Syntaxonomic and ecological peculiarities of extra-zonal pine forests with participation of Acer negundo L. from the forest-steppe and steppe zones of Altai Krai (South-Eastern Siberia)

The syntaxonomic analysis of pine forests with Acer negundo occurring on fluvio-glacial sandy deposits of Altai Krai (South-East Siberia) was made based on 93 releves. It was established that Acer negundo takes a different phytocenotic part in 2 associations, 2 variants, and 6 no-ranked communities of 4 classes and 4 orders according to the Braun-Blanquet approach. The method of detrended correspondence analysis (DCA coordination) implemented in the DECORANA software package was used to confirm the ecological and floristic integrity of the identified vegetation units. New data on the spatial syntaxa distributions depend on the complex humidity gradient, soil fertility, and anthropogenic factors. Acer negundo is most abundant and common in the communities of the Brachypodio-Betuletea pendulae class, which are characterized by habitats with moderate moistening and greater soil fertility. In the spatial series considered, according to the soil fertility and humidity gradients, we observe an increase in Acer negundo in the Vicia sylvatica – Pinus sylvestris community and an increase in the activity of mesophytes and mesohygrophytes that are more demanding to soil fertility.

SHADING AND LIGHT INTERCEPTION IN THICKETS OF INVASIVE ACER NEGUNDO AND SORBARIA SORBIFOLIA

The aim of the work is to establish how greatly the light conditions change under the leaf canopy of two invasive plant species in the Middle Urals - Acer negundo and Sorbaria sorbifolia . In June - August 2020, using a portable light meter, 8370 measurements of illumination were performed in forest parks (at a height of 1.5 and 0.5 m, i.e. above and below the canopy of the leaves of the invasive shrub S. sorbifolia and the native shrub Rubus idaeus ; in random points under the canopies of Pinus sylvestris ; on glades, paths and forest edges) and in urban habitats (at a height of 1.5 m and 0.5 m in dense thickets of the invasive tree A. negundo and other tree species). The average illumination intensity was as following: under S. sorbifolia - 4 ± 1 lux × 10; under R. idaeus - 7 ± 1 lux × 10; in A. negundo thickets - 13 ± 2 lux × 10; in thickets of other tree species - 25 ± 4 lux × 10; under the canopies of urban pine forests - 80 ± 10 lux × 10; in the forest edges - 96 ± 14 lux × 10. In dense thickets, A. negundo intercepts about 94% of the light falling on its canopies, S. sorbifolia - about 93%. This is significantly higher than the light interception level in habitats used as control: other tree species canopies of greatly urbanized habitats intercept about 89%, the thickets of R. idaeus - about 82%. Thus, invasive plants reduce the amount of light available to other plant species in communities significantly more than native plants.

Assessment of adaptive capacity of native and adventive species of trees and shrubs in Dnipro region

Nowadays, deterioration and loss of ecological functions of urban tree and shrub plantations take place in Europe and, in particular, in Ukraine; it was noted that their number is insufficient to counteract the negative impact of global climate change and protect the population against industrial pollution effects. The issue of resistance of native and adventitious tree species used in the plantations of industrial cities remains relevant; it necessitates the assessment of physiological and biochemical aspects of their adaptation to extreme environmental factors, such as moisture limit in the steppe zone, periodic dangerously low winter temperatures and anthropo-technogenic load (in large urban agglomerations). In order to optimize the assortment of tree species of large megalopolises of the steppe zone of Ukraine and determine their potential resistance to anthropogenic pressures the study was conducted in conditionally clean forest biogeocenoses of the Samara River levee zone and in artificial plantations on the territories located in the coastal zone of the Dnipro River within 1500 m from the Prydneprovskaya thermal electric station (PTES, Dnipro city). It well known that the TPP is the source of atmospheric air pollution by such heavy metals as lead and cadmium. A study of the activity of antioxidant protection enzymes in leaves of native and adventive tree species showed that in the zone of Prydneprovskaya TES impact there was an increase of guaiacol peroxidase activity in Acer platanoides, Ulmus minor, Morus alba; benzidine peroxidase in Acer negundo, Ulmus laevis, Acer platanoides; catalase in A. platanoides, A. negundo, U. laevis, Ulmus pumila and Robinia pseudoasasia. High peroxidase activity, which is complemented by higher catalase activity, indicates the relative resistance of these species to atropo-technogenic pressures supported by antioxidant defense mechanisms. Total chlorophyll content (Chla + Chlb) in leaves of native species Ulmus laevis, Acer platanoides and adventive Morus alba decreased in the zone of TPP impact in relation to conditionally clean areas. The ratio of chlorophyll a to chlorophyll b in contaminated areas significantly increased in leaves of native species Ulmus laevis, Ulmus minor, Acer platanoides compared with control. The invasive species Acer negundo, Morus alba, Ulmus pumila had no significant changes in this indicator. In invasive species such as Ulmus pumila, Acer negundo there was an increase in leaf mass, which may indicate adaptation of these species to anthropogenically altered growth conditions.

