in mixed forests and that no signs of compensation were observed by the surviving ash trees, a significant habitat loss and niche replacement could be anticipated in the mid-term.
|
|
| 14. |
- Nemesio Gorriz, Miguel, et al.
(författare)
-
Transcriptional responses of Norway spruce (Picea abies) inner sapwood against Heterobasidion parviporum
- 2015
-
Ingår i: Tree Physiology. - : Oxford University Press (OUP). - 0829-318X .- 1758-4469. ; 35, s. 1007-1015
-
Tidskriftsartikel (refereegranskat)abstract
- The white- rot fungus Heterobasidion parviporum Niemela & Korhonen establishes a necrotrophic interaction with Norway spruce ( Picea abies ( L.) H. Karst.) causing root and butt rot and growth losses in living trees. The interaction occurs first with the bark and the outer sapwood, as the pathogen enters the tree via wounds or root- to- root contacts. Later, when the fungus reaches the heartwood, it spreads therein creating a decay column, and the interaction mainly occurs in the inner sapwood where the tree creates a reaction zone. While bark and outer sapwood interactions are well studied, little is known about the nature of the transcriptional responses leading to the creation of a reaction zone. In this study, we sampled bark and sapwood both proximal and distal to the reaction zone in artificially inoculated and naturally infected trees. We quantified gene expression levels of candidate genes in secondary metabolite, hormone biosynthesis and signalling pathways using quantitative polymerase chain reaction. An up- regulation of mainly the phenylpropanoid pathway and jasmonic acid biosynthesis was found at the inoculation site, when inoculations were compared with wounding. We found that transcriptional responses in inner sapwood were similar to those reported upon infection through the bark. Our data suggest that the defence mechanism is induced due to direct fungal contact irrespective of the tissue type. Understanding the nature of these interactions is important when considering tree breeding- based resistance strategies to reduce the spread of the pathogen between and within trees.
|
|
| 15. |
- Oliva Palau, Jonàs, et al.
(författare)
-
Drought and Phytophthora Are Associated With the Decline of Oak Species in Southern Italy
- 2018
-
Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Forest decline induced by climate change is a global phenomenon that affects many tree species, mainly in drought-prone areas as the Mediterranean region. In southern Italy, several oak species have shown decline symptoms and elevated mortality since the 2000s due to drought stress. However, it remains to be answered whether decline occurred alone or whether a pathogen was also involved. To this aim, we compared two coexisting oak species in a forest located in southern Italy which are assumed to be less (Quercus cerris) and more tolerant to drought (Quercus pubescens). We sampled fifteen couples of neighboring declining (D) and non-declining (ND) trees of both species. Wood cores were taken from all trees to perform dendrochronological analyses to detect the decline onset and link it to potential climatic drivers. Carbon isotope ratios (d(13)C) were analyzed in wood of the two vigor classes to compare their water-use efficiency. Phytophthora presence was also assessed in soil samples from ten D-ND couples of trees per species. The oak species most affected by drought-induced decline in terms of leaf shedding and mortality was Q. cerris, i.e., the least tolerant to drought. In both species, the D trees showed a reduced growth rate compared with ND trees from 2000 onward when drought and warming intensified. Q. pubescens showed higher growth sensitivity to precipitation, temperature and drought than Q. cerris. This sensitivity to climate was magnified in D trees whose growth decreased in response to warm and dry conditions during the prior winter and the late summer. The Q. pubescens D trees were more efficient in their water use than ND trees before the growth divergence between D and ND trees amplified. In the studied area, Phytophthora quercina was isolated from 40% of the sampled trees, and tended to be more frequent amongst ND than amongst D trees. Our data suggests that droughts and warm summer conditions triggered oak decline. The high prevalence of P. quercina in the studied area warrants further study as a potential predisposing factor.
|
|
| 16. |
- Oliva Palau, Jonàs, et al.
(författare)
-
Drought Decreases Growth and Increases Mortality of Coexisting Native and Introduced Tree Species in a Temperate Floodplain Forest
- 2018
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Forest dieback and mortality events induced by drought stress are widely reported. However, few studies have jointly examined the role played by drought on growth and mortality in tree species inhabiting floodplain forests. Here, we focused on mortality events occurring since the early 2000s on large areas in a floodplain forest located within the Ticino regional park in Northwest Italy, where affected native (pedunculate oak, Quercus robur L.) and introduced tree species (black locust, Robinia pseudoacacia L.) coexist. We related growth with climate data and drought severity to discern if these species were similarly affected by drought. Then, we: (i) evaluated the presence of pathogens of the genus Phytophthora in recently dead oak trees since this was the most affected species and pathogens are often associated with oak decline cases; and (ii) compared xylem vessel diameter and tree-ring C isotope discrimination (delta C-13) to highlight differences in water-use strategies between living and dead trees in both species. The radial growth of living and dead trees started diverging in the 1970s, although only after warm-drought periods occurred during 1990s did this divergence become significant. Growth of trees that died responded more negatively to drought than in the case of living trees. Moreover, trees that died formed smaller xylem vessels in the past than living trees and also showed more negative delta C-13 values in both tree species, indicating a higher intrinsic water-use efficiency in living than in dead trees. The pathogen Phytophthora cinnamomi Rands was only detected in one recently dead tree, suggesting that it is unlikely that dead oaks were predisposed to drought damage by the pathogen. We conclude that a climate shift from wet to warm-dry summer conditions in the early 1990s triggered forest dieback and induced mortality in both tree species. Temperate floodplain forests are susceptible to drought-induced dieback. The drought-sensitivity of both species could lead to successional shifts driven by a reduction of N inputs through N-fixing by black locust and the replacement of oak by drought-tolerant species.
