Quercus Rubra Research Articles

Природні процеси розвитку та взаємовідносини компонентів садово-паркових екосистем в урбанізованому середовищі

Розкрито особливості формування зелених насаджень урбанізованих екосистем. Визначено видовий склад лісопаркових і паркових насаджень міста Львова та їх просторовий розподіл. Досліджено та узагальнено фітоценотичні особливості міських насаджень, зокрема, їх флористичну, вікову та екологічну структури, а також візуально-естетичні якості. Встановлено, що процеси урбанізації спричинили формування в лісопаркових і паркових насадженнях Львова нових рослинних асоціацій та появу у фітоценозах інтродукованих деревних видів. Встановлено, що видова різноманітність трав'яного вкриття лісопаркових і паркових зон безпосередньо залежить від топографічних, мікрокліматичних і ґрунтових умов місцевості, а також від видового складу деревного намету та його зімкнутості. Проаналізовано мікрокліматичні характеристики різних за видовим складом фітоценозів лісопаркових і паркових насаджень. З'ясовано, що найбільш контрастними показниками мікрокліматичних особливостей лісопаркових і паркових фітоценозів, порівняно із показниками відкритого простору, характеризуються насадження із щільним наметом з перевагою у складі Carpinus betulus L., Quercus rubra Du Roi, Аcer platanoides L., Acer pseudoplatanus L. та Quercus robur L. За особливостями мікрокліматичних показників у лісопаркових і паркових фітоценозах та відкритого простору виділено три групи рослинних асоціацій: за різницею температур і вологістю повітря – "холодні-вологі", "помірні" та "теплі-сухі"; за вітровим режимом – "комфортні", "середнього комфорту" та "некомфортні"; за освітленістю надґрунтової поверхні: "темні", "середньої освітленості" та "світлі". Встановлено, що більш прогрітим є верхній шар ґрунтового покриву у фітоценозах "теплого-сухого" угруповання з перевагою у складі Pinus sylvestris L., Robinia pseudoacacia L., Betulla pendula Roth., Larix decidua Mill. та Аcer negundo L. Визначено, що проективне трав'яне вкриття у рослинних асоціаціях, віднесених до груп "темних", або зовсім відсутнє, або не перевищує 5 %, а у "світлих" фітоценозах становить 95-100 %. Видове фіторізноманіття у "світлих" і "теплих-сухих" фітоценозах є вищим порівно із фітоценозами "середньої освітленості" і "помірних", а природне поновлення деревних видів у "темних" і "холодних-вологих" рослинних угрупованнях зазвичай відсутнє. Охарактеризовано групи рослинних асоціацій за шкалою естетичної цінності та санітарно-гігієнічними умовами згідно з виділеними кліматопами. Висвітлено значення відновлення фітоценотичної структури лісопаркових і паркових насаджень в оптимізації зелених зон урбанізованих екосистем.

Transcriptome profiles of Quercus rubra responding to increased O3 stress

BackgroundClimate plays an essential role in forest health, and climate change may increase forest productivity losses due to abiotic and biotic stress. Increased temperature leads to the increased formation of ozone (O3). Ozone is formed by the interaction of sunlight, molecular oxygen and by the reactions of chemicals commonly found in industrial and automobile emissions such as nitrogen oxides and volatile organic compounds.Although it is well known that productivity of Northern red oak (Quercus rubra) (NRO), an ecologically and economically important species in the forests of eastern North America, is reduced by exposure to O3, limited information is available on its responses to exogenous stimuli at the level of gene expression.ResultsRNA sequencing yielded more than 323 million high-quality raw sequence reads. De novo assembly generated 52,662 unigenes, of which more than 42,000 sequences could be annotated through homology-based searches. A total of 4140 differential expressed genes (DEGs) were detected in response to O3 stress, as compared to their respective controls. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the O3-response DEGs revealed perturbation of several biological pathways including energy, lipid, amino acid, carbohydrate and terpenoid metabolism as well as plant-pathogen interaction.ConclusionThis study provides the first reference transcriptome for NRO and initial insights into the genomic responses of NRO to O3. Gene expression profiling reveals altered primary and secondary metabolism of NRO seedlings, including known defense responses such as terpenoid biosynthesis.

