Currently, one of the most pressing issues in the field of biology is the study of anthropogenic dynamics of vegetation cover, as well as the composition of the flora of anthropogenic vegetation cover. When studying the features of Genesis, the emergence of synanthropic flora that occurs under the influence of man, great importance is attached to the division of plant species that are distributed throughout the city, into groups. Cities are growing, and as a result, the impact of centers on the natural environment is increasing. On the one hand, there is indigenous, that is as a result of penetration by local species of flora in stenotopic Bank types, their interferences with metophyma plants, Degradation, degradation of the natural Association of plants. On the other hand, along with the disappearance of apophytes, there is a purposeful development of new species of adventurous plants. The vegetation cover of cities is considered an important factor in people’s lives.
Decorative properties of a particular plant species allow you to diversify a certain territory. Various types of ornamental plants, performing a specific role in the construction of the composition, can also significantly affect the state of environmental sustainability of the environment when placed rationally .
According to the results of our research, 7 plant species were recorded in the flora of the studied cities, and their quantity is 243 (total number pc.). This is 1/3 of the total number of plant species distributed in the city of Nukus. From this point of view, it can be seen that plant species that are common in urban areas are almost identical in their richness compared to plant species that are common in natural conditions and are not significantly poorer.
2. Materials and Methods
The Objects of research are tree plantations in Nukus (on the streets of Ernazar Alakuz). The objects of research were selected woody plants adults who entered fruiting (seeding in coniferous trees). The observations were carried out in 2017-2018 years. When selecting an assortment for gardening, it is necessary to assess the viability of the species, that is, its ability to adapt to adverse environmental conditions (frost, drought, lack of moisture and light, etc.). The phenological observation of I. N. Beydeman “Method of studying plant phenologies” , the assessment of the features of the landscape of N. I. Shtonda was made on the basis of the method.
3. Results and Discussion
When studying the growth of woody plants, shoots were selected first of all the most richly represented genera. Seven species of Fraxinus excelsior L., Fraxinus pensylvanica March., Salix alba L., Populus alba L., Juniperus communis L., Catalpa bignonioides Walt., Ulmus densa Litv. were studied for seasonal growth (Table 1).
The Cupressaceae family contains 2 genera. Of these, Juniperus L. genera are distributed in 5 species in Uzbekistan . In the city of Nukus (streets of Ernazar Alakoz) grows 1 species.
Table 1. Spectrum of families and genera of urban dendroflora.
Juniperus communis L. Shrub or tree up to 8 - 10 (15) m high. Very variable in crown shape and height, depending on the growing conditions. Dioecious. Male specimens have a narrower, conical or ovoid crown; female specimens have a more prostrate crown. The bark of the main trunk is gray-brown, the side shoots are reddish-brown.
Grows slowly, very hardy, tolerates shading. It is undemanding to the soil, growing both on poor stony and dry sandy soils, and on swampy ones. It does not tolerate salinity of the soil and dry winds. Durable. Propagation by seeds, cuttings.
It has a vast area of natural distribution, covering a large part of Europe, Asia and North America.
In the Botanical garden of Karakalpak branch of Academy of Sciences of Uzbekistan (Nukus) Juniperus communis introduced in 1965 one-two age seedlings from Botanical garden of Academy of Sciences of Uzbekistan (Tashkent). In the conditions of the Botanical garden does not suffer from high summer temperatures, frost-and heat-resistant, painlessly tolerates significant dryness of the air. At 8 - 9 years of life, common juniper first bloomed, but there were few seeds, maturing in late July or early August of the following year .
The Oleaceae family contains 5 genera. Of these, Fraxinus L. genera, 7 species are distributed in Uzbekistan . In the city of Nukus (streets of Ernazar Alakoz) grows 3 species.
Fraxinus excelsior L. Tree. Leaves with 9 - 13 leaflets. Leaves sessile or on short petioles, ovate-lanceolate or oblong-elliptic, pointed at the top, on the edge almost tselkraynye or round-toothed, on the edge of gnawed or toothed, dark-below light green, on both sides glabrous or below the middle vein hairy. The calyx and Corolla are missing. Fruit wing oblong or obovate-oblong, slightly notched at the top, 3 - 4. 5 cm long. General distribution Europe, Caucasus .
Fraxinus pennsylvanica Marsh. Tree. Leaves with 5 - 9 leaflets. Leaves are almost sessile, ovate-lanceolate or oblong-lanceolate, pointed at the top, almost tselkraynye or round-toothed on the edge, young hairy. Calyx bell-shaped. The fruit wing is oblong, rounded, sharp or notched.
