The features of the distribution of the Siberian apricot (Prunus sibirica L.) in the southern (Mongolian) part of the Selenga river basin is discussed. It was found that there is a clear trend in the successional change of pine forests to shrubby vegetation represented by Siberian apricot communities. This trend is facilitated by the reduction in forest area after fires, felling, and grazing, which, in turn, leads to the change in the landscape and ecological conditions in forest ecotopes. In addition, the coenotic positions of Prunus sibirica are strengthened because of its physiological and biochemical adaptation to the pyrogenic factor, its consumption by livestock, and the variability of the functional parameters of the species.

Серебросодержащие нанокомпозиты синтезированы на основе гуминовых веществ — пелоидов экологически безопасным способом. В работе изучена ростостимулирующая активность супернизких концентраций гуминовых веществ лечебных грязей и серебросодержащих нанокомпозитов на их основе. Определен диапазон действующих концентраций (4·10–16–4·10–3 %) стимуляторов в процессе прорастания семян пшеницы. Наибольший эффект усиления роста главных корней — почти в два раза — у проростков наблюдается для нанокомпозита серебра на основе гуминовых веществ. Установленная активность нанокомпозитов является предпосылкой для разработки новых высокоэффективных ростостимулирующих препаратов.

Silver-containing nanocomposites are synthesized from humic peloid substances in an environmentally friendly way. The growth-stimulating activity of ultralow concentrations of humic substances of therapeutic muds and silver-containing compounds on their basis is studied. The stimulator active concentration range upon wheat seed generation is determined to be 4 × 10–3–4 × 10–16%. The fastest (almost double) growth of the main roots of sprouts is found to be for silver nanocomposites based on humic substances. The established activity of nanocomposites is a prerequisite for the development of novel highly efficient growth-stimulating drugs.

Leaf parameters, gas exchange parameters, photosynthetic pigments content, mesophyll structure, and sizes of shrubs were studied for Caragana bungei Ledeb. in contrasting habitats of the mountain slope—herb-grass-shrub steppe and larch forest. It was shown that the adaptation of photosynthetic apparatus of C. bungei to forest conditions does not lie in biochemical and primary photosynthetic processes but consists of quantitative changes in the leaf tissue-cellular structure. Steppe and forest individuals differed neither in photosynthetic capacity nor in kinetic parameters of photosynthesis. It is assumed that the development of Caragana’s leaves at high light in the spring larch forest leads to the formation of a strong photosynthetic apparatus as a preadaptation to fluctuating light under the forest canopy. At the same time, forest shrubs had thinner and less dense leaves due to the decreased size and number of mesophyll cells. The decrease in the structural complexity of the mesophyll was compensated for by enhancement of the photosynthetic capacity of cells and chloroplasts. The low rate of real photosynthesis under the forest canopy shadow was observed, but it was compensated by a high relative mass and area of the leaves. As a result there were no differences in shrub sizes between steppe and forest shrubs of Caragana. We concluded that photosynthesis adaptation at the levels of leaf mesophyll and of the ratio of photosynthetic organs allow this species to maintain growth and to gain an advantage in an open larch forest.

Судалгааг уринш-буудайн талбай болон лабораторийн нөхцөлд цагаан луулийг ургуулж гербицид хэрэглэхэд иш, навч, улайх, ягаарах зэрэг шинж тэмдэг илэрч түр зуур тайван байдалд орж дахин сэргэн ургаж гербицидийг тэсвэрлэж байлаа.Chenopodium album-ын хувьд гербицид хэрэглэснээр навч, ишний дотоод бүтцийн эс эдүүд эвдэрэлд орсон боловчхөгжлийн үе шат бүрэн явагдаж үр нь боловсорч байсан учир гербицидэд тэсвэрлэх байдлыг ургамлын ургал эрхтний дотоод бүтцийн судалгааг хийв.Судалгаанаас үзэхэд, сорьж туршсан гербицидийн хог ургамалд үзүүлэх нөлөөлөл сайн, хүрээлэн байгаа орчинд сөрөг нөлөөгүй болохыг лабораторийн болон хээрийн туршилтаар баталгаажуулан үйлдвэрлэлд нэвтрүүлэхэд чиглэнэ.

The studies of the steppe ecosystems in Central Mongolia have showed that the simplification of steppe communities has taken place over recent decades. This occurred by reduction of species diversity and abundance of indigenous dominants—tussock grasses—as a result of sharp rise in pasture loads and a long dry period. We have identified two types of introduction of invasive species from different landscapes: (a) extraand intrazonal and (b) zonal. The first type of succession is characterized by focal distribution of Ephedra sinica from ecosystems of low mountains to the surrounding mountain plains. The second type of succession in dry steppes is associated with the expansion of Allium polyrrhizum, whose distribution has largely a frontal character and is caused by weakening of the competitiveness of indigenous species of grass communities because of their significant digression. A further factor in ensuring the conditions for invasion is the aeolian alkalization of the upper horizons of zonal chestnut soils. The ecological and biological features of these two species, widespread in the desert-steppe and desert landscapes and penetrating into the steppe ecosystems, make it possible to speak about biological desertification. The wide area of Ephedra sinica and Allium polyrrhizum indicates a progressive character of the studied types of succession, and as a result of this, the borders of these areas have reached at present the southern periphery of the Baikal Lake basin. The paper describes the processes which lead to the reduction of the fodder value of pastures and jeopardize the maintenance of cattle breeding in Central Mongolia.

