Forest ecosystems are important for biodiversity conservation and human societies,but are under pressure due to climate change and human interventions.This applies to natural forests as well as tree plantations.The la...Forest ecosystems are important for biodiversity conservation and human societies,but are under pressure due to climate change and human interventions.This applies to natural forests as well as tree plantations.The latter are globally widespread and therefore gaining increasing importance for biodiversity conservation.However,even after dieback due to increasing disturbance frequencies,such plantations are primarily managed for economic returns,leading to growing conflicts among stakeholders.In particular,the impact of forest management on biodiversity is being discussed.This study investigates the effects of five management approaches in a landscape severely affected by spruce(Picea abies L.)dieback on beetle diversity,conservation,and community composition.We considered direct effects of management and indirect effects of environmental parameters separately in ground-dwelling and flight-active beetles.Beetle diversity was strongly affected by forest management,with nonintervention deadwood stands being most beneficial for beetles.In addition,we show indirect effects of environmental factors.In general,parameters related to salvage logging(e.g.open canopies,tree stumps)influenced beetle diversity and conservation negatively,while positive effects were found for soil nutrient availability and plant species richness.Community composition differed strongly among management categories and indicated a lack of landscape connectivity for open habitat species,as we found only low proportions of such species even on salvage-logged sites.We propose a mixture of management approaches after bark beetle outbreaks,including a substantial proportion of non-intervention deadwood stands,to increase landscape heterogeneity and connectivity.This may increase overall biodiversity while addressing the concerns of both forestry and species conservation.展开更多
Biodiversity loss is a significant problem at a global scale and may be amplified by climate change.In recent years,coniferous forests have had substantial die-back across Europe due to drought and subsequent bark-bee...Biodiversity loss is a significant problem at a global scale and may be amplified by climate change.In recent years,coniferous forests have had substantial die-back across Europe due to drought and subsequent bark-beetle outbreaks.As many studies on the consequences of disturbance and subsequent management have focused on natural stands,management implications for managed spruce stands are not well understood,even though such stands are widespread throughout Europe.In this study,beetle taxonomy,conservation value,and community com-position are compared among spruce plantations and four post-disturbance management approaches:standing dead-wood,lying deadwood,clear cuts,and long-term succession.Diversity and community composition differed significantly among management categories,while different beetle fami-lies responded similarly.Intact spruce stands harbored the lowest beetle diversity while the highest taxonomic diver-sity and conservation value was on clear cuts and stands with lying or standing deadwood.The proportion of forest specialists was highest in successional forests.In summary,different forest management categories harbored distinct beetle communities at the family-,species-,and ecological guild levels.Therefore,post-disturbance management should consider the landscape scale and include different management types.This enhances landscape heterogeneity and thus overall biodiversity but could also mitigate negative impacts of natural disturbances on ecosystem services.展开更多
Sweet osmanthus is one of the ten traditional famous flowers in China.The occurrence of the diseases caused by fungi other than Botryosphaeria spp.has been reported mainly from China on sweet osmanthus.A leaf dieback ...Sweet osmanthus is one of the ten traditional famous flowers in China.The occurrence of the diseases caused by fungi other than Botryosphaeria spp.has been reported mainly from China on sweet osmanthus.A leaf dieback of sweet osmanthus caused by Botryosphaeria sp.was found for the first time in 2007 in Nanning City,Guangxi,China.The objectives of the present study were to isolate and characterize the causal organism of sweet osmanthus leaf dieback.The fungus was isolated from the lesions of affected sweet osmanthus leaves and its pathogenicity to sweet osmanthus was confirmed using a detached-leaf-inoculation method.The identification of the pathogen was carried out mainly based on the morphological characters and molecular analysis of internal transcribed spacer （ITS） sequences.The morphological characters of the pathogenic isolate GHX6 were agreed with that of Botryosphaeria dothidea.The ITS sequence of the isolate was amplified with primers ITS1 and ITS4,and submitted to GenBank （accession no.GQ368251）.Molecular analysis based on ITS sequence comparison between the isolate GHX6 and the other related fungi derived from GenBank supported that the causal agent of the sweet osmanthus leaf dieback belonged to Botryosphaeria dothidea.This is the first report of Botryosphaeria dothidea causing leaf dieback on sweet osmanthus in China.展开更多
We tested the hypothesis that the biometrical characters of wood elements in ash trees(Fraxinus excelsior L.) become modified in response to the progression of disease caused by Chalara fraxinea. Anatomical analyses w...We tested the hypothesis that the biometrical characters of wood elements in ash trees(Fraxinus excelsior L.) become modified in response to the progression of disease caused by Chalara fraxinea. Anatomical analyses were performed on wood samples collected at breast height from the trunks of groups of ash trees which contained healthy, weakened and dead trees. We measured(1) treering width,(2) earlywood vessel diameter,(3) earlywood vessel element length,(4) fibre length,(5) fibre diameter,(6) fibre lumen diameter, and(7) fibre wall thickness. We showed that tree-ring width diminished in all analysed groups during disease progression. However, the greatest suppression of growth was observed in dead trees. In both weakened and dead ash trees, the reduction in tree-ring width was accompanied by diminished vessel diameter in the earlywood of the outermost annual rings. The annual rings of dead trees had shorter fibres having greater lumen diameter and thinner cell walls. Consequently, water conduction in the sapwood of dead ash trees was less efficient owing to reduced vessel diameter, and this seems to be one of the greatest disease-induced morphological modifications. All the anatomical modifications might be due to leaf loss and crown dieback triggered by Chalara fraxinea.展开更多