|
|
| 17. |
- Oliva Palau, Jonàs
(författare)
-
Ecology of Armillaria species on silver fir (Abies alba) in the Spanish Pyrenees
- 2009
-
Ingår i: Annals of Forest Science. - : Springer Science and Business Media LLC. - 1286-4560 .- 1297-966X. ; 66
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the distribution and the ecology of three Armillaria species observed in silver fir (Abies alba) forests of the Pyrenees.We surveyed the presence and abundance of Armillaria above and belowground in 29 stands. Isolates were identified by the PCR-RFLP pattern of the IGS-1 region of their ribosomal DNA. We measured several ecological and management parameters of each stand in order to describe Armillaria infected sites.Armillaria cepistipes was the most abundant of three species observed. Armillaria gallica was dominant in soils with a higher pH and at lower elevations. Armillaria ostoyae seemed to be more frequent in stands where A. alba recently increased its dominance relative to other forest tree species. Thinning activities correlated with an increased abundance of Armillaria belowground. In 83% of the stands the same Armillaria species was observed above and belowground.It seems that in a conifer forest, A. cepistipes can be more frequent than A. ostoyae, a virulent conifer pathogen. Since logging is related to a higher abundance of Armillaria in the soil, the particular Armillaria species present in a given stand could be considered an additional site factor when making management decisions.
|
|
| 18. |
- Oliva Palau, Jonàs
(författare)
-
Epidemiology of Heterobasidion abietinum and Viscum album on silver fir (Abies alba) stands of the Pyrenees
- 2010
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 40, s. 19-32
-
Tidskriftsartikel (refereegranskat)abstract
- In the last two decades, stand decline and increased mortality has affected silver fir (Abies alba) forests in the Spanish Pyrenees. Simultaneously severe occurrences of the root rot fungus Heterobasidion annosum s.l. and of the mistletoe Viscum album have been reported. We aimed to improve the understanding of the epidemiology of both pathogens in our region. All H. annosum isolates found on silver fir were typed as H. abietinum. H. abietinum was more frequently observed where cuttings had targeted fir trees rather than other species. H. abietinum fruiting bodies were observed in the most recently cut stumps. V. album was more abundant on more dominant fir trees, and in southern aspect stands. The number of V. album colonies in the stand correlated (R(2) = 0.40) with silver fir mortality. Stands with a high level of V. album infection tended to have a smaller percentage of basal area in species other than silver fir, and they tended to be located on more south-facing slopes. H. abietinum was widespread in silver fir forests of the Pyrenees. Our data suggest that, in the Pyrenees, the observed H. abietinum incidence may represent a combination of both primary and secondary spread of the pathogen. Favouring mixed forests should be tested as a potential control method for V. album. The correlation between silver fir mortality and V. album infection warrants further study, as the observed tree mortality could have occurred due to other factors than V. album, such as drought damage.
|
|
| 19. |
- Oliva Palau, Jonàs
(författare)
-
Mushroom Emergence Detected by Combining Spore Trapping with Molecular Techniques
- 2017
-
Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 83
-
Tidskriftsartikel (refereegranskat)abstract
- Obtaining reliable and representative mushroom production data requires time-consuming sampling schemes. In this paper, we assessed a simple methodology to detect mushroom emergence by trapping the fungal spores of the fruiting body community in plots where mushroom production was determined weekly. We compared the performance of filter paper traps with that of funnel traps and combined these spore trapping methods with species-specific quantitative real-time PCR and Illumina MiSeq to determine the spore abundance. Significantly more MiSeq proportional reads were generated for both ectomycorrhizal and saprotrophic fungal species using filter traps than were obtained using funnel traps. The spores of 37 fungal species that produced fruiting bodies in the study plots were identified. Spore community composition changed considerably over time due to the emergence of ephemeral fruiting bodies and rapid spore deposition (lasting from 1 to 2 weeks), which occurred in the absence of rainfall events. For many species, the emergence of epigeous fruiting bodies was followed by a peak in the relative abundance of their airborne spores. There were significant positive relationships between fruiting body yields and spore abundance in time for five of seven fungal species. There was no relationship between fruiting body yields and their spore abundance at plot level, indicating that some of the spores captured in each plot were arriving from the surrounding areas. Differences in fungal detection capacity by spore trapping may indicate different dispersal ability between fungal species. Further research can help to identify the spore rain patterns for most common fungal species.IMPORTANCE Mushroom monitoring represents a serious challenge in economic and logistical terms because sampling approaches demand extensive field work at both the spatial and temporal scales. In addition, the identification of fungal taxa depends on the expertise of experienced fungal taxonomists. Similarly, the study of fungal dispersal has been constrained by technological limitations, especially because the morphological identification of spores is a challenging and time-consuming task. Here, we demonstrate that spores from ectomycorrhizal and saprotrophic fungal species can be identified using simple spore traps together with either MiSeq fungus-specific amplicon sequencing or species-specific quantitative real-time PCR. In addition, the proposed methodology can be used to characterize the airborne fungal community and to detect mushroom emergence in forest ecosystems.
|
|
| 20. |
- Oliva Palau, Jonàs
(författare)
-
Past logging, drought and pathogens interact and contribute to forest dieback
- 2015
-
Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923 .- 1873-2240. ; 208, s. 85-94
-
Tidskriftsartikel (refereegranskat)abstract
- Forest dieback is one of the most widespread responses to global-change drivers, such as climate warming-related drought stress and the spread of pathogens. Although both climatic and biotic stressors have been studied separately, much less is known on how drought and pathogens interact and induce dieback, particularly in formerly used forests. We determine the roles played by each of those drivers as factors causing recent dieback in three Pyrenean silver fir stands: a managed site subjected to past logging and two unmanaged sites not logged for the past 50 years. The age, size, recent competition, and basal-area increment (BAI) trends of non-declining and declining trees, and the presence of fungal pathogens were investigated. Growth patterns at yearly to decadal time scales were compared to distinguish the roles and interactions played by the different stressors. In the managed site, declining trees displayed low growth already before logging (1950-1970s). In both unmanaged sites, declining and non-declining trees displayed divergent growth patterns after extreme droughts, indicating that dieback was triggered by severe water deficit. We did not find indications that fungal pathogens are the primary drivers of dieback, since a low proportion of declining trees were infested by primary pathogens (10%). However, trees with the primary fungal pathogen Heterobasidion showed lower BAI than non-declining trees. On the other hand, the secondary fungal pathogen Amylostereum was isolated from a higher number of trees than expected by chance. These findings highlight the importance of legacies, such as the past use in driving recent forest dieback. Past forest use could predispose to dieback by selecting slow-growing trees and thus, making some them more vulnerable to drought and fungal pathogens. (C) 2015 Elsevier B.V. All rights reserved.
|
|
| 21. |
- Oliva Palau, Jonàs, et al.
