The condition of green spaces in the central part of the city of Yekaterinburg

The article deals with the availability of public green spaces in the city of Ekaterinburg and itsCentral Planning District. We discuss the composition, condition of plants, and planting density in parks, garden squares and boulevards. We also discuss the negative phenomena affecting the general condition of green areas and their functions. We have analysed the main species used in landscaping and made suggestions for improving the situation.


Introduction
The city of Yekaterinburg is the administrative center of the Ural Federal District and the Sverdlovsk Region. This is a large industrial metropolis and at the same time the cultural capital of the Urals. In terms of the population size, it is one of the largest cities in Russia.
Yekaterinburg is a compact polycentric city; the boundaries of its administrative regions have developed historically. The growth of the city mostly occurred from the center to the periphery. The center of Yekaterinburg began to form in the late 18th -the first half of the 19th century. In the 19th century, the city's landscaping system was rapidly developing: the network of the first boulevards and garden squares organically fitted into the regular structure of the city center [1]. The main compositional axis of the city was adorned by a boulevard on the Main Avenue (now Lenin Avenue), and later (in the 20th century) the second compositional axis of the city was formed -the water-green diameter -the Iset River with recreation areas along it. These two axes are the basis of the green framework of the city.
The green framework of Yekaterinburg is formed by gardens, parks, garden squares and boulevards, and the main function of the "lungs of the city" is performed by forest parks located on the periphery [2]. In the framework of modern projects of intensive development and modern transformations of urban areas, the task of improving the comfort of the living environment should come to the fore [3]. The transformations associated with the reconstruction of old parks, garden squares and boulevards lead to significant, but not always positive, changes in the urban environment and in the appearance, structure and condition of landscape objects that have been formed over decades.

Methods and Materials
The article considers the public facilities of the Central Planning District (hereinafter referred to as CPD) of the city ofYekaterinburg: 6 parks, 11 garden squares and 1 boulevard. An inventory was carried out at all sites on the basis of the Regulations; the sanitary condition, the density of planting, and the type of spatial structure were studied. To determine the sanitary condition, a 6-point scale was  [4].The type of spatial structure (TSS) was determined by the classification of L M Fursova and V A Agaltsova as closed, half-open and open, with a canopy closeness from 0.6 to 1.0; 0.3 to 0.5 and less than 0.3, respectively [5,6].

Results and Discussion
The city of Yekaterinburg occupies an area of1,143 km 2 ; it is the administrative center of the Sverdlovsk region.It is divided into seven administrative districts(figure 1). The central part of the city is characterized by a high concentration of various types of socio-economic activities, is the historically established core of the city, and is located in several administrative districts. These are the most significant urban areas with a high building density and number of visits, both by residents and guests of the city. The General Development Plan until 2035 provides for the division of Yekaterinburg into 57 planning districts. The historically formed core of the city will be included in one planning area, Central. Its allocation, first of all, should affect the situation with the availability of public green spaces, since the population density of the area is 10312 people/km 2 , which is 8 times higher than that of the city as a whole [7]. In 2010, the average population density in the city was 2687.6 people/km 2 , but after the adjoining villages adjacent to the city, the figure dropped to 1297 people/km 2 .
In the CPD with a very high population density, significant measures should be taken to preserve, restore and create new green areas of common use. The area of green spaces per person in the city and in the CPD is nearly the same, and amounts to 5.2 and 5.3 m 2 , respectively, excluding street green areas. This indicator varies across the administrative districts, from 2.1 to 7.9 m 2 /person, which is clearly less than the recommended by SNIP 2.07.01-89* [8].And only in one district the indicator is more than 10 m 2 / person, which is due to the presence in this area of a large forest park, which includes a culture and recreation park. Figure 2 shows the location of parks, garden squares and boulevards within the boundaries of the CPD. The area of the public green spaces is 67 hectares, which is 5.4% of the total area of the District. The area per person is 5.3m 2 , which is not sufficient. There are six parks with a total area of 37 hectares, the sizes of which vary from 2.1 to 13.1 hectares. More than 20 hectares are occupied by FR 2020 IOP Conf. Series: Earth and Environmental Science 574 (2020) 012076 IOP Publishing doi:10.1088/1755-1315/574/1/012076 3 garden squares, but not all of them have official status, and therefore, it is likely that some of the objects will decrease in size or will be converted to other uses in the future.