Sugar maple autumn-shed leaf extract: a potential antibacterial agent for the management of lettuce bacterial leaf spot (Xanthomonas campestris pv. vitians) and varnish spot (Pseudomonas cichorii)

Different extracts prepared from wastes (barks, branches, needles, or leaves) of different trees (grey alder, balsam fir, American larch, red maple, sugar maple, white spruce, black spruce, jack pine, white pine, quaking aspen, sweet cherry, and northern red oak) were investigated for their potential use as antibacterial agents for the management of lettuce varnish spot and bacterial leaf spot caused by Pseudomonas cichorii (Swingle) Stapp and Xanthomonas campestris pv. vitians (Brown) Dye, respectively. Extracts were first screened for their antibacterial activities against P. cichorii and X. campestris pv. vitians using the in vitro disk diffusion assay. Based on the diameter of the inhibition zone, ethanol (95%) extract prepared from sugar maple autumn-shed leaves (SMASL) and aqueous ethanol (50%, v/v) extracts prepared from SMASL and from sugar maple green leaves showed the strongest antibacterial activities. Ethanol (95%) SMASL extract was further investigated for its efficacy to manage bacterial diseases when applied on lettuce plants grown in the greenhouse. Foliar application of ethanol (95%) SMASL extract at a concentration of 3.2 g L−1 was shown to significantly (P ≤ 0.05) reduce bacterial leaf spot severity compared with the control without causing phytotoxicity symptoms that could prevent the commercial marketing of the lettuce. Ethanol (95%) SMASL extract (1.6 and 3.2 g L−1) was also shown to significantly reduce varnish spot severity in one experiment out of two. This study identifies for the first time the possibility of exploiting SMASL to manage bacterial diseases affecting horticultural crops.

Mercury Accumulation in Tree Rings: Observed Trends in Quantity and Isotopic Composition in Shenandoah National Park, Virginia

AbstractRecent studies have shown that mercury (Hg) concentrations in tree rings have the potential to archive historical Hg exposure from local, regional, and global sources. The southeastern United States has received elevated Hg deposition, yet no studies have evaluated tree ring Hg in this region. Here, we quantify Hg accumulation and isotopic composition in tree rings collected in Shenandoah National Park, Virginia. Cores were collected from three individuals of three tree species—white oak (Quercus alba), northern red oak (Quercus rubra), and pitch pine (Pinus rigida)—within the northern, central, and southern areas of the Park (n = 27 cores). The cores were analyzed for Hg content in 10‐year increments, with some cores dating back to the early 1800s. Overall, tree ring Hg concentrations (ranging from below detection to 4.4 ng/g) were similar to other studies and varied between species, with pitch pine having higher concentrations than the deciduous species. The most notable feature of the tree ring Hg time series was a peak that occurred during the 1930s through 1950s, coinciding with the use of Hg at a local industrial facility. Atmospheric modeling indicates that potential emissions from the plant likely had a stronger impact on the southern region of the Park, consistent with the latitudinal gradient in tree ring Hg concentrations. Mass‐dependent and mass‐independent fractionation of Hg isotopes suggests contributions from both regional anthropogenic and local industrial sources during this period. This study demonstrates the potential usefulness of tree ring dendrochemistry for identifying historical sources of atmospheric Hg exposure.

Genetic variation of introduced red oak (Quercus rubra) stands in Germany compared to North American populations