Intraspecific variability in morphological and ecophysiological leaf traits might be theorized to be present in declining populations,since they seem to be exposed to stress and plasticity could be advantageous.Here w...Intraspecific variability in morphological and ecophysiological leaf traits might be theorized to be present in declining populations,since they seem to be exposed to stress and plasticity could be advantageous.Here we focused on declining Persian oaks(Quercus brantii Lindl.var.persica(Jaub and Spach)Zohary)in the Zagros Mountains of western Iran,representing the most important tree species of this region.We selected trees with contrasting crown dieback,from healthy to severely defoliated,to investigate the relationships between canopy dieback and leaf morphology,water content and pigments.We also measured esterase and peroxidase,as enzymatic antioxidants and indicators of contrasting genotypes.Trees showing moderate to severe defoliation showed higher leaf mass area(LMA),reduced relative water content(RWC),and lower stomatal density(SD).Increasing LMA indicates a more sclerophyllic structure,according to drier conditions.We did not find significant differences in leaf pigments(chlorophyll a and b,and carotenoids)among crown dieback classes,suggesting that Persian oak trees are able to maintain accurate photochemical efficiency,while reduced RWC and SD suggest hydraulic limitations.Our results do not provide a consistent pattern as regards enzymatic antioxidant defense in Persian oak.Morphological leaf traits would be important drivers of future adaptive evolution in Persian oak,leading to smaller and thicker leaves,which have fitness benefits in dry environments.Nonetheless,drought responses may be critically affecting carbon uptake,as photosynthetic compounds are less effectively used in leaves with higher sclerophylly.展开更多
Today,shisham plantations in Punjab,Pakistan face major constraints,especially dieback disease.This article reviews the multidisciplinary team work by forest and plant pathologists and economists to resolve the confus...Today,shisham plantations in Punjab,Pakistan face major constraints,especially dieback disease.This article reviews the multidisciplinary team work by forest and plant pathologists and economists to resolve the confusions in the pathology of dieback disease.It is intended to be of practical use to the foresters and plant pathologists reporting on this issue.展开更多
Cork oak forests in Morocco are rich in resources and services thanks to their great biological diversity,playing an important ecological and socioeconomic role.Considerable degradation of the forests has been accentu...Cork oak forests in Morocco are rich in resources and services thanks to their great biological diversity,playing an important ecological and socioeconomic role.Considerable degradation of the forests has been accentuated in recent years by signifi cant human pressure and eff ects of climate change;hence,the health of the stands needs to be monitored.In this study,the Google Engine Earth platform was leveraged to extract the normalized diff erence vegetation index(NDVI)and soil-adjusted vegetation index,from Landsat 8 OLI/TIRS satellite images between 2015 and 2017 to assess the health of the Sibara Forest in Morocco.Our results highlight the importance of interannual variations in NDVI in forest monitoring;the variations had a signifi cantly high relationship(p<0.001)with dieback severity.NDVI was positively and negatively correlated with mean annual precipitation and mean annual temperature with respective coeffi cients of 0.49 and−0.67,highlighting its ability to predict phenotypic changes in forest species.Monthly interannual variation in NDVI between 2016 and 2017 seemed to confi rm fi eld observations of cork oak dieback in 2018,with the largest decreases in NDVI(up to−38%)in December in the most-aff ected plots.Analysis of the infl uence of ecological factors on dieback highlighted the role of substrate as a driver of dieback,with the most severely aff ected plots characterized by granite-granodiorite substrates.展开更多
The relationships between different aspects of diversity(taxonomic,structural and functional)and the aboveground biomass(AGB)as a major component of global carbon balance have been studied extensively but rarely under...The relationships between different aspects of diversity(taxonomic,structural and functional)and the aboveground biomass(AGB)as a major component of global carbon balance have been studied extensively but rarely under the simultaneous influence of forest dieback and management.In this study,we investigate the relationships between taxonomic,functional and structural diversity of woody species(trees and shrubs)and AGB along a gradient of dieback intensity(low,moderate,high and no dieback as control)under two contrasted management conditions(protection by central government vs.traditional management by natives)in a semi-arid oak(Quereus brantii Lindl.)forest ecosystem.AGB was estimated and taxonomic diversity,community weighted average(CWM)and functional divergence indices were produced.We found that the aerial biomass was significantly higher in the intensively used area(14.57(±1.60)t/hm^(2))than in the protected area(8.70(±1.05)t/hm^(2))due to persistence of some large trees but with decreasing values along the dieback intensity gradient in both areas.CWM of height(H),leaf nitrogen content(LNC)and leaf dry matter content(LDMC)were also higher in the traditional