(författare)
-
Pathogen-induced defoliation of Pinus sylvestris leads to tree decline and death from secondary biotic factors
- 2016
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 379, s. 273-280
-
Tidskriftsartikel (refereegranskat)abstract
- The contribution of non-lethal pathogenic attacks to tree death is still unclear. Manion's theory of the spiral of decline predicts that tree decline and death occurs because of a sequence of predisposing, inciting and contributing events. To understand whether pathogens can act as predisposing or inciting factors, we tested whether a sequence of non-lethal pathogen attacks causing crown defoliation could lead to a chronic decline in tree health and predispose trees to die. Scots pine (Pinus sylvestris) trees predisposed or escaping (non-predisposed) a first outbreak by the pathogen Gremmeniella abietina (predisposing event) were compared in terms of survival and susceptibility to secondary pests (contributing event) after a second G. abietina outbreak (inciting event). Four years after the inciting event, mortality among predisposed trees was up to five times higher than among trees escaping the first epidemic. Predisposed trees were twice as susceptible to secondary attacks by the common pine shoot beetle (Tomicus piniperda). Ten years after the inciting event, severely predisposed trees had not been able to restore their crowns and still showed stagnated growth. This study showed that pathogen-induced defoliation can act as predisposing and inciting factors for tree death, reducing the capacity of trees to survive short- or long-term stressing events, such as bark beetle attacks. We also showed that tree decline can result from a combination of predisposing and inciting events caused by pathogens. (C) 2016 Elsevier B.V. All rights reserved.
|
|
| 22. |
- Oliva Palau, Jonàs, et al.
(författare)
-
Quantitative interactions between the biocontrol fungus Phlebiopsis gigantea, the forest pathogen Heterobasidion annosum and the fungal community inhabiting Norway spruce stumps
- 2017
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 402, s. 253-264
-
Tidskriftsartikel (refereegranskat)abstract
- Protection against the root rot fungus Heterobasidion annosum s. l. is achieved by mechanically spraying stumps with spores of the antagonistic fungus Phlebiopsis gigantea, commercialized as Rotstope. An extensive colonisation of the stump by P. gigantea is required for protection. Colonisation may depend on how the biocontrol agent interacts with the fungal community that is endophytically inhabiting the stump, as well as with other fungi establishing after the treatment is applied. In this research, we studied how the distribution and abundance of Heterobasidion and P. gigantea is modulated by the fungal community inhabiting Norway spruce (Picea abies) stumps. First thinning stumps were treated with Rotstop and/or artificially inoculated with H. parviporum under field conditions. After two months, P. gigantea or Heterobasidion distribution was measured by qPCR, and both pathogen and biocontrol abundance gradients were correlated with members of the fungal community determined by high throughput sequencing. Rotstop application decreased Heterobasidion biomass by almost 200 times, though the strongest biomass reductions were only achieved when stumps were well covered by P. gigantea. Poor Rotstop applications resulting in, for instance, a drop of 20% in terms of stump covered area by the biocontrol, were associated with a 2-fold biomass increase of the surviving Heterobasidion colonies. Unlike Heterobasidion, some fungi such as Peniophora sp. and F. pinicola did not change their relative abundance following the Rotstop treatment and were associated with areas of low P. gigantea presence. Yeast-like fungi of the genus Debaryomyces increased its relative abundance following Rotstop treatment, and were the only taxa associated with both a higher abundance of the biocontrol, and a lower abundance of the pathogen. Ours is the first study quantifying at microscale the interaction between H. parviporum and P. gigantea in stumps subjected to Rotstop treatment, showing how incomplete stump cover may result in large shifts in terms of biomass for either the pathogen or the biocontrol. Our results stress the importance of achieving a complete cover of the stump surface in practice. Debatyomyces sp. might facilitate P. gigantea colonisation of the stump and could be added as enhancers of Rotstop treatment, though the mechanism of interaction with the pathogen and the biocontrol should be further studied.
|
|
| 23. |
- Oliva Palau, Jonàs
(författare)
-
The impact of the socioeconomic environment on the implementation of control measures against an invasive forest pathogen
- 2016
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 380, s. 118-127
-
Tidskriftsartikel (refereegranskat)abstract
- Whenever a new invasive forest pathogen appears, resources are put into developing countermeasures such as breeding for resistance in the affected host species and/or by developing fungicide/biocontrol treatments. In most cases, little effort is placed into analysing the likelihood of those measures being implemented. Studying the reasoning behind management reactions of forest managers whose forests had been attacked by invasive pathogens can improve implementation of measures in case of future invasions. We used grounded theory to model forest owners' reactions against chestnut blight caused by the invasive pathogen Cryphonectria parasitica. We focussed on understanding what drove some managers to keep managing chestnut forests and applying biological control, and what made others abandon or even substitute chestnut by exotics. We found that the availability of a market for chestnut products, and not the disease was the main reason for discontinuing chestnut management. The will to continue managing chestnuts was four times higher amongst managers of chestnut stands for nut production (valuable crop), than amongst managers of coppice stands producing small diameter stems, currently without a market. Requesting application of biological control against chestnut blight was four times more likely amongst forest managers obtaining monetary benefits from their land (benefits used as profit or re-investment) than those not obtaining monetary benefits or currently losing money with their land. Substitution with exotic conifers was associated with forest managers that had learned management from family and leaders of opinion, and that have either themselves or previous owners of the land planted exotics beforehand. Abandonment was associated with self-taught managers valuing non-monetary aspects of forests and having moral reasons against exotics. Our research highlights the importance of considering the socioeconomic context around the affected tree species when developing measures against invasive forest pathogens, and raises concerns about the continuity of tree species affected by invasive pathogens with little or no commercial value. (C) 2016 Elsevier B.V. All rights reserved.
|
|
| 24. |
- Oliva Palau, Jonàs
(författare)
-
The role of defoliation and root rot pathogen infection in driving the mode of drought-related physiological decline in Scots pine (Pinus sylvestris L.)