Although Northern red oak (Quercus rubra L.) is the most important introduced deciduous tree species in Germany, only little is known about its genetic variation. For the first time, we describe patterns of neutral and potentially adaptive nuclear genetic variation in Northern red oak stands across Germany. For this purpose, 792 trees were genotyped including 611 trees from 12 stands in Germany of unknown origin and 181 trees from four populations within the natural distribution area in North America. Our marker set included 12 potentially adaptive (expressed sequence tag-derived simple sequence repeat = EST SSR) and 8 putatively selectively neutral nuclear microsatellite (nSSR) markers. Our results showed that German stands retain comparatively high levels of genetic variation at both EST-SSRs and nSSRs, but are more similar to each other than to North American populations. These findings are in agreement with earlier chloroplast DNA analyses which suggested that German populations originated from a limited geographic area in North America. The comparison between potentially adaptive and neutral microsatellite markers did not reveal differences in the analyzed diversity and differentiation measures for most markers. However, locus FIR013 was identified as a potential outlier locus. Due to the absence of signatures of selection in German stands, we suggest that introduced populations were established with material from provenances that were adapted to environmental conditions similar to those in Germany. However, we analyzed only a limited number of loci which are unlikely to be representative of adaptive genetic differences among German stands. Our results suggest that the apparent introduction from a limited geographic range in North America may go along with a reduced adaptive potential.

Bedrock type drives forest carbon storage and uptake across the mid-Atlantic Appalachian Ridge and Valley, U.S.A.

Lithology influences forest carbon storage and productivity yet is often overlooked for forests of the eastern United States, a large and important carbon sink. This research explores the influence of two common lithologies of the Ridge and Valley physiographic province in the Appalachian Mountains, shales and sandstones, on live aboveground carbon storage, carbon uptake, forest community composition and their interrelationships. We couple forest inventory data from 565 plots from Pennsylvania state agencies with a suite of GIS derived landscape metrics including measures of climate, topography and soil physical properties to identify biotic and abiotic drivers of live forest carbon dynamics in relation to lithology.Forests growing on shale bedrock store more live aboveground carbon compared to forests on sandstone when controlling for stand age, which ranged from 20 to 200 years. Furthermore, forests in the dominant ages (81–120 years) store more live aboveground carbon (108.1 Mg/ha vs. 86.5 Mg/ha) and uptake live aboveground carbon at a faster rate (1.32 Mg/ha/yr vs 0.85 Mg/ha/yr) on shale compared to sandstone respectively. Overall forest communities on both lithologies are dominated by oaks (Quercus spp.), however northern red oak (Q. rubra) is more dominant at shale sites compared to chestnut oak (Q. prinus), which dominates on sandstone. Most species in the forest tend to be more productive on shale, which may account for differences in carbon pools and fluxes across the landscape. Tree species richness is higher in sites on shale bedrock, but biodiversity-productivity relationships within lithologic classifications fail to account for differences in forest productivity. Modeled live aboveground carbon storage points to topography (elevation and aspect) and soil physical properties (% clay and available water capacity) as important influences on forest productivity that related back to lithology. Incorporating lithology into forest management strategies that are focused on a variety of ecosystem services can aid future site selection, and we demonstrate that forests on shale bedrock grow faster, store more carbon and have higher species diversity. The results presented here highlight the potential for underlying bedrock to exert differential influences on forest ecosystem structure and function across a region.

Effects of Quercus rubra L. on soil properties and humus forms in 50-year-old and 80-year-old forest stands of Lombardy plain

Besides the well-known effects on the native plant community, red oak may also impact the soil; the effects of afforestation with red oak involve both organic layers and mineral soil, resulting in changes in organic carbon quantity and quality and in soil acidification. Many alien species have become widespread in Europe; among these, red oak is a common invader of temperate forests. The effects of substitution of natural mixed forest by red oak forest on humus forms and soil properties were investigated in two paired plots: a 50-year-old (Bosco Vacaressino) and 80-year-old (Bosco Ginestre) forest stand. Soil sampling was performed from 3 layers at 40 and 49 points in Bosco Vacaressino and Bosco Ginestre respectively to determine humus forms, soil pH, organic carbon stock, carbon-nitrogen ratio (C:N), available phosphorus, and texture. Red oak resulted in a shift from Mull to Moder humus forms; soil acidification, higher C:N ratio, and soil organic carbon stock were observed compared with mixed forests. The major changes were reflected in a change toward less active humus forms; the effects of vegetation conversions were also visible in mineral layers; many of the modifications were more evident with increasing stand age.

