Growth and State of Mixed Stands of Forest Plantations of the Kamennaya Steppe

By now, a vast amount of experimental material has been accumulated in the field of protective afforestation of the Central Chernozem Region of Russia, which allows estimating the stability and longevity of various trees and shrubs in different environmental conditions. Good growth and high vitality of woody vegetation largely depend on growing conditions and are determined primarily by the relationship between species (individuals within a species) when they are placed in the forest area and the type of terrain. The researchdifferent combinations in tree and shrub mixing schemes and unequal location by types of terrain. The study was carried out in mature (115–118-year-old) forest strips laid out by the staff of the Kamennaya Steppe experimental forestry G.F. Morozov and N.A. Mikhailov on the territory of the Kamennaya Steppe (Voronezh region, Talovsky district) using archival materials, scientific works of the authors of this article and the employees of the Department of Agroforestry. A comparative analysis of the materials of forest survey work carried out in protective forest plantations created according to the tree-shrub type of mixing on different types of terrain revealed an excess of biometric indicators of tree species growing on the upland type of terrain over those on the slope. It is shown that the initial percentage of participation of English oak is a significant, but not always decisive factor in the creation of oak plantations. They can also be grown with a smaller proportion of this species in the culture, but in this case, timely thinning will be of paramount importance. Over time, there have been significant changes in the composition of plantations, the number of trees and their valuation indicators. There are no viable ash and elm specimens left in the upper tier of the stands. They are severely damaged by stem pests. Certain tree species are damaged by the following pests: common ash by large ash bark beetle (Hylesinus crenatus) and ash bark beetle (Hylesinus fraxini); elm species by cambium-feeding beetles (large elm bark beetle (Scolytus scolytus), European elm bark beetle (Scolytus multistriatus), and pygmy elm bark beetle (Scolytus pygmaeus); English oak by gold pit oak splendour beetle (Chrysobothris affinis), oak borer (Agrilus angustulus), longhorn beetle (Plagionotus detritus), and European oak bark beetle (Scolytus intricatus). The predominant number of trees of all tree species belongs to the categories of limited viable and inviable.

Bursaphelenchus michalskii sp. n. (Nematoda: Aphelenchoididae), a nematode associate of the large elm bark beetle, Scolytus scolytus Fabr. (Coleoptera: Curculionidae), in Dutch elm disease-affected elm, Ulmus laevis Pall.

Summary Bursaphelenchus michalskii sp. n. is described from the bark of the European white elm, Ulmus laevis. All propagative stages of the nematode were found in larval galleries of the large elm bark beetle, Scolytus scolytus, and in overlapping gallery systems of this species and the small European elm bark beetle, S. multistriatus. Dauer juveniles of the new nematode are transmitted to new breeding trees under elytra of adult S. scolytus. Bursaphelenchus michalskii sp. n. is characterised by the female body length of 953 (838-1108) μm and male body length of 893 (811-971) μm, very slender body (a = 53.9 (46.1-58.5) and 60.9 (52.2-72.0) in female and male, respectively), lateral fields with three incisures (two bands), excretory pore usually located anterior to the median bulb, lack of vulval flap, long post-uterine sac, relatively small spicules 12.3 (10.8-13.3) μm long with no cucullus and with distinct, somewhat thorn-like, dorsally bent or reflexed condylus and a conical or digitate rostrum, and the arrangement of the seven male caudal papillae (i.e., a single precloacal ventromedian papilla (P1), one pair of adcloacal ventrosublateral papillae (P2) at or just anterior to cloacal slit, one ventrosublateral, postcloacal pair (P3) located at ca 60% of the tail length, posterior to cloacal slit, and one pair (P4) of ventrosublateral papillae located near the base of the bursa). The newly described species shares most of the key morphological characters with members of the eremus-group (sensu Braasch et al., 2009). However, B. michalskii sp. n. is unique amongst Bursaphelenchus species by a combination of female tail and spicule shape, excretory pore position, and other morphometric characters. These findings were confirmed by DNA sequencing and phylogenetic analysis of the 18S and 28S rDNA regions and by the unique molecular profile of the ITS region (ITS-RFLP).

The change in the structure of hydrogen bonds in elm wood due to damage by European elm bark beetle Scolytus multistriatus (Marsham) (Coleoptera: Curculionidae, Scolytinae)

Водородная связь (Н-связь) обеспечивает необходимую гибкость и устойчивость биологических систем, в том числе древесины. Для исследования энергии и концентрации Н-связей в древесине возможно применение ИК-спектроскопии. В этом случае судить о природе гидроксильных групп можно опираясь на величины длин и энергий Н-связей, известных для водородных связей в целлюлозе, лигнине и других компонентах древесины, которые были исследованы ранее [Иванов-Омский и др., 2017; Иванова и др., 2016]. Особенный интерес представляет решение задачи об изменении прочности и иных свойств древесины при отмирании дерева в случае повреждения биологическими агентами. В данном исследовании поставлена задача – исследовать влияние повреждений короедов на структуру водородных связей древесины. Объектом исследования выбран вяз Ulmusglabra Huds, заселённый струйчатым заболонником. Этот короед является вектором распространения голландской болезни ильмовых в Санкт-Петербурге. Срезы для спектрального анализа взяты с поверхности заболони вяза, заселённого короедом. Полученные результаты показали, что на повреждённых заболонником участках происходит разрушение наиболее сильной межмолекулярной связи, обеспечивающей соединение молекул целлюлозы и, соответственно, прочность ствола. Увеличивается и концентрация внутримолекулярных связей, что может означать принципиальные изменения в водном обмене клеток древесины, связанные с разрушением аквапоринов. Это явление может быть связано с ответной реакцией вяза на нарушение движения растворов по сосудам при механическом разрушении древесины во время питания короедов и/или попаданием ферментов их слюнных желёз, амилазы или других карбогидраз. Не исключено попадание в древесину и других ферментов, например продуцируемых симбионтами короедов. Hydrogen bond (H-bond) provides the necessary flexibility and stability of biological systems, including wood. It is possible to use Infrared spectroscopy to study the energy and concentration of H-bonds in wood. In this case, it is possible to assess the nature of the hydroxyl groups based on the lengths and energies of H-bonds, known for hydrogen bonds in cellulose, lignin and other wood components, which had been studied earlier [Ivanov-Omskiy et al., 2017; Ivanova et al., 2016]. Of special interest is the solution of the problem of changing the strength and other properties of wood when the tree dies in case of damage by biological agents. In this paper, the task was to study the effect of damage by bark beetles on the structure of hydrogen bonds of wood. The object of research was elm Ulmus glabra Huds infested by the European elm bark beetle Scolytus multistriatus. This bark beetle is the vector of Dutch elm disease in St. Petersburg. Sections for spectral analysis are taken from the surface of the elm sapwood inhabited by bark beetle. The obtained results showed that on the sites damaged by the sapwood, the strongest intermolecular bond (which binds the cellulose molecules together and ensures the strength of the trunk) breaks down. The concentration of intramolecular bonds also increases. This means a fundamental change in the water metabolism of wood cells, associated with the destruction of aquaporins. This phenomenon may be related to the response of the elm to the violation of the movement of solutions through vessels during mechanical destruction of wood during the feeding of bark beetles and/or the ingestion of enzymes from their salivary glands, amylase or other carbohydrases. It is also possible that other enzymes (such as those produced by the beetles’ symbionts) come into contact with wood.