managed area than in the protected area.In contrast,in the protected area,the woody species diversity was higher and the inter-specific competition was more intense,explaining a reduced H,biomass and LDMC.Contrary to the results of CWM,none of the functional diversity traits(FDvar)was affected by dieback intensity and only FDvar values of LNC,leaf phosphorus content(LPC)and LDMC were influenced by management.We also found significantly positive linear relationships of AGB with CWM and FDvar indices in the protected area,and with taxonomic and structural diversity indices in the traditional managed area.These results emphasize that along a dieback intensity gradient,the leaf functional traits are efficient predictors in estimating the AGB in protected forests,while taxonomic and structural indices provide better results in forests under a high human pressure.Finally,species identity of the dominant species(i.e.,Brant’s oak)proves to be the main driver of AGB,supporting the selection effect hypothesis.展开更多
Unusually high levels of dieback have recently been reported in sugar maple, Acer saccharum Marsh., in Upper Michigan, and a network of plots was established to determine the extent and factors associated with the die...Unusually high levels of dieback have recently been reported in sugar maple, Acer saccharum Marsh., in Upper Michigan, and a network of plots was established to determine the extent and factors associated with the dieback. A possible contributor to this dieback is sapstreak disease caused by Ceratocystis virescens (Davidson) Moreau. Unhealthy trees with considerable crown dieback were evaluated across the western Upper Peninsula, MI to determine the prevalence of the sapstreak fungus using a minimally destructive sampling technique. Approximately 8% of 90 trees sampled were sapstreak positive and approximately 10% of trees were positive at one site that had recently been harvested. While the high levels of maple dieback present in these forests appear not to be directly caused by widespread sapstreak disease, the occurrence of sapstreak may be significantly impacting trees at some locations. However, even when present on a low number of trees, the biointeraction of sapstreak and decay rates from other fungi could be important for future tree mortality and value to the forest industry. Therefore, the effect of two sapstreak fungal isolates on the amount of decay caused by two common maple white rot fungi, Trametes versicolor (L.:Fr.) Pilat. And Irpex lacteus (Fr.:Fr.) Fr. was tested in the laboratory. Sugar maple wood blocks were precolonized by two native isolates of C. virescens followed by inoculation and incubation with decay fungi. Mean percent weight loss of blocks by white rot decay fungi ranged from 39% to 55%, but decay rates were not significantly affected by the presence of the sapstreak fungus.展开更多
In Bazhong City,Sichuan Province,China,top dieback symptoms were found on many pine trees(Pinus thunbergii Parl).The tips of old needles first turned grayish-green and then developed into brown bands in the field.Phyl...In Bazhong City,Sichuan Province,China,top dieback symptoms were found on many pine trees(Pinus thunbergii Parl).The tips of old needles first turned grayish-green and then developed into brown bands in the field.Phylogenetic analysis of concatenated ITS and EF1-αindicated the pathogen of this dieback disease as Diplodia neojuniperi.Additionally,effects of temperature,pH and medium on the mycelial growth were also characterized.The most favorable temperature and pH level for mycelial growth are 25°C and 8,respectively.The optimal medium for mycelial growth is PDA medium.To our knowledge,this is the first report of D.neojuniperi causes Diplodia top dieback on Pinus thunbergii.Our results provide fundamental information for monitoring and preventing such disease in the future.展开更多
In vitro Kirby-Bauer disc-diffusion assays coupled with bio-imaging software techniques were used to assess native forest dwelling “fairy ring” forming fungi (Clitocybe nebularis) and co-habitant forest tree-root co...In vitro Kirby-Bauer disc-diffusion assays coupled with bio-imaging software techniques were used to assess native forest dwelling “fairy ring” forming fungi (Clitocybe nebularis) and co-habitant forest tree-root colonising non pathogenic, antibiotic producing bacteria (Bacillus licheniformis, Bacillus pumilis) for their antagonism towards Japanese larch dieback oomycetes phytopathogens which also affects ornamental alternative hosts. The aqueous extracts of C. nebularis exhibited the highest clearance (inhibitory) zone of 21.4 × 105 pixels = 573%) against Phytophthora ramorum than growth/clear zone Cartesian integrates recorded in untreated (control) disc (3.7 × 105 pixels = 100%) over 3-day incubation. The fairy ring fungal extracts also exhibited substantive antagonism against P. kernoviae (147%), P. lateralis (347%) and a solanaceous crop infecting P. infestans (86%). Quite encouragingly, the soil oomycete phytopathogen P. ramorum was inhibited strongly (mean ~ 177%) by both forest bacilli. Aqueous extracts of non-forest antifungal herbaceous plants (garlic and elderberry) expressed similar inhibitory effects (mean ~ 70%). A seaweed fungal elicitor component fucoidan showed moderate levels (mean ~ 85%) of antagonism against P. ramorum, P. kernoviae, P. lateralis and P. infestans. The results in this in vitro study highlight the intensity and vigor of antagonistic forest microflora and non-forest herbaceous antifungal agents such as garlic and other plant extracts as serious candidates for suppression of the oomycete Phytophthora pathogenic fungi in forest soils. This study calls for urgent scoping and impact assessment studies in pot experiments and mini-plot forest trials to gauge the fitness of these natural resources for field level potential biotechnological applications to combat the devastating dieback disease in the native woodlands and horticulture.展开更多