Vitality structure of Acer negundo populations in an urban environment

The results of a comparative analysis of the vitality structure of Acer negundo populations during ontogenetic development in an urban environment are presented. The vitality structure of A. negundo populations is changing from prosperous to depressive, with the changing living condition of individuals and the quality of populations in urban conditions. The quality index of A negundo populations was in the amplitude from 0.5 to 0.166 along the urbanization gradient. High plasticity and variability of A negundo in combination with the dynamic vitality structure on the background of anthropogenic impacts provide active colonization of this invasive species in the city.

High canopy cover of invasive Acer negundo L. affects ground vegetation taxonomic richness

We assessed the link between canopy cover degree and ground vegetation taxonomic richness under alien ash-leaved maple (Acer negundo) and other (native or alien) tree species. We investigated urban and suburban forests in the large city of Yekaterinburg, Russia. Forests were evaluated on two spatial scales. Through an inter-habitat comparison we recorded canopy cover and plant taxonomic richness among 13 sample plots of 20 × 20 m where A. negundo dominated and 13 plots where other tree species dominated. In an intra-habitat comparison, we recorded canopy cover and ground vegetation taxonomic richness among 800 sample plots measuring 1 m2 in the extended urbanised forest, which featured abundant alien (308 plots) and native trees (492 plots). We observed decreased taxonomic richness among vascular ground plant species by 40% (inter-habitat) and 20% (intra-habitat) in areas dominated by A. negundo compared to areas dominated by native tree and shrub species. An abundance of A. negundo was accompanied by increased canopy cover. We found a negative relationship between canopy cover and the number of understory herbaceous species. Thus, the interception of light and the restriction of its amount for other species is a main factor supporting the negative influence of A. negundo on native plant communities.

First report of Fusarium lateritium causing shoots dieback of Acer negundo in Europe