- 2015
-
Ingår i: Tree Physiology. - : Oxford University Press (OUP). - 0829-318X .- 1758-4469. ; 35, s. 229-242
-
Tidskriftsartikel (refereegranskat)abstract
- Drought-related tree die-off episodes have been observed in all vegetated continents. Despite much research effort, however, the multiple interactions between carbon starvation, hydraulic failure and biotic agents in driving tree mortality under field conditions are still not well understood. We analysed the seasonal variability of non-structural carbohydrates (NSCs) in four organs (leaves, branches, trunk and roots), the vulnerability to embolism in roots and branches, native embolism (percentage loss of hydraulic conductivity (PLC)) in branches and the presence of root rot pathogens in defoliated and non-defoliated individuals in a declining Scots pine (Pinus sylvestris L.) population in the NE Iberian Peninsula in 2012, which included a particularly dry and warm summer. No differences were observed between defoliated and non-defoliated pines in hydraulic parameters, except for a higher vulnerability to embolism at pressures below -2 MPa in roots of defoliated pines. No differences were found between defoliation classes in branch PLC. Total NSC (TNSC, soluble sugars plus starch) values decreased during drought, particularly in leaves. Defoliation reduced TNSC levels across tree organs, especially just before (June) and during (August) drought. Root rot infection by the fungal pathogen Onnia P. Karst spp. was detected but it did not appear to be associated to tree defoliation. However, Onnia infection was associated with reduced leaf-specific hydraulic conductivity and sapwood depth, and thus contributed to hydraulic impairment, especially in defoliated pines. Infection was also associated with virtually depleted root starch reserves during and after drought in defoliated pines. Moreover, defoliated and infected trees tended to show lower basal area increment. Overall, our results show the intertwined nature of physiological mechanisms leading to drought-induced mortality and the inherent difficulty of isolating their contribution under field conditions.
|
|
| 25. |
- Oliva Palau, Jonàs
(författare)
-
To die or not to die: early warnings of tree dieback in response to a severe drought
- 2015
-
Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 103, s. 44-57
-
Tidskriftsartikel (refereegranskat)abstract
- 1. Some disturbances can drive ecological systems to abrupt shifts between alternative stages (tipping points) when critical transitions occur. Drought-induced tree death can be considered as a nonlinear shift in tree vigour and growth. However, at what point do trees become predisposed to drought-related dieback and which factors determine this (tipping) point? We investigated these questions by characterizing the responses of three tree species, silver fir (Abies alba), Scots pine (Pinus sylvestris) and Aleppo pine (Pinus halepensis), to a severe drought event.2. We compared basal area increment (BAI) trends and responses to climate and drought in declining (very defoliated and dying) vs. non-declining (slightly or not defoliated) trees by using generalized additive mixed models. Defoliation, BAI and sapwood production were related to functional proxies of tree vigour measured at the onset and end of the drought (non-structural carbohydrate concentrations, needle N content and C isotopic discrimination, presence of wood-inhabiting fungi). We evaluated whether early warning signals (increases in synchronicity among trees or in autocorrelation and standard deviation) could be extracted from the BAI series prior to tree death.3. Declining silver fir and Scots pine trees showed less growth than non-declining trees one to three decades, respectively, before the drought event, whereas Aleppo pines showed growth decline irrespective of tree defoliation. At the end of the drought period, all species showed increased defoliation and a related reduction in the concentration of sapwood soluble sugars. Defoliation was constrained by the BAI of the previous 5 years and sapwood production. No specific wood-inhabiting fungi were found in post-drought declining trees apart from blue-stain fungi, which extensively affected damaged Scots pines. Declining silver firs showed increases in BAI autocorrelation and variability prior to tree death.4. Synthesis. Early warning signals of drought-triggered mortality seem to be species specific and reflect how different tree species cope with drought stress. Highly correlated declining growth patterns during drought can serve as a signal in silver fir, whereas changes in the content of sapwood soluble sugars are suitable vigour proxies for Scots and Aleppo pines. Longer growth and defoliation series, additional vigour parameters and multi-species comparisons are required to understand and predict drought-induced tree death.
|
|
| 26. |
- Redondo, Miguel Angel, et al.
(författare)
-
Contrasting distribution patterns between aquatic and terrestrial Phytophthora species along a climatic gradient are linked to functional traits
- 2018
-
Ingår i: ISME Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370. ; 12, s. 2967-2980
-
Tidskriftsartikel (refereegranskat)abstract
- Diversity of microbial organisms is linked to global climatic gradients. The genus Phytophthora includes both aquatic and terrestrial plant pathogenic species that display a large variation of functional traits. The extent to which the physical environment (water or soil) modulates the interaction of microorganisms with climate is unknown. Here, we explored the main environmental drivers of diversity and functional trait composition of Phytophthora communities. Communities were obtained by a novel metabarcoding setup based on PacBio sequencing of river filtrates in 96 river sites along a geographical gradient. Species were classified as terrestrial or aquatic based on their phylogenetic Glade. Overall, terrestrial and aquatic species showed contrasting patterns of diversity. For terrestrial species, precipitation was a stronger driver than temperature, and diversity and functional diversity decreased with decreasing temperature and precipitation. In cold and dry areas, the dominant species formed resistant structures and had a low optimum temperature. By contrast, for aquatic species, temperature and water chemistry were the strongest drivers, and diversity increased with decreasing temperature and precipitation. Within the same area, environmental filtering affected terrestrial species more strongly than aquatic species (20% versus 3% of the studied communities, respectively). Our results highlight the importance of functional traits and the physical environment in which microorganisms develop their life cycle when predicting their distribution under changing climatic conditions. Temperature and rainfall may be buffered differently by water and soil, and thus pose contrasting constrains to microbial assemblies.
|
|
| 27. |
|
|
| 28. |
|
|
| 29. |
|
|
| 30. |
- Redondo, Miguel Angel, et al.