Eutypella vitis is reported for the first time on several new host trees viz.Fagus grandifolia,Fraxinus pennsylvanica and Syringa reticulata with associated branch dieback symptoms in the Niagara Region of Southern On...Eutypella vitis is reported for the first time on several new host trees viz.Fagus grandifolia,Fraxinus pennsylvanica and Syringa reticulata with associated branch dieback symptoms in the Niagara Region of Southern Ontario,Canada.Morphological characteristics and phylogenetic analyses of ITS sequence data confirmed the species identification.Eutypella vitis is known as a woody plant pathogen causing dieback of grapevines and other economically important fruit trees widely cultivated in Ontario.The fungus ability to infect several alternate new hosts can promote its faster and wider spread across vineyards and consequently increase a dieback hazard to viticulture in Canada.展开更多
Commercially managed forests are often poor in terms of biodiversity.Saproxylic beetle species could be a useful bioindicating group for the conservation of forest stands.In recent decades,oak stands have been affecte...Commercially managed forests are often poor in terms of biodiversity.Saproxylic beetle species could be a useful bioindicating group for the conservation of forest stands.In recent decades,oak stands have been affected by a wide range of factors that have intensified stand decline.Saproxylic beetle richness was investigated in declining oak stands that have been consequently targeted for clearcutting due to concerns about insect pest outbreaks.The research was conducted at six managed oak forests,where we compared beetle occurrences in declining stands and in healthy stands that did not show any symptoms of decline.Beetles were collected using window traps placed on the basal and mid-trunk sections of trees.A total of 2925 adults belonging to 239 saproxylic beetle species were captured,of which 56 species are on the IUCN Red List.The results show that declining stands were richer in saproxylic species,and that the diversity of beetle species was greater in these stands.Approximately 1.4 times more species were caught within declining stands than in healthy ones(1.6 times for Red List species).Declining stands hosted more pest species(e.g.,cambiophagous and xylophagous species).However,only low numbers of these species were recorded in these stands.In summary,results of this study suggest that decline of managed oak stands is creating a wide spectrum of habitats for many saproxylic species.Thus,salvage logging of declining oak trees can represent a natural trap and reduce local beetle biodiversity,mainly for saproxylic,endangered or low-mobility species that would be attracted by new suitable habitats.展开更多
Forest ecosystems are one of the largest terres-trial carbon(C)reservoirs on Earth and an important sink of anthropogenic CO_(2) emissions.Abiotic and biotic distur-bances such as windfalls,fires,outbreaks of insects ...Forest ecosystems are one of the largest terres-trial carbon(C)reservoirs on Earth and an important sink of anthropogenic CO_(2) emissions.Abiotic and biotic distur-bances such as windfalls,fires,outbreaks of insects or pests may negatively affect C storage in forest ecosystems decreas-ing their role as CO_(2) sink.The objective of this review was to summarize the current knowledge on the impact of large-scale forest ecosystem disturbances caused by windthrow and insect outbreaks on soil C stocks and cycles,and to gather information on the impact of restoration treatments performed in disturbed stands in the context of carbon accumulation in forest soils.Discussed were effects of wind-storms and insect outbreaks as well as impacts of various approaches of forest regeneration after disturbance on C stocks and fluxes.Disturbances decrease C stocks in forest ecosystems and turn them from C sink into C source for a certain time.Regeneration of the disturbed forest restores its role as a CO_(2) sink.In montane forests artificial afforestation seems to shorten the time of achieving C parity.However,no data exists for lowland forests.Hence,there is an urgent need for studies that assess effect of windfalls and insect outbreaks on carbon storage in forests of lowland Europe.展开更多
Botryosphaeria dieback is a serious disease problem for table and grape wine production worldwide.The disease however,has been less well-studied in China.In this study,we surveyed Botryosphaeria dieback in 72 vineyard...Botryosphaeria dieback is a serious disease problem for table and grape wine production worldwide.The disease however,has been less well-studied in China.In this study,we surveyed Botryosphaeria dieback in 72 vineyards of 20 grape-growing regions in China and found that Botryosphaeria dieback occurs in 18 out of 20 provinces.Morphological and multi-gene phylogenetic analyses confirmed that Botryosphaeria dothidea,Diplodia seriata,Lasiodiplodia theobromae and Neofusicoccum parvum are associated with different grapevine dieback symptoms.This study also revealed considerable differences in the geographical distribution of Botryosphaeriaceae species in China with Lasiodiplodia theobromae and Neofusicoccum parvum occurring only in subtropical monsoon climate regions,Diplodia seriata occurring only in temperate monsoon climate regions,and Botryosphaeria dothidea occurring in both temperate and subtropical monsoon climate regions.Analysis of 26 isolates showed that there is little genetic variation within species.Koch’s postulates were satisfied for all species,and pathogenicity testing showed that among the 25 major cultivars growing in China,none was resistant to the four taxa.The current paper represents the first detailed report on Botryosphaeria dieback of grapevines in China.展开更多