Individual Plant-Soil Feedback Effects Influence Tree Growth and Rhizosphere Fungal Communities in a Temperate Forest Restoration Experiment

Plant-soil feedbacks and the soil legacy effects that create them have important implications for community composition and restoration. However, relatively few field trials test the influence of soil legacy effectsplant-soil feedbacks, especially on longer-lived species, such as trees. Here we present a field restoration experiment with 10 ectomycorrhizal fungal tree species native to eastern North America. Trees were inoculated with soils collected from conspecifics in the field or from a heterospecific: Quercus rubra. Fagus grandifolia stem elongationFollowing 16 months of growth in the field, Carya ovata diameter increase was significantly increased greater in trees receiving the by heterospecific inoculant.tion following 16 months of growth in the field, and Tthis negative plant-soil feedback is consistent with its C. ovata’s natural co-occurrence with Q. rubra. Conversely, Quercus macrocarpa diameter increase and Carya cordiformis height increase were was significantly greater when inoculated with conspecific soils, and this positive plant-soil feedback is consistent with its their numerical dominance in natural communities. We found no evidence for phylogenetic Janzen-Connell effects or conservation of soil mutualists across tree species. We also quantified differences in soil fungal community structure with next generation sequencing methods (Illumina MiSeq) following 16 months in the field. Shannon’s diversity of fungal taxa was greater in heterospecific soils of seven of our nine experimental species, consistent with a diversifying influence of heterospecific Quercus rubra soil inocula. However, only one genus, Ulmus, exhibited differences in fungal community composition derived from conspecific and heterospecific sources, suggesting a stronger effect of focal tree species than of soil inocula source. The relatedness among focal tree species also influenced fungal community composition, with tree families and genera displaying different fungal communities. We suggest that future experiments should determine whether more diverse tree and fungal communities might have enhanced ecosystem functioning in tree restoration sites.

Hardwood Species Show Wide Variability in Response to Silviculture during Reclamation of Coal Mine Sites

Coal is a significant energy source for the United States, and reclamation of surface mined lands is required under the Surface Mining Control and Reclamation Act of 1977. Reforestation of mined lands is challenging due to soil substrate properties including soil compaction, herbaceous competition, and animal browse, necessitating silvicultural treatments to help overcome such limiting factors. We investigated the field performance of black walnut (Juglans nigra L.), northern red oak (Quercus rubra L.), and swamp white oak (Quercus bicolor Willd.) planted on two mine reclamation sites in southern Indiana, USA, and evaluated the interactions of nursery stocktypes (container and bareroot), herbicide application, and tree shelters. Two-year survival averaged 80% across all species and stocktypes. Container stocktype had greater relative height and diameter growth (i.e., relative to initial size at planting), whereas bareroot had greater absolute height and diameter growth corresponding to initial stocktype differences. Shelter use increased height growth and reduced diameter growth across both stocktypes. Swamp white oak (Q. bicolor) had the highest survival rate and field performance regardless of silvicultural treatment, whereas red oak (Q. rubra) and black walnut (J. nigra) showed strong early regeneration responses to silvicultural treatments. Container seedlings showed promise as an alternative to bareroot seedlings to promote early growth on mine reclamation sites. Species-specific responses documented here indicate the need to consider the ecology and stress resistance of target species in developing cost-effective silvicultural prescriptions.

On Leaf BRDF Estimates and Their Fit to Microfacet Models

Remote sensing provides high accuracy/precision for quantifying forest biophysical parameters needed for ecological management. Although the significant impact of bidirectional scattering distribution functions (BSDFs) on remote sensing of vegetation is well known, current forest metrics derived from sensor data seldom take leaf BSDF into account, and despite the importance of BSDF effects, leaf directional scattering measurements are almost nonexistent. Previous studies have been limited in the spectral coverage and resolution of observed electromagnetic radiation and lacked models to interpolate all source-sensor angles beyond measurements. This study captured deciduous broadleaf bidirectional reflectance distribution functions (BRDFs) from the visible through shortwave infrared spectral regions (350–2500 nm) and accurately modeled the BRDF for extension to any illumination angle, viewing zenith, or azimuthal angle. We measured biconical directional reflectance factor of leaves from three species of large trees, Norway maple ( Acer platanoides ), American sweetgum ( Liquidambar styraciflua ), and northern red oak ( Quercus rubra ). We then fit the data through nonlinear regression to physical, microfacet BRDF models, resulting in normalized root-mean-square errors of less than 8%, averaged across all wavelengths (excluding low signal-to-noise spectral regions). We extracted leaf physical parameters, including the index of refraction and a relative physical roughness from the microfacet models delineating the three species. The implications for forestry remote sensing are important, as rigorous models to represent leaves allow for the creation of more accurate forest scenes for radiative transfer modeling. Such accuracy enables higher fidelity sensor evaluations and data processing algorithms.