Parks
The characteristics of the parks are presented in table 1. All of them are unique, varying in time of creation, concept, purpose, organization of park space, structure and plant composition. Their differences emphasize the once thought-out system of urban gardening, providing the population with objects with different types of recreation. At the same time, the parks are similar in terms of their popularity and high visitor numbers.
The Green Grove is the oldest park in the city. The main purpose is recreation, long rest, and partially transit. The park with the area of 13 hectares was created in a forest area, where Pinus sylvestris L. still prevails (43.11%). The range of plants is wide and includes 20 species of trees and 10  Kharitonovsky Garden, founded in 1826, is an object of historical heritage. It has a long history; the park is almost two centuries old. It has undergone several transformations: from a city park to a children's park, and finally to a park in a residential area. Now its former significance is gradually being restored. A reconstruction project has been developed. In the park, unlike in the Green Grove, the proportion of deciduous species in the tree composition significantly exceeds the proportion of conifers, 90.8% and 9.2% (155 pcs), respectively. In total, 43 species are present: 31 tree species and 12 shrubs. Among deciduous species, trees of the second canopy layer (Tilia cordata Mill and Acer negundo L., 42.2%) dominate, to a lesser extent threes of the first (Populus balsamifera L. and Betula pendula Roth., 26.6%) and the third (Malus baccata (L.) Borkh and Padus avium Mill., 23%) canopy layers are represented. Tilia cordata Mill and Populus balsamifera L. are in satisfactory condition (2.7 and 2.6 points), the condition of Malus baccata (L.) Borkh is much worse. This is due to the fact that the oldest specimens of large trees were selectively removed, but no attention was payed to smaller ones.
The Dendrological Park, with an area of 7 hectares, is a popular vacation spot for residents and visitors of the city. In addition to recreation, its main purpose is educational, i.e. to acquaint visitors with a collection of local and exotic species. Here you can see species such as Juglans manshurica   The remaining three parks are of district importance and smaller in area; they were created during the development of the districts and have varying degrees of development.
The In the Engels Park, 24 species have been recorded, including 18 trees and 6 shrubs. Among them were Populus balsamifera L., Betula pendula Roth., Fraxinus pennsylvanica Marsh., Tilia cordata Mill., Crataegus sanguinea L., etc. The sanitary condition of the stands was satisfactory and varied from 2 to 2.7. The park is being prepared for reconstruction.
According to table 2, the most abundant species have different proportions in different parks and their sanitary condition varies substantially. For example, Populus balsamifera L. in the park named after Pavlik Morozov has an average sanitary score of 4, in the Kharitonovsky garden, 2.6 points, and in the Engels park, 2 points. One of the most common species not only in parks, but also in street green areas is Malus baccata (L.) Borkh (from 8.5 to 24% of the composition of stands), which is most often in a weakened state (below 3 points). The worst condition is observed in Populus balsamifera L. after crown trimming and Fraxinus pennsylvanica Marsh. (4 points). The best condition was noted in Tilia cordata Mill, its average score was 2.7. In general, the average sanitary score of the prevailing species is below 3, which indicates a decrease in plant resistance and the need for constant care for them. So, for example, in the park named after Pavlik Morozov, after the reconstruction the sanitary score increased from 3.4-4.0 to 1.4-2.0 (table3) [9]. For the rest of the parks, reconstruction projects are ready or being developed.
The parks of the first half of the 20th century have a similar spatial structure (table 2). Closed spaces occupy 20-25%, and a proportion of semi-open and open spaces is high. For small regional parks in the Middle Urals, this is acceptable. The area of open spaces increases after the reconstruction of objects. This is clearly demonstrated by the change in the indicators of the park named after Pavlik Morozov. After reconstruction, open spaces increased to 40%, and the planting density decreased to 138 trees/ha, which is the lowest among the CPD parks.
In one of the oldest parks, the Green Grove, despite the ongoing efforts to remove dead and dangerous trees, the proportion of enclosed spaces is high (75%), and the stands are in need of reconstruction because of the large number of oppressed plants and thickened clumps of Acer negundo L.