This study reports an inventory of marsh dieback events from spatial and temporal perspectives in the North Inlet-Winyah Bay(NIWB)estuary,South Carolina(SC).Past studies in the Gulf/Atlantic coast states have reported...This study reports an inventory of marsh dieback events from spatial and temporal perspectives in the North Inlet-Winyah Bay(NIWB)estuary,South Carolina(SC).Past studies in the Gulf/Atlantic coast states have reported acute marsh dieback events in which marsh rapidly browned and thinned,leaving stubble of dead stems or mudflat with damaged ecosystem services.Reported marsh dieback in SC,however,have been limited.This study identified all marsh dieback events in the estuary since 1998.With 20 annually collected Landsat images,the Normalized Difference Vegetation Index(NDVI)series was extracted.A Stacked Denoising Autoencoder neural network was developed to identify the NDVI anomalies on the trajectories.All marsh dieback patches were extracted,and their inter-annual changes were examined.Results showed a continuous,spatially variable multi-year dieback event in 1998–2005,which aligned with the reported dieback in the early 2000s from other states.The identified patches mostly returned to normal within one year while the phenomenon reoccurred in other areas of the estuary during the prolonged dieback period.This study presents the first attempt to explore long-term dieback dynamics in an estuary using satellite time series.It provides valuable information in documenting marsh healthiness and environmental resilience on SC coasts.展开更多
基金supported by Forschungsanstalt für Waldo kologie und Forstwirtschaft(FAWF)of Landesforsten Rheinland-Pfalz(FF 5.3-01-2021)。
文摘Forest ecosystems are important for biodiversity conservation and human societies,but are under pressure due to climate change and human interventions.This applies to natural forests as well as tree plantations.The latter are globally widespread and therefore gaining increasing importance for biodiversity conservation.However,even after dieback due to increasing disturbance frequencies,such plantations are primarily managed for economic returns,leading to growing conflicts among stakeholders.In particular,the impact of forest management on biodiversity is being discussed.This study investigates the effects of five management approaches in a landscape severely affected by spruce(Picea abies L.)dieback on beetle diversity,conservation,and community composition.We considered direct effects of management and indirect effects of environmental parameters separately in ground-dwelling and flight-active beetles.Beetle diversity was strongly affected by forest management,with nonintervention deadwood stands being most beneficial for beetles.In addition,we show indirect effects of environmental factors.In general,parameters related to salvage logging(e.g.open canopies,tree stumps)influenced beetle diversity and conservation negatively,while positive effects were found for soil nutrient availability and plant species richness.Community composition differed strongly among management categories and indicated a lack of landscape connectivity for open habitat species,as we found only low proportions of such species even on salvage-logged sites.We propose a mixture of management approaches after bark beetle outbreaks,including a substantial proportion of non-intervention deadwood stands,to increase landscape heterogeneity and connectivity.This may increase overall biodiversity while addressing the concerns of both forestry and species conservation.
基金supported by Forschungsanstalt fur Waldokologie und Forstwirtschaft (FAWF)of Landesforsten Rheinland-Pfalz (FF5.3-01-2021).
文摘Biodiversity loss is a significant problem at a global scale and may be amplified by climate change.In recent years,coniferous forests have had substantial die-back across Europe due to drought and subsequent bark-beetle outbreaks.As many studies on the consequences of disturbance and subsequent management have focused on natural stands,management implications for managed spruce stands are not well understood,even though such stands are widespread throughout Europe.In this study,beetle taxonomy,conservation value,and community com-position are compared among spruce plantations and four post-disturbance management approaches:standing dead-wood,lying deadwood,clear cuts,and long-term succession.Diversity and community composition differed significantly among management categories,while different beetle fami-lies responded similarly.Intact spruce stands harbored the lowest beetle diversity while the highest taxonomic diver-sity and conservation value was on clear cuts and stands with lying or standing deadwood.The proportion of forest specialists was highest in successional forests.In summary,different forest management categories harbored distinct beetle communities at the family-,species-,and ecological guild levels.Therefore,post-disturbance management should consider the landscape scale and include different management types.This enhances landscape heterogeneity and thus overall biodiversity but could also mitigate negative impacts of natural disturbances on ecosystem services.
基金supported in part by the Youth Science Foundation of Guangxi, China (Gui-Ke-Qing 0728031)the Foundation for Returned Students of Guangxi, China (Gui-Ke-Hui 0639010)the Henan Provincial Key Subject Construction Program for Biochemical and Molecular Biology subsidized by Nanyang Normal University, China
文摘Sweet osmanthus is one of the ten traditional famous flowers in China.The occurrence of the diseases caused by fungi other than Botryosphaeria spp.has been reported mainly from China on sweet osmanthus.A leaf dieback of sweet osmanthus caused by Botryosphaeria sp.was found for the first time in 2007 in Nanning City,Guangxi,China.The objectives of the present study were to isolate and characterize the causal organism of sweet osmanthus leaf dieback.The fungus was isolated from the lesions of affected sweet osmanthus leaves and its pathogenicity to sweet osmanthus was confirmed using a detached-leaf-inoculation method.The identification of the pathogen was carried out mainly based on the morphological characters and molecular analysis of internal transcribed spacer （ITS） sequences.The morphological characters of the pathogenic isolate GHX6 were agreed with that of Botryosphaeria dothidea.The ITS sequence of the isolate was amplified with primers ITS1 and ITS4,and submitted to GenBank （accession no.GQ368251）.Molecular analysis based on ITS sequence comparison between the isolate GHX6 and the other related fungi derived from GenBank supported that the causal agent of the sweet osmanthus leaf dieback belonged to Botryosphaeria dothidea.This is the first report of Botryosphaeria dothidea causing leaf dieback on sweet osmanthus in China.