Denitrifying Woodchip Bioreactor Leachate Tannic Acid and True Color: Lab and Field Studies

HighlightsOak leached more tannic acid, true color, and chemical oxygen demand (COD) than ash and mixed hardwood chips.The factors became similar (tannic acid, COD) or below stream levels (true color) after flushing.Eleven site-years of field bioreactor data showed decreasing tannic acid and true color over time.Post-startup tannic acid was lower in bioreactor outflow than in area streams.True color did not appear to be a reliable indicator of leachate tannic acid at low concentrations.Abstract. Woodchips have been a preferred denitrifying bioreactor medium to date, but concerns about potential harmful effects of tannins in the leachate have precluded the use of oak chips in many installations. A study was conducted to compare the suitability of oak (genus Quercus) woodchips as a denitrifying bioreactor medium relative to other types of woodchips, both in lab leachate tests and in the context of observed bioreactor leaching in the field. Assessment measures included the content of tannic acid and other compounds in the leachate, as well as leachate color, which can often be high during startup. An 84-day leaching test using rectangular bioreactor cells filled with either oak (Quercus rubra), ash (Fraxinus spp. L.), or a generic hardwood blend showed that oak initially leached higher concentrations of tannic acid, true color, and chemical oxygen demand (COD) than the other two media. The significant differences in leached concentrations among the three wood types were eliminated after a finite leaching period. Tannic acid and true color in 11 site-years of field bioreactor outflow data generally decreased over time, except following a dry period when one of the bioreactors received no drainage inflow for more than two months. The lab and field results indicated the capability of woodchip bioreactors to flush at least these two analytes to ambient stream levels. True color did not appear to be the best parameter for estimating the tannin content of woodchip leachate due to discrepancies at low concentrations. Mass normalized tannic acid leaching ranged from 0.03 to approximately 40 mg tannic acid g-1 woodchip across the lab and field assessments. Oak initially leached more tannic acid, color, and COD than the other wood types, but the eventual similarity among the wood types after flushing with a sufficient number of pore volumes meant that any potentially negative environmental impacts would likely be limited to the startup period or possibly after dry periods. Oak initially eluted higher mean total nitrogen (TN) concentrations than the other wood types, but the treatments were not significantly different by day 3, indicating that biological N removal was not significantly inhibited, even with high concentrations of tannic acid. Keywords: Chemical oxygen demand, Oak, Tannin, Water quality, Wood leachate.

Zdravstveno stanje drvenastih i žbunastih vrsta Topčiderskog parka

The research deals with the health condition of tree and shrub species of the natural resource known as Topčider Park assessed on the basis of the conducted visual assessment and determination of the degree of defoliation and discolouration. During the growing season 2018-2019, the health condition of plant species belonging to 50 different genera was determined. The following species were found to be healthy, without any visible damage: Cedrus atlantica, Corylus avelana, C. colurna, Juglans nigra, Maclura aurantiaca, Mahonia aquifolium, Prunus cerasifera, P. spinosa, Quercus rubra and Sambucus nigra. Trees with visible injuries included: Acer negundo, A. pseudoplatanus, Aesculus hippocastanum, Cryptomeria japonica, Fagus moesiaca, Gleditsia triacanthos, Morus alba, Platanus acerifolia, Populus alba. P. nigra, and P. tremula. Dying trees and dead trees were not recorded in Topčider Park. The plant species most threatened by the attack of pathogenic fungi and fungus-like organisms were the species of maple, horse chestnut, lime, poplar, and plane. The species of insects and mites here present did not significantly affect the health status of the investigated plant species.

