•Deer had only minor impact on growth and survival of sugar maple and ash seedlings.•Seedlings responded primarily to light availability, soil N, and initial size.•Measures of root collar ...diameter:height detected some effect of deer herbivory.
Deer herbivory has a reputation for suppressing tree seedling development in Northern hardwood forests. We examined survival and growth of sugar maple (Acer saccharum) and ash (Fraxinus spp.) seedlings in a controlled factorial experiment with differing light conditions and levels of deer access in a Northern hardwoods forest in Wisconsin, USA. Measurements were made in ∼380 m3 harvest gaps, in transition zones adjacent to gaps, and under closed canopy conditions, both inside and outside of deer exclosures. Browse incidence was initially greater in unfenced treatments, but a general decline through time eliminated this difference. Seven-year survival of both species groups was correlated positively with initial root collar diameter (RCD) and was greater in transition zones. Ash seedling survival was greater in plots with greater overall seedling aggregate height. Soils were primarily differentiated by available nitrogen, which positively influenced height growth of sugar maple in transition zones but did not influence ash growth. Although sugar maple height growth was correlated positively with initial RCD, greater initial height reduced growth rates, both as a simple effect (sugar maple) and in combination with initial RCD (ash). Ash growth correlated negatively with seedling aggregate height in gaps but was unaffected in transition or canopy zones. Allometric coefficients of RCD:height indicated some influence of deer herbivory which was not detected in other analyses. Coefficient values trended downward from year 2 to year 9, but wide confidence intervals limit the value of this metric as an indicator of seedling community resilience with regard to deer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Regeneration was analyzed for white, green, black, blue, pumpkin, and Carolina ash.•Ash represented the greatest proportion of regeneration across most forest groups.•Top competitors of ash tended ...to be far less economically and ecologically valuable.
Incidentally introduced in 2002, the expansion of emerald ash borer (EAB) led to widespread ash mortality throughout the eastern United States. A great deal of effort has been invested in containing and controlling this forest invasive species, whereas the ability to regenerate ash from extant seedling and sapling populations following the initial EAB invasion has received less attention. Using recent data available from the U.S. Department of Agriculture, Forest Service, Forest Inventory and Analysis program (FIA), we quantified ash seedling and sapling regeneration counts across FIA forest type groups containing white, green, black, blue, pumpkin, and Carolina ash. In addition, all other seedling and sapling species in these stands were quantified to determine overall species composition of the regeneration and the potential for inter-specific competition. Ash seedlings and saplings represented the greatest proportion of regeneration across most forest type groups containing mature ash. Top competitors of ash tended to be far less economically and ecologically valuable. If retaining ash in current stands remains a management goal, and provided that an effective biological control for EAB is identified and established across infested areas, the success of extant ash seedlings and saplings into larger size classes will depend on silvicultural treatments designed for controlling inter-specific competition across stand cohorts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•Both Spathius agrili and Tetrastichus planipennisi were recovered in Maryland.•Only T. planipennisi has established and dispersed in Maryland.•Parasitism by T. planipennisi was ...positively associated with number of years post-release.•An exponential decrease model was fitted to the relationship between T. planipennisi parasitism and tree size.
Classical biological control can be an important tool for managing invasive species such as emerald ash borer (EAB), Agrilus planipennis Fairmaire. Emerald ash borer was first detected in Maryland in 2003, and the biological control program to manage this beetle in Maryland was initiated in 2009. Here we examine the establishment and abundance of two introduced parasitoids of EAB larvae (Spathius agrili Yang and Tetrastichus planipennisi Yang). Overall, 56,677 S. agrili and 191,506 T. planipennisi were released at 26 and 32 sites, respectively, from 2009 to 2014. Monitoring parasitoids involved debarking trees, and harvesting trees to place in rearing barrels, and was conducted at 47 sites (23 of which received parasitoids, and 24 of which served as controls) from 2010 to 2015. We recovered 77 S. agrili from 16 EAB larvae at six sites, and 1856 T. planipennisi from 110 EAB larvae at 19 sites. Percentage parasitism by T. planipennisi, and the mean percentage of trees containing T. planipennisi broods, were positively associated with the number of years post-release of the parasitoids (reaching 11.6% and 41.7% four years post-release, respectively). The relationship between T. planipennisi parasitism and tree size was best described by an exponential decrease model, with over 95% of parasitism occurring in trees with a diameter at breast height of <16cm. In conclusion, T. planipennisi has established populations and dispersed in Maryland, while S. agrili releases have been largely unsuccessful. These findings are a step towards optimizing EAB biological control release and recovery strategies, and are particularly pertinent for other states in the Mid-Atlantic region.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We review research on ecological impacts of emerald ash borer (EAB)-induced ash mortality in the Upper Huron River watershed in southeast Michigan near the epicenter of the invasion of North America, ...where forests have been impacted longer than any others in North America. By 2009, mortality of green, white, and black ash exceeded 99%, and ash seed production and regeneration had ceased. This left an orphaned cohort of saplings too small to be infested, the fate of which may depend on the ability of natural enemies to regulate EAB populations at low densities. There was no relationship between patterns of ash mortality and ash density, ash importance, or community composition. Most trees died over a five-year period, resulting in relatively simultaneous, widespread gap formation. Disturbance resulting from gap formation and accumulation of coarse woody debris caused by ash mortality had cascading impacts on forest communities, including successional trajectories, growth of non-native invasive plants, soil dwelling and herbivorous arthropod communities, and bird foraging behavior, abundance, and community composition. These and other impacts on forest ecosystems are likely to be experienced elsewhere as EAB continues to spread.