基金partly supported by Grant No.NN309 077438 from the Ministry of Science and Higher Education
文摘We tested the hypothesis that the biometrical characters of wood elements in ash trees(Fraxinus excelsior L.) become modified in response to the progression of disease caused by Chalara fraxinea. Anatomical analyses were performed on wood samples collected at breast height from the trunks of groups of ash trees which contained healthy, weakened and dead trees. We measured(1) treering width,(2) earlywood vessel diameter,(3) earlywood vessel element length,(4) fibre length,(5) fibre diameter,(6) fibre lumen diameter, and(7) fibre wall thickness. We showed that tree-ring width diminished in all analysed groups during disease progression. However, the greatest suppression of growth was observed in dead trees. In both weakened and dead ash trees, the reduction in tree-ring width was accompanied by diminished vessel diameter in the earlywood of the outermost annual rings. The annual rings of dead trees had shorter fibres having greater lumen diameter and thinner cell walls. Consequently, water conduction in the sapwood of dead ash trees was less efficient owing to reduced vessel diameter, and this seems to be one of the greatest disease-induced morphological modifications. All the anatomical modifications might be due to leaf loss and crown dieback triggered by Chalara fraxinea.
基金Ministerio de Economía y Competitividad,Spain(CGL2013-48843-C2-2-R)European Union FEDER 0087(TRANSHABITAT)Tarbiat Modares University(Doctorate support to AH)
文摘Intraspecific variability in morphological and ecophysiological leaf traits might be theorized to be present in declining populations,since they seem to be exposed to stress and plasticity could be advantageous.Here we focused on declining Persian oaks(Quercus brantii Lindl.var.persica(Jaub and Spach)Zohary)in the Zagros Mountains of western Iran,representing the most important tree species of this region.We selected trees with contrasting crown dieback,from healthy to severely defoliated,to investigate the relationships between canopy dieback and leaf morphology,water content and pigments.We also measured esterase and peroxidase,as enzymatic antioxidants and indicators of contrasting genotypes.Trees showing moderate to severe defoliation showed higher leaf mass area(LMA),reduced relative water content(RWC),and lower stomatal density(SD).Increasing LMA indicates a more sclerophyllic structure,according to drier conditions.We did not find significant differences in leaf pigments(chlorophyll a and b,and carotenoids)among crown dieback classes,suggesting that Persian oak trees are able to maintain accurate photochemical efficiency,while reduced RWC and SD suggest hydraulic limitations.Our results do not provide a consistent pattern as regards enzymatic antioxidant defense in Persian oak.Morphological leaf traits would be important drivers of future adaptive evolution in Persian oak,leading to smaller and thicker leaves,which have fitness benefits in dry environments.Nonetheless,drought responses may be critically affecting carbon uptake,as photosynthetic compounds are less effectively used in leaves with higher sclerophylly.
文摘Today,shisham plantations in Punjab,Pakistan face major constraints,especially dieback disease.This article reviews the multidisciplinary team work by forest and plant pathologists and economists to resolve the confusions in the pathology of dieback disease.It is intended to be of practical use to the foresters and plant pathologists reporting on this issue.
文摘Cork oak forests in Morocco are rich in resources and services thanks to their great biological diversity,playing an important ecological and socioeconomic role.Considerable degradation of the forests has been accentuated in recent years by signifi cant human pressure and eff ects of climate change;hence,the health of the stands needs to be monitored.In this study,the Google Engine Earth platform was leveraged to extract the normalized diff erence vegetation index(NDVI)and soil-adjusted vegetation index,from Landsat 8 OLI/TIRS satellite images between 2015 and 2017 to assess the health of the Sibara Forest in Morocco.Our results highlight the importance of interannual variations in NDVI in forest monitoring;the variations had a signifi cantly high relationship(p<0.001)with dieback severity.NDVI was positively and negatively correlated with mean annual precipitation and mean annual temperature with respective coeffi cients of 0.49 and−0.67,highlighting its ability to predict phenotypic changes in forest species.Monthly interannual variation in NDVI between 2016 and 2017 seemed to confi rm fi eld observations of cork oak dieback in 2018,with the largest decreases in NDVI(up to−38%)in December in the most-aff ected plots.Analysis of the infl uence of ecological factors on dieback highlighted the role of substrate as a driver of dieback,with the most severely aff ected plots characterized by granite-granodiorite substrates.
基金the Islamic Azad Univercity of Chalusand Ilam University,Iran(research team managed by Dr.Mehdi HEYDARI)for financial support of the research。
文摘The relationships between different aspects of diversity(taxonomic,structural and functional)and the aboveground biomass(AGB)as a major component of global carbon balance have been studied extensively but rarely under the simultaneous influence of forest dieback and management.In this study,we investigate the relationships between taxonomic,functional and structural diversity of woody species(trees and shrubs)and AGB along a gradient of dieback intensity(low,moderate,high and no dieback as control)under two contrasted management conditions(protection by central government vs.traditional management by natives)in a semi-arid oak(Quereus brantii Lindl.)forest ecosystem.AGB was estimated and taxonomic diversity,community weighted average(CWM)and functional divergence indices were produced.We found that the aerial biomass was significantly higher in the intensively used area(14.57(±1.60)t/hm^(2))than in the protected area(8.70(±1.05)t/hm^(2))due to persistence of some large trees but with decreasing values along the dieback intensity gradient in both areas.CWM of height(H),leaf nitrogen content(LNC)and leaf dry matter content(LDMC)were also higher in the traditional managed area than in the protected area.In contrast,in the protected area,the woody species diversity was higher and the inter-specific competition was more intense,explaining a reduced H,biomass and LDMC.Contrary to the results of CWM,none of the functional diversity traits(FDvar)was affected by dieback intensity and only FDvar values of LNC,leaf phosphorus content(LPC)and LDMC were influenced by management.We also found significantly positive linear relationships of AGB with CWM and FDvar indices in the protected area,and with taxonomic and structural diversity indices in the traditional managed area.These results emphasize that along a dieback intensity gradient,the leaf functional traits are efficient predictors in estimating the AGB in protected forests,while taxonomic and structural indices provide better results in forests under a high human pressure.Finally,species identity of the dominant species(i.e.,Brant’s oak)proves to be the main driver of AGB,supporting the selection effect hypothesis.