Nondestructive Evaluation of Red Oak and White Oak Species

Abstract The objective of this article is to evaluate the relationship between the dynamic modulus of elasticity (MOEd), which was obtained with acoustic-based nondestructive testing (NDT) methods, and static bending properties of two domestic hardwood oak species. The mechanical properties were conducted using static modulus of elasticity (MOE) and modulus of rupture (MOR) in radial and tangential directions. Mechanical tests were performed according to ASTM D143 on small clear, defect-free specimens from the two tree species: red oak (Quercus rubra) and white oak (Quercus alba). The MOEd was determined by two NDT methods and three longitudinal vibration methods based on the fast Fourier transform. The destructive strength values obtained in this study were within the expected range for these species. The MOE was best predicted by NDT methods for both species but also had a strong capability to predict MOR.

Development of novel Quercus rubra chloroplast genome CAPS markers for haplotype identification

Abstract Our main objective was to generate cost-effective chloroplast (cp) DNA markers that are easy to apply and to score. In combination with already published cpSSR markers they should increase haplotype resolution in populations. To discover new cpDNA markers, we sequenced 87-97 % of the entire chloroplast genome (except the second inverted repeat) of 8 trees representing different regions of the Quercus rubra L. natural range with 4,030X-6,297X coverage and assembled the genome sequences using the publicly available chloroplast genome of Quercus rubra L. as a reference. In total, 118 single nucleotide polymorphisms (SNPs) and 107 insertions or deletions (indels) were detected, and 15 cleaved amplified polymorphic sequence (CAPS) markers were developed for Q. rubra. Using these new markers together with five chloroplast microsatellite or simple sequence repeat (cpSSR) markers, we identified 10 haplotypes in our diversity panel of 19 Q. rubra populations. Specifically, two haplotypes based only on the cpSSR markers could now be separated in five haplotypes. These markers are useful to assess haplotype diversity with high resolution and are also transferable to a closely related species, Quercus ellipsoidalis E. J. Hill.

Place of Cladrastis kentukea (Dum.-Cours.) Rudd in natural and cultural phytocenoses

Aim. The work is devoted to the comparative analysis of plant communities, soil and climatic conditions of natural and cultivated habitats of C. kentukea. The obtained results will allow us to offer suitable ecological conditions for cultivationof this species and to select plants that can successfully exist in artificial phytocenosis together with C. kentukea. Methods. The method of complex analysis of vegetation, climatic and soil conditions of natural and cultivated habitats of C. kentukea was used. The description of C. kentukea habitats in culture was made using an expeditionary survey of the botanical gardens and dendrological parks of the Right-bank Forest-Steppe of Ukraine. Results. A comparative analysis of the climatic and soil conditions of the study areas showed that there is a significant difference between the natural and thecultigenic habitats. The natural range is characterized by 2.5 times higher rainfall and twice the average air temperature. The natural habitat of C. kentukea, concentrated in the southeastern part of the North American continent, belongs to a large and monolithic subtropical moist forest sector of yellow soil, red soil and associated gleyed eluvial soil and subtropical ashen-gray soil. The Right-bank Forest-Steppe of Ukraine is dominated by degraded black podzolic soil, gray and dark gray podzolic forests soils. C. kentukea grows in the second tier of mixed deciduous forests in the natural habitat, the plants of this species do not form solid arrays, it occurs by separate localities. The C. kentukea cultivation habitat is extensive, the plants occur in collections of botanical gardens and parks in Europe and Central Asia. When creating durable ornamentalartificial phytocoenoses with the participation of C. kentukea, the optimal spatial placement of plants should be observed and a multilayered planting structure should be formed. Conclusions. Comparative analysis of climatic and soil conditions of natural and cultured habitats showed a significant difference between the average long-term air temperature and the average long-term rainfall in the explored areas. We have found out that plants of the species C. kentukea under cultivated habitat in the Right-bank Forest-Steppe of Ukraine are characterized by complete acclimatization, which indicates the ecologicalplasticity of the plants. In the North American natural range, C. kentukea occurs mainly in the associations of Quercus alba — Quercus rubra — Acer rubrum — Acer saccharum — Carya ovata (also described as Acer saccharum — Quercusmuehlenbergii — Cotinus obovatus), Fagus grandifolia — Acer saccharum — Quercus rubra — Quercus velutina and Quercus muehlenbergii — Carya carolinae-septentrionalis — Acer barbatum — Juniperus virginiana — Crotonalabamensis. In artificial phytocenoses of the Right-bank Forest-Steppe,plants of C. kentukea species grow successfully with Acer platanoides L., Ulmus laevis Pall., Tilia cordata Mill., Fraxinus excelsior L., Aesculus hippocastanum L. and Carpinus betulus L.