Box elder (Acer negundo) is a tree native to North America. In Europe it is considered a dangerous invasive species, and assigned to the highest (4th) category of environmental hazard (Tokarska-Guzik et al. 2012). The tree can threaten a wide range of ecosystems and compete with the native flora. The shoot dieback was observed on 20% of boxelder in July 2018 and 2019 in Bryzgiel (N53°59.963' E23°04.324') in NE Poland (Europe). Young trees (10-15 yr. old) with visible symptoms were observed in a small group on the rural roadside. Infected shoots were chlorotic. There were visible shallow cracks on the bark and brown discoloration in sapwood inside infected branches. Symptomatic shoots were collected in sterile envelopes, surface disinfected with 95% ethanol. Twelve fragments of wood were cut from the border of living and dead tissue, and then divided into 3-5 mm pieces, placed on PDA medium and incubated at 21°C. After 10 days ten Fusarium spp. strains were obtained. Pure cultures were derived by monosporic isolation. The identification of the isolates was initially based on morphology and molecular genotyping (Leslie & Summerell 2006). On PDA, strains produced white, dense, floccose aerial mycelium with a pink surface. The underside of the petri dish was brown. Growth of the colony was relatively slow and reached Ø 3.5 cm after two weeks. Microscopic observation revealed the presence of macroconidia located in a few orange sporodochia. Macroconidia were slightly curved, with dimensions of 38-45 µm × 3.2-3,5 µm, 4-5 septate, with well-formed foot cell and beak on the apex. On aerial hyphae, single intercalary chlamydospores were present. Microconidia were not found. Morphological identification was confirmed by sequencing the ITS regions, the TEF-1α and β-tubulin genes for representative isolates. Mycelia were grown on PDB and freeze dried prior to genomic DNA extraction using the CTAB method. Sequences of two isolates were deposited in GenBank as MN186748 and MN588156 for ITS; MZ191070 and MZ191072 for TEF-1α; and MZ191069 and MZ191071 for TEF-1α. BLASTn search in the NCBI database revealed 100, 98 and >99% similarities of ITS, TEF-1α and β-tubulin with F. lateritium isolates LC171689, KT350607 and FN554618 respectively. A pathogenicity test was conducted on five first year Ø 0.6-0.8cm shoots from a 10-year-old tree. Before inoculation their surface was disinfected with 95% ethanol. Then, bark of the twigs was split longitudinally with a sterile blade and pieces of 10-day-old aerial mycelium grown on PDA were applied on the wound sites. Control samples were inoculated with sterile distilled water only. Inoculated areas were covered with parafilm. First sign of infection was observed after three weeks, as a dark lesion in the place of inoculation and chlorosis. Three weeks later the brown ring on the sapwood was marked in the shoot cross-section. Morphologically identical to the original, F. lateritium isolate was reisolated from the infected tissues, thus fulfilling Koch’s postulates. F. lateritium is a species closely associated with trees and shrubs (Leslie & Summerell 2006). However, it has not been recorded on boxelder and this is the first report of F. lateritium causing dieback of boxelder maple. According to the Enemy Release Hypothesis (Elton 1958), new pathogens appearing on alien species can be an indicator of developing environmental resistance to the outlander, which indicate the grade of their domestication. This kind of notification poses a crucial role in invasion monitoring and the search for new biocontrol methods of invasive plant species.

Phytocenotic characterization of forest communities with Acer negundo L. of the Kasmalin ribbon forest (Altai Krai)

The results of the primary geobotanical survey of pine and mixed forest communities with ash maple inthe Kasmalin ribbon forest are presented. As a result of anthropogenic impact Ash maple occurs throughout the Kasmalinribbon forest locally in the composition of pine, birch-pine and birch-aspen-pine communities.

Flavonoids quantification in Acer negundo L., extracts by hplc analysis

Objective: The identify and quantify, by high performance liquid chromatography,Nflavonoids from leaf and stem extracts of Acer negundo.Design/methodology/approach: Ethanolic extracts of Acer negundo were analysed with high performance liquid chromatography to quantify and identify their major antioxidant flavonoids.Results: Leaf extracts had high concentrations of rutin (34.19 µg/mL) and catechin (33.97 µg/mL), intermediate concentrations of apigenin (19.05 µg/mL), gallic acid (19.04 µg/mL), ferulic acid (17.2 µg/mL) and 2.5 dihydroxybenzoic acid (12.72 µg/mL), and low concentrations of caffeic acid (6.15 µg/mL), quercetin-3-β-glucoside (4.97 µg/mL) and isorhamnetin (4.68 µg/mL). In the stem´s extracts, the highest concentrations were of ferulic acid (7.96 µg/mL), rutin (5.61 µg/mL) and catechin (4.37 µg/mL); medium concentration were identified for isorhamnetin (3.31 µg/mL) and quercetin-3-β-glucoside (2.01 µg/mL) and apigenin (0.79 µg/mL) was identified at the low concentrations. Gallic acid, caffeic acid or 2,5-dihydroxybenzoic acid were not detected.Limitations/implications: Some flavonoids have been identified in other Acer species but have not been identified and quantified in Acer negundo, a Mexicanspecies.Findings/conclusions: For the first time we report gentisic acid in Acer negundo leaf extracts. This analytical method can be standardized to serve as a qualityanalysis of maple tree products.