文摘Unusually high levels of dieback have recently been reported in sugar maple, Acer saccharum Marsh., in Upper Michigan, and a network of plots was established to determine the extent and factors associated with the dieback. A possible contributor to this dieback is sapstreak disease caused by Ceratocystis virescens (Davidson) Moreau. Unhealthy trees with considerable crown dieback were evaluated across the western Upper Peninsula, MI to determine the prevalence of the sapstreak fungus using a minimally destructive sampling technique. Approximately 8% of 90 trees sampled were sapstreak positive and approximately 10% of trees were positive at one site that had recently been harvested. While the high levels of maple dieback present in these forests appear not to be directly caused by widespread sapstreak disease, the occurrence of sapstreak may be significantly impacting trees at some locations. However, even when present on a low number of trees, the biointeraction of sapstreak and decay rates from other fungi could be important for future tree mortality and value to the forest industry. Therefore, the effect of two sapstreak fungal isolates on the amount of decay caused by two common maple white rot fungi, Trametes versicolor (L.:Fr.) Pilat. And Irpex lacteus (Fr.:Fr.) Fr. was tested in the laboratory. Sugar maple wood blocks were precolonized by two native isolates of C. virescens followed by inoculation and incubation with decay fungi. Mean percent weight loss of blocks by white rot decay fungi ranged from 39% to 55%, but decay rates were not significantly affected by the presence of the sapstreak fungus.
基金supported by the National Natural Science Foundation of China 31800543(X.D).
文摘In Bazhong City,Sichuan Province,China,top dieback symptoms were found on many pine trees(Pinus thunbergii Parl).The tips of old needles first turned grayish-green and then developed into brown bands in the field.Phylogenetic analysis of concatenated ITS and EF1-αindicated the pathogen of this dieback disease as Diplodia neojuniperi.Additionally,effects of temperature,pH and medium on the mycelial growth were also characterized.The most favorable temperature and pH level for mycelial growth are 25°C and 8,respectively.The optimal medium for mycelial growth is PDA medium.To our knowledge,this is the first report of D.neojuniperi causes Diplodia top dieback on Pinus thunbergii.Our results provide fundamental information for monitoring and preventing such disease in the future.
文摘In vitro Kirby-Bauer disc-diffusion assays coupled with bio-imaging software techniques were used to assess native forest dwelling “fairy ring” forming fungi (Clitocybe nebularis) and co-habitant forest tree-root colonising non pathogenic, antibiotic producing bacteria (Bacillus licheniformis, Bacillus pumilis) for their antagonism towards Japanese larch dieback oomycetes phytopathogens which also affects ornamental alternative hosts. The aqueous extracts of C. nebularis exhibited the highest clearance (inhibitory) zone of 21.4 × 105 pixels = 573%) against Phytophthora ramorum than growth/clear zone Cartesian integrates recorded in untreated (control) disc (3.7 × 105 pixels = 100%) over 3-day incubation. The fairy ring fungal extracts also exhibited substantive antagonism against P. kernoviae (147%), P. lateralis (347%) and a solanaceous crop infecting P. infestans (86%). Quite encouragingly, the soil oomycete phytopathogen P. ramorum was inhibited strongly (mean ~ 177%) by both forest bacilli. Aqueous extracts of non-forest antifungal herbaceous plants (garlic and elderberry) expressed similar inhibitory effects (mean ~ 70%). A seaweed fungal elicitor component fucoidan showed moderate levels (mean ~ 85%) of antagonism against P. ramorum, P. kernoviae, P. lateralis and P. infestans. The results in this in vitro study highlight the intensity and vigor of antagonistic forest microflora and non-forest herbaceous antifungal agents such as garlic and other plant extracts as serious candidates for suppression of the oomycete Phytophthora pathogenic fungi in forest soils. This study calls for urgent scoping and impact assessment studies in pot experiments and mini-plot forest trials to gauge the fitness of these natural resources for field level potential biotechnological applications to combat the devastating dieback disease in the native woodlands and horticulture.
文摘Eutypella vitis is reported for the first time on several new host trees viz.Fagus grandifolia,Fraxinus pennsylvanica and Syringa reticulata with associated branch dieback symptoms in the Niagara Region of Southern Ontario,Canada.Morphological characteristics and phylogenetic analyses of ITS sequence data confirmed the species identification.Eutypella vitis is known as a woody plant pathogen causing dieback of grapevines and other economically important fruit trees widely cultivated in Ontario.The fungus ability to infect several alternate new hosts can promote its faster and wider spread across vineyards and consequently increase a dieback hazard to viticulture in Canada.