(författare)
-
Functional traits associated with the establishment of introduced Phytophthora spp. in Swedish forests
- 2018
-
Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 55, s. 1538-1552
-
Tidskriftsartikel (refereegranskat)abstract
- 1. Invasive forest pathogens of the genus Phytophthora are threatening ecosystems globally. Phytophthora species are mainly introduced by humans importing infected nursery stock. However, due to the presence of environmental filters, not all introduced Phytophthoras manage to establish and spread. Phytophthoras' ability to overcome these filters may be linked to functional traits. In northern Europe, the increasing number of reports calls for a better understanding of the invasion process to prevent future outbreaks.2. We hypothesized that the incidence of invasive Phytophthoras in urban locations would be higher than in remote forests, that there would be a decrease of species richness along the invasion process because of environmental filtering, and that there would be a functional shift among Phytophthora communities between stages of invasion. We compared the species composition of 96 sites from 16 rivers running through areas that constitute a gradient of human influence. We also compared the species composition and functional diversity of Phytophthora communities in eight nurseries and 14 forests, including anthropogenic and natural forests. Phytophthoras were isolated from river water, soil and/or plant tissue. Cultures were identified based on the Internal Transcribed Spacer region.3. Three Phytophthoras were detected in all environments (Phytophthora cactorum, Phytophthora plurivora and Phytophthora cambivora). The incidence of these species was higher in urban locations than in remote forests, suggesting that human activities act as a driver of invasion. Most of the Phytophthoras detected in forests were detected in nurseries. The Phytophthora community in nurseries was richer and more diverse than in forests, pointing to environmental filtering affecting the establishment. Phytophthora communities in nurseries and forests differed in their functional divergence. Traits associated with establishment were the ability to form asexual survival structures and lower cardinal temperatures for growth.4. Synthesis and applications. Our findings support the view that human activities act as drivers of Phytophthora invasions, and suggest that Phytophthoras able to form asexual structures are more likely to establish in northern Europe. The results increase the capacity to predict the establishment of Phytophthora species in Sweden and expand our understanding of the invasion process of forest pathogens.
|
|
| 31. |
- Redondo, Miguel Angel, et al.
(författare)
-
Unravelling hybridization in Phytophthora using phylogenomics and genome size estimation
- 2021
-
Ingår i: IMA fungus. - : Springer Science and Business Media LLC. - 2210-6340 .- 2210-6359. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- The genus Phytophthora comprises many economically and ecologically important plant pathogens. Hybrid species have previously been identified in at least six of the 12 phylogenetic clades. These hybrids can potentially infect a wider host range and display enhanced vigour compared to their progenitors. Phytophthora hybrids therefore pose a serious threat to agriculture as well as to natural ecosystems. Early and correct identification of hybrids is therefore essential for adequate plant protection but this is hampered by the limitations of morphological and traditional molecular methods. Identification of hybrids is also important in evolutionary studies as the positioning of hybrids in a phylogenetic tree can lead to suboptimal topologies. To improve the identification of hybrids we have combined genotyping-by-sequencing (GBS) and genome size estimation on a genus-wide collection of 614 Phytophthora isolates. Analyses based on locus- and allele counts and especially on the combination of species-specific loci and genome size estimations allowed us to confirm and characterize 27 previously described hybrid species and discover 16 new hybrid species. Our method was also valuable for species identification at an unprecedented resolution and further allowed correct naming of misidentified isolates. We used both a concatenation- and a coalescent-based phylogenomic method to construct a reliable phylogeny using the GBS data of 140 non-hybrid Phytophthora isolates. Hybrid species were subsequently connected to their progenitors in this phylogenetic tree. In this study we demonstrate the application of two validated techniques (GBS and flow cytometry) for relatively low cost but high resolution identification of hybrids and their phylogenetic relations.
|
|
| 32. |
- Redondo, Miguel Angel, et al.
(författare)
-
Winter Conditions Correlate with Phytophthora alni Subspecies Distribution in Southern Sweden
- 2015
-
Ingår i: Phytopathology. - 0031-949X .- 1943-7684. ; 105, s. 1191-1197
-
Tidskriftsartikel (refereegranskat)abstract
- During the last century, the number of forest pathogen invasions has increased substantially. Environmental variables can play a crucial role in determining the establishment of invasive species. The objective of the present work was to determine the correlation between winter climatic conditions and distribution of two subspecies of the invasive forest pathogen Phytophthora alni: P. alni subspp. alni and unifonnis killing black alder (Abuts glutinosa) in southern Sweden. It is known from laboratory experiments that P alni subsp. alni is more pathogenic than P. alni subsp. uniformis, and that alni subsp. alni is sensitive to low temperatures and long frost periods. By studying the distribution of these two subspecies at the northern limit of the host species, we could investigate whether winter conditions can affect the geographical distribution of P. alni subsp. alni spreading northward. Sixteen major river systems of southern Sweden were systematically surveyed and isolations were performed from active cankers. The distribution of the two studied subspecies was highly correlated with winter temperature and duration of periods with heavy frost. While P. alni subsp. unifonnis covered the whole range of temperatures of the host, P. alni subsp. alni was recovered in areas subjected to milder winter temperatures and shorter frost periods. Our observations suggest that winter conditions can play an important role in limiting P. alni subsp. alni establishment in cold locations, thus affecting the distribution of the different subspecies of P. alni in boreal regions.
|
|
| 33. |
- Samils, Nicklas, et al.