The General distribution is North America . The family Salicaceae contains 2 genera, of which Salix L. genera are distributed 5 species in Uzbekistan . In the city of Nukus (streets of Ernazar Alakuz) grows 3 species.
Salix alba L. Tree, 10 - 15 m high. Branches are flexible, naked, young silvery-fluffy. The kidneys are elongated, reddish-yellow. Stalks with glands. The leaves are large, linear-lanceolate and lanceolate, pointed, often finely filiform, dark green above, with pressed hairs, glaucous below, with pressed longitudinal silvery hairs. Catkins develop simultaneously with the leaves, rather loose.
General distribution Eurasian part, Caucasus, Siberia, Western Europe, Mediterranean, Iran, India, China . The genus Populus L. contains 6 species, of which 3 are distributed in Nukus (streets of Ernazar Alakoz).
Populus alba L. Tree up to 15 - 20 m tall., spreading or pyramidal crown. Young branches are white-wooled. Buds are young felt, later often naked. Leaf petioles pubescence. The leaves of long shoots are triangular, 3 - 5 lobed, at first white-flake-like on the bottom, later lose pubescence. The leaves of short shoots are oval or round-ovate, with large rounded notches and blunt teeth along the edge.
General distribution Middle Asia, Europe part, North Caucasus, Western Siberia, Western Europe, Kashgaria . The family Bignoniaceae contains 1 genus , of which Catalpa Scop. the genus is distributed in 3 species in the city of Nukus (streets of Ernazar Alakuz).
Catalpa bignonioides Walt. Tree, 10 - 12 m high., leaf heart-shaped-ovate, suddenly pointed, pubescent from below, 12 - 24 cm long. and up to 20 cm wide., long-stemmed, up to 16 cm long. calyx two-sided, 0.8 cm long. The Corolla is white, 3 - 3.2 cm long, with two yellow stripes inside and reddish-brown spots.
General distribution in North America. Introduced to Western Europe in 1726, on the territory of the USSR since 1813 (Pilipenko, 1962). Decorative with large leaves and flowers .
The family Ulmaceae contains 2 genera, of which Ulmus L. genera are distributed 8 species in Uzbekistan . In the city of Nukus (streets of Ernazar Alakuz) grows 3 species.
Ulmus densa Litv. Tree up to 15 m tall, dense crown, spherical. Branches are pubescent. The leaves are ovate, just or twice large-toothed, glabrous or softly downy above, with hairs at the corners of the veins at the bottom. Leaf petioles 6 - 7 mm long, rarely pubescent. Flowers in bunches on very short legs. The perianth is ciliated along the edge. The wing is 2 cm long and 1.2 cm wide, with a recess at the top.
General distribution of Central Asia .
In this table we see that the genus Fraxinus L. is common in the city of Nukus (streets of Ernazar Alakoz). 2 species of category. F. excelsior L., F. pensylvanica March., their total number is 87 pc. (according to data for 2017-2018), as you know, Nukus (streets of Ernazar Alakuz) is one of the most common categories in the city and makes up 35.79% of the total number. One of the most common categories is Populus L. in the city of Nukus (streets of Ernazar Alakoz) there is 1 species of the category P. alba L. Its total population is 85 thousand individuals. Total-35%. J. communis L., U. densa Litv. this category of species is also widespread. Salix alba L., Catalpa bignonioides Walt. moreover, the species is not widespread, so the biological diversity of urban flora depends primarily on the diversity of biotopes in the urban area and the demand for various environmental conditions that cause them, on the anthropogenic-tolerant characteristics of plant species.
As a result of surveys conducted in 2017-2018 years of green spaces in the city of Nukus (streets of Ernazar Alakuz), it was found that they contain 7 species and forms of ornamental plants belonging to 5 families from various floral areas. The most diverse families are: Salicacaeae Lindl., Oleaceae Lindl., Cupressaceae F. M., Bignoniaceae, Ulmaceae Mirb. Relatively widely used 6 species of woody plants, the rest of the species are represented by a small number (single specimens).
Dendrology urban green spaces in the city of Nukus (streets of Ernazar Alakuz) according to their geographical origin are heterogeneous. According to the analysis, woody plants of the Central Asian flora predominate. Among the introduced plants, species from the European-Caucasian dendroflora predominate.
A comparative study of plant growth and development has shown that the adaptation of plants to drought and soil salinity, as well as to other adverse factors of the urban environment is manifested in the habits, growth suppression, reduction of plant height, changes in physiological and biochemical processes, etc.
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