基金supported by grant No.QL24020204funded by the Ministry of Agriculture of the Czech Republic and Internal Grant Agency of Faculty of Forestry and Wood Science CZU(reg.no.A_01_22)"EVA 4.0"No.CZ.02.1.01/0.0/0.0/16_019/0000803 financed by OP RDE.
文摘Commercially managed forests are often poor in terms of biodiversity.Saproxylic beetle species could be a useful bioindicating group for the conservation of forest stands.In recent decades,oak stands have been affected by a wide range of factors that have intensified stand decline.Saproxylic beetle richness was investigated in declining oak stands that have been consequently targeted for clearcutting due to concerns about insect pest outbreaks.The research was conducted at six managed oak forests,where we compared beetle occurrences in declining stands and in healthy stands that did not show any symptoms of decline.Beetles were collected using window traps placed on the basal and mid-trunk sections of trees.A total of 2925 adults belonging to 239 saproxylic beetle species were captured,of which 56 species are on the IUCN Red List.The results show that declining stands were richer in saproxylic species,and that the diversity of beetle species was greater in these stands.Approximately 1.4 times more species were caught within declining stands than in healthy ones(1.6 times for Red List species).Declining stands hosted more pest species(e.g.,cambiophagous and xylophagous species).However,only low numbers of these species were recorded in these stands.In summary,results of this study suggest that decline of managed oak stands is creating a wide spectrum of habitats for many saproxylic species.Thus,salvage logging of declining oak trees can represent a natural trap and reduce local beetle biodiversity,mainly for saproxylic,endangered or low-mobility species that would be attracted by new suitable habitats.
基金funded by DGLP-General Directorate of the State Forest,Poland,in frame of the grant:“Changes in the carbon fixation potential of forest ecosystems in various regeneration scenarios after large-scale disturbances and stand decay in the context of climate protection and the role of forest management”,Agreement No.MZ.271.3.12.2023.University Grant No.BZ 4436/WL URK.
文摘Forest ecosystems are one of the largest terres-trial carbon(C)reservoirs on Earth and an important sink of anthropogenic CO_(2) emissions.Abiotic and biotic distur-bances such as windfalls,fires,outbreaks of insects or pests may negatively affect C storage in forest ecosystems decreas-ing their role as CO_(2) sink.The objective of this review was to summarize the current knowledge on the impact of large-scale forest ecosystem disturbances caused by windthrow and insect outbreaks on soil C stocks and cycles,and to gather information on the impact of restoration treatments performed in disturbed stands in the context of carbon accumulation in forest soils.Discussed were effects of wind-storms and insect outbreaks as well as impacts of various approaches of forest regeneration after disturbance on C stocks and fluxes.Disturbances decrease C stocks in forest ecosystems and turn them from C sink into C source for a certain time.Regeneration of the disturbed forest restores its role as a CO_(2) sink.In montane forests artificial afforestation seems to shorten the time of achieving C parity.However,no data exists for lowland forests.Hence,there is an urgent need for studies that assess effect of windfalls and insect outbreaks on carbon storage in forests of lowland Europe.
文摘Botryosphaeria dieback is a serious disease problem for table and grape wine production worldwide.The disease however,has been less well-studied in China.In this study,we surveyed Botryosphaeria dieback in 72 vineyards of 20 grape-growing regions in China and found that Botryosphaeria dieback occurs in 18 out of 20 provinces.Morphological and multi-gene phylogenetic analyses confirmed that Botryosphaeria dothidea,Diplodia seriata,Lasiodiplodia theobromae and Neofusicoccum parvum are associated with different grapevine dieback symptoms.This study also revealed considerable differences in the geographical distribution of Botryosphaeriaceae species in China with Lasiodiplodia theobromae and Neofusicoccum parvum occurring only in subtropical monsoon climate regions,Diplodia seriata occurring only in temperate monsoon climate regions,and Botryosphaeria dothidea occurring in both temperate and subtropical monsoon climate regions.Analysis of 26 isolates showed that there is little genetic variation within species.Koch’s postulates were satisfied for all species,and pathogenicity testing showed that among the 25 major cultivars growing in China,none was resistant to the four taxa.The current paper represents the first detailed report on Botryosphaeria dieback of grapevines in China.
基金supported by NASA EPSCoR Research Grant Program[Award#:NNX15AK53A]in South Carolina,USA.
文摘This study reports an inventory of marsh dieback events from spatial and temporal perspectives in the North Inlet-Winyah Bay(NIWB)estuary,South Carolina(SC).Past studies in the Gulf/Atlantic coast states have reported acute marsh dieback events in which marsh rapidly browned and thinned,leaving stubble of dead stems or mudflat with damaged ecosystem services.Reported marsh dieback in SC,however,have been limited.This study identified all marsh dieback events in the estuary since 1998.With 20 annually collected Landsat images,the Normalized Difference Vegetation Index(NDVI)series was extracted.A Stacked Denoising Autoencoder neural network was developed to identify the NDVI anomalies on the trajectories.All marsh dieback patches were extracted,and their inter-annual changes were examined.Results showed a continuous,spatially variable multi-year dieback event in 1998–2005,which aligned with the reported dieback in the early 2000s from other states.The identified patches mostly returned to normal within one year while the phenomenon reoccurred in other areas of the estuary during the prolonged dieback period.This study presents the first attempt to explore long-term dieback dynamics in an estuary using satellite time series.It provides valuable information in documenting marsh healthiness and environmental resilience on SC coasts.