(författare)
-
Nuclear interactions in a heterokaryon : insight from the model Neurospora tetrasperma
- 2014
-
Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 281:1786, s. UNSP 20140084-
-
Tidskriftsartikel (refereegranskat)abstract
- A heterokaryon is a tissue type composed of cells containing genetically different nuclei. Although heterokaryosis is commonly found in nature, an understanding of the evolutionary implications of this phenomenon is largely lacking. Here, we use the filamentous ascomycete Neurospora tetrasperma to study the interplay between nuclei in heterokaryons across vegetative and sexual developmental stages. This fungus harbours nuclei of two opposite mating types (mat A and mat a) in the same cell and is thereby self-fertile. We used pyrosequencing of mat-linked SNPs of three heterokaryons to demonstrate that the nuclear ratio is consistently biased for mat A-nuclei during mycelial growth (mean mat A/mat a ratio 87%), but evens out during sexual development (ratio ranging from 40 to 57%). Furthermore, we investigated the association between nuclear ratio and expression of alleles of mat-linked genes and found that expression is coregulated to obtain a tissue-specific bias in expression ratio: during mycelial extension, we found a strong bias in expression for mat A-linked genes, that was independent of nuclear ratio, whereas at the sexual stage we found an expression bias for genes of the mat a nuclei. Taken together, our data indicate that nuclei cooperate to optimize the fitness of the heterokaryon, via both altering their nuclear ratios and coregulation genes expressed in the different nuclei.
|
|
| 34. |
- Stenlid, Jan, et al.
(författare)
-
Accuracy of the Rotfinder instrument in detecting decay on Norway spruce (Picea abies) trees
- 2011
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 262, s. 1378-1386
-
Tidskriftsartikel (refereegranskat)abstract
- Rotfinder is a non-destructive decay-sensing apparatus based on resistance measurements in standing trees. The accuracy of Rotfinder in detecting decay was evaluated in 500 standing trees in three Norway spruce (Picea abies) plots. Trees were measured at three heights, 0.30, 0.66 and 1.30 m. Sections were later inspected for the presence of decay and reaction zones. Inspected trees were mostly infected by Heterobasidion annosum and showed a large variation in the amount of decay present, ranging from 0.1% to 88.0% of the section. Correctly and incorrectly classified trees were compared in terms of ion and element concentration, density and moisture. Measurements at stump level (0.30 m) were more accurate than measurements at breast height (1.30 m) where the reaction zone and decay columns showed lower moisture content. The accuracy of Rotfinder increased when trees with small decay columns were regarded as 'non-decayed'. When only trees with more than 15% of the section decayed were regarded as 'decayed', Rotfinder had an accuracy of 0.86 when performing assessments at stump level. False negatives, as opposed to true positives, corresponded to trees with smaller and drier decay columns, drier reaction zones and lower K(+) (potassium) concentration in the decay column. False positives corresponded to trees with large sapwood and high sodium content in the sapwood. Rotfinder represents an alternative to the standard method of using increment core observations to assess decay in living trees. (C) 2011 Elsevier B.V. All rights reserved.
|
|
| 35. |
- Stenlid, Jan, et al.
(författare)
-
Emerging Diseases in European Forest Ecosystems and Responses in Society
- 2011
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 2, s. 486-504
-
Tidskriftsartikel (refereegranskat)abstract
- New diseases in forest ecosystems have been reported at an increasing rate over the last century. Some reasons for this include the increased disturbance by humans to forest ecosystems, changed climatic conditions and intensified international trade. Although many of the contributing factors to the changed disease scenarios are anthropogenic, there has been a reluctance to control them by legislation, other forms of government authority or through public involvement. Some of the primary obstacles relate to problems in communicating biological understanding of concepts to the political sphere of society. Relevant response to new disease scenarios is very often associated with a proper understanding of intraspecific variation in the challenging pathogen. Other factors could be technical, based on a lack of understanding of possible countermeasures. There are also philosophical reasons, such as the view that forests are part of the natural ecosystems and should not be managed for natural disturbances such as disease outbreaks. Finally, some of the reasons are economic or political, such as a belief in free trade or reluctance to acknowledge supranational intervention control. Our possibilities to act in response to new disease threats are critically dependent on the timing of efforts. A common recognition of the nature of the problem and adapting vocabulary that describe relevant biological entities would help to facilitate timely and adequate responses in society to emerging diseases in forests.
|
|
| 36. |
|
|
| 37. |
- Stenlid, Jan, et al.
(författare)
-
Gene flow and inter-sterility between allopatric and sympatric populations of Heterobasidion abietinum and H. parviporum in Europe
- 2011
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 41, s. 243–252-
-
Tidskriftsartikel (refereegranskat)abstract
- The tree pathogenic fungi Heterobasidion parviporum and H. abietinum are recently described sibling species that show marked host preference for Picea abies and Abies alba, respectively. H. parviporum shows a higher reproductive character displacement (i.e. higher intersterility) towards H. abietinum in sympatry than in allopatry. We inspected whether this pattern was also present in H. abietinum by studying the inter-sterility and gene flow amongst sympatric central European populations of H. abietinum and H. parviporum, and two isolated allopatric populations, Pyrenean H. abietinum and Scandinavian H. parviporum. Inter- and intra-specific fixation index values were calculated from DNA sequence data of the GST-1 locus and four microsatellite loci. Present allopatric and sympatric populations of H. abietinum were equally inter-sterile towards H. parviporum, not suggestive of relaxed reinforcement. Several hypotheses explaining the observed pattern are presented. Genetic differentiation was observed between H. abietinum in the Pyrenees and in the Alps, suggesting geographical structure of H. abietinum in Europe.
|
|
| 38. |
- Stenlid, Jan, et al.