Native to Asia, the emerald ash borer (
Agrilus planipennis
Fairmaire) has caused extensive mortality of ash tree species (
Fraxinus
spp.) in the eastern United States. As of 2013, the pest was ...documented in 18 % of counties within the natural range of ash in the eastern United States. Regional forest inventory data from the U.S. Forest Service Forest Inventory and Analysis program were used to quantify trends in ash mortality rate and volume per hectare relative to the year of initial emerald ash borer detection. Results indicate that the annual ash mortality rate increases by as much as 2.7 % per year after initial detection of the pest in a county. Corresponding decreases in ash volume (as much as 1.8 m
3
per hectare per year) continue for several more years until most live ash is killed. These results, while not necessarily representative of the effects on ash in urban ecosystems, document the severe impact this invading herbivore is having on forests as it expands its range in North America.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The Emerald Ash Borer (EAB),
, Fairmaire, an Asian invasive alien buprestid has devastated tens of millions of ash trees (
spp.) in North America. Foliar phytochemicals of the genus
(Oleaceae):
...(Green ash),
(White ash),
(Bush) Bush. (Pumpkin ash),
Michx. (Blue ash),
Marsh. (Black ash) and
.
(Manchurian ash) were investigated using HPLC-MS/MS and untargeted metabolomics. HPLC-MS/MS help identified 26 compounds, including phenolics, flavonoids and coumarins in varying amounts. Hydroxycoumarins, esculetin, esculin, fraxetin, fraxin, fraxidin and scopoletin were isolated from blue, black and Manchurian ashes. High-throughput metabolomics revealed 35 metabolites, including terpenes, secoiridoids and lignans. Metabolomic profiling indicated several upregulated putative compounds from Manchurian ash, especially fraxinol, ligstroside, oleuropin, matairesinol, pinoresinol glucoside, 8-hydroxypinoresinol-4-glucoside, verbenalin, hydroxytyrosol-1-
-glucoside, totarol and ar-artemisene. Further, dicyclomine, aphidicolin, parthenolide, famciclovir, ar-turmerone and myriocin were identified upregulated in blue ash. Principal component analysis demonstrated a clear separation between Manchurian and blue ashes from black, green, white and pumpkin ashes. The presence of defensive compounds upregulated in Manchurian ash, suggests their potential role in providing constitutive resistance to EAB, and reflects its co-evolutionary history with
, where they appear to coexist in their native habitats.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Emerald ash borer (EAB), Agrilus planipennis, is a phloem-boring beetle, native to East Asia that has become a serious invasive pest of ash (Fraxinus spp.) trees in North America and European Russia ...since the early 2000s. In 2019, EAB was detected in Ukraine. It had spread over 300 km from the entry point over two years and killed hundreds of Fraxinus excelsior and F. pennsylvanica trees. EAB poses a threat to the ash forests of neighboring European countries, which have already been damaged by the invasive fungus Hymenoscyphus fraxineus. The purpose of this research was (i) to reveal the traits of EAB and the climatic variables that affect its survival; (ii) to predict the EAB expansion range in Ukraine and westward; and (iii) to compare the most significant bioclimatic variables in the native, invasive ranges of EAB, as well as outside these ranges. The results demonstrated the following: (i) in all ranges, EAB has adapted to the seasonal temperature variations; (ii) the MaxEnt model predicted the potential distribution of EAB with high accuracy (AUC = 0.988); the predicted area of EAB invasion covered 87%, 48%, and 32% in Luhansk, Kharkiv, and Donetsk regions, respectively; and (iii) the ranges of climatic variables in EAB-inhabited regions demonstrated the high ecological plasticity of this pest. However, the predictions could be improved by considering forest structure, as well as the localization of roads.
Die Einschleppung des Asiatischen Eschenprachtkäfers, Agrilus planipennis, in den europäischen Raum kann erhebliche Auswirkungen auf die heimischen Eschen als Wirtspflanzen und deren Ökosysteme ...haben. Um das Ausmaß der Gefährdung einzuschätzen, wird ein neues Umweltrisikobewertungsverfahren angewendet. Hierfür werden die Auswirkungen auf Ökosystemleistungen und Biodiversität in urbanen Gebieten und Wäldern untersucht. Über zwei Zeithorizonte werden die Auswirkungen von A. planipennis analysiert um Kurzzeit- und Langzeitfolgen der Einschleppung abzuschätzen. Das Gesamtrisiko durch einen Befall wird für den kurzen Zeitraum von 5 Jahren als gering, für den langen von 15 Jahren als moderat eingeschätzt, wobei langfristig vor allem die Biodiversitätskomponenten betroffen sind. Die Anwendung dieses Verfahrens erleichtert die Erstellung der Umweltrisikobewertung und auch die Einschätzung der Unsicherheiten der Analyse.
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