The article describes the regional features of ecosystem desertification in the southern periphery of the Baikal basin that are located in the zone of cross-border interaction between the southern Siberian and the Central Asian internal drainage basin landscapes. The nature of such interactions is identified as invasive, which is associated with the penetration of desert-steppe plant species: Caragana bungei are found in larch forests, and Allium polyrrhizum are found in dry steppes. A high degree of species adaptation to the modern arid climate is defined by ecological and physiological analysis of these species characteristics. The significant predominance of Caragana bungei and Allium polyrrhizum in the current structure of plant communities makes it possible to identify a long-term and widespread invasive succession and to characterize this process as a specific desertification form.

Артишок (Cynara scolymus L.)-ын ургал эрхтний дотоод бүтцийн онцлогийг тодорхойлон, эмийн түүхий эдийн стандарт бэлтгэх эх материал бүрдүүлэхийн тулд тухайн зүйлийн ургал болон үржлийн эрхтний дотоод бүтцийг ургамлын анатомийн уламжлалт арга зүйн дагуу судалгааг явууллаа. Cynara scolymus L. -ийн навч дорзовентераль хэлбэрийн бүтэцтэй. Эпидермийн эсийн хана тэгш өнцөг үүсгэж, нэг ба олон эст үсэнцрүүд, аномоцит хэлбэрийн амсруудыг навчны дээд, доод гадаргууд агуулдаг, коллатераль хэлбэрийн дамжуулах багцны дээд талд хүчтэй хөгжил бүхий склеренхимтэй; навчны бариул хөндлөн огтлолоороо гурван өнцөгтэй (9-р зураг). Гадна талаараа нэг эгнээгээр байрласан эпидерм, түүний дотор талаар нэг эгнээгээр байрласан гиподермийн давхраа, паренхимийн эсүүдтэй, ишний дамжуулах багцны харалдаа дээд ба доод талд хүчтэй хөгжил бүхий склеренхимтэй зэрэг шинжээрээ ялгагдах онцлогтой болохыг илрүүллээ.DOI: http://dx.doi.org/10.5564/mjas.v10i1.335

The structural and functional parameters and productive characteristics of ten species of Mongolian forest steppe shrubs were studied. The shrubs had 5- to 10-fold difference in size and aboveground biomass and 1.5- to 2-fold difference in leaf parameters. The emphasis was placed on two groups of structural and functional parameters related to the ecological characteristics of the shrubs. The first group, i.e., shrub height and diameter, leaf area ratio, leaf thickness and volumetric density, and water ratio, characterizes the competitive ability of the species. The second group, i.e., leaf area, transpiration rate, and water use efficiency, is related to tolerance to arid stress.

Исследовали морфологию и структуру фотосинтетических органов, дневные изменения фотосинтеза и транспирации, а также эффективность использования воды у трех видов горно-степных экосистем Монголии Ephedra sinica Stapf, Stipa glareosa P. Smirn. и Allium polyrhisum Furcz. ex Regel. Исследованные виды имели разные структурно-функциональные механизмы адаптации фотосинтетического аппарата к аридным условиям. У E. sinica - толстые, вертикально ориентированные ассимилирующие побеги с высокой плотностью (620 мг/см 3) и небольшой долей фотосинтетических тканей (13%). Доля мезофилла в листьях A. polyrhizum и S. glareosa была соответственно в 2 и 3 раза выше. Низкое содержание фототрофных тканей в побеге у E. sinica компенсировалось высокой фотосинтетической активностью единичного хлоропласта (25 мг СО 2/(10 9 хлп ч)), которая была в 6 раз выше, чем у двух других видов. Дневной ход фотосинтеза и транспирации E. sinica отличался от таковых A. polyrhizum и S. glareosa отсутствием полуденной депрессии. Эффективность использования воды у E. sinica была максимальна (45 мг СО 2/г Н 2О) вследствие низкой интенсивности транспирации (0.25 г/г сырого веса ч). Сделан вывод, что основной “стратегией” адаптации к аридному стрессу у E. sinica является развитие относительно небольшого количества фотосинтезирующих клеток в побеге с повышенной ассимиляционной активностью. Такая структурная организация фотосинтетических органов эфедры способствует повышению эффективности использования воды и стабилизации физиологических параметров при смене экологических условий. Выявленные специфические черты структуры ассимилирующих органов и их функциональные особенности способствуют экспансии E. sinica при аридизации климата Монголии.

Morphological and structural characteristics of photosynthetic organs, diurnal changes in photosynthetic and transpiration rates, and the efficiency of water use were studied in three plant species from mountain-steppe ecosystems in Mongolia, Ephedra sinica Stapf, Stipa glareosa P. Smirn., and Allium polyrhizum Furcz. ex Regel. The species studied differed in the structural and functional mechanisms for the adaptation of photosynthetic apparatus to arid conditions. E. sinica has thick, vertical assimilating shoots, which are characterized by a high density (620 mg/cm3) and a small proportion of photosynthetic tissues (13%). The proportion of meso-phyll in the leaves of A. polyrhizum and S. glareosa was two and three times higher, respectively. The low content of phototrophic tissues in E. sinica shoot was compensated for by a high photosynthetic activity of single chloroplasts (25 mg CO2/(109 chloroplast h)), which was six times higher, than in two other species. Daily course of photosynthesis and transpiration inE. sinica differed from those of A. polyrhizum and S. glareosa by the absence of the midday depression. E. sinica had the highest efficiency of water use (45 mg CO2/g H2O) due to a low transpiration rate (0.25 g/g fr wt h). It is concluded that, in E. sinica, the main strategy for adaptation to arid stress is to develop in the shoot a few photosynthesizing cells of high assimilation activity. Such structural organization of photosynthetic organs in ephedra contributes to its higher efficiency of water use and stability of physiological characteristics under changing environmental conditions. These specific features of the structure of assimilating organs and their functional features contribute to a greater expansion of E. sinica with increasing climate aridization in Mongolia.