(författare)
-
Heartwood stump colonisation by Heterobasidion parviporum and H. annosum s.s. in Norway spruce (Picea abies) stands
- 2013
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 295, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- Stump-to-tree spread is a key step in the root and butt-rot disease caused by Heterobasidion annosum sensu lato. In Norway spruce stands, Heterobasidion parviporum is more likely to spread to neighbouring trees from stumps with a large diameter than from small stumps. However, H. annosum sensu stricto does not appear to share this pattern of infection. Given that the ratio of heartwood to sapwood varies depending on the size of the stump, we investigated the role of heartwood and sapwood in stump infection by H. parviporum and H. annosum s.s. To determine whether heartwood sapwood susceptibility was different in different host species, both Norway spruce and Scots pine stumps were included in the study. Sapwood, heartwood and the border zone between sapwood and heartwood of spruce stumps and the heartwood and sapwood of pine stumps were artificially inoculated with different genotypes of H. annosum as. and H. parviporum. Only one zone was inoculated per stump. Infection was assessed 2 and 10 months after inoculation at 5 and 30 cm below the point of inoculation. On spruce stumps, H. parviporum and H. annosum s.s. were mostly confined to the heartwood. The area infected by H. annosum s.s. was smaller than that infected by H. parviporum. Both sapwood and border infections tended to grow towards the heartwood, whereas heartwood inoculations tended to remain in the heartwood, indicating that heartwood was more favourable for H. parviporum and H. annosum s.s. colonisation in spruce stumps. On pine, heartwood colonisation failed and only H. annosum s.s. was found in the sapwood. Our results suggest a possible association between the size of the stump and the spread of H. annosum s.s. to neighbouring trees mediated by the heartwood content, suggesting that screening for heartwood resistance could be a potentially interesting direction for future research. Treating stumps at final felling would be advisable owing to the large area of heartwood exposed by this operation. (C) 2013 Elsevier B.V. All rights reserved.
|
|
| 39. |
- Stenlid, Jan, et al.
(författare)
-
Long-term effects of mechanized stump treatment against Heterobasidion annosum root rot in Picea abies
- 2010
-
Ingår i: Canadian Journal of Forest Research. - 0045-5067 .- 1208-6037. ; 40, s. 1020-1033
-
Tidskriftsartikel (refereegranskat)abstract
- Airborne Heterobasidion annosum(Fr.) Bref. sensu lato infections can be controlled by winter thinning or by mechanically spreading urea orPhlebiopsis gigantea(Fr.) Jülich spores on stump surfaces during summer thinning operations. The long-term outcomes of these control methods when applied as part of the conventional forest operations are unclear. We studied the rot incidence and population structure ofH. annosumin plots ofPicea abies(L.) Karst. thinned in winter or thinned in summer with and without treatment of the stumps. Plots were distributed among 11 stands in Sweden representing two different land use histories: forest and agricultural. After 13years, the effect of stump treatment on rot incidence was only evident in stands on former agricultural land. In stands planted on former forest land with higher levels of preexisting rot than on former agricultural land, the expansion of preexisting genets ofH. annosummight have masked the effects of stump protection. In former forest land, unprotected summer plots showed a greater diversity ofH. annosumgenotypes and a smaller number of trees infected by each genet than in protected plots, suggesting that protection treatments prevented the establishment of new genets, which may result in a reduced rot incidence in the future.
|
|
| 40. |
- Stenlid, Jan, et al.
(författare)
-
Nya insikter om rotröta
- 2013
-
Ingår i: Svampar och insekter : rapport från Future Forests 2009-2012. ; 2013:5, s. 28-29
-
Bokkapitel (populärvet., debatt m.m.)
|
|
| 41. |
- Stenlid, Jan, et al.
(författare)
-
Phenotypic interactions between tree hosts and invasive forest pathogens in the light of globalization and climate change
- 2016
-
Ingår i: Philosophical Transactions B: Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 371
-
Forskningsöversikt (refereegranskat)abstract
- Invasive pathogens can cause considerable damage to forest ecosystems. Lack of coevolution is generally thought to enable invasive pathogens to bypass the defence and/or recognition systems in the host. Although mostly true, this argument fails to predict intermittent outcomes in space and time, underlining the need to include the roles of the environment and the phenotype in host-pathogen interactions when predicting disease impacts. We emphasize the need to consider host-tree imbalances from a phenotypic perspective, considering the lack of coevolutionary and evolutionary history with the pathogen and the environment, respectively. We describe how phenotypic plasticity and plastic responses to environmental shifts may become maladaptive when hosts are faced with novel pathogens. The lack of host-pathogen and environmental coevolution are aligned with two global processes currently driving forest damage: globalization and climate change, respectively. We suggest that globalization and climate change act synergistically, increasing the chances of both genotypic and phenotypic imbalances. Short moves on the same continent are more likely to be in balance than if the move is from another part of the world. We use Gremmeniella abietina outbreaks in Sweden to exemplify how host-pathogen phenotypic interactions can help to predict the impacts of specific invasive and emergent diseases.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'.
|
|
| 42. |
|
|
| 43. |
- Stenlid, Jan, et al.
(författare)
-
Spread of Heterobasidion annosum s.s. and Heterobasidion parviporum in Picea abies 15 years after stump inoculation
- 2011
-
Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 0168-6496 .- 1574-6941. ; 75, s. 414–429-
-
Tidskriftsartikel (refereegranskat)abstract
- The tree pathogenic fungiHeterobasidion annosums.s. and Heterobasidion parviporumcause root and butt rot in Norway spruce (Picea abies) and produce serious economic losses to the forest sector in Europe. We experimentally studied inter- and intraspecific differences betweenH. parviporumandH. annosums.s. in the way they infect stumps and spread into neighbouring trees. ElevenH. parviporumand nineH. annosums.s. isolates were artificially inoculated on stumps of two spruce stands after first thinning. After 15 years, the same isolates were reisolated from neighbouring trees.Heterobasidion parviporumspread more frequently from the inoculated stumps to the neighbouring trees thanH. annosums.s. The surroundings ofH. annosums.s. stumps that did not spread were often colonized byH. parviporum.Heterobasidion annosums.s. spread was restricted mainly to the areas of the plot where no otherHeterobasidiongenotypes had been inoculated. In such cases,H. annosums.s. tended to develop into bigger genets thanH. parviporum. The probability of stump-to-tree spread ofH. parviporumdepended on the diameter of the stumps, suggesting thatH. parviporumspread may relate to the presence of heartwood. BothH. parviporumandH. annosums.s. proved to be strong pathogens on Norway spruce; however, when competing for the same trees,H. parviporumseemed capable of excludingH. annosums.s. from the stand.
|
|
| 44. |
|
|
| 45. |
- Stenlid, Jan, et al.