Invasive alien plants in Polish national parks-threats to species diversity.

Due to the relevance of protected areas to the conservation of native biota, the magnitude of invasions and threats posed by alien plants are currently important issues for the preservation of these areas. The paper summarises data on invasive alien plant species presence in the most valuable protected areas in Poland, i.e. national parks (NPs). We investigated the distribution of invasive alien plant species and management attempts concerning those species. We analysed data obtained from 23 national parks originating from published and unpublished sources. Invasive plants were present in all protected areas analysed, from two to 42 species in a particular national park, and 68 in total. The most widely distributed species were: Impatiens parviflora (present in 19 NPs), I. glandulifera (17), Solidago gigantea (17), Reynoutria japonica (17), and Robinia pseudoacacia (16). The conducted analyses showed that the number of invasive species decreased with the higher altitude (asl) of the national park. The most often managed species were Impatiens glandulifera (being removed in seven NPs), I. parviflora (six), Padus serotina (four) and Quercus rubra (four). In the majority of NPs, control activities are limited to small areas and singular species, thus having an incidental character. Only in five objects (Białowieża NP, Biebrza NP, Kampinos NP, Tuchola NP, Wigry NP), management has been focused on several species. We conclude that a lack of comprehensive management of invasive plant species in the majority of national parks currently limits the effectiveness of IAS (invasive alien species) eradication. Exchange of expertise among protected areas, documenting best practice examples, synthesising lessons learnt in IAS management, as well as the development of minimum standards for invasive plants surveillance and management are pivotal.

Urban tree specific gravity and ash content: A case study from Baltimore, Maryland USA

Interest in conducting urban tree inventories and quantifying the associated wood resource has accelerated at a pace faster than supporting research needs can be identified and accomplished. For example, it is common to apply allometric models and wood properties values developed from studies of rural forest-grown trees to urban trees, despite unknown degrees of inaccuracy that may exist. To examine potential differences in wood properties between trees grown in forest and urban settings, wood samples were collected from stumps of recently felled trees for nine native hardwood species in the city of Baltimore, MD USA. The samples were analyzed for basic specific gravity (SG) and ash content (AC). The results from urban trees were compared with published values from studies based on forest-grown trees. There was no general trend in the results for SG; however, urban Acer rubrum L., Fraxinus spp., and Quercus rubra L. appeared to have higher SG, with Quercus palustris Münchh. having lower SG, than their forested counterparts. Based on these results, the use of existing forest-based SG data may produce weight estimates of urban woody biomass that are 5–10% too low. Conversely, most of the species studied exhibited higher AC than their forested counterparts, although some results were mixed depending on the basis of comparison. Further work is needed on a wider range of species and geographic locations to refine the results and better support the analysis of urban tree inventories, which are increasingly used for carbon accounting and assessing feedstocks for biofuel use.