(författare)
-
Understanding the role of sapwood loss and reaction zone formation on radial growth of Norway spruce (Picea abies) trees decayed by Heterobasidion annosum s.l.
- 2012
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 274, s. 201-209
-
Tidskriftsartikel (refereegranskat)abstract
- Allocation of photosynthates to defence responses at the expense of biomass increase is a common strategy amongst plants to cope with stress factors. Trees reduce the spread of decay by creating a secondary metabolite-rich reaction zone as fungal ingresses the sapwood. Reaction zone formation implies a sacrificial conversion of sapwood, thus, as decay progresses, the sapwood area of the tree is reduced. The relative contribution that reaction-zone formation and sapwood loss make to radial growth decrease is unclear. To answer this question we reconstructed radial-growth patterns in 100 Norway spruce (. Picea abies) trees with a range of reaction zone and sapwood disruption. Basal area increment (BAI) between 1960 and 2007 and its relationship with sapwood reduction and reaction zone formation was assessed using structural equation models (SEM). BAI data showed that over 10. years, trees with small or no decay columns (<40%) and a reaction zone shifted from a growth rate that was similar to trees without a reaction zone towards low growth rate similar to trees with large decay columns. The fitted SEM indicated that: (i) the effects of decay on growth would begin with the formation of the reaction zone, and (ii) the smaller sapwood in decayed trees as compared with healthy trees would not reduce radial growth, but would be in part the result of previous periods of low growth due to reaction-zone formation.
|
|
| 46. |
- Stenlid, Jan, et al.
(författare)
-
Validation of the Rotstand model for simulating Heterobasidion annosum root rot in Picea abies stands
- 2011
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 261, s. 1841-1851
-
Tidskriftsartikel (refereegranskat)abstract
- Rotstand is a computer model that can simulate the development of a forest stand together with the root rot disease caused by Heterobasidion annosum s.l. on several tree species in Europe. We evaluated the accuracy of Rostand model for its use in Sweden by using data from two field experiments of Norway spruce (Picea abies) in which the long term outcome of stump protection methods had been evaluated (14 and 20 plots, respectively). One of the experiments included artificial infection of the stumps that enabled an almost complete parameterization of the model. Artificially infected plots were used for assessing the loss of precision of using average parameter values vs. plot-specific values. Average values obtained from artificially infected plots were used for validating the model on plots subjected to natural infection. Rotstand proved to be able to predict plots with a large variation of decay development (20-90% of stems with decay) as early as 15 years after infection. The parameter controlling the inoculum expansion within the tree root system appeared as a major factor affecting the accuracy of the predictions. Expansion of decay centres of artificially and naturally infected plots in Southern Sweden was not significantly different from natural infected plots in the rest of the country, opening the possibility of using a single average value all over Sweden. By using an expansion rate of 0.20 m year(-1). Rotstand gave unbiased predictions of decay development 15 years after infection with a relative error of 38.4%. When using average parameter values, Rotstand tended to underestimate plots showing more than 50% of decay 15 years after infection; however, when simulating those plots beyond the last decay assessment, these errors were predicted to disappear. (C) 2011 Elsevier B.V. All rights reserved.
|
|
| 47. |
- Zhao, Anan, et al.
(författare)
-
Effect of temperature on the interaction between Phlebiopsis gigantea and the root-rot forest pathogen Heterobasidion spp.
- 2015
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 340, s. 22-30
-
Tidskriftsartikel (refereegranskat)abstract
- The biocontrol agent Phlebiopsis gigantea is widely applied to stump surfaces during commercial thinning operations in Northern Europe to prevent airborne infection of Norway spruce (Picea abies) stumps by the root and butt-rot pathogen Heterobasidion spp. It has been suggested that warmer climatic conditions in the future may affect the interaction between the pathogen and the biocontrol agent, and may enable Heterobasidion annosum sensu stricto, which is currently restricted to southern areas of Sweden, to move further northward. To determine whether warm temperatures do effect the interaction between P. gigantea and Heterobasidion spp., we conducted a series of experiments to investigate the effect of temperature on the growth of P. gigantea and several Heterobasidion spp. and on the ability of P. gigantea to overgrow Heterobasidion spp. in paired interaction experiments in vitro. To validate our in vitro findings, we set up field experiments to examine the interaction between P. gigantea and the Heterobasidion spp. that infect spruce in Sweden, Heterobasidion parviporum and H. annosum s.s., under different temperature regimes. Our study showed that temperature did not diminish the effectiveness of P. gigantea to protect spruce stumps against infection by H. parviporum. The growth rate of P. gigantea in stumps was higher than that of H. parviporum, particularly in sapwood. We found little support for a hypothetical increase in H. annosum s.s. damage under warmer climatic conditions. In vitro studies showed that regardless of the temperature regime, H. annosum s.s. was less resistant to overgrowth by P. gigantea than H. parviporum. Under field conditions, the relatively low infection capacity of H. annosum s.s. to P. abies stumps seems to be the crucial factor determining the outcome of the interaction. The results of paired in vitro experiments between P. gigantea and non-European Heterobasidion species, for example, Heterobasidion araucariae, Heterobasidion irregulare and others, suggest that P. gigantea may be less effective as a biocontrol agent against species or isolates adapted to high temperatures (20-25 degrees C), particularly those species that are able to grow rapidly at temperatures as high as 25 degrees C. (C) 2014 Elsevier B.V. All rights reserved.
|
|