Effects of burn season on large seedlings of oak and other hardwood regeneration three years after shelterwood harvest

Abstract The effects of fall and spring prescribed fires on large seedlings (0.3 to 1.3 m height) of oak and other hardwood species three years after a shelterwood harvest were examined in Richland Furnace and Zaleski State Forests in southern Ohio. Fall and spring burns appeared to be more deleterious to red oaks (Quercus rubra L., Q. velutina Lam., Q. coccinea Muenchh.) than white oaks (Q. alba L., Q. prinus L.). Red oak experienced reductions in numbers and canopy volume after spring burns, and canopy reductions after fall burns. White oak experienced small increases in numbers of stems after both fall and spring burns, and an increase in the canopy volume after fall burns, but a slight decrease after spring burns. Yellow-poplar (Liriodendron tulipifera L.), a major oak competitor prior to fire, experienced dramatic reductions in the number of regenerating stems and canopy volume after both fall and spring burns. On the other hand, red maple (Acer rubrum L.) experienced large increases in the number of regenerating stems and canopy volume after both fall and spring burns. Based on importance value, the oak species remained relatively unchanged after both fall and spring burns. Yellow-poplar became the least dominant species after spring burns and the second to last dominant species after fall burns.

Legacy effects of emerald ash borer on riparian forest vegetation and structure

High levels of ash (Fraxinus spp.) mortality have been reported in areas of North America following invasion of emerald ash borer (EAB) (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae), but little is known about the impacts of EAB in riparian forests, particularly along first order streams. We delineated canopy gaps resulting from EAB-caused ash mortality along four first order streams in each of three distinct watersheds, which represented a temporal gradient of the EAB invasion across southern Michigan. Time lapsed aerial imagery showed canopy gaps were apparent by 2005, 2010, and 2012 in southeast, central and southwest sites, respectively. We assessed overstory trees, regeneration, shrubs, herbaceous plants, coarse woody debris, and photosynthetically active radiation in each canopy gap and in forests surrounding the gap. Canopy gaps were originally dominated by green ash (F. pennsylvanica) and black ash (F. nigra) but more than 85% of ash basal area was killed by EAB across all sites. Live basal area was greater in forests than in gaps, but was similar among all three watersheds. A lower percentage of dead ash trees remained standing and volume of ash coarse woody debris was higher in southeastern sites, with the longest history of EAB invasion, than in central and southwestern sites. Species richness of overstory trees was higher in forests (34 species) than in gaps (27 species). Photosynthetically active radiation, measured 1.5 m above ground, was 55% higher in canopy gaps than in adjacent forests during summer, but was similar during winter. Species composition of pre-EAB forest overstories and current saplings were similar among canopy gaps; overall, 66.3% of saplings were ash. Sapling species in forested areas adjacent to gaps were often dominated by Acer rubrum, while Quercus rubra, Prunus serotina, Acer saccharum and A. rubrum were common in overstories. Seedlings were rare within gaps now dominated by dense mats of sedges (Carex spp.). Although ash has been functionally lost from riparian forest overstories in most of southern Michigan, consistently high sapling densities, combined with reduced EAB densities, could facilitate ash persistence in post-invasion areas. If EAB densities increase, however, recruitment of ash saplings into the overstory will be limited. Continued monitoring will be important to assess the future status of ash and overstory dynamics in of post-EAB riparian forests.

Risk is in the eye of the assessor: comparing risk assessments of four non-native tree species in Germany

AbstractNon-native tree species (NNT) that pose risks to biodiversity are classified as ‘invasive’ in some European countries. However, country-specific risk assessment methods may lead to different results for the same NNT between countries of comparable growth conditions, raising doubts about the reliability of risk classifications. Here, we analysed six risk assessment tools used in Germany and adjacent countries for their practical applicability and consistency using four NNT (Fraxinus pennsylvanica Marsh., Paulownia tomentosa (Thunb. ex Murray), Pseudotsuga menziesii (Mirb.) Franco and Quercus rubra L.) as case studies. Using these tools to classify risks for the same NNT and reference area (Germany) yielded inconsistent results for all NNT. The reasons for this were (1) differences in classification and weighting of criteria, (2) a lack of data to quantify invasion risks and (3) uncertainties related to assessment methodologies. Moreover, the tools fail to distinguish between risks posed by NNT in different sites. We suggest that instead the risks should be assessed for different ecosystem types by using site-specific inventory data covering the establishment, spread and potential impact of NNT. Our recommendations provide a foundation for developing a consistent, systematic Pan-European approach to assess invasiveness while addressing both risk and forest management aspects.